HK40005297B - Dormant mode measurement optimization - Google Patents

Description

Sleep mode measurement optimization

Technical Field

The present disclosure relates generally to performing measurements for radio resource management, and more particularly, to methods and apparatus for performing measurements in sleep mode.

Background Art

In any cellular system, it is very important that battery-powered mobile nodes (hereinafter referred to as "user equipment" or "UE") can spend most of their time in a low-activity state to conserve energy. Typically, a cellular system will have one or more defined "active" modes, in which the UE is controlled by the network and instructed to connect to a certain cell, make certain measurements, etc. The system will also typically have one or more "idle" or "sleeping" modes, in which the UE typically only listens for certain signals from the network and decides for itself which cell or cells to listen to and when to report back status updates.

Most UEs in most cellular systems today spend most of their time in sleep mode, so it is of utmost importance that the UE consumes as little power as possible in sleep mode.

In cellular systems such as the 5th Generation Radio Access Network (RAN) currently being defined by the 3rd Generation Partnership (3GPP), often referred to as "New Radio" or "NR," beamforming can be used for the transmission of cell information signals. "Beamforming" here refers to the (usually) highly directional transmission of signal energy for a given signal or set of signals, e.g., with a 3dB beamwidth of less than (usually significantly less than) 90 degrees in the horizontal plane for downlink transmissions. While conventional transmissions are shaped to some extent, e.g., to avoid sending too much energy in the vertical direction and/or to direct most of the signal energy to a particular cell sector, the beamformed transmissions discussed herein are intended to be shaped to a greater extent, so that, for example, any given downlink beam only provides useful signal strength within a small portion of the area typically served by the transmitting node. Thus, to serve the entire area, the transmitting node may use multiple (possibly very many) beams, which may be time-multiplexed, frequency-multiplexed, or both.

Cell information signals or broadcast signals (e.g., so-called mobility reference symbols) can be beamformed instead of being transmitted over the entire cell for several reasons. One reason is to increase the effective antenna gain of the transmitter, for example, to compensate for higher path loss in high-frequency bands or to achieve extended coverage for legacy frequencies. Another reason is to obtain a coarse spatial positioning of the UE based on the directionality of the beam.

Typically, the beamformed cell information signals will be time multiplexed between the beams so that high output power can be used for each beam.

Summary of the Invention

With beamformed cell information signals, there is a multiplication factor introduced with respect to the number of signals that a UE in sleep mode must search and measure. In traditional systems where cell information is not beamformed, there is typically one signal to measure per "cell" - for the same type of "cell" (where cell information is beamformed), there may be dozens of signals or beams (e.g., beams carrying mobility reference signals) that need to be searched. This can increase the power consumption of a UE in sleep mode, especially when the signals are time-multiplexed, because searching such beams requires the UE receiver to remain on for a long duration.

Embodiments disclosed herein to address these issues include a method performed by a UE or other wireless device operating in a sleep mode, wherein operating in the sleep mode includes intermittently activating receiver circuitry to monitor and/or measure signals. The method includes, while the wireless device is in the sleep mode and the receiver circuitry is activated, performing measurements on each of a plurality of resources from a predetermined resource set, or demodulating and decoding information from each of the plurality of resources from the predetermined resource set, wherein the resources in the predetermined resource set are each defined by one or more of a beam, timing, and frequency. In some embodiments, the resources in the predetermined resource set are each defined as a beam. The method also includes evaluating the measurements or demodulated and decoded information for each of the plurality of resources against predetermined criteria, and then, in response to determining that the predetermined criteria are met, discontinuing the performance and evaluation of the measurements, or discontinuing the demodulation, decoding, and evaluation of the information, such that neither measurements nor demodulation and decoding are performed on one or more resources in the predetermined resource set. The method also includes deactivating the activated receiver circuitry, further in response to determining that the predetermined criteria are met.

In some embodiments, the predetermined criteria include one or more of: a received power level or a measured signal-to-interference-plus-noise ratio (SINR) or signal-to-noise ratio (SNR) above a predetermined threshold for one or a predetermined number of resources; being able to correctly decode cell information from one or a predetermined number of resources; and decoded information from one or a predetermined number of resources indicating a change in operation of the wireless device.

In some embodiments, the interruption is performed in response to determining that a predetermined criterion for one of the resources is met. In some embodiments, the method further comprises: prior to said executing or demodulating and decoding, and prior to said evaluating, interrupting and deactivating, determining a priority order (from highest to lowest) of the predetermined set of resources, wherein said executing or demodulating and decoding is performed according to the priority order (from highest to lowest). Determining the priority order of the predetermined set of resources may be based on any one or more of the following, for example: radio resource timing of one or more resources; and measured signal quality or measurement attributes from previous measurements for one or more resources. In some embodiments, determining the priority order of the predetermined set of resources is based on information about the likelihood that one or more resources are useful, which information is received from other sources or a cell neighbor list.

Other embodiments disclosed herein include wireless devices adapted to perform methods according to any of the above outlines, as well as corresponding computer program products and computer-readable media.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 shows the high-level logical architecture of NR and LTE.

Figure 2 shows the NR and LTE logical architectures.

Figure 3 shows the LTE/NR UE states.

4 includes a block diagram of a filtering/windowing orthogonal frequency division multiplexing (OFDM) process and illustrates the mapping of subcarriers to the time-frequency plane.

FIG5 illustrates windowing of OFDM symbols.

FIG6 shows basic subframe types.

FIG7 shows an example structure of a mobility and access reference signal (MRS).

FIG8 shows a tracking area configuration.

FIG9 is a signal flow diagram illustrating a Tracking RAN Area (TRA) update procedure.

Figure 10 shows options for beam shaping.

FIG11 is a signaling flow diagram illustrating an active mode mobility procedure.

FIG12 is a signaling flow diagram illustrating beam selection based on uplink measurements.

FIG13 is a signaling flow diagram illustrating intra-node beam selection based on uplink measurements.

14 is a process flow diagram illustrating an example method in a wireless device.

15 is a process flow diagram illustrating another example method in a wireless device.

16 is a process flow diagram illustrating yet another example method in a wireless device.

17 is a block diagram illustrating an example wireless device.

18 is a block diagram illustrating example radio network equipment.

19 is another block diagram illustrating an example wireless device.

DETAILED DESCRIPTION

As described above, beamforming of cell information signals creates a potential problem for power consumption of wireless devices or UEs operating in sleep mode. In conventional systems where cell information is not beamformed, there is typically one signal to measure for each "cell," where a "cell" refers to the geographic area covered by the signal transmitted by a cellular network access point. For the same type of "cell" (where cell information is beamformed), there may be dozens of signals or beams (e.g., beams carrying mobility reference signals) that need to be searched. This can increase power consumption of UEs in sleep mode, especially when the signals are time-multiplexed, because searching for such beams requires the UE receiver to remain on for a long duration.

The techniques and apparatus described herein address these problems by reducing or limiting power consumption in sleep mode in cellular systems that use beamformed cell information signals (e.g., in systems such as 3GPP's NR systems). The techniques and apparatus described herein achieve this by limiting the measurement and cell search sequences in the UE based on the signal quality of the beamformed cell information signals that have been measured. For each measurement instance, the UE can focus its search on a previously known strong signal and simultaneously search for new cells on that carrier. If the previously known strong signal is verified to be strong enough, the measurement sequence can be stopped so that the UE does not need to search for every possible cell information signal. Similarly, if one or a predetermined number of cell information signals are received and determined to be strong enough, the measurement sequence can be stopped again so that the UE does not search for every cell information signal in the predetermined set of signals for which the search has been performed.

An advantage of several embodiments described herein is that the measurement duration of a UE in sleep mode can be significantly reduced in those environments where the UE can quickly determine that it has "good enough" signal quality for one or more cell information signals, where "good enough" means that the signal quality meets one or more predetermined criteria.

Details of these techniques and apparatus are provided below, including detailed descriptions of several specific embodiments. However, first, descriptions of several concepts, system/network architectures, and detailed designs of several aspects of wireless communication networks for the requirements and use cases of fifth generation networks (referred to as "5G") are presented to provide context for the subsequent disclosure of sleep mode operation. However, it should be understood that an actual 5G network may include none, some, or all of the detailed features described below. It should also be understood that the techniques and apparatus described herein for performing measurements in sleep mode are not limited to so-called 5G networks, but may be used and/or adapted for use with other wireless networks.

In the subsequent discussion, the wireless communication network including wireless devices, radio access network and core network is referred to as "NR". It should be understood that the term "NR" is used herein only as a label for convenience. Of course, implementations of wireless devices, radio network devices, network nodes and networks that include some or all of the features detailed herein may be referred to by any of a variety of names. For example, in the development of future 5G specifications, other terminology may be used - it should be understood that some or all of the features described herein may be directly applicable to those specifications. Similarly, although the various techniques and features described herein are directed to a "5G" wireless communication network, specific implementations of wireless devices, radio network devices, network nodes and networks that include some or all of the features detailed herein may or may not be represented by the term "5G".

NR targets new use cases, such as factory automation and extreme mobile broadband (MBB), and can be deployed in a variety of frequency bands, requiring a high degree of flexibility. Licensed spectrum remains the primary component of NR radio access, but unlicensed spectrum (both standalone and license-assisted) and various forms of shared spectrum (e.g., the 3.5 GHz band in the United States) are inherently supported. A wide range of frequency bands are supported, from below 1 GHz to nearly 100 GHz. Ensuring that NR can be deployed in a variety of frequency bands is a key consideration, with some targeting lower-frequency regions below 6 GHz for coverage, others offering balanced coverage, outdoor-to-indoor penetration, and wide bandwidths up to 30 GHz. Finally, some bands above 30 GHz will address wide-bandwidth use cases but may be at a disadvantage in terms of coverage and deployment complexity. Both FDD, where the scheduler dynamically assigns transmission directions, and dynamic TDD are part of NR. However, it should be understood that most practical NR deployments are likely to be in unpaired spectrum, necessitating the importance of TDD.

The minimalist design (where transmissions are self-contained and reference signals are sent along with the data) minimizes signal broadcast. Terminals make no assumptions about the contents of subframes unless the scheduling terminal does. The result is a significant improvement in energy efficiency, as signaling not directly related to user data is minimized.

Supports standalone deployment as well as tight interworking with LTE. This interworking is expected for a consistent user experience with NR when used in higher frequency ranges or in initial NR rollouts with limited coverage. The Radio Access Network (RAN) architecture can handle a mix of NR-only, LTE-only, or dual-standard base stations. eNBs (“evolved Node B,” a 3GPP term for base stations) are connected to each other via new interfaces that are expected to be standardized. It is envisioned that these new interfaces will be an evolution of the existing S1 and X2 interfaces to support features such as network slicing, on-demand activation of signals, user plane/control plane split in the Core Network (CN), and support for new connection dormancy states, as described herein. As described below, LTE-NR base stations can share at least integrated higher radio interface protocol layers, such as the Packet Data Convergence Protocol (PDCP) and Radio Resource Control (RRC) layers, as well as a common connection to the Evolved Packet Core (EPC).

NR separates dedicated data transmission from system access functions. The latter include system information distribution, connection establishment, and paging. Broadcasting of system information is minimized and not necessarily transmitted from all nodes handling user plane data. This separation facilitates beamforming, energy efficiency, and support for new deployment solutions. Specifically, this design principle allows densification to increase user plane capacity without increasing signaling overhead.

A symmetric design that achieves OFDM in both the downlink and uplink directions is described in detail below. To handle a variety of carrier frequencies and deployments, a scalable numerology can be used. For example, local area high frequency nodes use larger subcarrier spacing and shorter cyclic prefixes than wide area low frequency nodes. To support very low latency, short subframes with fast ACK/NACK (acknowledgement/negative acknowledgement) are proposed, with the possibility of subframe aggregation for less latency critical services. In addition, contention based access is part of NR to facilitate fast UE initiated access. New coding schemes such as polar codes or various forms of low density parity check (LDPC) codes can be used instead of turbo codes to facilitate fast decoding of high data rates with reasonable chip area. Long discontinuous reception (DRX) cycles and a new UE state - RRC sleep (in which the UE RAN context is maintained) allow for a fast transition to active mode with reduced control signaling.

Unleashing the full potential of multi-antenna technology is the most important part of NR design. Supporting hybrid beamforming and leveraging the advantages of digital beamforming. User-specific beamforming through self-contained transmission is beneficial for coverage, especially at high frequencies. For the same reason, UE transmit (TX) beamforming is proposed as a beneficial component, at least for high frequency bands. The number of antenna elements can vary from a relatively small number of antenna elements in LTE-like deployments (e.g., 2 to 8) to hundreds, where a large number of active or individually steerable antenna elements are used for beamforming, single-user MIMO and/or multi-user MIMO to fully exploit the potential of massive MIMO. Reference signal and medium access control (MAC) characteristics are designed to allow the use of reciprocity-based schemes. By sending the same data from multiple points, multi-point connectivity (where a terminal is simultaneously connected to two or more transmission points) can be used to provide diversity/robustness.

NR includes a beam-based mobility concept to efficiently support high-gain beamforming. This concept is transparent to both inter-eNB and intra-eNB beam switching. When the link beam is relatively narrow, the mobility beam should track the UE with high accuracy to maintain a good user experience and avoid link failures. When mobility measurements from the UE are required, the mobility concept adheres to minimalist design principles by defining a network-configurable downlink mobility reference signal set that can be sent on demand. Mobility based on uplink measurements can also be used where reciprocity is supported by the appropriate base stations.

5G mobile broadband (MBB) services will require a range of different bandwidths. At the low end of the scale, support for large-scale machine connectivity with relatively low bandwidth will be driven by total energy consumption at the user device. Conversely, high-capacity scenarios (e.g., 4K video and future media) may require very wide bandwidths. The NR air interface focuses on high-bandwidth services and is designed around the availability of large, preferably contiguous, spectrum allocations.

The high-level requirements addressed by the NR system described in this paper include one or more of the following:

1) Support for higher frequency bands with wider carrier bandwidth and higher peak rate. Note that this requirement motivates new numerologies as described below.

2) Supporting lower latency requires shorter and more flexible transmission time intervals (TTIs), new channel structures, etc.

3) Support for very dense deployments, energy-efficient deployments, and extensive use of beamforming, for example by removing traditional limitations associated with cell-specific reference signals (CRS), physical downlink control channels (PDCCH), etc.

4) Support for new use cases, services, and customers, such as machine-type communication (MTC) scenarios, including so-called vehicle-to-everything (V2X) scenarios, etc. This can include more flexible spectrum usage, support for very low latency, higher peak rates, etc.

The following is a description of the NR architecture, followed by a description of the radio interface of NR. This is followed by a description of the various technologies and features supported by the NR architecture and radio interface. It should be understood that while the following detailed description provides a comprehensive discussion of many aspects of wireless communication systems, in which many advantages are obtained by combining many of the described features and technologies, it is not necessary to include all of the technologies and features described herein in a system in order for the system to benefit from the disclosed technologies and features. For example, while details are provided on how NR is tightly integrated with LTE, a standalone version of NR is also possible. More generally, unless a given feature is specifically described herein as dependent on another feature, any combination of the many technologies and features described herein may be beneficial.

The NR architecture supports standalone deployments and deployments that can be integrated with LTE, or potentially with any other communication technology. In the following discussion, much of the context is about LTE integration. However, it should be noted that similar architectural assumptions apply to NR standalone deployments or integration with other technologies.

