WO2025083458A1

WO2025083458A1 - Methods and apparatus for time and frequency tracking

Info

Publication number: WO2025083458A1
Application number: PCT/IB2023/060632
Authority: WO
Inventors: Sami-Jukka Hakola; Timo Koskela; Juha Pekka Karjalainen
Original assignee: Nokia Technologies Oy
Current assignee: Nokia Technologies Oy
Priority date: 2023-10-20
Filing date: 2023-10-20
Publication date: 2025-04-24
Anticipated expiration: 2026-04-20

Abstract

A method includes receiving, by a user device from a network node, a reference signal (RS) configuration for a time/frequency tracking purpose including: a synchronization signal block (SSB) index identifying a synchronization signal block to be frequency extended to include physical resource blocks (PRBs) for a reference signal for the time/frequency tracking purpose; and information indicating physical resource blocks for the reference signal appended to the synchronization signal block to provide the frequency extended synchronization signal block, wherein the information indicates at least one of: 1) a first number of physical resource blocks for the reference signal that are above, or having subcarrier frequencies higher than, the synchronization signal block, and/or 2) a second number of physical resource blocks for the reference signal that are below, or having subcarrier frequencies lower than, the synchronization signal block; and determining, by the user device, the reference signal configuration for the time/frequency tracking purpose to receive the reference signal within the frequency extended synchronization signal block.

Description

METHODS AND APPARATUS FOR TIME AND FREQUENCY TRACKING

TECHNICAL FIELD

[0001] This description relates to wireless communications.

BACKGROUND

[0002] A communication system may be a facility that enables communication between two or more nodes or devices, such as fixed or mobile communication devices. Signals can be carried on wired or wireless carriers.

[0003] An example of a cellular communication system is an architecture that is being standardized by the 3^rd Generation Partnership Project (3GPP), for example, the long-term evolution (LTE) of the Universal Mobile Telecommunications System (UMTS) radio-access technology. E-UTRA (evolved UMTS Terrestrial Radio Access) is the air interface of 3GPP's Long Term Evolution (LTE) upgrade path for mobile networks. In LTE, base stations or access points (APs), which are referred to as enhanced Node AP (eNBs), provide wireless access within a coverage area or cell. In LTE, mobile devices, or mobile stations are referred to as user equipments (UE). LTE has included a number of improvements or developments. Aspects of LTE are also continuing to improve.

[0004] 5G New Radio (NR) development is part of a continued mobile broadband evolution process to meet the requirements of 5G, similar to earlier evolution of 3G and 4G wireless networks. In addition, 5G is also targeted at the new emerging use cases in addition to mobile broadband. A goal of 5G is to provide significant improvement in wireless performance, which may include new levels of data rate, latency, reliability, and security. 5G NR may also scale to efficiently connect the massive Internet of Things (loT) and may offer new types of mission-critical services. For example, ultra-reliable and low-latency communications (URLLC) devices may require high reliability and very low latency.

6G and other wireless networks and technologies are also being developed.

SUMMARY

[0005] According to an example embodiment, an apparatus may include: 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, by a user device from a network node, a reference signal (RS) configuration for a time/frequency tracking purpose including: a synchronization signal block (SSB) index identifying a synchronization signal block to be frequency extended to include physical resource blocks (PRBs) for a reference signal for the time/frequency tracking purpose; and information indicating physical resource blocks for the reference signal appended to the synchronization signal block to provide the frequency extended synchronization signal block, wherein the information indicates at least one of: 1) a first number of physical resource blocks for the reference signal that are above, or having subcarrier frequencies higher than, the synchronization signal block, and/or 2) a second number of physical resource blocks for the reference signal that are below, or having subcarrier frequencies lower than, the synchronization signal block; and determine, by the user device, the reference signal configuration for the time/frequency tracking purpose to receive the reference signal within the frequency extended synchronization signal block.

[0006] According to an example embodiment, a method may include: receiving, by a user device from a network node, a reference signal (RS) configuration for a time/frequency tracking purpose including: a synchronization signal block (SSB) index identifying a synchronization signal block to be frequency extended to include physical resource blocks (PRBs) for a reference signal for the time/frequency tracking purpose; and information indicating physical resource blocks for the reference signal appended to the synchronization signal block to provide the frequency extended synchronization signal block, wherein the information indicates at least one of: 1) a first number of physical resource blocks for the reference signal that are above, or having subcarrier frequencies higher than, the synchronization signal block, and/or 2) a second number of physical resource blocks for the reference signal that are below, or having subcarrier frequencies lower than, the synchronization signal block; and determining, by the user device, the reference signal configuration for the time/frequency tracking purpose to receive the reference signal within the frequency extended synchronization signal block.

