WO2025136395A1

WO2025136395A1 - Rach access for energy saving

Info

Publication number: WO2025136395A1
Application number: PCT/US2023/085418
Authority: WO
Inventors: Navin Hathiramani; Karri Markus Ranta-Aho
Original assignee: Nokia Technologies Oy; Nokia of America Corp
Current assignee: Nokia Technologies Oy; Nokia of America Corp
Priority date: 2023-12-21
Filing date: 2023-12-21
Publication date: 2025-06-26
Anticipated expiration: 2026-06-21
Also published as: WO2025136395A9

Abstract

Disclosed is a method comprising receiving at an apparatus from a network node a set of access parameters relating to an energy saving state of the network; determining a random access preamble; transmitting the random access preamble to the network node and monitoring for a random access response based on at least one of an energy saving state of the network node, the set of access parameters and the random access preamble.

Description

RACK ACCESS FOR ENERGY SAVING

TECHNICAL FIELD

Various example embodiments described relate generally to wireless communication and to random access procedure.

BACKGROUND

Random Access Channel plays an important role in establishing an initial connection (Initial Access) between a device and a network. Initial Access is a procedure between the device and the network for the device to enable radio access communications and can typically entail a procedure for the device to dynamically acquire uplink synchronization and obtain a specific identity (ID) for radio access communications. A preamble is sent by the device to the network over the random access channel to acquire the uplink synchronization. The transmission power for a preamble is determined by the device based on its maximum transmission power, the pathloss to the network and a received target power provided by the network.

Energy Efficiency is becoming a key requirement for network deployments. Industry is focusing on different methodologies and technologies that enable network nodes and more concretely their radio units to leverage deeper sleep states for longer periods. In addition to exploring the transition to deeper sleep states, methods to reduce energy consumption during active states of the radio units have also been explored, where for example, avoiding downlink transmissions with high peak to average power ratio are deemed to be beneficial from an energy consumption point of view. BRIEF DESCRIPTION

According to some aspects, there is provided the subject matter of the independent claims. Some further aspects are defined in the dependent claims. The embodiments that do not fall under the scope of the claims are to be interpreted as examples useful for understanding the disclosure.

According to an aspect, there is provided an apparatus. The apparatus comprises at least one processor and at least one memory storing instructions. When the instructions are executed by the at least one processor they cause the apparatus at least to receive from a network node a set of access parameters relating to an energy saving state of the network node, to determine a random access preamble, to transmit the random access preamble to the network node and to monitor for a random access response based on at least one of an energy saving state of the network node, the set of access parameters or the random access preamble.

According to a further aspect, when the instructions are executed by the at least one processor they further cause the apparatus to receive a random access response based on at least one of the energy saving state of the network node, the set of access parameters and the random access preamble.

According to a further aspect, determining the random access preamble is based on a preamble partitioning.

According to a further aspect the set of access parameters are comprised in a system information block or in a different type of radio resource control message.

According to a further aspect the access parameters indicate an increased preamble transmission power. According to a further aspect the access parameters indicate a time period during which the apparatus is configured to monitor for the random access response.

According to a further aspect the apparatus is configured to monitor for the random access response during the time period, according to a discontinuous reception cycle.

According to a further aspect the access parameters comprise a number of discontinuous reception cycles during which the apparatus is configured to monitor for the random access response and wherein a random access attempt is considered failed if no random access response is received within the number of discontinuous reception cycles.

According to a further aspect, when the instructions are executed by the at least one processor they further cause the apparatus to determine a network identifier based on a random access occasion in which the random access preamble was transmitted and the random access preamble, wherein monitoring for the random access response is based on the network identifier.

According to a further aspect, determining the network identifier is further based on the access parameters.

According to a further aspect, the network identifier is fixed for the time period when the apparatus will monitor for the random access response, the time period being less than a number of consecutive radio frames.

According to a further aspect, a delay prior to transmitting a further random access preamble is determined based on the apparatus not receiving a random access response and on at least one of the energy saving state of the network node, the access parameters, or a service request related to transmitting the random access preamble.

According to a further aspect, a monitoring window within the discontinuous reception cycle is skipped based on a determination that a received energy of physical downlink control channel demodulation reference symbols is below a threshold.

According to a further aspect, the threshold is based on the access parameters.

According to an aspect there is provided a network node. The network node comprises at least one processor and at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus at least to transmit to an apparatus a set of access parameters relating to an energy saving state of the network node, receive a random access preamble from the apparatus and transmit a random access response to the apparatus based on at least one of the energy saving state of the network node, the set of access parameters and the random access preamble.

According to a further aspect, the random access response is not transmitted based on a service request related to transmitting the random access preamble comprising a low priority traffic.

According to an aspect, there is provided a method comprising the steps of receiving at an apparatus from a network node a set of access parameters relating to an energy saving state of the network, determining a random access preamble; transmitting the random access preamble to the network node and monitoring for a random access response based on at least one of an energy saving state of the network node, the set of access parameters and the random access preamble. According to a further aspect, the method further comprises the step of receiving a random access response based on at least one of the energy saving state of the network node, the set of access parameters and the random access preamble.

According to an aspect, there is provided a method comprising the steps of transmitting from a network node to an apparatus a set of access parameters relating to an energy saving state of the network node, receiving at the network node a random access preamble from the apparatus and transmitting from the network node a random access response to the apparatus based on at least one of the energy saving state of the network node, the set of access parameters and the random access preamble.