Figure 1 shows the high-level logical architecture of an example system that supports both NR and LTE. The logical architecture includes both NR-only and LTE-only eNBs, as well as eNBs that support both NR and LTE. In the system shown, the eNBs are connected to each other via dedicated eNB-to-eNB interfaces (referred to herein as X2* interfaces) and to the core network via dedicated eNB-to-CN interfaces (referred to herein as S1* interfaces). Of course, the names of these interfaces may vary. As shown, the core network/radio access network (CN/RAN) split is clear, as is the case with the evolved packet subsystem (EPS).

The S1* and X2* interfaces may be an evolution of the existing S1 and X2 interfaces to facilitate the integration of NR with LTE. These interfaces may be enhanced to support multi-radio access technology (RAT) features for NR and LTE dual connectivity (DC), potential new services (IoT or other 5G services), and features such as network slicing (where, for example, different slicing and CN functionality may require different CN designs), on-demand activation of mobility reference signals, new multi-connectivity solutions, potential new user plane/control plane splits in the CN, implementation of new connection dormancy states, etc.

Figure 2 shows the same logical architecture as Figure 1 , but now also includes an example of an internal eNB architecture, including possible protocol partitioning and mapping to different sites.

The following are the characteristics of the architecture discussed in this article:

- LTE and NR can share at least the integrated higher radio interface protocol layers (PDCP and RRC) and a common S1* connection to the packet core (EPC).

o For 5G-capable UEs, the use of LTE or NR can be transparent to the EPC (if desired).

- The RAN/CN functional division on S1* is based on the current division used on S1. However, please note that this does not preclude S1* from being enhanced compared to S1, for example, to support new features such as network slicing.

-5G network architecture supports flexible placement (deployment) of CN (EPC) functions for each user/flow/network slice.

- Support for centralization of PDCP/RRC. The interface between PDCP/RRC and lower layer entities does not need to be standardized (although it can be), but can be proprietary (vendor specific).

o The radio interface is designed to support architectural flexibility (allowing multiple possible functional deployments, e.g. centralized/distributed).

o The architecture also supports fully distributed PDCP/RRC (such as current LTE).

- To support NR/LTE dual connectivity with centralized PDCP and RRC, NR supports splitting somewhere between the RRC/PDCP layer and the physical layer (e.g., at the PDCP layer). Flow control can be implemented over X2*, supporting splitting of PDCP and radio link control (RLC) in different nodes.

-PDCP is divided into PDCP-C part and PDCP-U part. The PDCP-C part is used for signaling radio bearers (SRBs) and the PDCP-U part is used for user radio bearers (URBs), which can be implemented and deployed in different places.

The architecture supports a split between the radio unit (RU) and the baseband unit (BBU) based on the Common Public Radio Interface (CPRI), and other splits that move some processing to the RU/antenna to reduce the fronthaul bandwidth required at the BBU (e.g., when supporting very large bandwidths, many antennas).

Note that notwithstanding the above discussion, alternative RAN/CN splits are possible while still maintaining many of the features and advantages described herein.

This section discusses the different UE states in NR and LTE, focusing on the UE sleep state or "dormant" state. In LTE, two different sleep states are supported:

- ECM_IDLE/RRC_IDLE, where only the Core Network (CN) context is stored in the UE. In this state, the UE has no context in the RAN and is known at the tracking area (or tracking area list) level. (The RAN context is re-created during the transition to RRC_CONNECTED.) Mobility is controlled by the UE based on cell reselection parameters provided by the network.

- ECM CONNECTED/RRC_CONNECTED with UE configured DRX. In this state, the UE is known on cell level and the network controls mobility (handover).

Of the two states, ECM_IDLE/RRC_IDLE is the primary UE sleep state for inactive terminals in LTE. RRC_CONNECTED with DRX is also used, however the UE is typically released to RRC_IDLE after X seconds of inactivity (where X is configured by the operator and is typically in the range of 10 to 61 seconds). Reasons for wanting to keep the UE in RRC_CONNECTED with DRX for longer periods of time include limitations in eNB hardware capacity or software licensing, or other aspects such as slightly higher UE battery consumption or a desire to reduce the number of handover failures.

Given that initiating data transmission from ECM_IDLE in LTE involves significantly more signaling than data transmission from "RRC_CONNECTED with DRX," the "RRC_CONNECTED with DRX" state is enhanced in NR to become the primary sleep state. This enhancement includes adding support for UE-controlled mobility within the local area, thereby avoiding the need for the network to actively monitor UE mobility. Note that this approach allows for the possibility of further evolving the LTE solution to create a common RRC-connected sleep state for NR and LTE.

The following are the characteristics of this NR UE sleep state, referred to herein as RRC_CONNECTED sleep (or simply RRC sleep):

- It supports DRX (from milliseconds to hours).

- It supports UE controlled mobility, e.g. the UE can move within a Tracking RAN Area (TRA) or TRA list without informing the network (TRA (list) spans across LTE and NR).

- Transitions to and from this state are fast and lightweight (depending on the scenario, whether optimized for energy saving or fast access performance), for example achieved by storing and restoring the RAN context (RRC) in the UE and the network.

When it comes to the detailed solution of how to support this RRC dormant state, there are different options based on the different levels of CN participation. One option is as follows:

- CN is not aware of whether the UE is in RRC_CONNECTED dormant or RRC_CONNECTED active (described later), meaning that the S1* connection is always active when the UE is in RRC_CONNECTED, regardless of the sub-state.

- Allows a UE in RRC dormancy to move within a TRA or TRA list without notifying the network.

o When a packet arrives via S1*, the eNB triggers paging. When there is no X2* connection to all eNBs in the paging area, the MME can assist the eNB by forwarding the paging message.

When a UE contacts the network from RRC dormancy in a RAN node that does not have the UE context, the RAN node attempts to retrieve the UE context from the RAN node that stores the context. If successful, the process looks like an LTE X2 handover in the CN. If the retrieval fails, the UE context is re-established from the CN.

- The area where the UE is allowed to move without notifying the network may include a set of tracking RAN areas and cover both LTE and NR RATs, thus avoiding the need for signaling when switching RATs in RRC dormancy.

In addition to the RRC dormant state (optimized for power saving), there is also the RRC_CONNECTED active (RRC active) state for actual data transmission. This state is optimized for data transmission, but due to the DRX configuration, the UE is allowed to perform micro-sleeps for situations where there is no data to send but very fast access is required. This can be called a monitoring configuration within the RRC active state. In this state, the UE cell or beam-level mobility is controlled and known by the network.

Given the tight integration between NR and LTE, the desire to have a RAN-controlled sleep state in NR also drives the requirement for a RAN-controlled sleep state in LTE for NR/LTE-capable UEs. The reason is that to support tight NR and LTE integration, a common S1* connection is required for both LTE and NR. If a RAN-controlled sleep state is introduced on the NR side, it would be very beneficial to have a similar sleep state on the LTE side with an active S1* connection, so that sleeping UEs can move between NR and LTE without performing signaling to establish and tear down the S1* connection. This type of inter-RAT reselection between LTE and NR is likely to be very common, especially during early NR deployments. Therefore, a common RAN-based sleep state, called RRC_CONNECTED dormancy, should be introduced in LTE. UE behavior in this state is similar to that defined for LTE RRC suspend/resume, however, paging is performed by the RAN rather than the CN, as the S1* connection is not torn down when RRC is suspended.

Similarly, a common RRC_CONNECTED active state is expected between NR and LTE. This state is characterized by an NR/LTE capable UE being active in NR, LTE, or both. Whether the UE is active in NR, LTE, or both is a configuration aspect within the RRCACTIVE state, and these conditions do not need to be considered different sub-states, as the UE behavior is similar regardless of which RAT is active. As an example, in the case where only one link (regardless of which link) is active, the UE is configured to send data in one link and perform measurements in the other link for dual connectivity and mobility purposes.

Figure 3 shows the UE states in an LTE/NR system where LTE supports the common RRC_CONNECTED active and RRC_CONNECTED dormant states discussed above. These states are further described below.

Detach (non-RRC configuration)

- EMM_DETACHED (or EMM_NULL) state defined in the Evolved Packet Subsystem (EPS) when the UE is switched off or has not yet been connected to the system.

- In this state, the UE does not have any Internet Protocol (IP) address and cannot be reached from the network.

- The same EPS state is valid for both NR and LTE access.

ECM/RRC_IDLE

- This is similar to the current ECM_IDLE state in LTE.

o This state may be optional.

o While maintaining this state, it is desirable that the paging cycle and tracking RAN area be aligned between RAN-based paging in RRC dormancy and CN-based paging in ECM_IDLE, because this way the UE can listen to both CN-based and RAN-based paging, so that the UE can be recovered if the RAN-based context is lost.

RRC_CONNECTED activity (RRC state)

- The UE is RRC configured, e.g. it has one RRC connection, one S1* connection and one RAN context (including security context), which may be valid for both LTE and NR in the case of a dual-radio UE.

- In this state, data can be sent and received from/to NR or LTE or both, depending on UE capabilities (RRC configurable).

-In this state, the UE is configured with at least an LTE serving cell or an NR serving beam and can quickly establish dual connectivity between NR and LTE when needed. The UE monitors the downlink scheduling channel of at least one RAT and can access the system via a scheduling request sent in the uplink, for example.

- Network controlled beam/node mobility: The UE performs neighbor beam/node measurements and measurement reporting. In NR, mobility is primarily based on NR signals such as TSS/MRS, and in LTE, the primary synchronization sequence (PSS)/secondary synchronization sequence (SSS/CRS) is used. NR/LTE knows the best beam (or best beam set) for the UE and its best LTE cell.

- For example, the UE may acquire system information via the Signature Sequence Index (SSI) and the corresponding Access Information Table (AIT) and/or via NR-dedicated signaling or via the LTE system information acquisition procedure.

- A UE can configure DRX in both LTE and NR to allow micro-sleep (sometimes called beam tracking or monitoring mode in NR). For a UE active in two RATs, DRX is most likely coordinated between the RATs.

- The UE may be configured to perform measurements on the inactive RAT, which may be used to establish dual connectivity, for mobility purposes or simply as a fallback if coverage of the active RAT is lost.

RRC_CONNECTED sleep (RRC state)

- The UE is RRC configured, e.g. the UE has one RRC connection and one RAN context regardless of access.

-UE can monitor NR, LTE or both, depending on coverage or configuration. RRC connection reactivation (entering RRC active) can be via NR or LTE.

- Support for UE controlled mobility. In the case of LTE-only coverage, this can be cell reselection, or in the case of NR-only coverage, it can be NR tracking RAN area selection. Alternatively, this can be cell/area reselection for joint optimization of overlapping NR/LTE coverage.

UE-specific DRX can be configured by the RAN. DRX is primarily used in this state to allow for different power saving cycles. The cycle can be configured independently for each RAT, however some coordination may be required to ensure good battery life and high paging success rates. Since NR signals have configurable periodicity, there are methods to allow the UE to recognize the change and adjust its DRX cycle.

-The UE can obtain system information via SSI/AIT in NR or via LTE. The UE monitors NR common channels (e.g., NR paging channel) to detect incoming calls/data, AIT/SSI changes, Earthquake and Tsunami Warning System (ETWS) notifications, and Commercial Mobile Alert System (CMAS) notifications. The UE can request system information via a previously configured random access channel (RACH).

Several different types of measurements and/or signals are measured in NR, such as MRS, SSI, Tracking RAN Area Signal (TRAS), etc. Therefore, mobility events and procedures need to be addressed for NR.

The RRC connection reconfiguration message should be able to configure both NR measurements and legacy LTE measurements for a single RRC option. The measurement configuration should include the possibility to configure the UE to measure NR/LTE coverage, for example, to initiate DC establishment or inter-RAT handover (as in legacy).

For NR, there are two different measurement reporting mechanisms: non-RRC-based reporting, where the UE indicates the best beam from a set of candidate downlink beams via a pre-configured uplink synchronization signal (USS) sequence; and RRC-based reporting, which is similar in some respects to event-triggered LTE measurement reporting. These two measurement reporting mechanisms are preferably deployed in parallel and used selectively, for example, depending on the UE's mobility state.

System information known from previous versions of the LTE standard includes very different types of information, access information, node-specific information, system-wide information, Public Warning System (PWS) information, etc. Providing this wide range of information does not use the same implementation in NR. In systems with high-gain beamforming, providing large amounts of data in a broadcast manner can be expensive compared to point-to-point distribution in dedicated beams with high link gain.

NR's paging solution uses one or both of two channels: the Paging Indication Channel (PICH) and the Paging Message Channel (PMCH). A paging indication may contain one or more of the following: a paging flag, a warning/alert flag, an identifier (ID) list, and resource allocations. Optionally, the PMCH may be sent after the PICH. When a PMCH message is sent, it may contain one or more of the following: an ID list and a warning/alert message. Warnings and broadcast messages are preferably sent via the PMCH (and not in the AIT). For tight integration with LTE, the paging configuration (and DRX configuration) may be based on a single frequency network (SFN).

To support paging functionality, a Tracking RAN Area is configured at the UE. A Tracking RAN Area (TRA) is defined by a set of nodes that send the same Tracking RAN Area Signal (TRAS). This signal contains the Tracking RAN Area Code and the SFN.

Each TRA may have a specific paging and TRAS configuration, which is provided to the UE via dedicated signaling (e.g., via a TRA Update Response or an RRC Reconfiguration message). Additionally, the TRA Update Response may contain a paging message.

In NR, multiple different reference signals are provided for channel estimation and mobility. The presence of reference signals and measurement reports is controlled by the scheduler. The presence of the signal can be dynamically or semi-persistently signaled to one or a group of users.

In addition, reference signals for active mode mobility (MRS) can be dynamically scheduled. The UE is then allocated a search space for mobility transmission. It is observed that the search space may be monitored by one or more UEs and/or transmitted from one or more transmission points.

A scheduled reference signal transmission (eg, MRS) contains a locally unique (at least within the search space) measurement identity in the data message and reuses some or more pilots in the transmission for demodulation and measurement purposes, meaning it is a self-contained message.

NR uses OFDM as the modulation scheme in both the uplink and downlink, and may also include low peak-to-average power ratio (PAPR) modes for energy-efficient low-PAPR operation (e.g., discrete Fourier transform-spread OFDM or DFTS-OFDM) and filtered/windowed OFDM for frequency-domain mixing of parameter sets. Note that the term "parameter set" used in this article refers to a specific combination of OFDM subcarrier bandwidth, cyclic prefix length, and subframe length. The term subcarrier bandwidth (referring to the bandwidth occupied by a single subcarrier) is directly related to (and sometimes used interchangeably with) subcarrier spacing.

NR's modulation scheme is cyclic prefix OFDM for both uplink and downlink, which allows for more symmetrical link designs. Given NR's large operating range (sub-1 GHz to 100 GHz), multiple numerologies for different frequency regions can be supported. OFDM is a good choice for NR because it combines very favorably with multi-antenna schemes, another important component in NR. In OFDM, each symbol block is very well positioned in time, making OFDM very attractive for short transmission bursts, which is important for various MTC applications. OFDM does not provide as good isolation between subcarriers as some filter bank-based schemes; however, windowing or subband filtering provides sufficient isolation between subbands (e.g., not individual subcarriers, but sets of subcarriers) when needed.