[0007] According to an example embodiment, an apparatus may include: 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, by a network node to a user device, a reference signal (RS) configuration for a time/frequency tracking purpose including: a synchronization signal block index identifying the selected synchronization signal block to be frequency extended to include physical resource blocks (PRBs) for a reference signal for the time/frequency tracking purpose; and information indicating physical resource blocks for the reference signal appended to the synchronization signal block to provide the frequency extended synchronization signal block, wherein the information indicates at least one of: 1) a first number of physical resource blocks for the reference signal that are above, or having subcarrier frequencies higher than, the synchronization signal block, and/or 2) a second number of physical resource blocks for the reference signal that are below, or having subcarrier frequencies lower than, the synchronization signal block.

[0008] According to an example embodiment, a method may include: transmitting, by a network node to a user device, a reference signal (RS) configuration for a time/frequency tracking purpose including: a synchronization signal block index identifying the selected synchronization signal block to be frequency extended to include physical resource blocks (PRBs) for a reference signal for the time/frequency tracking purpose; and information indicating physical resource blocks for the reference signal appended to the synchronization signal block to provide the frequency extended synchronization signal block, wherein the information indicates at least one of: 1) a first number of physical resource blocks for the reference signal that are above, or having subcarrier frequencies higher than, the synchronization signal block, and/or 2) a second number of physical resource blocks for the reference signal that are below, or having subcarrier frequencies lower than, the synchronization signal block.

[0009] According to an example embodiment, an apparatus may include: 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, by a user device from a network node, a reference signal (RS) configuration for a time/frequency tracking purpose including: a synchronization signal block (SSB) index identifying a synchronization signal block to be frequency extended to include physical resource blocks (PRBs) for a reference signal for the time/frequency tracking purpose; and information indicating physical resource blocks for the reference signal appended to the synchronization signal block to provide the frequency extended synchronization signal block, wherein the information indicates at least one of: 1) a first number of physical resource blocks for the reference signal that are above, or having subcarrier frequencies higher than, the synchronization signal block, and/or 2) a second number of physical resource blocks for the reference signal that are below, or having subcarrier frequencies lower than, the synchronization signal block; determine, by the user device, the reference signal configuration for the time/frequency tracking purpose to receive the reference signal within the frequency extended synchronization signal block; and receive, by the user device, the reference signal.

[0010] According to an example embodiment, a method may include: receiving, by a user device from a network node, a reference signal (RS) configuration for a time/frequency tracking purpose including: a synchronization signal block (SSB) index identifying a synchronization signal block to be frequency extended to include physical resource blocks (PRBs) for a reference signal for the time/frequency tracking purpose; and information indicating physical resource blocks for the reference signal appended to the synchronization signal block to provide the frequency extended synchronization signal block, wherein the information indicates at least one of: 1) a first number of physical resource blocks for the reference signal that are above, or having subcarrier frequencies higher than, the synchronization signal block, and/or 2) a second number of physical resource blocks for the reference signal that are below, or having subcarrier frequencies lower than, the synchronization signal block; determining, by the user device, the reference signal configuration for the time/frequency tracking purpose to receive the reference signal within the frequency extended synchronization signal block; and, receiving, by the user device, the reference signal.

[0011] Other example embodiments are provided or described for each of the example methods, including: means for performing any of the example methods; a non-transitory computer-readable storage medium comprising instructions stored thereon that, when executed by at least one processor, are configured to cause a computing system to perform any of the example methods; and an apparatus including 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 perform any of the example methods.

[0012] The details of one or more examples of embodiments are set forth in the accompanying drawings and the description below. Other features will be apparent from the description and drawings, and from the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

[0013] FIG. 1 is a block diagram of a wireless network according to an example embodiment.

[0014] FIG. 2A is a flow chart illustrating operation of a user device (or UE) according to an example embodiment.

[0015] FIG. 2B is a flow chart illustrating operation of a network node (e.g., gNB, TRP or other network node) according to an example embodiment.

[0016] FIG. 3 is a flow chart illustrating operation of a user device (or UE) according to another example embodiment.

[0017] FIG. 4 is a diagram illustrating a frequency extended synchronization signal block including reference signal for time and frequency tracking purpose according to an example embodiment. [0018] FIG. 5 is a diagram illustrating a signal sequence allocation in frequency extended SSB according to an example embodiment.

[0019] FIG. 6 is a block diagram of a wireless station or node (e.g., AP, BS, RAN node, UE or user device, or network node).

DETAILED DESCRIPTION

[0020] FIG. 1 is a block diagram of a wireless network 130 according to an example embodiment. In the wireless network 130 of FIG. 1, user devices 131, 132, 133 and 135, which may also be referred to as mobile stations (MSs) or user equipment (UEs), may be connected (and in communication) with a base station (BS) 134, which may also be referred to as an access point (AP), an enhanced Node B (eNB), a gNB or a network node.