According to an aspect, there is provided a non-transitory computer readable medium which comprises program instructions stored thereon for performing a method comprising the steps of receiving at an apparatus from a network node a set of access parameters relating to an energy saving state of the network, determining a random access preamble; transmitting the random access preamble to the network node and monitoring for a random access response based on at least one of an energy saving state of the network node, the set of access parameters and the random access preamble. According to a further aspect the method comprises the step of receiving a random access response based on at least one of the energy saving state of the network node, the set of access parameters and the random access preamble.

According to an aspect, there is provided a non-transitory computer readable medium which comprises program instructions stored thereon for performing a method comprising the steps of transmitting from a network node to an apparatus a set of access parameters relating to an energy saving state of the network node, receiving at the network node a random access preamble from the apparatus and transmitting from the network node a random access response to the apparatus based on at least one of the energy saving state of the network node, the set of access parameters and the random access preamble.

LIST OF ABBREVIATIONS

BWP: Bandwidth Part

CORESET: Control Resource Set

DMRS: Demodulation Reference Symbol

DRX: Discontinuous Reception

PA: Power Amplifier

PBCH: Physical Broadcast Channel

PDCCH: Physical Downlink Control Channel

PRACH: Physical RACH

RA: Random Access

RACH: Random Access Channel

RAR: Random Access Response

RA-RNTI: Random Access - RNTI

RNTI: Radio Network Temporary Identifier

RS: Reference Symbol

SSB: Synchronization Signal and PBCH Block

UE: User Equipment

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments will now be described, by way of example only, with reference to the accompanying Figures in which: FIG. 1 illustrates an example of a network environment in which example embodiments of the present disclosure may be implemented;

FIG. 2 illustrates an example Random Access procedure according to an embodiment;

FIG. 3 and 4 illustrate signalling flow diagrams according to some embodiments;

FIG. 5A and 5B illustrate methods according to some embodiments;

FIG.6 illustrates an apparatus according to some embodiments;

FIG.7 illustrates a network node according to some embodiments.

DESCRIPTION OF EMBODIMENTS

Principles of the present disclosure will now be described with reference to some example embodiments. It is to be understood that these embodiments are described only for the purpose of illustration and help those skilled in the art to understand and implement the present disclosure, without suggesting any limitation as to the scope of the disclosure. The disclosure described herein can be implemented in various manners other than the ones described below.

In the following description and claims, unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skills in the art to which this disclosure belongs.

References in the present disclosure to “one embodiment,” “an embodiment,” “an example embodiment,” and the like indicate that the embodiment described may include a particular feature, structure, or characteristic, but it is not necessary that every embodiment includes the particular feature, structure, or characteristic. Moreover, such phrases are not necessarily referring to the same embodiment. Further, when a particular feature, structure, or characteristic is described in connection with an embodiment, it is submitted that it is within the knowledge of one skilled in the art to affect such feature, structure, or characteristic in connection with other embodiments whether or not explicitly described.

It shall be understood that although the terms “first”, “second”, “further” etc. may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another. For example, a first element could be termed a second element, and similarly, a second element could be termed a first element, without departing from the scope of example embodiments. As used herein, the term “and/or” includes any and all combinations of one or more of the listed terms.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments. As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises”, “comprising”, “has”, “having”, “includes” and/or “including”, when used herein, specify the presence of stated features, elements, and/or components etc., but do not preclude the presence or addition of one or more other features, elements, components and/ or combinations thereof. As used herein, “at least one of the following: <a list of two or more elements>” and “at least one of <a list of two or more elements>” and similar wording, where the list of two or more elements are joined by “and” or “or”, mean at least any one of the elements, or at least any two or more of the elements, or at least all the elements.

As used in this application, the term “circuitry” may refer to one or more or all of the following:

(a) hardware-only circuit implementations (such as implementations in only analog and/or digital circuitry) and

(b) combinations of hardware circuits and software, such as (as applicable): (i) a combination of analog and/or digital hardware circuit(s) with software/firmware and

(ii) any portions of hardware processor(s) with software (including digital signal processor(s)), software, and memory(ies) that work together to cause an apparatus, such as a mobile phone or server, to perform various functions) and

(c) hardware circuit(s) and or processor(s), such as a microprocessor(s) or a portion of a microprocessor(s), that requires software (for example, firmware) for operation, but the software may not be present when it is not needed for operation.

This definition of circuitry applies to all uses of this term in this application, including in any claims. As a further example, as used in this application, the term circuitry also covers an implementation of merely a hardware circuit or processor (or multiple processors) or portion of a hardware circuit or processor and its (or their) accompanying software and/or firmware. The term circuitry also covers, for example and if applicable to the particular claim element, a baseband integrated circuit or processor integrated circuit for a mobile device or a similar integrated circuit in server, a cellular network device, or other computing or network device.

As used herein, the term “network”, “communication network” or “data network” refers to a network following any suitable communication standards, such as long term evolution (LTE), LTE-advanced (LTE-A), wideband code division multiple access (WCDMA), high-speed packet access (HSPA), narrow band Internet of things (NB-loT), wireless fidelity (Wi-Fi) and so on. Furthermore, the communications between a terminal device and a network device/element in the communication network may be performed according to any suitable generation communication protocols, including, but not limited to, the fourth generation (4G), 4.5G, the fifth generation (5G), IEEE 802.11 communication protocols, and/or any other protocols either currently known or to be developed in the future. Embodiments of the present disclosure may be applied in various communication systems. Given the rapid development in communications, there will be future type communication technologies and systems in which the present disclosure may be embodied. The scope of the present disclosure is not to be considered limited to only the aforementioned system.