For some use cases, it is beneficial to mix different OFDM parameter sets. The mixing of OFDM parameter sets can be done in the time domain or the frequency domain. In order to mix MBB data and extremely delay-critical MTC data on the same carrier, frequency domain mixing of OFDM parameter sets is beneficial. Frequency domain mixing can be achieved using filtered/windowed OFDM. Figure 4(a) shows a block diagram of filtered/windowed OFDM. In this example, the upper branch uses narrow (16.875kHz) subcarriers 400-1100. The lower branch uses wide (67.5kHz) subcarriers 280-410, which correspond to narrow subcarriers 1120-1640. Figure 4(b) shows the mapping of the upper and lower branches to the time-frequency plane. Four small IFFTs (512 samples) are performed during the duration of a large inverse fast Fourier transform (IFFT) (2048 samples).

In filtered OFDM, subbands are filtered to reduce interference with other subbands. In windowed OFDM, the start and end of an OFDM symbol are multiplied by a smoothing time-domain window (conventional OFDM uses a rectangular window that spans the length of the OFDM symbol including the cyclic prefix) to reduce discontinuities at symbol transitions, thereby improving spectral roll-off. This is illustrated in Figure 5, which shows how the start and end of an OFDM symbol are multiplied by a smoothing time-domain window.

In the example of frequency-domain mixing of OFDM numerologies shown in Figure 4, the lower branch uses a numerology with subcarriers that are four times wider than the upper branch, for example, 16.875 kHz and 67.5 kHz for the upper and lower branches, respectively. In this example, both branches use the same clock rate after IFFT processing and can be added directly. However, this may not be the case in a real implementation; in particular, if one of the numerologies spans a narrower bandwidth than the other, where a lower sampling rate is preferable.

Although filtered OFDM is feasible, windowed OFDM is preferred due to its greater flexibility.

Subband filtering or windowing (at both the transmitter and receiver) and guard bands are desired to suppress inter-subcarrier interference since the subcarriers of different parameter sets are not orthogonal to each other. In addition to subband filtering or windowing, filtering is also desired over the transmission bandwidth to meet the required out-of-band transmission requirements. A guard band of 12 narrowband subcarriers achieves an SNR of 20+dB on all subcarriers, while a guard band of 72 narrowband subcarriers allows an SNR of 35+dB on all subcarriers. To avoid unnecessary guard band loss, filtered/windowed OFDM can be limited to two consecutive blocks of different parameter sets. In the case where the NR standard supports filtered/windowed OFDM, every NR device - even those that only support a single parameter set - should support transmit and receive filtering/windowing since it can run on NR carriers running a mixed parameter set (due to the low complexity of windowing, it can be assumed that each UE can implement windowing). On the other hand, if the network node supports a mix of use cases that require frequency domain mixing of parameter sets, it only needs to support filtered/windowed OFDM. Note that a detailed description of windowing or subband filtering is not required, but rather performance requirements are needed to test the chosen implementation. Subband filtering and windowing can also be mixed at the transmitter and receiver.

OFDM can also include low PAPR modes, such as DFTS-OFDM. OFDM is used to maximize performance, while low PAPR modes can be used for node implementations (both eNB and UE) where a low peak-to-average power ratio (PAPR) of the waveform is important for hardware, for example, at very high frequencies.

At the physical layer, the smallest transmission unit is the subframe. Subframe aggregation enables longer transmissions. This concept implements a variable time interval (TTI), where for a given transmission, the TTI corresponds to the length of a subframe, or, in the case of subframe aggregation, the length of the aggregated subframe.

Three subcarrier bandwidths are defined to cover the operating range from below 1 GHz to 100 GHz and a large use case space.

NR supports both frequency division duplex (FDD) and dynamic time division duplex (TDD) modes. Although not relevant for the first release of NR, the concept can be extended to full duplex (especially at the base station) as the technology becomes more mature.

The NR physical layer as described herein does not have frames but only subframes. The concept of frames will be introduced later. Two basic subframe types are defined, one for uplink and one for downlink. These subframe types are the same for both FDD and TDD. Figure 6 depicts the basic subframe types, where T _sf is the subframe duration. T _DL and T _UL are the durations of active transmissions in the downlink and uplink, respectively. A subframe consists of N _symb OFDM symbols, but not all symbols in a subframe are always used for active transmissions. Transmissions in a downlink subframe start at the beginning of the subframe and can extend from 0 to a maximum of N _symb OFDM symbols (it is also possible to start transmissions later in a downlink subframe for listen-before-talk operation). Transmissions in an uplink subframe stop at the end of the subframe and can extend from 0 to a maximum of N _symb OFDM symbols. Gaps - if present - are used in TDD for transmissions in opposite directions within a subframe, as described below.

The duration of a single subframe is very short. Depending on the parameter set, the duration can be several hundred μs or even less than 100 μs, and in extreme cases even less than 10 μs. Very short subframes are important for critical machine type communication (C-MTC) devices that require low latency, and such devices typically check for control signaling sent at the beginning of each downlink subframe. Given the latency-critical nature, the transmission itself can also be very short, for example, a single subframe.

For MBB devices, very short subframes are usually not required. Therefore, multiple subframes can be aggregated and scheduled using a single control channel.

It is well known that the robustness of OFDM systems to phase noise and Doppler shift increases with subcarrier bandwidth. However, wider subcarriers mean shorter symbol durations, which, together with the constant cyclic prefix length per symbol, lead to higher overhead. The cyclic prefix should match the delay spread and is therefore dictated by the implementation. The required cyclic prefix (in μs) is independent of the subcarrier bandwidth. The "ideal" subcarrier bandwidth keeps the cyclic prefix overhead as low as possible, but wide enough to provide sufficient robustness to Doppler and phase noise. Since the effects of both Doppler and phase noise increase with carrier frequency, the required subcarrier bandwidth in OFDM systems increases with increasing carrier frequency.

Given the wide operating range of sub-1 GHz to 100 GHz, it is not possible to use the same sub-carrier bandwidth for the entire frequency range and maintain reasonable overhead. Instead, three sub-carrier bandwidths span the carrier frequency range of sub-1 GHz to 100 GHz.

In order to enable a subframe duration of several 100μs using the LTE parameter set (for LTE frequencies), one subframe must be defined as several OFDM symbols. However, in LTE, the OFDM symbol duration including the cyclic prefix varies (the first OFDM symbol in a slot has a slightly larger cyclic prefix), which will result in a varying subframe duration. (In practice, the varying subframe duration may not be a significant issue and can be handled. In LTE, the varying cyclic prefix length leads to more complex frequency error estimation.) Alternatively, a subframe can be defined as an LTE slot, resulting in a subframe duration of 500μs. However, it is considered too long.

Therefore, even for LTE frequencies, this document describes a new parameter set. The parameter set is close to the LTE parameter set to enable the same deployment as LTE, but provides a 250μs subframe. The subcarrier bandwidth is 16.875kHz. Based on this subcarrier bandwidth, several other parameter sets can be derived: 67.5kHz for approximately 6 to 30/40GHz or dense deployments (even at lower frequencies) and 540kHz for very high frequencies. Table 1 lists the most important parameters in these parameter sets, such as _fs : clock frequency, _Nsymb : OFDM symbols per subframe, _Nsf : samples per subframe, _Nofdm : Fast Fourier Transform (FFT) size, _Ncp : cyclic prefix length in samples, _Tsf : subframe duration, _Tofdm : OFDM symbol duration (excluding cyclic prefix), and _Tcp : cyclic prefix duration. Table 1 is based on an FFT size of 4096 and a clock frequency of 34.56MHz to allow coverage of a wide range of carrier bandwidths.

The proposed parameter set is not based on the LTE clock frequency (30.72 MHz), but on 16.875/15×30.72 MHz=9/8×30.72 MHz=9×3.84 MHz=34.56 MHz. This new clock is related to the LTE and Wideband Code Division Multiple Access (WCDMA) clocks by a (fractional) integer relationship and can therefore be derived from them.

Table 1

Note that the implemented parameter sets may differ from those listed in Table 1. In particular, the parameter sets with long cyclic prefixes may be adjusted.

Table 1 shows that OFDM symbol duration and subframe duration decrease with subcarrier bandwidth, making parameter sets with wider subcarriers suitable for low latency applications. The cyclic prefix length also decreases with subcarrier bandwidth, limiting wider subcarrier configurations to dense deployments. This can be compensated by a long cyclic prefix configuration, at the expense of increased overhead. In other words, shorter subframes and the resulting latency are more efficient in small cells than in large cells. However, in practice, many latency-critical applications expected to be deployed in wide areas (and therefore requiring a cyclic prefix greater than 1μs) do not require a subframe duration of less than 250μs. In the rare case where a smaller subframe duration is required for wide-area deployments, a 67.5kHz subcarrier bandwidth can be used - with a long cyclic prefix if necessary. The 540kHz parameter set provides shorter subframes.

For the 16.875kHz, 67.5kHz, and 540kHz parameter sets, the maximum channel bandwidths for the different parameter sets are approximately 60MHz, 240MHz, and 2GHz, respectively (assuming an FFT size of 4096). Wider bandwidths can be achieved through carrier aggregation.

Using filtered/windowed OFDM, different numerologies can be mixed on the same carrier. One motivation is to achieve lower latency on a portion of the carrier. Mixing numerologies on a TDD carrier should respect the half-duplex nature of TDD—it cannot be assumed that the transceiver has the ability to transmit and receive simultaneously. Therefore, the most frequent duplex switching in TDD is limited by the "slowest" numerology set among the simultaneously used numerologies. One possibility is to enable duplex switching based on the "fastest" numerology set subframe when needed, accepting the loss of the currently ongoing transmission in the reverse link.

As described below, a signature sequence (SS) is used to indicate an entry in the AIT and establish a level of subframe synchronization for at least the random access preamble transmission. The SS is constructed in a similar manner to the synchronization signal in LTE by concatenating the primary and secondary signature sequences.

The combination of the Time and Frequency Synchronization Signal (TSS) and the Beam Reference Signal (BRS) is used to obtain time/frequency/beam synchronization after initial synchronization and access to the SS and Physical Random Access Channel (PRACH). This combined signal is also called the MRS (Mobility Reference Signal) and is used for handover (between nodes and beams), transitions from dormant to active state (e.g., from RRC_CONNECTED dormant to RRC_CONNECTED active, as described above), mobility, beam tracking and refinement, etc. The MRS is constructed by concatenating the TSS and BRS so that the MRS is transmitted within a single DFT-precoded OFDM symbol.

Channel State Information Reference Signals (CSI-RS) are transmitted in the downlink and are primarily intended for use by UEs to obtain Channel State Information (CSI). CSI-RS are grouped into subgroups based on the possible reporting levels measured by the UE. Each subgroup of CSI-RS represents a set of orthogonal reference signals.

Positioning Reference Signals (PRS) assist in positioning. Existing reference signals should be reused for PRS. In addition, modifications and additions can be made to improve positioning performance if necessary.

Table 2: Downlink reference and synchronization signals in NR

The basic functions of a signature sequence (SS) are one or more of the following:

- Obtain SSI to identify relevant entries in the AIT;

- Provides coarse frequency and time synchronization and relative AIT allocation for subsequent initial random access;

- Provides reference signals for initial layer selection (selecting which SS transmission point the UE connects to based on the path loss experienced by the SS);

- Provide a reference signal for open-loop power control of initial PRACH transmissions; and

- Provides a coarse timing reference to assist UEs in inter-frequency measurements and possibly beam finding. It is currently assumed that SS transmissions are synchronized within a ±5ms uncertainty window unless explicitly stated otherwise. The SS period should be on the order of 100ms, but can vary depending on the scenario.

Note that the number of candidate sequences needs to be large enough to indicate any entry in the AIT. Taking into account the terminal detection complexity, the number of SS sequences is 2 ¹² (corresponding to 12 bits of sequence reuse 1), or less if less aggressive sequence reuse is required. Note that the number of bits to be carried depends on the requirements. If the number of bits increases to exceed the number of bits that the sequence modulation can carry, the SS format is expected to change. In this case, a codeword containing the extra bits beyond what the sequence can carry can be appended. The block that follows the SS transmission is called an SS block (SSB). The content in this block is flexible and contains other relevant information bits, which require a period of about 100ms. For example, they can be "AIT pointers" indicating the time and frequency band where the terminal can find the AIT, or even indicating the transmission format of the AIT to avoid completely blind detection.

The sequence design of SS can follow the TSS/BRS sequence design, as they will provide coarse synchronization function before the initial random access.

To support large-scale analog beamforming, a fixed absolute duration (e.g., 1 millisecond) is reserved to scan multiple analog beams.

During the acquisition of system access information (acquisition of system information and detection of appropriate SSI), the UE uses the SS to obtain time and frequency synchronization to one or more nodes. The latter is achieved when the system access information is sent simultaneously from several nodes in a SFN (Single Frequency Network) manner.

When a UE enters active mode, its goal is to receive or transmit with a high data rate connection, where more accurate synchronization may be required and beamforming may be required. Here, mobility and access reference signals (MRS) are used. The UE may also need to change the node to which it is connected, for example, from the node used to send system access information to another node capable of beamforming. In addition, when moving to certain operating modes in active mode, the UE may also change the carrier frequency or parameter set to a higher subcarrier spacing and a shorter cyclic prefix.

The MRS is constructed to perform time and frequency offset estimation and estimate the best downlink transmitter and receiver beams to "active mode access points." The frequency accuracy and timing provided by the MRS may not be sufficient for high-order modulation reception, and finer estimates can be based on the demodulation reference signal (DMRS) embedded in the physical data channel (PDCH) and/or CSI-RS.

An MRS can be constructed by temporally concatenating the time and frequency synchronization signal (TSS) and the beam reference signal (BRS) into a single OFDM symbol, as shown in Figure 7. This structure can be implemented as a DFT-precoded OFDM symbol with a cyclic prefix. By utilizing both the TSS and BRS in the same OFDM symbol, the transmitter can change its beamforming between each OFDM symbol. Compared to having separate OFDM symbols for the TSS and BRS, the time required to scan a set of beam directions is now halved. As a result, both the TSS and BRS have shorter durations compared to separate OFDM symbols for each. The cost of these shorter TSS and BRS is reduced energy per signal, thereby reducing coverage. This can be compensated by increasing bandwidth allocation, repeating the signal, or increasing beamforming gain through narrower beams. When hybrid numerology is supported, the numerology used for the MRS is the same as that used by the UE scheduling the MRS. If multiple UEs within the same beam use different numerology sets, the MRS cannot be shared and should be transmitted separately for each numerology set.

Different beamforming configurations can be used to send MRSs in different OFDM symbols, for example, in each of the three symbols shown in Figure 7. The same MRS can also be repeated multiple times in the same beam to support analog receiver beamforming. There is only one or a few TSS sequences, similar to the PSS in LTE. The UE uses the TSS sequence for matched filtering to obtain OFDM symbol timing estimates; therefore, the TSS should have good periodic autocorrelation properties. This sequence can be signaled by system information so that different APs (access points) can use different TSS sequences.

The MRS (composed of TSS+BRS) signal package can be used for all operations related to active mode mobility: initial beam discovery, triggering beam mobility updates in data transmission and monitoring modes, and continuous mobility beam tracking. It can also be used in SS design.

The TSS sequence is the same across all OFDM symbols and beam directions sent from the base station, while the BRS uses different sequences for different OFDM symbols and beam directions. The reason for having the same TSS in all symbols is to reduce the number of TSSs that the UE must search for in OFDM symbol synchronization, which is computationally very complex. When timing is found from the TSS, the UE can continue searching within the BRS candidate set in order to identify the OFDM symbol within the subframe and the best downlink beam. The USS can then report the best downlink beam.