The terms user device and user equipment (UE) may be used interchangeably. A BS may also include or may be referred to as a RAN (radio access network) node, and may include a portion of a BS or a portion of a RAN node, such as (e.g., such as a centralized unit (CU) and/or a distributed unit (DU) in the case of a split BS or split gNB). At least part of the functionalities of a BS (e.g., access point (AP), base station (BS) or (e)Node B (eNB), gNB, RAN node) may also be carried out by any node, server or host which may be operably coupled to a transceiver, such as a remote radio head. BS (or AP) 134 provides wireless coverage within a cell 136, including to user devices (or UEs) 131, 132, 133 and 135. Although only four user devices (or UEs) are shown as being connected or attached to BS 134, any number of user devices may be provided. BS 134 is also connected to a core network 150 via a SI interface 151. This is merely one simple example of a wireless network, and others may be used.

[0021] A base station (e.g., such as BS 134) is an example of a radio access network (RAN) node within a wireless network. A BS (or a RAN node) may be or may include (or may alternatively be referred to as), e.g., an access point (AP), a gNB, an eNB, a transmission and reception point (TRP), or portion thereof (such as a /centralized unit (CU) and/or a distributed unit (DU) in the case of a split BS or split gNB), or other network node.

[0022] According to an illustrative example, a BS node (e.g., BS, eNB, gNB, TRP, CU/DU, . . .) or a radio access network (RAN) may be part of a mobile telecommunication system. A RAN (radio access network) may include one or more BSs or RAN nodes that implement a radio access technology, e.g., to allow one or more UEs to have access to a network or core network. Thus, for example, the RAN (RAN nodes, such as BSs or gNBs) may reside between one or more user devices or UEs and a core network. According to an example embodiment, each RAN node (e.g., BS, eNB, gNB, TRP, CU/DU, . . .) or BS may provide one or more wireless communication services for one or more UEs or user devices, e.g., to allow the UEs to have wireless access to a network, via the RAN node. Each RAN node or BS may perform or provide wireless communication services, e.g., such as allowing UEs or user devices to establish a wireless connection to the RAN node, and sending data to and/or receiving data from one or more of the UEs. For example, after establishing a connection to a UE, a RAN node or network node (e.g., BS, eNB, gNB, TRP, CU/DU, . . .) may forward data to the UE that is received from a network or the core network, and/or forward data received from the UE to the network or core network. RAN nodes or network nodes (e.g., BS, eNB, gNB, TRP, CU/DU, . . .) may perform a wide variety of other wireless functions or services, e.g., such as broadcasting control information (e.g., such as system information or on-demand system information) to UEs, paging UEs when there is data to be delivered to the UE, assisting in handover of a UE between cells, scheduling of resources for uplink data transmission from the UE(s) and downlink data transmission to UE(s), sending control information to configure one or more UEs, and the like. These are a few examples of one or more functions that a RAN node or BS may perform.

[0023] A user device (user terminal, user equipment (UE), mobile terminal, handheld wireless device, etc.) may refer to a portable computing device that includes wireless mobile communication devices operating either with or without a subscriber identification module (SIM), including, but not limited to, the following types of devices: a mobile station (MS), a mobile phone, a cell phone, a smartphone, a personal digital assistant (PDA), a handset, a device using a wireless modem (alarm or measurement device, etc.), a laptop and/or touch screen computer, a tablet, a phablet, a game console, a notebook, a vehicle, a sensor, and a multimedia device, as examples, or any other wireless device. It should be appreciated that a user device may also be (or may include) a nearly exclusive uplink only device, of which an example is a camera or video camera loading images or video clips to a network.

[0024] In LTE (as an illustrative example), core network 150 may be referred to as Evolved Packet Core (EPC), which may include a mobility management entity (MME) which may handle or assist with mobility/handover of user devices between BSs, one or more gateways that may forward data and control signals between the BSs and packet data networks or the Internet, and other control functions or blocks. Other types of wireless networks, such as 5G (which may be referred to as New Radio (NR)) may also include a core network. [0025] Embodiments described herein may be applied to the above-described wireless network or to another wireless network. The wireless network may be or comprise a radio access network of a cellular communication system.

[0026] In addition, the techniques described herein may be applied to various types of user devices or data service types, or may apply to user devices that may have multiple applications running thereon that may be of different data service types. New Radio (5G) development may support a number of different applications or a number of different data service types, such as for example: machine type communications (MTC), enhanced machine type communication (eMTC), Internet of Things (loT), and/or narrowband loT user devices, enhanced mobile broadband (eMBB), and ultra-reliable and low-latency communications (URLLC). Many of these new 5G (NR) - related applications may require generally higher performance than previous wireless networks. 6G is also being developed, and will have even higher performance requirements.