As used herein, the term “network node” refers to a node in a communication network via which a terminal device, also referred to as an apparatus, accesses the network and receives services therefrom. The network node may refer to a base station (BS) or an access point (AP) or a transmission and reception point (TRP), for example, a node B (NodeB or NB), an evolved NodeB (eNodeB or eNB), a NR NB (also referred to as a gNB), a remote radio unit (RRU), a radio header (RH), a remote radio head (RRH), a WiFi device, a relay, a low power node such as a femto, a pico, and so forth, depending on the applied terminology and technology. In the following description, the terms “network node”, “AP device”, “AP” and “access point” may be used interchangeably.

The term “apparatus” refers to any end device that may be capable of wireless communication. By way of example rather than limitation, an apparatus may also be referred to as a communication device, user equipment (UE), terminal device, a subscriber station (SS), a portable subscriber station, a mobile station (MS), a station (STA) or station device, or an access terminal (AT). The apparatus may include, but not limited to, a mobile phone, a cellular phone, a smart phone, voice over IP (VoIP) phones, wireless local loop phones, a tablet, a wearable terminal device, a personal digital assistant (PDA), portable computers, desktop computer, image capture terminal devices such as digital cameras, gaming terminal devices, music storage and playback appliances, vehicle-mounted wireless terminal devices, wireless endpoints, mobile stations, laptop-embedded equipment (LEE), laptopmounted equipment (LME), USB dongles, smart devices, wireless customerpremises equipment (CPE), an Internet of Things (loT) device, a watch or other wearable, a head-mounted display (HMD), a vehicle, a drone, a medical device and applications (for example, remote surgery), an industrial device and applications (for example, a robot and/or other wireless devices operating in an industrial and/or an automated processing chain contexts), a consumer electronics device, a device operating on commercial and/or industrial wireless networks, and the like. In the following description, the terms “apparatus”, “station”, “station device”, “STA”, “terminal device”, “communication device”, “terminal”, “user equipment” and “UE” may be used interchangeably.

A term non-transitory, as used herein, is a limitation of the medium itself (i.e. tangible, not a signal) as opposed to a limitation on data storage persistency (e.g. RAM vs ROM).

FIG. 1 illustrates an example of a network environment 100 in which some example embodiments of the present disclosure may be implemented. The network environment 100, may include a communication network 102, a UE 120 and a network node 110.

In the descriptions of the example embodiments of the present disclosure, the network environment 100 may also be referred to as a communication system 100. For illustrative purposes only, various aspects of example embodiments will be described in the context of one or more terminal devices and network devices that communicate with one another. It should be appreciated, however, that the description herein may be applicable to other types of apparatus or other similar apparatuses that are referenced using other terminology.

As illustrated in FIG. 1 , the communication network 102 may include a network node 110 (which may also be referred to as a gNB or a base station (BS)). The communication network 102 may further include a UE 120 (which may be referred to as apparatus 120). In an embodiment, the apparatus 120 may comprise the terminal device of a communication system, e.g. a user terminal (UT), a computer (PC), a laptop, a tabloid computer, a cellular phone, a mobile phone, a communicator, a smart phone, a palm computer, a mobile transportation apparatus (such as a car), a household appliance, or any other communication apparatus, commonly called as UE in the description. Alternatively, the apparatus is comprised in such a terminal device. Further, the apparatus may be or comprise a module (to be attached to the UE) providing connectivity, such as a plug-in unit, an “USB dongle”, or any other kind of unit. The unit may be installed either inside the UE or attached to the UE with a connector or even wirelessly. Although only one network node 110 and one UE 120 are shown in FIG. 1 , the number of the is not limiting as there may be one or more network nodes 110 and UEs 120 in the network.

The network node 110 can provide services to the UE 120, and the network node 110 and the UE 120 may communicate data and control information with each other. In some embodiments, the network node 1 10 and the UE 120 may communicate with direct links/channels.

In the communication network 102, a link from the network node 110 to the UE 120 is referred to as a downlink (DL), while a link from the UE 120 to the network node 110 is referred to as an uplink (UL). In downlink, the network node 110 is a transmitting (TX) device (or a transmitter) and the apparatus 120 is a receiving (RX) device (or a receiver). In uplink, the UE 120 is a transmitting (TX) device (or a transmitter) and the network node 110 is a RX device (or a receiver). It is to be understood that the network node 110 may provide one or more serving cells. As illustrated in FIG. 1 , the network node 110 provides one serving cell 102, and the UE 120 camps on the serving cell 102. In some embodiments, the network node 110 can provide multiple serving cells and the UE 120 may switch from a source cell to a target cell between the serving cells during its mobility. It is to be understood that the number of serving cell(s) shown in FIG. 1 is for illustrative purposes without suggesting any limitation.

Communications in the communication network 102 may be implemented according to any proper communication protocol(s), comprising, but not limited to, cellular communication protocols of the fourth generation (4G) and the fifth generation (5G) and on the like, wireless local network communication protocols such as Institute for Electrical and Electronics Engineers (IEEE) 802.11 and the like, and/or any other protocols currently known or to be developed in the future, such as universal mobile telecommunications System (UMTS), long term evolution (LTE), LTE-Advanced (LTE-A), the fifth generation (5G) new radio (NR), wireless fidelity (Wi-Fi) and worldwide interoperability for microwave access (WiMAX) standards, and employs any suitable communication technologies, including, for example, multiple-input multiple-output (MIMO), orthogonal frequency division multiplexing (OFDM), time division multiplexing (TDM), frequency division multiplexing (FDM), code division multiplexing (CDM), Bluetooth, ZigBee, and machine type communication (MTC), enhanced mobile broadband (eMBB), massive machine type communication (mMTC), ultra-reliable low latency communication (URLLC), carrier aggregation (CA), dual connectivity (DC), and new radio unlicensed (NR-U) technologies.