One choice of such a sequence is the Zadoff-Chu sequence used for the PSS in LTE Release 8. However, these sequences are known to have large spurious correlation peaks for combined timing and frequency offsets. Another choice is the differentially coded Golay sequence, which is very robust to frequency errors and has small spurious correlation peaks.

The beam reference signal (BRS) is characterized by different sequences transmitted in different transmit beams and OFDM symbols. In this way, the beam identity can be estimated in the UE for reporting to the access node.

If the timing difference between SS and active mode transmissions is large, it is desirable to identify OFDM symbols within a subframe. This may happen in the following situations: parameter sets with short OFDM symbols, there is a large distance between the node sending system access information and the node where the UE should send user data (in the case that these nodes are different), or for unsynchronized networks. This identification can be done if different BRS sequences are used for different OFDM symbols. However, in order to reduce computational complexity, the number of BRS sequences to be searched should be low. Depending on the OFDM symbol index uncertainty, a different number of BRS sequences can be considered in the UE's blind detection.

The BRS can be a dedicated transmission to one UE, or the same BRS can be configured for a group of UEs. The channel estimate from the TSS can be used for coherent detection of the BRS.

CSI-RS is transmitted in the downlink and is primarily used by the UE to obtain channel state information (CSI), but may also be used for other purposes. CSI-RS may be used for (at least) one or more of the following purposes:

-Efficient channel estimation at the UE: Frequency-selective CSI acquisition at the UE within the downlink beam, e.g., for Precoder Matrix Indicator (PMI) and rank reporting.

- Discovery signal: Reference Signal Received Power (RSRP) type measurements are performed on the CSI-RS reference signal set, which is transmitted at a temporal density according to the large-scale coherence time of the relevant (downlink) channel.

- Beam refinement and tracking: Obtain statistics about downlink channels and PMI reports to support beam refinement and tracking. PMI does not need to be frequency selective. It is transmitted with a time density based on the large-scale coherence time of the relevant (downlink) channel.

- Reciprocity is assumed for UE transmit beamforming in uplink.

- UE beam scanning for analog receive beamforming in downlink (similar to the requirements for 1) or 3) depending on the use case).

- Assists in fine frequency/time synchronization for demodulation.

In some cases, not all of the above estimation purposes need to be handled by CSI-RS. For example, frequency offset estimation can sometimes be handled by downlink DMRS, and beam finding can sometimes be handled by BRS. Each CSI-RS transmission is scheduled and can be located in the same frequency resource as the PDCH downlink transmission or in a frequency resource that is unrelated to the PDCH downlink data transmission. Generally, it can be assumed that the CSI-RS in different transmissions are independent of each other, so the UE should not filter in time. However, the UE can be explicitly or implicitly configured to assume that the CSI-RS are dependent on each other, for example, to support time filtering of CSI-RS measurements (for example, in 2 above), and also to be dependent on other transmissions including PDCCH and PDCH. Generally, all UE filtering should be controlled by the network, including filtering CSI in time, frequency, and through diversity branches. In some transmission formats, CSI-RS are located in separate OFDM symbols to better support analog beamforming for both the base station transmitter (TX) and the UE receiver (RX). For example, to support UE analog beam scanning (item 5 above), the UE needs multiple CSI-RS transmissions to measure in order to scan multiple analog beam candidates.

In LTE, a UE camps on a "cell". Before camping, the UE performs measurement-based cell selection. Camping means that the UE tunes to the cell control channel and all services are provided from a specific cell, and the UE monitors the control channel of a specific cell.

In NR, different nodes can send different information. For example, some nodes may send SSI/AIT tables, while others may not send SSI and/or AIT. Similarly, some nodes may send tracking information, while others may send paging messages. In this context, the concept of a cell becomes blurred, and therefore, the concept of cell camping no longer applies to NR.

The relevant signals that can be monitored when the UE is in a dormant state or mode (e.g., the RRC_CONNECTED DORMANT state discussed above) are one or more of:

-SSI

-Tracking RAN area signals-TRAS

-Paging indication channel/paging message channel.

NR camping is therefore tied to the reception of a set of signals. The UE should camp on the "best" SSI, TRAS, and PICH/PMCH. NR camping (re)selection rules for these signals apply, just as there are cell (re)selection rules in LTE. However, these rules can also be slightly more complex due to the higher level of flexibility.

Location information is desired to assist the network in locating the UE. A solution that can provide location information is the use of SSI/AIT; however, this comes at the cost of introducing certain constraints. Another solution is to use an SSI block. The SSI block can carry the content or part of the content described in the Tracking RAN Area Signal Index (TRASI). The SSI block is independent of the SSI. Therefore, it can be used as an option for providing location information. However, another solution that provides a higher degree of flexibility is to introduce a new signal to carry this information. This signal is called the Tracking RAN Area Signal TRAS in this context. The area in which this signal is sent is called the Tracking RAN Area TRA. A TRA can contain one or more RAN nodes, as shown in Figure 8. TRAS can be sent by all or a limited set of nodes within a TRA. This also means that the signal and its configuration should preferably be common to all nodes sending TRAS within a given TRA, for example, in terms of (at least) coarse synchronization of transmissions, to facilitate the UE's process and help the UE reduce its energy consumption.

The Tracking RAN Area Signal (TRAS) consists of two components: Tracking RAN Area Signal Synchronization (TRASS) and Tracking RAN Area Signal Index (TRASI).

In sleep mode, before each instance of TRA information is read, the UE is typically in a low-power DRX state and exhibits considerable timing and frequency uncertainty. Therefore, the TRA signal should also be associated with a synchronization field that allows the UE to obtain timing and frequency synchronization for subsequent payload reception. To avoid duplication of synchronization support overhead in yet another signal, TRASI reception can use SSI for synchronization in deployments where SSI and TRAS are sent from the same node and configured with appropriate periodicity. In other deployments where SSI is not available for synchronization before reading TRASI, a separate synchronization signal (TRASS) is introduced for this purpose.

The SSI design is optimized to provide UE synchronization. Because the synchronization requirements for TRA detection, particularly the UE's link quality operating point and the capabilities required to read downlink payload information, are similar, we reuse the SS physical channel design and reserve one or a few of the PSS+SSS sequence combinations for use as TRA synchronization signals. The SS detection process at the UE can be reused for TRA synchronization. Since the TRASS consists of a single predetermined sequence or a small number of sequences, UE search complexity is reduced.

The information about whether TRASS is configured by the network may be signaled to the UE, or the UE may blindly detect the information.

The Tracking Area Index is broadcasted. At least two components have been identified as being contained in the Tracking RAN Area Signaling Index (TRASI) payload:

- Tracking RAN area code. In LTE, the tracking area code has 16 bits. NR can use the same spatial range.

- Timing information. As an example, a System Frame Number (SFN) length of 16 bits may be used, which would allow for 10 minute DRX, given a radio frame length of 10 ms.

The payload is therefore estimated to be 20-40 bits. Since encoding into a separate signature sequence with this number of bits is impractical, the TRA information is sent as a coded information payload (TRASI) together with associated reference symbols (TRASS) to serve as a phase reference.

The TRASI payload is sent using the downlink physical channel structure:

- Alternative 1 [Preferred]: Use PDCCH (persistent scheduling). The UE is configured with a set of one or more PDCCH resources to monitor

-Alternative 2: Use PDCH (persistent scheduling). The UE is configured with a set of one or more PDCCH resources to monitor

- Alternative 3: Use PDCCH+PDCH (standard shared channel access). The UE is configured with one or more Paging Control Channel (PCCH) resources to monitor, which in turn contains a pointer to the PDCH with TRA information.

The choice between PDCCH and PDCH should be based on whether reserving resources in one or the other channel imposes fewer scheduling constraints on other signals. (For naming purposes, the used PDCCH/PDCH resources may be renamed TRASI physical or logical channels.

The TRASI encoding includes a cyclic redundancy check (CRC) to reliably detect correct decoding at the UE.

The UE uses its standard SSI search/synchronization procedure to obtain synchronization for TRASI reception. The following sequence can be used to minimize UE energy consumption:

-First look for TRASS

- If TRASS not found, look for the latest SSI

- If the SSI is not found, continue with the full SSI search

In some UE implementations, the receiver wake-up time (ie, the period of time during which all or a substantial portion of the receiver circuitry is activated) is the dominant energy consumption factor, in which case a full search may always be performed.

If there is no TRASS but several SSIs are receivable, the UE attempts TRASI reception at all found SSIs and/or TRASS timings, one of which will succeed. All SSIs are detected during the same wake-up period and the corresponding TRASI detection is attempted, so no receiver overhead is introduced.

If relatively loose synchronization with a known tolerance within the TRA is provided, the UE searches for TRAS-related time synchronization within a relative vicinity of the current timing, plus the worst-case timing drift during DRX. Therefore, the UE RX wake-up time increases proportionally with increasing timing tolerance.

The TRA configuration should be the same within the TRA. This means that all nodes sending TRAS should use the same configuration. The reason behind this is the DRX configuration. A UE in sleep mode (e.g., the RRC_CONNECTED sleep state discussed above) wakes up for a period of time. During this period, the UE is expected to monitor and perform measurements configured by the network (or specified by the standard).

The TRA configuration is transmitted via dedicated signaling. The AIT is not the most appropriate choice for transmitting this information. The TRA configuration may be sent to the UE, for example, when the network commands the UE to move from active mode (e.g. RRC_CONNECTED active state) to dormant mode (e.g. RRC_CONNECTED dormant state), or when the network sends a TRA update response to the UE. The TRA update response - may also carry paging information (see Figure 9). This is particularly useful for minimizing paging delays in situations where the network is trying to locate the UE in a TRA that the UE has exited. In order to be able to support this type of functionality, the UE may need to add some type of ID or other information in the TRA update to help the new TRA or node identify the previous TRA or node, which may contain UE context, paging messages or user data.

Figure 9 illustrates the TRA update process, where a UE moves from TRA_A to TRA_B, which is not configured in its TRA list. When the UE exits TRA_A but is not yet registered in TRA_B, the network begins sending paging indications via a node or set of nodes in TRA_A. The UE does not respond because it has exited TRA_A and may no longer be monitoring TRA_A. When the UE performs a TRA update, the network provides the new TRA list and configuration, and may also include any paging indications that the UE may have missed.

The lower the network synchronization, the greater the impact on UE battery. Therefore, maintaining tight synchronization across TRAs is important but also challenging, especially in deployments with poor backhaul.

Several options are listed below:

- All TRAs are loosely synchronized.

- There is no synchronization across TRAS.

- Sliding synchronization across neighboring nodes.

- Loose synchronization within a TRA, but not between TRAS.

Figure 10 shows the options for beam shaping for feedback-based solutions in NR.

Transmitting in a beam implies a directed, potentially narrow, stream of propagating energy. Therefore, the concept of a beam is closely related to the spatial characteristics of transmission. To facilitate discussion, we first explain the concept of a beam. Specifically, we describe the concept of high-order beams.

Here, a beam is defined as a set of beam weight vectors, where each beam weight vector has a separate antenna port, and all antenna ports have similar average spatial characteristics. Therefore, all antenna ports of a beam cover the same geographic area. However, note that the fast fading characteristics of different antenna ports may differ. An antenna port is then mapped to one or more antenna elements using a possible dynamic mapping. The number of antenna ports in a beam is its rank.

To illustrate beam definition, we'll use the most common example of a rank-2 beam. This beam is implemented using an antenna with cross-polarized elements, where all antenna elements with one polarization are combined using a beam weight vector, and all antenna elements with the other polarization are combined using the same beam weight vector. Each beam weight vector has one antenna port, and since the same beam weight vector is used for both antenna ports, the two beam weight vectors together form a rank-2 beam. The beam can then be expanded to higher-rank beams.

Note that high-rank beams may not be suitable for the UE. Due to the irregular antenna element layout, the rich scattering at the UE, and the fact that the UE antenna elements may have different characteristics, it is very difficult to construct several beam weight vectors with similar spatial characteristics. Note that this does not exclude spatial multiplexing in the uplink: it can be achieved using several rank-1 beams.

It is important to note that the beam shape can be very flexible. Therefore, "beam-based transmission" is different from "fixed beam transmission", although in many cases using a fixed beam grid may be an appropriate implementation. The working assumption is that each beam has 1 to 8 ports and each beam is associated with a CSI-RS with a range of 1 to 8.

From the UE's perspective, no major differences are foreseen for element-based feedback other than the CSI-RS configuration; i.e., for beam-based transmission, the CSI-RS allocation needs to be more flexible. Even if the configuration is flexible, it does not preclude the UE from performing filtering and interpolation, but this is done under strict network control.

In beam-based transmission, communication occurs via beams, where the number of beams can be much smaller than the number of antenna elements. Since the beams are still steerable, the antenna system as a whole retains all its degrees of freedom. However, a single UE cannot support all of these degrees of freedom using instantaneous feedback. Note that this is in contrast to element-based transmission, where the UE is aware of all antenna degrees of freedom and can report based on this knowledge.

From a network perspective, multiple simultaneous beams can be generated using either analog beamforming or digital domain processing. The overhead of maintaining UE beam associations is assumed to be reasonable as long as the formed beams have a similar width to the angular spread of the channel: then the best beam for any single UE does not change with fast fading. When the beams are narrower than the angular spread of the channel, the best beam for any single UE changes over time, resulting in the need to frequently update the best beam association. In some cases, the antenna pattern is fixed; see Figure 10, option 2. In some cases, the beams are adapted to the UE channel characteristics; see Figure 10, option 3, where user 2 with a rich channel receives data via a wide, high-rank beam, while line-of-sight user 1 receives a narrow rank-2 beam.

Beam-based transmission is applicable to both FDD and TDD for any frequency band and antenna size.

Beam-based uplink reception means the baseband does not have individual access to all antenna elements. In this case, some spatial preprocessing or preliminary beamforming can be applied. This preprocessing can be performed in the analog domain, in the digital domain, or a hybrid of the two. Typically, spatial preprocessing can be very flexible. It needs to be time-varying to adapt the antenna's coverage area to the user's location. Both phase and amplitude tapering can be considered.

In the downlink, individual antenna elements are never exposed to the UE. The UE only perceives multiple linear combinations of the signals transmitted from different antenna elements. The number of exposed linear combinations is determined by the rank of the transmission. Data is received at the UE via these linear combinations (beams), and downlink quality is measured and reported for each beam.

One possible scenario is that the UE is equipped with multiple arrays, each consisting of multiple (small) elements. Different arrays cover different spatial directions. The arrays can be configured to have different angular coverage (pointing direction and beamwidth).

The UE transmits reference signals (RS) via multiple beams sequentially or simultaneously. Sequential transmission can also be used with analog TX beamforming, and detection at the eNB is easier. On the other hand, if the RS is transmitted in parallel on multiple beams, more beams can be detected in a shorter time. The RS may be a reciprocity reference signal (RRS) because different RS should be sent via different beams so the eNB can identify each transmission. The shape of each beam is decided by the UE, but the number of beams is decided between the UE and the eNB. The eNB measures the quality of each received RS and determines the most appropriate UE transmit beam. This decision is then sent to the UE via the dPDCH along with the channel quality information (CQI) value and the scheduling grant.