[0027] loT may refer to an ever-growing group of objects that may have Internet or network connectivity, so that these objects may send information to and receive information from other network devices. For example, many sensor type applications or devices may monitor a physical condition or a status, and may send a report to a server or other network device, e.g., when an event occurs. Machine Type Communications (MTC, or Machine to Machine communications) may, for example, be characterized by fully automatic data generation, exchange, processing and actuation among intelligent machines, with or without the intervention of humans. Enhanced mobile broadband (eMBB) may support much higher data rates than currently available in LTE.

[0028] Ultra-reliable and low-latency communications (URLLC) is a new data service type, or new usage scenario, which may be supported for New Radio (5G) systems. This enables emerging new applications and services, such as industrial automations, autonomous driving, vehicular safety, e-health services, and so on. 3GPP targets in providing connectivity with reliability corresponding to block error rate (BLER) of 10-5 and up tol ms U-Plane (user/data plane) latency, by way of illustrative example. Thus, for example, URLLC user devices/UEs may require a significantly lower block error rate than other types of user devices/UEs as well as low latency (with or without requirement for simultaneous high reliability). Thus, for example, a URLLC UE (or URLLC application on a UE) may require much shorter latency, as compared to a eMBB UE (or an eMBB application running on a UE). [0029] The techniques described herein may be applied to a wide variety of wireless technologies or wireless networks, such as LTE, LTE-A, 5G (New Radio (NR)), cmWave, and/or mmWave band networks, loT, MTC, eMTC, eMBB, 6G, URLLC, ambient wireless networks such as ambient loT wireless networks or systems, etc., or any other wireless network or wireless technology. These example networks, technologies or data service types are provided only as illustrative examples.

[0030] To enable a UE to find a cell when moving within a network or entering a new network, a gNB or cell may transmit a synchronization signal block (SSB), which may include, e.g., a primary synchronization signal (PSS), a secondary synchronization signal (SSS), a physical broadcast channel (PBCH) and PBCH demodulation reference signal (PBCH-DMRS). Multiple SSBs may be transmitted periodically at 20ms intervals. The SSB period may vary, e.g., from 5ms to 160ms. An SSB can be transmitted via different beams in time domain. The set of SSBs within a beam sweep (e.g., a SSB transmitted via each of multiple beams across the beam sweep) may be referred to as a SSB burst. The UE may use the PSS to determine system timing of the network carrier frequency, and then may use the SSS to determine the physical cell identity (PCI) of the detected cell. The PBCH- DMRS is a reference signal for decoding the PBCH. The PBCH may inform the UE of the SSB frequency domain position within the carrier. The PBCH carries the master information block (MIB), which includes information that the UE needs in order to acquire the remaining system information broadcast by the network. The PBCH may include or indicate information such as, e.g., SS block time index, a SIB1 (system information block 1) configuration, a common resource block (CRB) offset, a system frame number, SIB1 numerology, and other information.

[0031] In addition, to assist the UE to compensate for variations in time and frequency to successfully receive downlink transmissions, a tracking reference signal (TRS) may be configured and transmitted by the gNB or cell. TRS may be or may include a resource set including multiple periodic channel state information-reference signal (CSI-RS). For the time and frequency domain parameter estimation to set the channel estimator parameters properly for the reception of the PDCCH (physical downlink control channel), PDSCH (physical downlink shared channel) and CSI-RS, the UE may be configured with a periodical tracking reference signal (TRS) in 5G/NR. Thus, the network (e.g., gNB or cell to which the UE may be connected to) may transmit a UE-specific TRS. A TRS may be configured for the UE to enable UE to perform fine time and frequency (time/frequency) synchronization tracking in the serving cell. Thus, a UE-specific TRS may be configured for time/frequency (e.g., time and frequency) tracking purposes. As said, the TRS facilitates UE to perform the parameter optimization for a channel estimator, e.g., a length of a 2-D Wiener filter over frequency and time. TRS may be configured as one-port CSI-RS resource(s) with the following parameters, for example: a TRS burst length is two consecutive valid downlink slots in FR1 and one or two consecutive valid downlink slots in FR2; in each TRS slot there are two TRS symbols; TRS symbols in the slot may typically have three or four symbol separation; and/or, TRS burst periodicity may be (for example) either 10, 20, 40 or 80 ms. The UE may be configured with multiple TRS configurations to receive TRS and track time and frequency domain parameters for the channel estimators, e.g., from different transmission points or transmit beams. Also, a common tracking reference (CTRS) may also be configured that is not UE-specific, but may be detected and used by UEs that may be in Idle or Inactive mode, e.g., to update channel estimation parameters.