In order for the network node 110 to provide services to the UE 120, the UE 120 needs to be connected to the network node 110. The UE 120 can establish a connection to the network node 110 using the so called Random Access (RA) procedure. The RA procedure allows the UE 120 to make a “first contact” with the network node 1 10. The reason for this contact may be that the UE 120 wants to register to the network (a procedure called initial attach), that the UE 120 has been paged for downlink data or signalling transmission or that the UE 120 has pending uplink data or signalling to transmit. The RA procedure is also used for other purposes such as accessing a new cell due to a handover or requesting uplink resources or re-acquiring uplink synchronization.

In order for the network node 110 and the UE 120 to be able to exchange messages, the RA procedure defines two basic steps. In the first step the UE 120 transmits to the network node 110 a random access preamble (RA preamble), using the physical random access channel (PRACH) and hence may also be referred to as a RACH preamble. In the second step the network node 110 transmits to the UE 120 a random access response (RAR) indicating the reception of the preamble. Once the RA preamble is transmitted the UE 120 shall monitor for the RAR in the so-called RA response window. The principle of cell discontinuous transmission (DTX) and discontinuous reception (DRX) means that a network node can do Discontinuous Transmission and Discontinuous Reception. There is defined an active and a non-active period and the network node performs normal transmission and reception during the active period. This principle is mainly used to allow power consumption reduction of the network node. A network node during a non-active period can be considered to reside in a sleep state. In some sleep states a network node could shut off its power amplifiers and other modules in the radio unit of the network node related to downlink functions, while the uplink receivers are still active. One example could be a network node activating deeper (also referred to as longer) sleep states for downlink functions enabled via a long periodicity between its downlink synchronization signals. These downlink synchronization signals could have uplink RACH occasions associated with them. A RACH Occasion is an area specified in time and frequency domain that is available for the reception of a RACH preamble. A network node in this state could differentiate the type of access a LIE is attempting based on the partition of the preamble space for a RACH procedure based on the preamble ID selected by the UE. The network node could then decide whether to continue with the RA procedure or to reject it with a RAR including a back off indicator. The network node would have to re-activate its downlink power amplifiers to transmit a RAR upon the reception of a RA preamble. If this RA preamble is associated with e.g. background traffic and the network node decides to reject the RA attempt this could lead to an inefficient use of energy. In more detail, the network node would have to activate its power amplifiers to transmit the rejection of the RA attempt to the UE. At some point, the UE would re-attempt the connection to the network node as the need to transmit the data has not been fulfilled. In this case the network node would again need to activate its power amplifiers in order to transmit another RAR which may cause the network node to consume twice the energy.

If the network node does not provide a RAR, the UE would continue to transmit RA preambles following RACH configuration parameters and higher layer parameters. This would be power inefficient from UE point of view and also cause unnecessary interference if it retries transmitting the preamble with increasing transmit power.

Fig. 2 illustrates an example of how a Random Access (RA) procedure is handled for a cell provided by a network node 110 in a network energy saving state. Initially the UE 120 acquires the Synchronization Signal and PBCH Block (SSB) 200 and cell access information from a cell in network energy saving state.

The UE 120 based on the provided access information determines the cell is in an energy saving state and initiates a RA procedure 202 on the next RACH occasion. The initiation of the RA procedure may be dictated by an upper layer of the UE.

The UE 120 may select a specific preamble based on a preamble space partitioning provided in the access information and the type of service it desires to initiate.

The cell in network energy saving state, receives the random-access preamble, but based on the preamble received it determines that the service the UE wants to initiate is delay tolerant and/or lower priority than network energy saving requirements. Based on this determination the network does not immediately transmit a RAR 204 and instead leverages larger sleep durations. After several RACH occasions 206 and corresponding DRX-RA response windows 208 the network may have accumulated several requests (via reception of RA preambles) from different UEs 120 to change into RRC connected mode or to handover to the cell. Based on these requests the network could decide to exit the energy saving state 212 and transmit RAR 204 to all the UEs 120 who had transmitted a RA preamble, allowing them now to e.g., change to RRC connected state.

From UE 120 point of view, after the transmission of the RACH preamble 202, the UE monitors for RAR 204 during a monitoring period which is defined by a DRX-RA response window 208. The duration of this DRX RA-response window 208 could be provided to the UE 120 via the access information or via a RRC procedure. Upon successfully decoding a RAR 204 during the DRX-RA response window 208 the UE 120 can consider the RA procedure to be successful.

A cell in network energy saving state implies that the cell has performed some energy saving procedure or optimization. These can range from less frequent transmissions of control plane broadcast information to reduction in number of SSB beams transmitted to leveraging deep sleep states of the radio unit by allowing it to shut down e.g. power amplifiers and other components during times of no DL transmission. The energy saving measure adopted by a cell can vary depending on the radio unit capability and the estimated sleep time. Deeper the sleep states are preferred, since they allow for lower energy consumption but the transition time out of these sleep states tends to be longer.

Fig. 3 illustrates a signal flow diagram according to an example embodiment. In Fig. 3, the serving cell is represented separately as DL 330 and LIL 330A, for illustrative purposes, not meaning that they are necessarily separate entities or network nodes. Referring also to FIG. 2, the serving cell 330, 330A is in an energy saving state which can also be called a sleep mode 210. At 300, the UE 120 receives a RACH configuration from the serving cell DL 330 provided by the network node 110. This configuration contains access parameters that define how the UE 120 should access the serving cell in order e.g. to request a service. This configuration is also defined by the fact that the serving cell 330, 330A is in the energy saving state. The configuration could include RACH configuration parameterization for active and non-active energy saving states or the configuration could be specific to the serving cell energy saving state. The access parameters can be provided or included in e.g. a system information block (SIB) or in a different type of message like a Radio Resource Control (RRC) message.