As mentioned above, it may not be possible to form a high-rank beam at the UE.To enable uplink multiple-input multiple-output (MIMO), several rank-1 beams may be used.

At the eNB, beam-based transmission typically means that the number of elements seen by the baseband is much lower than the number of elements used to form the beams. This means that at the same time the (angular) coverage of a single beam is smaller than the number of elements.

At the UE, beam-based transmission for feedback purposes may be used to improve the link budget of the RS, but may not reduce the angular coverage so that the number of beams may still be equal to the number of elements.

For ongoing transmissions, there is the possibility of reducing the angular coverage (as done on the eNB side), but this may mean that after a while the channel is not fully utilized. To prevent this, sounding with wide or possibly full angular coverage is required.

For NR, in contrast to traditional cell mobility in Long Term Evolution (LTE), the aforementioned active mobility management solution is configured to manage mobility between beams. Beam-oriented transmission and mobility introduces many characteristics that differ from LTE cell mobility. Using large planar antenna arrays (numbering in the hundreds of elements) at the access node, a fairly regular beam grid coverage pattern with hundreds of candidate beams per node can be created. The beamwidth of each beam in elevation and azimuth is determined by the number of rows and columns of elements in the array.

As shown in simulation studies, the coverage area of a single beam from a large planar array can be small, with a width of the order of tens of meters. The channel quality outside the current serving beam area degrades rapidly, which may require frequent beam switching to exploit the full potential of the antenna array with low overhead. Static mobility signals in all beams are not feasible, so MRS only needs to be turned on in the relevant beams and only when needed. The relevant beam is selected based on the UE location and previous beam coverage statistics of different candidate beams based on the Self-Organizing Network (SON) database. When the serving beam quality degrades, the SON data can also be used to trigger a mobility measurement session without the need for continuous neighbor beam quality comparisons.

Evaluations also showed that sudden beam loss is possible due to shadow fading (e.g., when turning a street corner). Active Mode Mobility (AMM) solutions include features that help avoid or quickly recover from sudden link degradation or out-of-sync conditions.

The AMM solution includes both low-layer procedures (mobility triggering, measurements, beam selection, RS design and robustness) and RRC topics (beam identification management, inter-node switching and other high-layer aspects). The AMM solution mainly supports beam switching within a node and between different nodes using measurements on MRS. Note that the procedures described in this section can be used to change the beam within a node that uses CSI-RS for measurements. Or more precisely: beam switching using CSI-RS can be used in situations where the data plane does not have to be rerouted and resynchronization does not need to be performed. In these cases, the CSI-RS-based procedures are more streamlined and are also completely transparent to the UE.

Furthermore, the AMM solution distinguishes between link beams and mobility beams. Link beams are beams used for data transmission, while mobility beams are used for mobility purposes.

The NR system should provide a seamless service experience for users who are moving, aiming to support seamless mobility with minimal resource usage. As mentioned above, there is a dormant mode (referred to as the RRC_CONNECTED dormant state above) and an active mode (referred to as the RRC_CONNECTED active state above) in NR, which means that mobility includes dormant mode mobility and active mode mobility. Mobility in dormant mode (location update and paging) will be discussed in detail below. In this section, only active mode mobility within NR is handled. A description of the reference signals used for the mobility process is given above.

Mobility solutions should prioritize specific needs, including one or more of the following:

- The mobility solution should support movement between beams without any packet loss. (In LTE, packet forwarding is used - some temporary extra latency is OK, but packet loss is not.)

- The mobility solution should support multiple connections, where coordination features are available for nodes connected via excellent backhaul (e.g., dedicated fiber) as well as via relaxed backhaul (e.g., 10ms and above latency for wired or wireless).

- The mobility solution should be applicable to both analog beamforming and digital beamforming.

- Mobility and UE measurements shall be applicable to both synchronized and unsynchronized access nodes.

- The mobility solution should support radio link failure detection and recovery actions for UEs. The mobility solution should support mobility between NR and all existing RATs, with tighter integration between NR and LTE leveraging short inter-RAT handover interruption times.

Ideal design principles for active-mode mobility include one or more of the following:

- A mobility framework built with configurable capabilities should be used.

- The mobility solution should have the flexibility that downlink and uplink mobility can be triggered and executed independently of each other.

- For active mode, the mobility solution should as a general rule be network controlled, with UE control of network configuration being used to the extent that large gains have been demonstrated.

- Mobility-related signaling should follow the principle of minimalism. Preferably, it should occur on demand to minimize measurement signal transmission. Mobility-related signaling overhead and measurement overhead should be minimized.

- The mobility solution should always maintain a good enough link between the terminal and the network (as opposed to "always in the best state").

- Mobility solutions should work independently of the "transport mode".

Multi-antenna transmission already plays an important role in current mobile communications and is even more important in NR to provide high data rate coverage. The challenge of active mode mobility in NR is related to supporting high-gain beamforming. When the link beam is relatively narrow, the mobility beam should track the UE with high accuracy to maintain a good user experience and avoid link failures.

NR’s downlink mobility concept is beam-based. In deployments with large antenna arrays and many possible candidate beam configurations, it is not possible for all beams to transmit reference and measurement signals in a static manner that is always on. Instead, the connected access node selects a set of relevant mobility beams to transmit when needed. Each mobility beam carries a unique mobility reference signal (MRS). The UE is then instructed to take measurements on each MRS and report back to the system. From the UE’s perspective, the process is independent of how many access nodes are involved. As a result, the UE does not have to care which access node is transmitting which beam; this is sometimes referred to as the UE being node-agnostic and mobility being UE-centric. For mobility to work effectively, the access nodes involved need to maintain beam neighbor lists, exchange beam information, and coordinate MRS usage.

Tracking a moving UE is achieved by the UE measuring and reporting the quality of relevant candidate beams, allowing the system to select a beam for data transmission based on measurements and proprietary criteria. In this context, the term beam switching is used to describe the event when an access node updates parameters (e.g., the transmission point and direction of a beam). Therefore, intra-access and inter-access node beam switching can be considered beam switching. As a result, switching in NR is performed between beams rather than between cells as in traditional cellular systems.

The beam types discussed in this section are primarily mobility beams, which are entities that are updated during mobility. In addition to mobility beams, there is also a type of "geofencing" beam that can simplify inter-node mobility in some deployments.

The following sections describe downlink mobility: selecting the beam/node for downlink transmission. One section describes mobility based on downlink measurements, and one section describes mobility based on uplink measurements. So far, it has been assumed that the same beam/node is used for uplink communication. However, in some cases, it may be advantageous to use different beams/nodes for downlink and uplink communication. This is called uplink/downlink decoupling. In that case, a separate process can be used to select the best uplink beam/node. Uplink measurements are used to select the uplink beam/node, and the above process is used with minimal changes.

Several detailed studies have been conducted on the selection of mobility solutions, and all of these concepts follow a common mobility framework that can be summarized at a high level in Figure 11, which shows a general active mode mobility (downlink measurement-based) procedure. After the decision to trigger beam switching is made, a set of candidate beams are selected for activation and measurement. These beams can originate from the serving access node and potential target access nodes. The measurements are based on the Mobility Reference Signal (MRS) transmission in the mobility beam. After the UE reports the measurement results to the network, the network decides on the target beam and optionally notifies the UE of the selected target beam. (Alternatively, the UE can be actively configured to autonomously have the candidate beam with the best measurement results and then send a measurement report to the target beam.) The process includes one or more of the following:

UE side:

- Measurement configuration. The UE receives from the network the mobility configuration of the MRS to be measured (or the UE can also perform a blind search without a configuration list), when to measure, how to measure, and how to report. Measurement configuration can be performed in advance (and continuously updated).

- Measurement. After receiving a measurement activation that indicates to start measuring some or all items in the measurement configuration, the UE performs mobility measurement.

-Measurement report. UE sends mobility measurement report to the network

-Mobility enforcement.

o The UE may receive a request to send USS in the uplink to perform timing advance (TA) measurement and send the USS. The request to send the USS may be part of the measurement configuration.

The UE may receive a command (reconfiguration) to perform beam switching, which may include a new beam ID and a TA adjustment command. The switching command may also be notified first, and the TA may be measured and adjusted in the target node.

o Alternatively, the UE may not receive the handover command if downlink synchronization and uplink TA remain valid and no additional configuration (new DMRS, security, etc.) is needed or can be notified via the target node.

Network side:

-Measurement Configuration: The network sends the mobility measurement configuration to the UE.

- Mobility trigger. The network determines whether to trigger the beam switching process.

- Mobility measurement. The network decides to perform the mobility measurement process, including:

ο Neighbor selection: The network selects candidate beams.

o Measurement configuration: If the measurement configuration is not configured in step 1, the network sends the measurement configuration to the UE.

o Measurement activation: The network activates the MRS in the relevant beam and sends a measurement activation command to the UE.

o Measurement report. The network receives a measurement report from the UE.

-Mobility enforcement.

o The network may send a USS request command (reconfiguration) to the UE to send USS for TA measurement.

o The target node may measure the TA value and send the value to a node communicating with the UE which will send the TA configuration to the UE.

o The network can send a beam switching (reconfiguration) command to the UE.

The network may send the measurement configuration to the UE before triggering the beam switching procedure (step 1) or after (during step 3).

The outlined sequence can be configured with appropriate settings to serve as a common framework for all active mode mobility related operations: first beam discovery, triggering beam mobility updates in data transmission and monitoring modes, and continuous mobility beam tracking.

The configuration of the general downlink active mode mobility procedure for a UE moving from serving access node 1 (SAN1) to SAN2 as shown in FIG11 is described in the following section.

The network can send a mobility measurement configuration to the UE. This configuration is sent in an RRC message and may contain information related to the measurement event - "what" to measure (e.g., which MRS index), "when" and "how" to measure (e.g., start time or criteria and filtering duration), or "when" and "how" to send a measurement report (e.g., reporting time slot, reporting the best beam ID or its power, etc.). This list may be useful if only a small number of MRSs are turned on and can be measured. However, sending the list is optional for the network NW and the UE may perform measurements blindly, e.g., detecting all audible MRS signals. Another example of configurability may be inter-node measurements, where longer filtering may be required to avoid ping-pong effects. For intra-node beam measurements, a short filter is used.

The measurement configuration can be sent by the network at any time. Typically, once the UE receives the configuration, it starts performing measurements. However, the process can be further enhanced by sending an activation command in the Downlink Control Information (DCI) field. Thus, the RRC message will only configure the measurement, but it may not be necessary to start the UE to start performing such measurements.

The UE sends measurement reports based on the configuration provided by the network. Measurement reports are typically sent as RRC messages to the network. However, in certain circumstances, certain types of reports can be sent via the MAC. Layer 3-based reporting allows for reporting of varying numbers of beams simultaneously, allowing for faster selection of the preferred beam. However, this requires more signaling overhead and makes it difficult to integrate beam switching with the scheduler. Layer 2-based reporting offers less overhead and is easier to integrate with the scheduler. However, a fixed maximum number of beam measurements can be reported simultaneously.

MRS transmission and measurements are triggered based on the link beam/node quality observed when data transmission is ongoing, mobility beam quality in the absence of data, or reports sent by the UE. Other triggers (e.g., load balancing) may also trigger mobility measurements to be performed.

There are different triggering metrics and different conditions. The metric that reflects beam quality is RSRP or SINR. The condition can be one or more of the following:

-a1) compare with an absolute value

-a2) Compare multiple relative values based on position with the reference table

-a3) compare with the values of other beams, or

-a4) Link beam quality degradation rate. A practical triggering mechanism that reacts to changes in the current quality metric is also demonstrated.

The observed beam can be one or more of the following:

-b1) Current serving link beam (DMRS or CSI-RS),

-b2) the current serving link beam plus its "sector" beams,

-b3) Current Serving Mobility Beam (MRS).

Different types of handover (e.g., intra-node or inter-node) can have different thresholds. For example, when link quality falls below threshold 1, intra-node beam handover is triggered. When link quality falls below threshold 2, inter-node beam evaluation and handover is triggered. If there is a good backhaul (e.g., dedicated fiber) and ping-pong is not a problem, the same parameters can be used for both intra-node and inter-node.

When the network decides that the serving beam/node identity needs to be changed/updated/modified, the network prepares the mobility procedure. This may mean some communication with other nodes in the network.

There are several options for reporting MRS measurements to the network:

-c1) If the UE reports all measurements to the serving node, the serving node determines the node to hand over to and signals this to the UE. This method relies on the existing serving link for all signaling during the mobility procedure. The TA towards the new serving beam is estimated in conjunction with the handover command.

-c2) If the UE reports measurements back to various nodes from which different MRSs originate, the report itself requires the previous USS transmission and TA estimation—then it is considered part of the measurement process. Once the network decides on a new serving node and signals this to the UE, the UE uses the already available TA for the new serving node. This approach requires more uplink signaling, but removes the strict dependency on the old serving link once the measurement command has been issued.

- c3) is similar to c2), but the UE reports all measurements via the serving beam and via the best measured new beam. Then, the TA estimation procedure should be performed only once.

Eventually, the network can request the UE to apply the new configuration. There may be cases where the reconfiguration is transparent to the UE, for example, in an intra-node beam handover. Reconfiguration then occurs on the network side, and the serving beam/node may change; however, the UE retains the existing configuration. If reconfiguration is required, it can be done before or after the handover.

Typically, MRS transmits only on demand. The network decides which candidate beams or neighbor beams should be activated. Candidate beam selection can be based on, for example, a beam relation lookup table. This neighbor lookup table is indexed by the UE's location or radio fingerprint. The location can be exact (e.g., Global Positioning System (GPS) information) or approximate (current serving beam information). Creating and maintaining neighbor lookup tables is a generalization of the Automatic Neighbor Relation (ANR) management process, handled by the SON function in the network. These tables are used both to provide trigger criteria for initiating a measurement session toward a given UE and to determine relevant candidate beams for measurement and possible beam switching. The beams in the lookup table can be common mobility beams or "sector" beams. The size of the neighbor beam relation table can be reduced; from a memory and signaling consumption perspective, if the candidate beams are wide and the number of beams is low. In some network deployments, such as deploying NR in LTE bands or in highly loaded and frequently handover-prone areas, it may be preferable to configure the MRS to always be on so that many UEs potentially covered by the same mobility beam can continuously track the quality of neighbor beams.

In order to report MRS measurements to a node other than the serving node and to resume uplink data transmission towards the new serving node, the UE needs to apply the correct timing advance, which is usually different from the TA of the current serving node. In asynchronous networks, TA estimation always needs to be performed. USS transmission is then configured according to the measurement in the MRS measurement command or statically configured by RRC. This also applies to synchronous macro NWs, where the inter-site distance (ISD) exceeds or is comparable to the CP length.

On the other hand, in a tightly synchronized network with a short ISD (inter-site distance), the TA towards the old serving node may also work well for the new serving node. The UE can infer whether this is the case: whether the old downlink timing synchronization is applicable to the new node. It is effective not to make a new TA estimation unless it is really necessary. The network-controlled approach is that the network configures the UE to send USS (or not send USS) on a per-measurement basis in the MRS measurement command. If the network estimates that the old node and the new node can share the same TA value, the TA is not estimated, otherwise the UE is requested to send USS. Alternatively, in the UE-controlled approach, if the UE determines that resynchronization is not required to measure the MRS of the new node, the UE can omit sending USS in the uplink. Here, the node still needs to reserve resources for USS reception.