[0032] However, challenges may arise when the network (e.g., gNB or cell) schedules transmissions via time-domain multiplexing for the UE-specific TRS for each UE, SSBs, PDCCH and system information block 1 (SIB1). The multiple SSBs, TRSs and SIB1 are typically time-domain multiplexed. However, if there are many UEs (thus requiring transmission of many UE-specific TRSs), this may be an inefficient way to allocate resources for transmission of these signals, requiring a significant number of symbols or time-domain resources, which may be inefficient and/or may introduce significant latency.

[0033] Therefore, according to an example embodiment, a frequency extended synchronization signal block (SSB) is configured and transmitted by a network node (e.g., gNB or cell) to a UE. The frequency extended SSB may include a first number of physical resource blocks (PRBs) above (or PRBs having subcarrier frequencies higher (or greater) than) the SSB and/or a second number of PRBs below (or PRBs having subcarrier frequencies lower than) the SSB, for a plurality of symbols of the SSB. Each PRB may include a plurality of subcarriers (e.g., 12 subcarriers) for 1 symbol (e.g., for one orthogonal frequency division multiplexed (OFDM) symbol). In this manner the frequency spectrum (or PRBs) of the SSB are extended to add reference signal (e.g., to add a tracking reference signal, or portion thereof), resulting in a frequency extended SSB. The gNB may transmit to the UE (and the UE may receive) a reference signal configuration for a time/frequency tracking purpose (e.g., a TRS configuration), which may include a SSB index identifying the SSB to be frequency extended, and information indicating a first number of PRBs above and/or a second number of PRBs below the SSB that are appended to the SSB (e.g., for at least two symbols of the SSB) to provide the frequency extended SSB. The UE may determine the reference signal configuration (e.g., the TRS configuration) based on the received configuration. The UE may receive the reference signal (e.g., receive the tracking reference signal (TRS)), e.g., as part of the frequency extended SSB, for time/frequency tracking purpose. The UE may then perform time/frequency tracking based at least on part of the reference signal (e.g., based at least on part of the received TRS) received via the frequency extended SSB.

[0034] FIG. 2A is a flow chart illustrating operation of a user device (or UE) according to an example embodiment. Operation 210 includes receiving, by a user device from a network node, a reference signal (RS) configuration for a time/frequency tracking purpose including: a synchronization signal block (SSB) index identifying a synchronization signal block to be frequency extended to include physical resource blocks (PRBs) for a reference signal for the time/frequency tracking purpose; and information indicating physical resource blocks for the reference signal appended to the synchronization signal block to provide the frequency extended synchronization signal block, wherein the information indicates at least one of:

1) a first number of physical resource blocks for the reference signal that are above, or having subcarrier frequencies higher than, the synchronization signal block, and/or

2) a second number of physical resource blocks for the reference signal that are below, or having subcarrier frequencies lower (or less) than, the synchronization signal block. Operation 220 includes determining, by the user device, the reference signal configuration for the time/frequency tracking purpose to receive the reference signal within the frequency extended synchronization signal block.

[0035] With respect to the method of FIG. 2A, the reference signal configuration determined by the user device comprises at least: the synchronization signal block index identifying the synchronization signal block that is frequency extended; and the physical resource blocks for the reference signal that are appended to the synchronization signal block to provide the frequency extended synchronization signal block.

[0036] With respect to the method of FIG. 2A, the method may further include receiving, by the user device, the reference signal.

[0037] With respect to the method of FIG. 2A, the method may further include performing, by the user device, time/frequency tracking based at least on part of the reference signal received via the frequency extended synchronization signal block.

[0038] With respect to the method of FIG. 2A, the method may include performing, by the user device, channel estimation based at least on part of the reference signal received via the frequency extended synchronization signal block for demodulating a physical broadcast channel (PBCH).

[0039] With respect to the method of FIG. 2A, the channel estimation is performed based on part of the reference signal received via the physical resource blocks of the synchronization signal block but not the physical resource blocks appended to the synchronization signal block.

[0040] With respect to the method of FIG. 2A, comprising performing, by the user device, optimization of a channel estimation related to demodulation of at least one of a control channel, a data channel or a channel state information reference signal, based at least on the time/frequency tracking.

[0041] With respect to the method of FIG. 2A, the demodulation of the at least one of the control channel, the data channel or the channel state information reference signal is based on one or more quasi co-location between the reference signal received via the frequency extended synchronization signal block and the at least one of the control channel, the data channel or the channel state information reference signal.

[0042] With respect to the method of FIG. 2A, the quasi co-location is associated with at least one of: doppler shift, doppler spread, average delay, and/or delay spread.

[0043] With respect to the method of FIG. 2A, further comprising providing, by the user device to the network node, an indication of one or more synchronization signal blocks (SSBs), based on either transmitting a random access preamble associated with a synchronization signal block, or transmitting a report to the network node indicating one or more synchronization signal blocks.