At 304 the UE 120 acquires the RACH configuration. The acquisition of the configuration(s) for non-energy saving and energy saving states may also take place at 300. At 304 it may be determined by the UE 120 itself that it needs to use that RACH configuration based on a detected energy saving state of the serving cell 300. The term “acquire” may refer more to the act of the UE 120 fetching the configuration to apply from its internal storage. The UE may also detect the network’s energy saving state based on a cell DRX timer configured by the network, a network energy saving state signal received from the network, availability/unavailabi lity of a network broadcast signal, or any combination of the three.

At 306 following the UEs need to transition into connected state, the UE proceeds with the determination of a RA preamble and the UE 120 sends it to the serving cell 330A. The determination of the RA preamble could be based on a so-called preamble partitioning provided by the network configuration. The preamble space or set out of which a specific preamble may occur could be partitioned in, for example, high priority services and low priority services. High priority services may require that the network should exit an energy saving state promptly. Low priority services may require that the network may delay random access responses and not exit an energy saving state. This preamble space or set partitioning configuration may be the one obtained at 300. It may be possible to have the partition implicit, e.g. so that the UE 120 may derive the priority services preamble set from the other configured preamble sets based on defined rules. The serving cell determines the preamble set partitioning needs according to the estimated preambles required for different RA procedures (handovers, beam failure reporting, initial access for different reasons or for UE with different capabilities).

At 310, after the UE 120 has transmitted the RA preamble, it starts monitoring for a Random Access Response (RAR). The access parameters may define a time period during which UE 120 will monitor for RAR 310. In an embodiment, the UE 120 may monitor for the RAR when it has been on (i.e. ready to transmit and receive) for at least one slot. The UE 120 being on may be determined by a discontinuous reception mode (DRX). DRX defines that the UE 120 is transitioning between sleep and wake up (or on) mode. The time period may be called DRX-RA- responsewindow 208 or simply RA response window. This allows the serving cell 330 to remain in a DL sleep state and to check if there are more incoming requests before transitioning to a wake up state and providing a response to the UE 120. This also allows to conserve UE battery life during this extended RA response window.

The access parameters may further define for how many discontinuous reception mode (DRX) cycles the UE 120 should monitor the RAR response window 208 before considering the RA attempt as a failure or failed. This allows the RACH transmission occasions to be spread more evenly in time but grouping the RA response locations associated to multiple different transmission occasions. The evenly spread RACH occasions allows for reduced impact to call setup times for critical services.

In an embodiment, the access parameters may define a change in the power control for the RACH, indicating for example an increase in the transmission power of the preamble. Based on this change, the serving cell could disable the RACH power control and configure the UE 120 to transmit a single RA preamble using full power. The premise for modified RACH power control could be based on the basis of low network traffic during energy saving periods of the cell 300 and consequently lower UL interference profiles allowing for better detection of preambles and minimal interference to other cell communications. Power control refers to the mechanism described in 3GPP that defines the transmission power for a physical random access channel (PRACH). The example below shows how the transmission power is calculated according to 3GPP TS 38.213 version 17.7.0.

In an embodiment, the UE 120 could be configured to use a different (e.g. higher) open loop power control offset for the received target power for the RA preamble. Open Loop Control is referring to the mechanism to determine PRACH transmission power. An additional open loop power control offset could be used. When the UE 120 transmits the RA preamble with increased power, the probability that the serving cell 330A is able to detect the RA preamble transmission attempt and be aware of a UEs request to change to RRC connected mode is higher.

The UE 120 expects to receive a Random-Access Response 204 corresponding to the Random Access Radio Network Temporary Identifier (RA-RNTI) associated with its preamble transmission. A long DRX-RA-responsewindow can correspond to more than one RACH occasion. The response window duration can be multiple times longer than the rate at which the RACH occasions occur. For this reason, the RA-RNTI may be determined so that UE 120 can associate a RAR with its initial preamble transmitted 306. The RA-RNTI is used from the UE 120 to monitor for the RAR 310. At 308 the RA-RNTI is determined based on a random access occasion in which the random access preamble was transmitted and the random access preamble. More specifically, the currently used RA-RNTI range is from 0x0001 to 0xFFF2, and current values employed are 0x0001 to 0x4600, not expanding the full range. As an example, the RA-RNTI used in one RA response window could be different depending on which RACH transmission occasion the preamble being responded to was received. Additional RA-RNTIs may be calculated, starting from the base RA-RNTI and using the timing location of the transmitted random access preamble relative to the response window.

In an embodiment, some of the range limits for the calculation of the RA-RNTI by the UE 120 could be variable and communicated to the UE 120 via e.g. broadcast from the serving cell 330, when e.g., the values are different from the default. This may provide a more efficient usage of the reserved RA-RNTI space increasing the possible DRX-RA-responsewindow duration without additional overhead.

In an embodiment the RA-RANTI determined by the UE could be fixed for a hyper frame. To establish the start and the end of the RA-Response monitoring periods a set of consecutive radio frames could be employed. This set may comprise a so- called hyperframe. The hyperframe could be derived as a set of consecutive radio frames that start when SFN mod N = 0, where N is determining the hyperframe length. Hyperframe information could be, for example, relayed to the UE 120 via the Master Information Block (MIB). In this embodiment the RACH occasion within the hyperframe may be considered as an additional variable when determining the RA- RANTI, such that, the RA-RNTI determination by the UE 120 may be considered specific for energy saving states and referred to as RA-RNTI-ES.