If the TA is to be changed, it is transmitted using dPDCH or PCCH over the old serving beam or from the new node (where the downlink is already "operating" because the UE is already synchronized with the MRS).

In the MRS reporting solution c1 above, the USS may be sent in the uplink and the TA update in the downlink may be sent as part of the beam switching command and handshake.

In the above MRS reporting solutions c2 and c3, the UE sends the USS to the MRS sending node as part of the measurement reporting procedure and receives the TA update as a separate message.

In some deployments where the UE position can be determined with high accuracy, the TA correction required when switching from an old serving beam to a new serving beam can be retrieved from a previously collected database. The database is created based on previous TA measurements managed according to SON principles.

The mobility measurement sequence is essentially the same as in LTE. The mobility monitoring and triggering sequences are similar to those in LTE, but some details differ, such as the criteria for sending and the UE-specific signals that can be used for mobility measurements. The MRS activation sequence, which dynamically activates the reference signal (MRS) in a UE-specific candidate beam set, is a new procedure in NR. Activating and deactivating MRSs on request and in a UE-specific manner is crucial for a minimalist design. The main new challenge in NR is that the network decides which candidate MRSs to activate and when. The latter aspect can be particularly important at high frequencies due to shadow fading. When activating candidate beams in several different nodes, some preparation and signaling may be required in the network. However, the process is transparent to the UE. The UE is only notified of the measurement configuration and reports accordingly, without associating the beam with a specific node. After the initial notification of the handover command, the TA update sequence can also be measured and adjusted in the target node. In addition, additional reconfiguration may be required.

The beam switching triggering process varies depending on the design and transmission method of the MRS. More specifically, there are three typical cases:

- Activate beam MRS only when the quality of the serving beam is detected to have degraded. Activate MRS for all relevant candidate beams in the lookup table, regardless of whether the beam is from the same node or from a neighboring node. Table construction can be part of the SON function. The UE measures all MRSs and sends a measurement report.

- All sector MRSs in the lookup table or the sector MRSs containing the serving beam for an active UE are periodically configured and transmitted. The UE may also track the quality of the transmitted sector MRSs and report the quality periodically or in an event-based manner.

- The serving mobility beam is adapted to continuously track the UE to maintain maximum beam gain, similar to the CSI-RS process. The UE reports the error signal between the current serving beam direction and the estimated best beam direction using other beams near the serving beam.

Case 1 is more suitable for services without strict QoS requirements, while case 2 is more suitable for time-critical services with additional overhead. (There are also hybrid options, such as activating all MRSs in the lookup table for a given UE with additional overhead.) In case 3, any modification of the beam shape within one node can be transparent to the UE using UE-specific reference symbols - no signaling is required unless RX analog beamforming is applied on the UE side.

Uplink measurements can also be used to select downlink beams. At a high level, it can be assumed that such measurements are performed on demand when beam switching is deemed necessary. Therefore, the concept of mobility events still applies and relies on some trigger to initiate the event.

Since the downlink beam is being updated, any of the measurements described in the previous section are still used to monitor the downlink performance. For example, the CQI measured on the CSI-RS or MRS can be monitored.

Using uplink measurements to select an access node for downlink transmission generally works well if different access nodes use the same transmit power and have the same antenna capabilities. Otherwise, compensation needs to be made.

In order to select downlink beams using uplink measurements within a node, reciprocity between the uplink and downlink is desired. Passive antenna components and the propagation medium are physically reciprocal for TX and RX, but active components and radio frequency (RF) filters in the RX and TX paths typically exhibit asymmetries and phase variations that do not result in automatic reciprocity in all cases. However, by introducing additional hardware design constraints and calibration procedures, any desired degree of reciprocity can be provided.

To obtain uplink measurements, the network requests the UE to send an uplink reference signal to the network. One possible reference signal used for mobility measurements is the USS. The USS can be detected not only by the serving node but also by neighboring nodes. Neighboring nodes should maintain transmissions for the UE they are serving to clear transmission resources where USS will occur.

If the coverage situation is challenging, the UE may need to use TX beamforming to send USS. In this case, the UE is required to send USS in all candidate directions, and different USS identifiers can be assigned to different uplink TX beams in the UE side so that the network can feed back the best UE TX beam identifier. If the UE cannot transmit in more than one direction at the same time, the beam transmission can be time multiplexed. The USS can be sent from the UE periodically or event-triggered (when the quality of the link beam degrades). Due to the irregular UE antenna array layout, this beam scanning configuration is more complex in the uplink than in the downlink. The appropriate scanning pattern can be determined in several ways using previous calibration of the UE or on-the-fly learning.

In the network, candidate access nodes attempt to detect USSs in different beams and select the best one. If the network uses analog beamforming, nodes cannot perform measurements on numerous beams in a single USS cycle. Access nodes can sequentially scan USSs using different RX beams. Coordination of the UE TX and access node RX beam scanning patterns is complex. This combination should only be considered if coverage requirements are met.

There are some requirements for signaling between the UE and the network, including, for example, the number of USSs used in the UE and the repetition period of network scanning. It can be assumed that the same procedure as for MRS configuration is adopted: USS transmission parameters are configured using RRC and transmission is activated using MAC.

There are several alternative methods to perform downlink beam switching based on uplink measurements:

- Narrow (link) beams can be selected directly based on uplink measurements.

- Beam selection based on uplink measurements determines the mobility beam, and narrow beams can be selected later based on supplementary downlink measurements.

- The mobility beam is first determined by uplink measurements with a wider RX beam. Afterwards, the narrow beam can be further determined by uplink measurements with a narrow RX beam. When a narrow beam is determined, another RS can be measured in a narrow beam located within or near the selected RX beam in the first part.

In the three beam switching alternatives listed above, the beam selection process (beam selection in the first alternative; wide beam selection in the second and third alternatives) is similar. An example beam selection process is shown in Figure 12. The beam selection process based on uplink measurements can be briefly described as follows:

- Trigger beam switching

- Activate USS reception between neighboring nodes in the relevant beam

- Activate USS transmission in UE

-Perform USS measurements in the network

- Determine the best beam based on measurement reports

- Prepare for beam switching if necessary

- Issue beam switching commands if necessary

As mentioned previously, USS can be sent from the UE periodically or in an event-triggered manner. If USS is sent periodically according to an earlier configuration, steps 1-3 can be omitted. If a timing advance update is required, the TA value can be obtained from the USS measurement, and the new TA value can be notified to the UE during the beam switching command.

There is only one small difference with the narrow (link) beam selection that follows mobility beam selection in the third downlink beam switching alternative listed above, where beams from neighboring nodes are not involved. It is an intra-node beam selection, as shown in Figure 13. Here, "USS" can also be other types of references, such as RRS. The supplementary downlink measurement in the second alternative above is similar to the intra-node beam switching in Case 2 of the downlink measurement-based approach.

This section describes several additional techniques that complement the above techniques. In various embodiments, any one or more of these additional techniques can be implemented with any combination of the above techniques.

In NR, the amount of CSI typically increases with the number of antennas/beams, which means that the number of beam/hypothesis evaluations performed by the UE may increase accordingly. This in turn will lead to an increase in UE power consumption.

One way to address this issue and thereby reduce UE power consumption is to have at least two reporting modes for CSI. One mode is one in which the UE or other wireless device seeks the "best" transmission configuration. This may be considered a "default" or "legacy" mode. The other mode may be referred to as a "low power mode" and is based on the use of a threshold on the quality of the reported CSI (e.g., PMI). In this mode, the UE reports (to the wireless network) the first CSI/PMI that meets the quality threshold requirement. Thus, instead of finding the absolute best possible transmission configuration, the UE finds a transmission configuration that is sufficient to meet the quality threshold requirement and reports that transmission configuration, reducing UE power consumption by not necessarily seeking the absolute best possible transmission configuration. In some embodiments, the UE may select the threshold for the quality of the reported CSI itself based on a pre-programmed quality threshold or other selection criteria. In an alternative embodiment, the UE may receive an indication of a threshold for the quality of the reported CSI from the network and select the indicated threshold.

In some embodiments, for example, the low power mode may involve the UE scanning only a subset of the PMIs. The low power mode may also involve the UE shutting down one or more receiver/transmitter chains, or more generally, switching one or more receiver and/or transmitter circuits to a low power state when operating in the low power mode, such that the circuits consume less power in this low power state relative to the power consumption in the default mode. The low power mode allows stopping the evaluation of beams after a sufficiently good beam is found, thereby saving power. The advantage of this approach is that for most signaling of small packets, the UE can use a CSI reporting mode that saves a lot of energy.

In NR, a UE operating in sleep mode (e.g., RRC_CONNECTED sleep state) searches for synchronization signals and other system information, as described in detail in the above section. In systems using beamforming, the UE searches for these synchronization signals and other system information across a range of possible resources, where the range covers various combinations of time, frequency, and spatial beams. Note that this freedom regarding resources does not exist in LTE.

A potential problem with this is that a dormant UE may need to remain awake for longer periods of time to perform this search than when operating in LTE. This may have a negative impact on the UE's power consumption.

In some embodiments, this problem can be solved by having the UE (return) back to "sleep" once it receives good enough system information and/or synchronization, where "good enough" is determined by meeting a predetermined threshold or multiple predetermined thresholds, without having to search the entire predetermined search interval. This approach allows the UE to achieve power savings, especially in environments with good signals.

Figure 14 is a process flow diagram illustrating an example method according to the method. As shown in block 1410, the method begins by performing measurements and/or demodulation/decoding of synchronization and/or system information on one of a predetermined set of resources, where the resources are defined by one or more of beam, timing, and frequency. As shown in block 1420, the method also includes determining whether sufficient synchronization and/or system information has been obtained as a result of measuring and/or demodulating/decoding the current resource. If so, the method also includes, as shown in block 1430, performing one or more actions based on the measurement (if and to the extent such action is required) and returning to "sleep", where "sleep" is simply a low-power operating mode of the UE circuitry compared to an operating mode in which measurements are actively performed. On the other hand, if it is determined that sufficient synchronization and/or information has not been obtained, the next resource from the predetermined set of resources is allocated, as shown in block 1440, and the measurement and/or demodulation/decoding steps shown in block 1410 are repeated.

An advantage of this technique is that UE power consumption in sleep mode can be reduced, in some cases to a lower level than achieved in conventional LTE operation. Note that "sleep mode" as used herein generally refers to a mode in which a wireless device intermittently activates receiver circuitry to monitor and/or measure signals, deactivating at least some portions of the receiver circuitry between these monitoring/measurement intervals. These periods of deactivation of some portions of the circuitry may be referred to as "sleep" periods. In the discussion above, NR is described as having a sleep mode referred to as the RRC_CONNECTED sleep state. However, it should be understood that there may be one or more sleep modes supported by any given network, and their names may vary.

FIG15 shows another example process involving a UE sleep mode measurement process, wherein a cell information signal according to beamforming is received and processed.

The UE in sleep mode triggers a measurement occasion based on any of a variety of triggers, as shown in block 1510. For a typical cellular system, this may be periodic, with a period of approximately 1 second.

As shown in block 1520, the UE forms a list of cell information signals and corresponding radio resources, where the list represents those signals and resources that it already knows about or that it knows may exist. The radio resources may be beams, time intervals, and other groups of radio resources (e.g., OFDM resource elements) where cell information signals may exist.

As represented by block 1530, the UE sorts the resource and signal lists in order, for example, based on, but not limited to, the following:

- Radio resource timing (first signaled first etc.)

- Known signal quality or measurement properties from previous measurement opportunities

- Information on the likelihood of usefulness from other sources, cell neighbor lists, other measurements, etc.

The sorting order is such that the highest priority cell information signal (or resource) is listed first.

The UE receives the radio resource of the first item in the list using its radio receiver, as shown in block 1540. Upon receiving this information, signal processing of previously collected measurements of the resource may still be in progress.

As represented by block 1550, the UE measures protected signal properties from the collected radio resources.

These may include (but are not limited to) any one or more of the following:

-Received signal power

-Received signal SINR or SNR

- Decodability of cell information

-Decode messages such as paging messages from cellular networks.

As shown in block 1560, the UE determines whether the measurement values collected so far are "good enough" to stop the measurement and cell search activities based on one or more of the measured signal properties from 1550. If not, the measurement continues, as shown in block 1540. "Good enough" generally means meeting one or more predetermined criteria, which may include one or more of the following:

-Received power, SINR, or SNR is above a certain threshold

-Can correctly decode the cell information

-Something in the cell information indicates that a mode change is required (eg paging indication).

Furthermore, “good enough” may be that a given number (eg, 3) of the measured cells are detected as “good cells”.

Determining that the measurement signal is "good enough" results in the end of the measurement opportunity, as represented by block 1570. The UE then resumes its normal procedures, which may include reporting measurements, deactivating one or more receiver circuits, and the like.

The key aspect of the solution shown in Figure 15 is that the UE in the cellular system has beamformed cell information and is in sleep mode, collecting measurements at each measurement opportunity until the collected information is "good enough." This allows the UE to save power by returning to sleep before exhaustively searching all possible cell information signals.

Figure 16 shows another example method implemented by a UE or other wireless device for operating in a wireless communication network. This method is similar in at least some respects to the method shown previously - it should be understood that features of this method can be mixed and matched with features of the above methods as appropriate.

The method shown in FIG. 16 is performed when the UE is operating in a sleep mode, wherein operating in the sleep mode includes intermittently activating the receiver circuit to monitor and/or measure signals. The sleep mode may be, for example, the RRC_CONNECTED sleep state discussed above. While in this sleep mode and when the receiver circuit is activated, the UE performs the steps shown in FIG. 16 .

As shown in block 1610, the UE performs measurements on each of a plurality of resources from a predetermined set of resources, or demodulates and decodes information on each of a plurality of resources from a predetermined set of resources, wherein the resources in the predetermined set of resources are each defined by one or more of a beam, timing, and frequency. In some embodiments, the resources in the predetermined set of resources are each defined as a beam. Each of these beams can represent a receiver beam (where the UE "listens" in different directions using a specific combination of antennas and combined weights) or a specific transmitter beam formed by an access node, or a combination of both.

As shown in block 1620, the method further includes evaluating the measurement or demodulated and decoded information for each of the plurality of resources against a predetermined criterion. Subsequently, as shown in block 1630, in response to determining that the predetermined criterion is met, the UE discontinues the performance and evaluation of the measurement, or discontinues the demodulation and decoding of the information and the evaluation thereof, such that neither measurement nor demodulation and decoding of one or more resources in the predetermined set of resources is performed. Finally, as shown in block 1640, the method further includes deactivating the activated receiver circuitry in response to determining that the predetermined criterion is met. In some embodiments, the steps in this figure may be repeated upon the next occurrence of a triggering event for reactivating the receiver circuitry, such as upon periodic expiration of a sleep mode timer.

In some embodiments, the predetermined criteria include one or more of: a received power level or a measured signal-to-interference-plus-noise ratio (SINR) or signal-to-noise ratio (SNR) above a predetermined threshold for one or a predetermined number of resources; being able to correctly decode cell information from one or a predetermined number of resources; and decoded information from one or a predetermined number of resources indicating a change in operation of the wireless device.