[0044] With respect to the method of FIG. 2A, the first number and/or the second number of physical resource blocks are provided for the reference signal on two symbols of the synchronization signal block, wherein there is an inter-symbol gap between the two symbols same as a separate tracking reference signal, and wherein the first number of physical resource blocks and the second number of physical resource blocks are user device - (e.g., UE-) specific. With respect to the method of FIG. 2A, the inter-symbol gap is either three or four symbols.

[0045] With respect to the method of FIG. 2A, the part of the reference signal used for demodulating the physical broadcast channel is carried in physical resource blocks with an inter-symbol gap different from that of physical resource blocks carrying the part of the reference signal used for time/frequency tracking purpose. [0046] With respect to the method of FIG. 2A, the part of the reference signal carried in the physical resource blocks appended to the synchronization signal block has at least one of same subcarrier density or same subcarrier offset as the part of the reference signal carried in the physical resource blocks of the synchronization signal block.

[0047] With respect to the method of FIG. 2A, the reference signal comprises a signal sequence mapped or allocated to resource elements of the frequency extended synchronization signal block, and wherein the resource elements in the symbols with appended physical resource blocks are mapped or allocated in a cyclic extension manner.

[0048] With respect to the method of FIG. 2A, the first number of physical resource blocks for the reference signal and the second number of physical resource blocks of the signal are provided based on at least one of the following: the first number and the second number have different values; the first number and the second number have the same value; the first number is lower than the second number; the first number is higher than the second number; the first number is zero, and the second number is non-zero; and the first number is non-zero, and the second number is zero.

[0049] With respect to the method of FIG. 2A, physical resource blocks for the reference signal may include: at a first symbol of the extended synchronization signal block, the first number of physical resource blocks that are above the synchronization signal block and the second number of physical resource blocks that are below the synchronization signal block; and at a second symbol of the extended synchronization signal block that has an inter-symbol gap of three or four symbols from the first symbol, the first number of physical resource blocks that are above the synchronization signal block and the second number of physical resource blocks that are below the synchronization signal block.

[0050] FIG. 2B is a flow chart illustrating operation of a network node (e.g., gNB, TRP or other network node) according to an example embodiment. Operation 280 includes transmitting, by a network node to the user device, a reference signal (RS) configuration for a time/frequency tracking purpose including: a synchronization signal block index identifying the selected synchronization signal block to be frequency extended to include physical resource blocks (PRBs) for a reference signal for the time/frequency tracking purpose; and information indicating physical resource blocks for the reference signal appended to the synchronization signal block to provide the frequency extended synchronization signal block, wherein the information indicates at least one of: 1) a first number of physical resource blocks for the reference signal that are above, or having subcarrier frequencies higher than, the synchronization signal block, and/or 2) a second number of physical resource blocks for the reference signal that are below, or having subcarrier frequencies lower than, the synchronization signal block.

[0051] FIG. 3 is a flow chart illustrating operation of a user device (or UE) according to another example embodiment. Operation 310 includes receiving, by a user device from a network node, a reference signal (RS) configuration for a time/frequency tracking purpose including: a synchronization signal block (SSB) index identifying a synchronization signal block to be frequency extended to include physical resource blocks (PRBs) for a reference signal for the time/frequency tracking purpose; and information indicating physical resource blocks for the reference signal appended to the synchronization signal block to provide the frequency extended synchronization signal block, wherein the information indicates at least one of: 1) a first number of physical resource blocks for the reference signal that are above, or having subcarrier frequencies higher than, the synchronization signal block, and/or 2) a second number of physical resource blocks for the reference signal that are below, or having subcarrier frequencies lower than, the synchronization signal block. Operation 320 includes determining, by the user device, the reference signal configuration for the time/frequency tracking purpose to receive the reference signal within the frequency extended synchronization signal block. And, operation 330 includes receiving, by the user device, the reference signal.

[0052] With respect to the method of FIG. 3, the method may include performing, by the user device, time/frequency tracking based at least on part of the reference signal received via the frequency extended synchronization signal block.

[0053] With respect to the method of FIG. 3, the reference signal configuration determined by the user device may include at least: the synchronization signal block index identifying the synchronization signal block that is frequency extended; and the physical resource blocks for the reference signal that are appended to the synchronization signal block to provide the frequency extended synchronization signal block.

[0054] With respect to the method of FIG. 3, the method may include performing, by the user device, channel estimation based at least on part of the reference signal received via the frequency extended synchronization signal block for demodulating a physical broadcast channel (PBCH).

[0055] With respect to the method of FIG. 3, the channel estimation may be performed based on part of the reference signal received via the physical resource blocks of the synchronization signal block but not the physical resource blocks appended to the synchronization signal block. [0056] With respect to the method of FIG. 3, the method may include performing, by the user device, optimization of a channel estimation related to demodulation of at least one of a control channel, a data channel or a channel state information reference signal, based at least on the time/frequency tracking.