An extra component may be added to the calculation of the RA-RNTI-ES such that RA-RNTI-ES=RA-RNTI + RACH_occassion_within_hyper frame * K where K is a constant value to ensure no overlap with other possible RA-RNTI value exists and may be determined based on the set of access parameters in the RACH configuration.

In another embodiment, the UE 120 may re-calculate the RA-RNTI value depending on where its DRX-RA on duration is within the hyperframe. In this case the RA-RNTI determination for energy saving states (RA-RNTI-ES) could have an extra component such that

RA-RNTI-ES=RA-RNTI + 14*80*8*RO_within_max DRX cycle

Where:

RO_within_max_DRX_cycle is the position of the RACH occasion within the RA- response window time period based on the hyperframe and number of RACH occasions in the monitoring period. Its maximum value could be determined based on the set of access parameters in the RACH configuration.

At 312, the serving cell UL 330A detects the RA preamble that the UE 120 has transmitted. At 314 the type of the RA procedure is determined based on the RA preamble. For example, the RA preamble may be associated with background traffic. In another example it may be associated with a voice call. These examples may be considered having a different priority for being served by the serving cell 330. In case the RA preamble indicates that the traffic request is of low priority, at 316 the serving cell 330, 330A may reject the service request of the UE 120 or it may delay sending a RAR. In an embodiment, the serving cell 330, 330A decides to remain in sleep mode and reject the request from the UE 120. At 318, no RAR is transmitted to the UE 120. A non-transmission if a RAR at 318 may signify that the RACH attempt of the UE 120 has been unsuccessful.

The access parameters may configure the UE 120 to modify a T300 timer and other higher layer timers. This would cause the UE 120 to wait longer before initiating a new Random Access attempt towards the serving cell, possibly following a failed random access attempt. In an embodiment, the higher layers of the UE would wait longer before attempting a new access. These modified timers could be service specific. They may be used when the UE 120 recognizes that the serving cell is in a power saving state.

At 320, the UE 120 continues monitoring for the RAR when it is in on mode (according to the DRX cycle) and during the DRX-RA-ResponseWindow 208. The UE 120 expects to receive a RAR which includes the RA-RNTI which matches the RA preamble. In an example the RA-RNTI matching the RA preamble has been determined by the UE 120 at 308, as described above.

In one embodiment during monitoring for the RAR during the DRX-RA-Response window, the UE 120 upon attempting to decode PDCCH during the RA- responsewindow(Energy Saving state), if the UE measured RSRP of the PDCCH DMRS within the CORESET is below a certain threshold then the UE 120 doesn’t attempt to perform the blind decodes for any search space. The threshold in this case could be determined by the UE based on the path loss from the serving cell 330 and assistance information from the serving cell 330. This embodiment assumes that during the energy saving state of the serving cell 330, the serving cell may not have anything to transmit and may determine not to transmit the RAR during an on period of the UEs DRX-RA-Response window. Hence the early detection of the absence of any PDCCH signals or power by the UE can further allow energy saving for the UE during its on period of the DRX-RA-Response window.

In another embodiment the PDCCH presence detection could additionally or alternatively be based on the energy detection within the CORESET.

The energy detection of PDCCH DMRS detection could be generalized as the first step for PDCCH presence detection and reduce the PDCCH blind decoding power consumption by not attempting to process the PDCCH candidates if the energy or DMRS detection step indicates that there is no PDCCH being transmitted in the PDCCH search space the UE is monitoring. Fig. 4 illustrates a signal flow diagram according to an example embodiment. The description of Fig. 3 applies also for Fig. 4 up to step 314. At 314, similar to Fig. 3, the type of the RA procedure is determined based on the RA preamble. In an example, the RA preamble may be associated with an emergency call. In that case, the call needs to be served by the serving cell and there can be no delay in responding to the LIE 120. At 212, the serving cell transitions out of the sleep state. At 400, similar to 320, the UE 120 continues monitoring for the RAR when it is in on mode (according to the DRX cycle) and during the DRX-RA-ResponseWindow 208. The UE 120 expects to receive a RAR which includes the RA-RNTI which matches the RA preamble. At 402, the UE 120 receives a RAR from the serving cell which may contain the RA-RNTI matching the RA preamble as it has been determined by the UE 120 at 308.

Fig. 5A illustrates a method according to some embodiments. The method may be executed by the apparatus 120. In step 500 the apparatus 120 may receive from a network node a set of access parameters relating to an energy saving state of the network node. In step 502, the apparatus may determine a random access preamble. In step 504 the apparatus 120 may transmit the random access preamble to the network node. Finally in step 506 the apparatus may start monitoring for a random access response based on at least one of an energy saving state of the network node, the set of access parameters or the random access preamble.

Fig. 5B illustrates a method according to some embodiments. The method may be executed by the network node 110. In step 508 the network node may transmit to the apparatus 120 a set of access parameters relating to an energy saving state of the network node 110. In step 510 the network node may receive a random access preamble from the apparatus 120. Further in step 512 the network node 120 may transmit a random access response to the apparatus 120. The random access response may be based on at least one of the energy saving state of the network node, the set of access parameters and the random access preamble.