In some embodiments, the interruption is performed in response to determining that one of the resources meets a predetermined criterion. In some embodiments, the method further comprises, prior to said executing or demodulating and decoding, and prior to said evaluating, interrupting and deactivating, determining a priority order (from highest to lowest) of the predetermined set of resources, wherein said executing or demodulating and decoding is performed according to the priority order (from highest to lowest). Determining the priority order of the predetermined set of resources may be based on any one or more of the following, for example: radio resource timing of one or more resources; and measured signal quality or measurement attributes from previous measurements for one or more resources. In some embodiments, determining the priority order of the predetermined set of resources is based on information about the likelihood that one or more resources are useful, which information is received from other sources or a cell neighbor list.

In this section, some of the many detailed techniques and processes described above are summarized and applied to specific methods, network nodes, and wireless devices. Each of these methods, network nodes, and wireless devices, as well as the numerous variations thereof described in the more detailed description above, can be considered embodiments of the present invention. It should be understood that the specific groupings of these features described below are examples—other groupings and combinations are possible, as demonstrated in the previous detailed discussion.

Note that in the following discussion and the appended claims, the use of the labels "first," "second," "third," etc. is merely meant to distinguish one item from another and should not be construed as indicating a particular order or priority unless the context clearly indicates otherwise.

As used herein, a "wireless device" refers to a device that is capable of, configured to, arranged to, and/or operable to wirelessly communicate with a network device and/or another wireless device. In this context, wireless communication involves sending and/or receiving wireless signals using electromagnetic signals. In certain embodiments, a wireless device can be configured to send and/or receive information without direct human interaction. For example, a wireless device can be designed to send information to a network on a predetermined schedule when triggered by an internal or external event, or in response to a request from the network. In general, a wireless device can refer to any device that is capable of, configured to, arranged to, and/or operable for wireless communication, such as a radio communication device. Examples of wireless devices include, but are not limited to, user equipment (UE) such as a smartphone. Other examples include wireless cameras, wireless-enabled tablets, laptop embedded devices (LEEs), laptop mounted devices (LMEs), USB dongles, and/or wireless client equipment (CPEs).

As a specific example, a wireless device may refer to a UE that is configured for communicating in accordance with one or more communication standards promulgated by the Third Generation Partnership Project (3GPP) (e.g., 3GPP's GSM, UMTS, LTE, and/or 5G standards). As used herein, a "user equipment" or "UE" does not necessarily have a "user" in the sense of a human user who owns and/or operates the associated device. Rather, a UE may refer to a device that is intended to be sold to or operated by a human user but that may not initially be associated with a specific human user. It should also be understood that in the previous detailed discussion, for convenience (and even more generally), the term "UE" is used to include, in the context of an NR network, any type of wireless device that accesses and/or can be served by an NR network, regardless of whether the UE is associated with a "user" itself. Thus, the term "UE" used in the above detailed discussion includes, for example, machine type communication (MTC) devices (sometimes referred to as machine-to-machine or M2M devices), as well as mobile phones or wireless devices that may be associated with a "user."

Some wireless devices may support device-to-device (D2D) communication, for example by implementing the 3GPP standard for sidelink communication, and in this case may be referred to as D2D communication devices.

As another specific example, in an Internet of Things (IoT) scenario, a wireless device may represent a machine or other device that performs monitoring and/or measurement and sends the results of such monitoring and/or measurement to another wireless device and/or network device. In this case, the wireless device may be a machine-to-machine (M2M) device, which may be referred to as a machine type communication (MTC) device in the 3GPP context. As a specific example, the wireless device may be a UE that implements the 3GPP Narrowband Internet of Things (NB-IoT) standard. Specific examples of such machines or devices are sensors, metering devices (e.g., power meters), industrial machines, or household or personal appliances (e.g., refrigerators, televisions, personal wearable devices such as watches, etc.). In other scenarios, a wireless device may represent a vehicle or other device that is capable of monitoring and/or reporting its operating status or other functions associated with its operation.

As described above, wireless device can represent the end point of wireless connection, in which case, the device can be referred to as wireless terminal.In addition, as described above, wireless device can be mobile, in which case, it can also be referred to as mobile device or mobile terminal.

While it will be understood that specific embodiments of wireless devices discussed herein may include any of various suitable combinations of hardware and/or software, in specific embodiments, a wireless device configured to operate in the wireless communication network described herein and/or in accordance with the various techniques described herein may be represented by the example wireless device 1000 shown in FIG. 17 .

As shown in FIG17 , an example wireless device 1000 includes an antenna 1005, a radio front-end circuit 1010, and a processing circuit 1020. In the example shown, the processing circuit 1020 includes a computer-readable storage medium 1025 (e.g., one or more memory devices). The antenna 1005 may include one or more antennas or antenna arrays and is configured to transmit and/or receive wireless signals and is connected to the radio front-end circuit 1010. In some alternative embodiments, the wireless device 1000 may not include the antenna 1005. Instead, the antenna 1005 may be separate from the wireless device 1000 and may be connected to the wireless device 1000 via an interface or port.

For example, radio front-end circuitry 1010, which may include various filters and amplifiers, is connected to antenna 1005 and processing circuitry 1020 and is configured to condition signals communicated between antenna 1005 and processing circuitry 1020. In certain alternative embodiments, wireless device 1000 may not include radio front-end circuitry 1010; instead, processing circuitry 1020 may be connected to antenna 1005 without radio front-end circuitry 1010. In some embodiments, radio frequency circuitry 1010 is configured to, in some cases, simultaneously process signals in multiple frequency bands.

The processing circuitry 1020 may include one or more of a radio frequency (RF) transceiver circuitry 1021, a baseband processing circuitry 1022, and an application processing circuitry 1023. In some embodiments, the RF transceiver circuitry 1021, the baseband processing circuitry 1022, and the application processing circuitry 1023 may be located on separate chipsets. In alternative embodiments, part or all of the baseband processing circuitry 1022 and the application processing circuitry 1023 may be combined into one chipset, and the RF transceiver circuitry 1021 may be located on a separate chipset. In other alternative embodiments, part or all of the RF transceiver circuitry 1021 and the baseband processing circuitry 1022 may be located on the same chipset, and the application processing circuitry 1023 may be located on a separate chipset. In other alternative embodiments, part or all of the RF transceiver circuitry 1021, the baseband processing circuitry 1022, and the application processing circuitry 1023 may be combined in the same chipset. The processing circuit 1020 may include, for example, one or more central processing units (CPUs), one or more microprocessors, one or more application specific integrated circuits (ASICs), and/or one or more field programmable gate arrays (FPGAs).

In specific embodiments, some or all of the functionality described herein with respect to user equipment, MTC devices, or other wireless devices may be embodied within the wireless device, or alternatively, may be embodied by processing circuitry 1020 executing instructions stored on a computer-readable storage medium 1025, as shown in FIG17 . In alternative embodiments, some or all of the functionality may be provided by processing circuitry 1020 without executing instructions stored on a computer-readable medium, such as in a hardwired manner. In any of those specific embodiments, processing circuitry 1020 may be configured to perform the described functionality regardless of whether or not executing instructions stored on a computer-readable storage medium. The benefits provided by such functionality are not limited to processing circuitry 1020 or to other components of the wireless device, but are enjoyed by the wireless device as a whole and/or generally by the end user and the wireless network.

The processing circuit 1020 may be configured to perform any of the determination operations described herein. The determination performed by the processing circuit 1020 may include processing information obtained by the processing circuit 1020, for example, by converting the obtained information to other information, comparing the obtained information or the converted information to information stored in the wireless device, and/or performing one or more operations based on the obtained information or the converted information, and making a determination as a result of the processing.

The antenna 1005, the radio front-end circuit 1010, and/or the processing circuit 1020 can be configured to perform any of the transmit operations described herein. Any information, data, and/or signals can be transmitted to a network device and/or another wireless device. Similarly, the antenna 1005, the radio front-end circuit 1010, and/or the processing circuit 1020 can be configured to perform any of the receive operations described herein as being performed by a wireless device. Any information, data, and/or signals can be received from a network device and/or another wireless device.

Computer-readable storage medium 1025 generally operates to store instructions, such as computer programs, software, applications including one or more of logic, rules, code, tables, etc., and/or other instructions that can be executed by a processor. Examples of computer-readable storage medium 1025 include computer memory (e.g., random access memory (RAM) or read-only memory (ROM)), mass storage media (e.g., a hard disk), removable storage media (e.g., a compact disk (CD) or a digital video disk (DVD)), and/or any other volatile or non-volatile, non-transitory computer-readable and/or computer-executable storage device that stores information, data, and/or instructions that can be used by processing circuit 1020. In some embodiments, processing circuit 1020 and computer-readable storage medium 1025 can be considered integrated.

Alternative embodiments of the wireless device 1000 may include additional components beyond those shown in FIG. 17 , which may be responsible for providing certain aspects of the functionality of the wireless device, including any of the functionality described herein and/or any functionality required to support the solutions described above. As just one example, the wireless device 1000 may include input interfaces, devices, and circuitry, as well as output interfaces, devices, and circuitry. The input interfaces, devices, and circuitry are configured to allow information to be input into the wireless device 1000 and are connected to the processing circuitry 1020 to allow the processing circuitry 1020 to process the input information. For example, the input interfaces, devices, and circuitry may include a microphone, proximity or other sensor, key/button, touch display, one or more cameras, USB port, or other input element. The output interfaces, devices, and circuitry are configured to allow information to be output from the wireless device 1000 and are connected to the processing circuitry 1020 to allow the processing circuitry 1020 to output information from the wireless device 1000. For example, the output interfaces, devices, or circuitry may include a speaker, display, vibration circuitry, USB port, headphone jack, or other output element. Using one or more input and output interfaces, devices, and circuits, the wireless device 1000 may communicate with end users and/or wireless networks, allowing them to benefit from the functionality described herein.

As another example, the wireless device 1000 may include a power supply circuit 1030. The power supply circuit 1030 may include power management circuitry. The power supply circuit may receive power from a power source, which may be included in the power supply circuit 1030 or external to the power supply circuit 1030. For example, the wireless device 1000 may include a power source in the form of a battery or battery pack that is connected to or integrated into the power supply circuit 1030. Other types of power sources, such as photovoltaic devices, may also be used.

As another example, the wireless device 1000 may be connected to an external power source (such as a power outlet) via an input circuit or an interface such as a cable, whereby the external power source provides power to the power circuit 1030 .

The power supply circuit 1030 may be connected to the radio front end circuit 1010 , the processing circuit 1020 , and/or the computer-readable storage medium 1025 , and configured to provide power to the wireless device 1000 (including the processing circuit 1020 ) for performing the functionality described herein.

The wireless device 1000 may also include multiple sets of processing circuits 1020, computer-readable storage media 1025, radio circuits 1010, and/or antennas 1005 for different wireless technologies (e.g., GSM, WCDMA, LTE, NR, WiFi, or Bluetooth wireless technologies) integrated into the wireless device 1000. These wireless technologies may be integrated into the same or different chipsets and other components within the wireless device 1000.

In various embodiments, the wireless device 1000 is adapted to perform any of the various combinations of features and techniques described herein. In some embodiments, for example, the processing circuitry 1020 (e.g., using the antenna 1005 and the radio front-end circuitry 1010) is adapted to, when operating in a sleep mode and with the receiver circuitry activated, perform measurements on each of a plurality of resources from a predetermined set of resources, or demodulate and decode each of a plurality of resources from a predetermined set of resources, wherein the resources in the predetermined set of resources are each defined by one or more of beam, timing, and frequency. The processing circuitry 1020 may also be adapted to evaluate the measured or demodulated and decoded information for each of the plurality of resources against predetermined criteria, and then, in response to determining that the predetermined criteria are met, interrupt the performance and evaluation of the measurements, or interrupt the demodulation and decoding and evaluation of the information, such that neither measurements nor demodulation and decoding are performed on one or more resources in the predetermined set of resources. The processing circuitry 1020 may also be adapted to deactivate the activated receiver circuitry in response to determining that the predetermined criteria are met.

Again, a wireless device adapted to operate in sleep mode according to any of the several techniques described above may also be adapted to perform one or more of the several other techniques described herein. Thus, for example, in some embodiments, resources in a predetermined set of resources may be individually defined as beams, and in various embodiments, the predetermined criteria may include one or more of the following: a received power level or a measured signal-to-interference-plus-noise ratio (SINR) or signal-to-noise ratio (SNR) is above a predetermined threshold for one or a predetermined number of resources; cell information can be correctly decoded from one or a predetermined number of resources; decoded information from one or a predetermined number of resources indicates a change in operation of the wireless device.

In some embodiments, the wireless device is adapted to perform said interruption in response to determining that one of the resources meets a predetermined criterion. In some of these and some other embodiments, the wireless device is further adapted to determine a priority order (from highest to lowest) of the predetermined sets of resources prior to said performing or demodulating and decoding, and prior to said evaluating, interrupting, and deactivating, wherein the wireless device is adapted to perform said performing or demodulating and decoding according to the priority order (from highest to lowest). In some of these latter embodiments, the wireless device is adapted to determine the priority order of the predetermined sets of resources based on one or more of: radio resource timing of the one or more resources; and measured signal quality or measurement attributes from previous measurements of the one or more resources. In some of these and some other embodiments, the wireless device is adapted to determine the priority order of the predetermined sets of resources based on information regarding the likelihood that the one or more resources are useful, the information being received from another source or a cell neighbor list.

As used herein, the term "network device" refers to a device that is capable of, configured to, arranged to, and/or operable to communicate directly or indirectly with a wireless device and/or with other devices in a wireless communication network, enabling and/or providing wireless access to the wireless device. Examples of network devices include, but are not limited to, access points (APs), in particular radio access points. A network device may represent a base station (BS), such as a radio base station. Specific examples of radio base stations include Node Bs and evolved Node Bs (eNBs). Base stations may be categorized based on the amount of coverage they provide (or, in other words, their transmit power level), and may then also be referred to as femto base stations, pico base stations, micro base stations, or macro base stations. "Network device" also includes one or more (or all) parts of a distributed radio base station, such as a centralized digital unit and/or a remote radio unit (RRU), sometimes referred to as a remote radio head (RRH). Such a remote radio unit may or may not be integrated with an antenna as an antenna-integrated radio. Some parts of a distributed radio base station may also be referred to as nodes in a distributed antenna system (DAS).

As a specific non-limiting example, the base station may be a relay node or a relay donor node that controls a relay.

Other examples of network devices include multi-standard radio (MSR) radio equipment such as an MSR BS, a network controller such as a radio network controller (RNC) or a base station controller (BSC), a base transceiver station (BTS), a transmission point, a transmission node, a multi-cell/multicast coordination entity (MCE), a core network node (e.g., a mobile switching center or MSC, a mobility management entity or MME), an operation and maintenance (O&M) node, an operation and support system (OSS) node, a SON node, a positioning node (e.g., an E-SMLC), and/or an MDT. However, more generally, a network device may represent any suitable device (or group of devices) capable of, configured to, arranged to, and/or operable to enable and/or provide wireless device access to a wireless communication network or to provide some service to a wireless device that has access to the wireless communication network.

As used herein, the term "radio network equipment" is used to refer to network equipment that includes radio capabilities. Thus, examples of radio network nodes are the radio base stations and radio access points discussed above. It should be understood that some radio network equipment may include distributed equipment - for example, the distributed radio base stations (with RRHs and/or RRUs) discussed above. It should be understood that various references herein to eNB, eNodeB, NodeB, etc. refer to examples of radio network equipment. It should also be understood that the term "radio network equipment" used herein may in some cases refer to a single base station or a single radio node, or to multiple base stations or nodes (e.g., at different locations). In some cases, this document may refer to "instances" of radio network equipment to more clearly describe certain scenarios involving multiple different embodiments or installations of radio equipment. However, the lack of reference to "instances" related to the discussion of radio network equipment should not be understood to mean that only a single instance is involved. Alternatively, a given instance of a radio network equipment may be referred to as a "radio network node," where the use of the word "node" indicates that the device in question operates as a logical node in the network, but does not mean that all components are necessarily located in the same location.