[0057] With respect to the method of FIG. 3, the demodulation of the at least one of the control channel, the data channel or the channel state information reference signal is based on one or more quasi co-location between the reference signal received via the frequency extended synchronization signal block and the at least one of the control channel, the data channel or the channel state information reference signal.

[0058] With respect to the method of FIG. 3, the quasi co-location is associated with at least one of: doppler shift, doppler spread, average delay, and/or delay spread.

[0059] With respect to the method of FIG. 3, the method may further include providing, by the user device to the network node, an indication of one or more synchronization signal blocks (SSBs), based on either transmitting a random access preamble associated with a synchronization signal block, or transmitting a report to the network node indicating one or more synchronization signal blocks.

[0060] FIG. 4 is a diagram illustrating a frequency extended synchronization signal block including reference signal for time and frequency tracking purpose according to an example embodiment. Two examples are shown in FIG. 4, including Example 1 and Example 2. Example 1 will be described first. As shown in example 1 of FIG. 4, a synchronization signal block (SSB) 408 is shown, which includes a PSS, a SSS, PRBs for PBCH and PRBs for PBCH DMRS. SSB 408 is four symbols wide, extending from symbol 0 through symbol 3. PRBs for the tracking reference signal (TRS) (or PRBs for a reference signal for time and frequency tracking purpose) are appended above and below the SSB, to create a frequency extended SSB 450. The TRS may include an upper TRS portion 410A (on upper left side of SSB 408), a lower TRS portion 410B (on lower left side of SSB 408), an upper TRS portion 412A (on upper right side of SSB 408), and a lower TRS portion 412B (on lower right side of SSB 408). Upper TRS portions 410A and 412A may include a first number of PRBs above (or having subcarrier frequencies higher than) the SSB 408. Lower TRS portions 410B and 412B may include a second number of PRBs below (or having subcarrier frequencies lower than) the SSB 408. By appending PRBs above and/or below the PRBs (or subcarrier frequencies) of the SSB 408, the frequency spectrum or frequency resources of the SSB 408 can include reference signal for purpose of time/frequency tracking, and the SSB 408 is extended to provide a frequency extended SSB 450. [0061] Therefore, for example, rather than transmitting a SSB and TRS via different or separate time resources, this frequency extended SSB 450, which includes PRBs for the TRS appended to the SSB 408, provides a more resource efficient technique for the transmission of SSB and TRS signals, e.g., because the SSB and TRS may be transmitted via the same set of symbols through PRBs that have been appended to the SSB for the TRS.

[0062] According to an example embodiment, the UE may use both the TRS transmitted via the PRBs above (or having subcarrier frequencies higher than) the SSB and/or the PRBs below (or having subcarrier frequencies lower than) the SSB, as well as the PBCH DMRS signals provided in the same symbols as the TRS, for time frequency tracking purpose. In other words, the UE may use as a tracking reference signal, the upper TRS portion 410A, the lower TRS portion 410B and the PBCH DMRS provided on PRBs therebetween, as a left half TRS 430A. Likewise, the UE may use as a tracking reference signal, the upper TRS portion 412A, the lower TRS portion 412B and the PBCH DMRS provided on PRBs therebetween, as a right half TRS 430B. Thus, for example, the left half TRS 430A and right half TRS 430B may provide the complete TRS. The UE may use all or part of the complete TRS (e.g., UE may use all or portions of the left half TRS 430A and right half TRS 430B) for time and frequency tracking purposes. Thus, in this example, the PBCH DMRS provided on symbols 0 and 3 adjacent to the TRS PRBs may also operate or may be used as part of tracking reference signal or for purposes of time/frequency tracking by the UE. Therefore, the PRBs appended for the TRS (or for the reference signals for purpose of time/frequency tracking) may be considered PBCH DMRS extension, since the TRS PRBs extend the frequency range of the PBCH DMRS signal. The TRS shown in FIG. 4 may be a periodic TRS, which may be UE-specific. A common tracking reference signal may be provided in the same manner, by appending TRS PRBs above and/or below a SSB.

[0063] Example 2 shown in FIG. 4 is the same as or very similar to Example 1 of FIG. 4. However, in example 2, the TRS PRBs (and the PBCH DMRS of edge symbols) have an inter-symbol gap of 4 symbols in example 2, while such inter-symbol gap is 3 symbols in Example 1. The TRS PRBs are provided in symbols 0 and 3 in example 1, providing an inter-symbol gap of 3 symbols for example 1, while TRS PRBs are provided in symbols 0 and 4 (an inter-symbol gap of 4 symbols) for example 2. The TRS may be periodic or nonperiodic.