Fig. 6 illustrates an apparatus 120 comprising a control circuitry CONTROL 60, such as at least one processor, and at least one memory 62 storing instructions that, when executed by the at least one processor, cause the apparatus at least to carry out any one of the above-described processes. In an example, the at least one memory and the computer program code (software, SW), are configured, with the at least one processor, to cause the apparatus to carry out any one of the abovedescribed processes. The memory may be implemented using any suitable data storage technology, such as semiconductor-based memory devices, flash memory, magnetic memory devices and systems, optical memory devices and systems, fixed memory and removable memory. The memory may comprise a database DB for storing data.

The apparatus may be caused to execute some of the functionalities of the above described processes, such as the steps of Figure 5A.

The apparatus may further comprise a radio interface 64 comprising hardware and/or software for realizing communication connectivity according to one or more communication protocols. The radio interface may provide the apparatus with communication capabilities to access the radio access network, for example. The apparatus may also comprise a user interface 66 comprising, for example, at least one keypad, a microphone, a touch display, a display, a speaker, etc. The user interface may be used to control the apparatus by the user.

The control circuitry 60 may comprise further circuitry 68 for performing the functions, according to any of the embodiments described above. Figure 7 illustrates a network node 110, comprising a control circuitry CONTROL 70, such as at least one processor, and at least one memory 72 storing instructions that, when executed by the at least one processor, cause the apparatus at least to carry out any one of the above-described processes. In an example, the at least one memory and the computer program code (SW), are configured, with the at least one processor, to cause the apparatus to carry out any one of the above-described processes. The memory may be implemented using any suitable data storage technology, such as semiconductor-based memory devices, flash memory, magnetic memory devices and systems, optical memory devices and systems, fixed memory and removable memory. The memory may comprise a database for storing data.

In an embodiment, the network node 110, may be a gNB/gNB-CU/gNB-DU of 5G New Radio. The network node may be caused to execute some of the functionalities of the above described processes, such as the steps of Figure 5B.

The network node 110 may further comprise radio interface 74 comprising hardware and/or software for realizing communication connectivity according to one or more communication protocols. The radio interface may provide the network node with communication capabilities with at least one user equipment, for example.

The network node may also comprise a user interface 76 comprising, for example, at least one keypad, a microphone, a touch display, a display, a speaker, etc. The user interface may be used to control the network node by the user.

The control circuitry 70 may comprise further circuitry 78 for performing the functions, according to any of the embodiments described above.

In an embodiment, at least some of the processes described in connection with Figures 1 to 7 may be carried out by an apparatus comprising corresponding means for carrying out at least some of the described processes. Some example means for carrying out the processes may include at least one of the following: detector, processor (including dual-core and multiple-core processors), digital signal processor, controller, receiver, transmitter, encoder, decoder, memory, RAM, ROM, software, firmware, display, user interface, display circuitry, user interface circuitry, user interface software, display software, circuit, antenna, antenna circuitry, or circuitry. In an embodiment, the at least one processor, the memory, and the computer program code form processing means or comprises one or more computer program code portions for carrying out one or more operations according to any one of the embodiments of Figures 1 to 7 or operations thereof.

According to an aspect, there is provided an apparatus (e.g., a user equipment or a part thereof) comprising means for receiving from a network node a set of access parameters relating to an energy saving state of the network node; determining a random access preamble; transmitting the random access preamble to the network node and monitoring for a random access response based on at least one of an energy saving state of the network node, the set of access parameters or the random access preamble. According to another aspect, the apparatus may further comprise means for receiving a random access response based on at least one of the energy saving state of the network node, the set of access parameters and the random access preamble.

According to an aspect, there is provided a network node comprising means for transmitting to an apparatus a set of access parameters relating to an energy saving state of the network node; receiving a random access preamble from the apparatus and transmitting a random access response to the apparatus based on at least one of the energy saving state of the network node, the set of access parameters and the random access preamble.

As used herein the term “means” is to be construed in singular form, i.e. referring to a single element, or in plural form, i.e. referring to a combination of single elements. Therefore, terminology “means for receiving from a network node a set of access parameters relating to an energy saving state of the network node; determining a random access preamble; transmitting the random access preamble to the network node and monitoring for a random access response based on at least one of an energy saving state of the network node, the set of access parameters or the random access preamble”, is to be interpreted to cover an apparatus in which there is only one means for performing these actions or where there are separate means for performing these actions, or partially or fully overlapping means for performing these actions. Further, terminology “means for receiving from a network node a set of access parameters relating to an energy saving state of the network node; means for determining a random access preamble, means for transmitting the random access preamble to the network node and means for monitoring for a random access response based on at least one of an energy saving state of the network node, the set of access parameters or the random access preamble” is to be interpreted to cover an apparatus in which there is only one means for performing these actions, or where there are separate means for performing these actions or partially or fully overlapping means for performing these actions.

Further, terminology “means for receiving a random access response based on at least one of the energy saving state of the network node, the set of access parameters and the random access preamble” is to be interpreted to cover an apparatus in which there is only one means for performing this action or where there are separate means for performing this action, or partially or fully overlapping means for performing this action.

In a similar fashion, terminology, “means for transmitting to an apparatus a set of access parameters relating to an energy saving state of the network node; receiving a random access preamble from the apparatus and transmitting a random access response to the apparatus based on at least one of the energy saving state of the network node, the set of access parameters and the random access preamble” is to be interpreted to cover an apparatus in which there is only one means for performing these actions or where there are separate means for performing these actions, or partially or fully overlapping means for performing these actions. Further, terminology “means for transmitting to an apparatus a set of access parameters relating to an energy saving state of the network node, means for receiving a random access preamble from the apparatus and means for transmitting a random access response to the apparatus based on at least one of the energy saving state of the network node, the set of access parameters and the random access preamble” is to be interpreted to cover an apparatus in which there is only one means for performing this action or where there are separate means for performing this action, or partially or fully overlapping means for performing this action.