While a radio network device may include any suitable combination of hardware and/or software, FIG18 illustrates an example of an embodiment of a radio network device 1100 in greater detail. As shown in FIG18 , the example radio network device 1100 includes an antenna 1105, a radio front-end circuit 1110, and processing circuitry 1120. In the illustrated example, the processing circuitry 1120 includes a computer-readable storage medium 1025 (e.g., one or more memory devices). The antenna 1105 may include one or more antennas or antenna arrays and is configured to transmit and/or receive wireless signals and is connected to the radio front-end circuitry 1110. In certain alternative embodiments, the radio network device 1100 may not include the antenna 1005. Instead, the antenna 1005 may be separate from the radio network device 1100 and may be connected to the radio network device 1100 via an interface or port. In some embodiments, all or some portions of the radio front-end circuitry 1110 may be located in one or more locations separate from the processing circuitry 1120, such as in an RRH or RRU. Similarly, some portions of the processing circuitry 1120 may be physically separate from one another. The radio network device 1100 may further include a communication interface circuit 1140 for communicating with other network nodes, for example, with other radio network devices and with nodes in a core network.

For example, radio front-end circuitry 1110, which may include various filters and amplifiers, is connected to antenna 1105 and processing circuitry 1120 and is configured to condition signals communicated between antenna 1105 and processing circuitry 1120. In certain alternative embodiments, radio network device 1100 may not include radio front-end circuitry 1010; instead, processing circuitry 1020 may be connected to antenna 1005 without radio network device 1100. In some embodiments, radio frequency circuitry 1110 is configured to, in some cases, process signals in multiple frequency bands simultaneously.

The processing circuitry 1120 may include one or more of RF transceiver circuitry 1121, baseband processing circuitry 1122, and application processing circuitry 1123. In some embodiments, the RF transceiver circuitry 1121, baseband processing circuitry 1122, and application processing circuitry 1123 may reside on separate chipsets. In alternative embodiments, part or all of the baseband processing circuitry 1122 and application processing circuitry 1123 may be combined into a single chipset, and the RF transceiver circuitry 1121 may reside on a separate chipset. In other alternative embodiments, part or all of the RF transceiver circuitry 1121 and baseband processing circuitry 1122 may reside on the same chipset, and the application processing circuitry 1123 may reside on a separate chipset. In other alternative embodiments, part or all of the RF transceiver circuitry 1121, baseband processing circuitry 1122, and application processing circuitry 1123 may be combined in the same chipset. The processing circuitry 1120 may include, for example, one or more central CPUs, one or more microprocessors, one or more ASICs, and/or one or more on-site FPGAs.

In specific embodiments, some or all of the functionality described herein with respect to radio network devices, radio base stations, eNBs, and the like may be embodied within the radio network device, or alternatively, may be embodied by processing circuitry 1120 executing instructions stored on a computer-readable storage medium 1125, as shown in FIG18 . In alternative embodiments, some or all of the functionality may be provided by processing circuitry 1120 without executing instructions stored on a computer-readable medium, e.g., in a hardwired manner. In any of those specific embodiments, the processing circuitry may be configured to perform the described functionality regardless of whether or not instructions stored on a computer-readable storage medium are executed. The benefits provided by such functionality are not limited to processing circuitry 1120 or to other components of the radio network device, but are enjoyed by the radio network device 1100 as a whole and/or generally by end users and wireless networks.

The processing circuit 1120 may be configured to perform any of the determination operations described herein. The determination performed by the processing circuit 1020 may include processing information obtained by the processing circuit 1020, for example, by converting the obtained information into other information, comparing the obtained information or the converted information with information stored in the radio network device, and/or performing one or more operations based on the obtained information or the converted information, and making a determination as a result of the processing.

Antenna 1105, radio front-end circuitry 1110, and/or processing circuitry 1120 may be configured to perform any transmit operations described herein. Any information, data, and/or signals may be transmitted to any network device and/or wireless device. Similarly, antenna 1005, radio front-end circuitry 1010, and/or processing circuitry 1020 may be configured to perform any receive operations described herein as being performed by a wireless network device. Any information, data, and/or signals may be received from any network device and/or wireless device.

Computer-readable storage medium 1125 generally operates to store instructions, such as computer programs, software, applications including one or more of logic, rules, code, tables, etc., and/or other instructions that can be executed by a processor. Examples of computer-readable storage medium 1125 include computer memory (e.g., RAM or ROM), mass storage media (e.g., hard disk), removable storage media (e.g., CD or DVD), and/or any other volatile or non-volatile, non-transitory computer-readable and/or computer-executable storage device that stores information, data, and/or instructions that can be used by processing circuit 1120. In some embodiments, processing circuit 1120 and computer-readable storage medium 1125 can be considered integrated.

Alternative embodiments of the radio network device 1100 may include additional components beyond those shown in FIG. 18 , which may be responsible for providing certain aspects of the functionality of the radio network device (including any of the functionality described herein and/or any functionality required to support the solutions described above). As just one example, the radio network device 1100 may include input interfaces, devices, and circuitry, as well as output interfaces, devices, and circuitry. The input interfaces, devices, and circuitry are configured to allow information to be input into the radio network device 1100 and are connected to the processing circuitry 1120 to allow the processing circuitry 1120 to process the input information. For example, the input interfaces, devices, and circuitry may include a microphone, proximity or other sensor, keys/buttons, a touch display, one or more cameras, a USB port, or other input elements. The output interfaces, devices, and circuitry are configured to allow information to be output from the radio network device 1100 and are connected to the processing circuitry 1120 to allow the processing circuitry 1120 to output information from the radio network device 1100. For example, the output interfaces, devices, or circuitry may include a speaker, a display, a USB port, a headphone jack, or other output elements. Using one or more input and output interfaces, devices, and circuits, the radio network device 1100 may communicate with end users and/or wireless networks and allow them to benefit from the functionality described herein.

As another example, the radio network device 1100 may include a power supply circuit 1130. The power supply circuit 1130 may include power management circuitry. The power supply circuit 1130 may receive power from a power source, which may be included in the power supply circuit 1130 or external to the power supply circuit 1130. For example, the radio network device 1100 may include a power source in the form of a battery or battery pack that is connected to or integrated into the power supply circuit 1130. Other types of power sources, such as photovoltaic devices, may also be used. As another example, the radio network device 1100 may be connected to an external power source (such as a power outlet) via an input circuit or an interface such as a cable, whereby the external power source supplies power to the power supply circuit 1130.

The power supply circuit 1130 may be connected to the radio front end circuit 1110 , the processing circuit 1120 , and/or the computer-readable storage medium 1125 , and configured to provide power to the radio network device 1100 (including the processing circuit 1120 ) for performing the functionality described herein.

The radio network device 1100 may also include multiple sets of processing circuits 1120, computer-readable storage media 1125, radio circuitry 11010, antennas 1105, and/or communication interface circuitry 1140 for different wireless technologies (e.g., GSM, WCDMA, LTE, NR, WiFi, or Bluetooth wireless technologies) integrated into the radio network device 1100. These wireless technologies may be integrated into the same or different chipsets and other components within the radio network device 1100.

One or more instances of the radio network device 1100 can be adapted to perform some or all of the techniques described herein in any of a variety of combinations. It should be understood that in a given network implementation, multiple instances of the radio network device 1100 will be used. In some cases, several instances of the radio network device 1100 may communicate with or send signals to a given wireless device or group of wireless devices. Thus, it should be understood that while many of the techniques described herein can be performed by a single instance of the radio network device 1100, these techniques can be understood as being performed by a system of one or more instances of the radio network device 1100, in some cases in a coordinated manner. Accordingly, the radio network device 1100 shown in FIG. 18 is the simplest example of such a system.

FIG19 illustrates an example functional module or circuit architecture that may be implemented in wireless device 1000, for example, based on processing circuit 1020. The illustrated embodiment functionally includes at least a sleep mode module 1910 for controlling operation of wireless device 1000 in sleep mode, wherein operation in sleep mode includes intermittently activating receiver circuitry to monitor and/or measure signals. This embodiment also includes several other modules that operate while wireless device 1000 is in sleep mode and the receiver circuitry is activated, including a measurement module 1920 for performing measurements on each of a plurality of resources from a predetermined set of resources, or for demodulating and decoding information from each of a plurality of resources from a predetermined set of resources, wherein the resources in the predetermined set of resources are each defined by one or more of beam, timing, and frequency; and an evaluation module 1930 for evaluating the measured or demodulated and decoded information for each of the plurality of resources against predetermined criteria. The illustrated embodiment also includes an interruption module 1940 for interrupting the execution and evaluation of measurements or interrupting the demodulation, decoding and evaluation of information in response to determining that predetermined criteria are met, so that one or more resources in the predetermined resource set are neither measured nor demodulated and decoded; and a deactivation module 1950 for further deactivating the activated receiver circuit in response to determining that the predetermined criteria are met.

In some embodiments of the wireless device 1000 as shown in FIG19 , resources in the predetermined set of resources are defined as beams. In some embodiments, the predetermined criteria include one or more of the following: a received power level or a measured signal-to-interference-plus-noise ratio (SINR) or signal-to-noise ratio (SNR) is above a predetermined threshold for one or a predetermined number of resources; cell information can be correctly decoded from one or a predetermined number of resources; and decoded information from one or a predetermined number of resources indicates a change in operation of the wireless device.

In some embodiments, the interrupt module 1940 is adapted to execute its interrupt in response to determining that one of the resources meets predetermined criteria.

In some embodiments, the wireless device 1000 further includes a determination module (not shown) for determining a priority order (from highest to lowest) of the predetermined resource sets prior to the operations performed by the measurement module 1920, the evaluation module 1930, the terminal module 1940, and the deactivation module 1950. In these embodiments, the operations performed by the measurement module are performed from highest to lowest according to the priority order. In some of these embodiments, determining the priority order of the predetermined resource sets is based on one or more of: radio resource timing of one or more resources; and measured signal quality or measurement attributes from previous measurements of the one or more resources. In some of these and some other embodiments, determining the priority order of the predetermined resource sets is based on information about the likelihood that one or more resources are useful, which information is received from other sources or a cell neighbor list.

Claims (14)

1. A method in a wireless device operating in a wireless communication network, the method comprising: Operating in hibernation mode includes: Intermittently activate receiver circuitry to monitor and/or measure signals; and When in sleep mode and the receiver circuitry is activated: Perform (1710) measurement on each of the multiple resources from a predetermined resource set, or demodulate and decode information from each of the multiple resources from a predetermined resource set, wherein the resources in the predetermined resource set are defined by one or more of beam, timing and frequency; The measurement or demodulation and decoding information of each of the plurality of resources is evaluated against predetermined standards (1720); In response to determining that the predetermined criteria are met, the execution and evaluation of measurement (1730) are interrupted, or the demodulation and decoding of information and the evaluation are interrupted, such that neither measurement nor demodulation and decoding are performed on one or more resources in the predetermined resource set; and Further in response to determining that the predetermined criteria are met, the receiver circuit activated by (1740) is deactivated. The method further includes: determining the priority order of the predetermined resource set from highest to lowest before the execution or demodulation and decoding, and before the evaluation, interruption and deactivation, wherein the execution or demodulation and decoding are performed according to the priority order from highest to lowest. 2. The method according to claim 1, wherein all resources in the predetermined resource set are defined as beams. 3. The method according to claim 1 or 2, wherein the predetermined standard includes one or more of the following: For one or a predetermined number of resources, the received power level or the measured signal-to-interference-plus-noise ratio (SINR) or signal-to-noise ratio (SNR) is higher than a predetermined threshold. It can correctly decode cell information from one or a predetermined number of resources; Decoded information from one or a predetermined number of resources indicates a change in the operation of the wireless device. 4. The method according to any one of claims 1 to 2, wherein the interruption is performed in response to determining that one of the resources meets the predetermined criterion. 5. The method of claim 1, wherein determining the priority order of the predetermined resource set (1630) is based on one or more of the following: Radio resource timing of one or more of the resources; and The measured signal quality is derived from previous measurements of one or more of the resources. 6. The method of claim 1, wherein determining the priority order of the predetermined resource set (1630) is based on one or more of the following: Radio resource timing of one or more of the resources; and Measured attributes derived from previous measurements of one or more of the resources. 7. The method according to claim 1, 5 or 6, wherein determining (1630) the priority order of the predetermined resource set is based on information about the likelihood that one or more of the resources are useful, the information about the likelihood that one or more of the resources are useful being received from other sources or a list of cell neighbors. 8. A wireless device (1000) for operation in a wireless communication network, said wireless device (1000) being adapted to: Operating in hibernation mode includes: Intermittently activate receiver circuitry to monitor and/or measure signals; and When in sleep mode and the receiver circuitry is activated: Measurements are performed on each of a plurality of resources from a predetermined resource set, or information from each of a plurality of resources from a predetermined resource set is demodulated and decoded, wherein the resources in the predetermined resource set are defined by one or more of beam, timing and frequency. The measurement or demodulation and decoding information of each of the plurality of resources is evaluated against predetermined standards; In response to determining that the predetermined criteria are met, the execution and evaluation of measurements are interrupted, or the demodulation and decoding of information and the evaluation are interrupted, such that neither measurement nor demodulation and decoding are performed on one or more resources in the predetermined resource set; and Further in response to determining that the predetermined criteria are met, the activated receiver circuitry is deactivated. The wireless device is further adapted to determine the priority order of the predetermined resource set from highest to lowest before the execution or demodulation and decoding, and before the evaluation, interruption and deactivation, wherein the wireless device is adapted to perform the execution or demodulation and decoding according to the priority order from highest to lowest. 9. The wireless device (1000) according to claim 8, wherein all resources in the predetermined resource set are defined as beams. 10. The wireless device (1000) according to claim 9, wherein the predetermined standard includes one or more of the following: For one or a predetermined number of resources, the received power level or the measured signal-to-interference-plus-noise ratio (SINR) or signal-to-noise ratio (SNR) is higher than a predetermined threshold. It can correctly decode cell information from one or a predetermined number of resources; Decoded information from one or a predetermined number of resources indicates a change in the operation of the wireless device. 11. The wireless device (1000) according to any one of claims 8 to 10, wherein the wireless device is adapted to perform the interrupt in response to determining that one of the resources satisfies the predetermined criterion. 12. The wireless device (1000) according to claim 8, wherein the wireless device is adapted to determine the priority order of the predetermined resource set based on one or more of the following: Radio resource timing of one or more of the resources; and The measured signal quality is derived from previous measurements of one or more of the resources. 13. The wireless device (1000) according to claim 8, wherein the wireless device is adapted to determine the priority order of the predetermined resource set based on one or more of the following: Radio resource timing of one or more of the resources; and Measured attributes derived from previous measurements of one or more of the resources. 14. The wireless device (1000) according to claim 8, 12 or 13, wherein the wireless device is adapted to determine the priority order of the predetermined resource set based on information about the likelihood that one or more of the resources are useful, the information about the likelihood that one or more of the resources are useful being received from other sources or a list of cell neighbors.