The techniques and methods described herein may be implemented by various means. For example, these techniques may be implemented in hardware (one or more devices), firmware (one or more devices), software (one or more modules), or combinations thereof. For a hardware implementation, the apparatus(es) of embodiments may be implemented within one or more application-specific integrated circuits (ASICs), digital signal processors (DSPs), digital signal processing devices (DSPDs), programmable logic devices (PLDs), field programmable gate arrays (FPGAs), processors, controllers, micro-controllers, microprocessors, other electronic units designed to perform the functions described herein, or a combination thereof. For firmware or software, the implementation can be carried out through modules of at least one chip set (e.g. procedures, functions, and so on) that perform the functions described herein. The software codes may be stored in a memory unit and executed by processors. The memory unit may be implemented within the processor or externally to the processor. In the latter case, it can be communicatively coupled to the processor via various means, as is known in the art. Additionally, the components of the systems described herein may be rearranged and/or complemented by additional components in order to facilitate the achievements of the various aspects, etc., described with regard thereto, and they are not limited to the precise configurations set forth in the given figures, as will be appreciated by one skilled in the art.

Embodiments as described may also be carried out in the form of a computer process defined by a computer program or portions thereof. Embodiments of the methods described may be carried out by executing at least one portion of a computer program comprising corresponding instructions. The computer program may be in source code form, object code form, or in some intermediate form, and it may be stored in some sort of carrier, which may be any entity or device capable of carrying the program. For example, the computer program may be stored on a computer program distribution medium readable by a computer or a processor. The computer program medium may be, for example but not limited to, a record medium, computer memory, read-only memory, electrical carrier signal, telecommunications signal, and software distribution package, for example. The computer program medium may be a non-transitory medium. Coding of software for carrying out the embodiments as shown and described is well within the scope of a person of ordinary skill in the art.

Claims

1. An apparatus, comprising: at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus at least to: receive from a network node a set of access parameters relating to an energy saving state of the network node; determine a random access preamble; transmit the random access preamble to the network node and monitor for a random access response based on at least one of an energy saving state of the network node, the set of access parameters or the random access preamble.

2. The apparatus according to claim 1 , wherein the apparatus is further caused to receive a random access response based on at least one of the energy saving state of the network node, the set of access parameters and the random access preamble.

3. The apparatus according to claim 1 , wherein determining the random access preamble is based on a preamble partitioning.

4. The apparatus according to claim 1 , wherein the set of access parameters are comprised in a system information block or in a different type of radio resource control message.

5. The apparatus according to claim 1 , wherein the access parameters indicate an increased preamble transmission power.

6. The apparatus according to claim 1 , wherein the access parameters indicate a time period during which the apparatus is configured to monitor for the random access response.

7. The apparatus according to claim 6, wherein apparatus is configured to monitor for the random access response during the time period, according to a discontinuous reception cycle.

8. The apparatus according to claim 1 , wherein the access parameters comprise a number of discontinuous reception cycles during which the apparatus is configured to monitor for the random access response and wherein a random access attempt is considered failed if no random access response is received within the number of discontinuous reception cycles.

9. The apparatus according to claim 8, wherein the access parameters indicate a modification of at least one timer determining a delay before the apparatus attempts a further random access procedure following a failed previous random access procedure.

10. The apparatus according to claim 1 , wherein the apparatus is further caused to determine a network identifier based on a random access occasion in which the random access preamble was transmitted and the random access preamble, wherein monitoring for the random access response is based on the network identifier.

11. The apparatus of claim 10, wherein determining the network identifier is further based on the access parameters.

12. The apparatus according to claim 10, wherein the network identifier is fixed for the time period when the apparatus will monitor for the random access response, the time period being less than a number of consecutive radio frames.

13. The apparatus according to claim 1 , wherein a delay prior to transmitting a further random access preamble is determined based on the apparatus not receiving a random access response and on at least one of the energy saving state of the network node, the access parameters, or a service request related to transmitting the random access preamble.

14. The apparatus of claim 7, wherein a monitoring window within the discontinuous reception cycle is skipped based on a determination that a received energy of physical downlink control channel demodulation reference symbols is below a threshold.

15. The apparatus of claim 7, wherein a monitoring window within the discontinuous reception cycle is skipped based on a determination that a received energy of physical downlink control channel control resource set is below a threshold, wherein the threshold is based on the access parameters

16. A network node, comprising: at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus at least to: transmit to an apparatus a set of access parameters relating to an energy saving state of the network node; receive a random access preamble from the apparatus and transmit a random access response to the apparatus based on at least one of the energy saving state of the network node, the set of access parameters and the random access preamble.

17. The network node according to claim 16 wherein the random access response is not transmitted based on a service request related to transmitting the random access preamble comprising a low priority traffic.

18. A method comprising: receiving at an apparatus from a network node a set of access parameters relating to an energy saving state of the network; determining a random access preamble; transmitting the random access preamble to the network node and monitoring for a random access response based on at least one of an energy saving state of the network node, the set of access parameters and the random access preamble.

19. The method according to claim 18 further comprising receiving a random access response based on at least one of the energy saving state of the network node, the set of access parameters and the random access preamble.

20. A method comprising: transmitting from a network node to an apparatus a set of access parameters relating to an energy saving state of the network node; receiving at the network node a random access preamble from the apparatus and transmitting from the network node a random access response to the apparatus based on at least one of the energy saving state of the network node, the set of access parameters and the random access preamble.

21. A non-transitory computer readable medium comprising program instructions stored thereon for performing the method according to any of claims 18 - 19 or 20.