[0064] According to an example embodiment, the number of PRBs (e.g., within the SSB 408, FIG. 4) allocated to PBCH and/or allocated to PBCH-DMRS may be fixed or may be the same for all UEs or multiple UEs served by a cell or network node (e.g., the frequency extended SSB 450 configured for all UEs or configured for multiple UEs served by the cell or gNB may include the same SSB (408) structure and/or same number of PRBs allocated for PBCH and/or allocated for PBCH-DMRS within the SSB 408). On the other hand, 1) the first number of physical resource blocks (PRBs) for the reference signal (e.g., TRS) that are above, or having subcarrier frequencies higher than, the SSB 408, and/or 2) the second number PRBs for the reference signal that are below, or having subcarrier frequencies lower than, the SSB 408 may be UE-specific, e.g., each UE may be assigned its own UE-specific first and second numbers of PRBs above and below the SSB 408. For example, a first UE may be assigned or may be configured with a frequency extended SSB that includes 7 PRBs above the SSB 408 and 12 PRBs below the SSB 408. And, a second UE may be assigned or may be configured with a frequency extended SSB that includes 9 PRBs above the SSB 408 and 9 PRBs below the SSB 408. These are merely some illustrative examples, and other numbers may be used. Thus, numbers of PRBs allocated for PBCH and/or PBCH-DMRS within SSB 408 may be the same for multiple or all UEs, while the first and second numbers of PRBs allocated above and/or below (respectively) the SSB 408 to provide the frequency extended SSB 450, may be different for various or different UEs that are served by a cell or gNB. FIG. 5 is a diagram illustrating a signal sequence allocation in frequency extended SSB 450 according to an example embodiment. According to an example embodiment, the signal sequence may be a PBCH DMRS sequence. At 510, the PBCH DMRS sequence allocation is shown for SSB 408 without frequency extension. At 520, the sequence allocation is shown for the frequency extended SSB 450, where the PBCH DMRS sequence can be allocated to the extended SSB 450 in a way of cyclic extension. For example, the PBCH DMRS sequence can be allocated to the resource elements of the extended SSB 450 in a cyclic extension manner. In the example of FIG. 5, the PBCH DMRS sequence is allocated to PRBs of SSB 408 in the same way as in 510. At symbol 0, for upper PRBs 540 (of frequency extended SSB 450) that are above (or have subcarrier frequencies higher than) the SSB 408, and then lower PRBs 550 that are below (or have subcarrier frequencies lower than) the SSB 408, signal sequence allocation continues from the index following the indexes of PBCH DMRS sequence allocated to PRBs of SSB 408 at symbol 0. At symbol 4, for upper PRBs 540 (of frequency extended SSB 450) that are above (or have subcarrier frequencies higher than) the SSB 408, and then lower PRBs 550 that are below (or have subcarrier frequencies lower than) the SSB 408, the sequence allocation may, for example, begin or start from index 0. FIG. 5 illustrates one example, and other approaches or techniques may be used for sequence allocation for the frequency extended SSB. [0065] According to an example embodiment, with reference to FIG. 4, the UE may receive a reference signal (e.g., TRS) configuration for a time/frequency tracking purpose, including an index of the SSB that will be frequency extended (e.g., SSB index 4), and information indicating a number of PRBs above and/or below the SSB, e.g., 5 PRBs above the SSB, and 6 PRBs below the SSB. Thus, this configuration information informs or configures the UE with the information regarding the frequency extended SSB 450, including the SSB that will be frequency extended, and the number of PRBs that are appended to the SSB to be used for TRS. The UE may then determine this TRS configuration, may receive the TRS (e.g., including the TRS received via the PRBs above the SSB at symbol 0, the PBCH DMRS received for symbol 0, the TRS received via the PRB below the SSB 408, for both the left half 430A TRS and right half TRS 430B. Thus, for example, the UE may either: 1) use only the TRS received via PRBs appended above and/or below the SSB, or 2) may use both the TRS received via the PRBs appended above and/or below the SSB 408 and the PBCH DMRS of the same symbols (e.g., symbols 0 and 3, example 1) for TRS, for time/frequency tracking of the network (gNB or cell).

[0066] According to an example embodiment,, the UE may perform channel estimation based on the TRS received via the extended SSB 450 (e.g., based on the PBCH DMRS carried in SSB 408). Also, the UE may perform channel optimization related to demodulation of a control channel (e.g., PDCCH), a data channel (e.g., a PDSCH), or a channel state information-reference signal (CSI-RS), based on the time-frequency tracking.

[0067] Also, the reference signal received via the extended SSB 450 for time-frequency tracking purpose may be quasi co-located (QCL) with the control channel (e.g., PDCCH), the data channel (PDSCH), and/or the CSI-RS, e.g., with respect to one or more QCL parameters, such as doppler shift, doppler spread, average delay, and/or delay spread. Thus, once the channel estimation has been performed with respect to the TRS, the UE may use the same channel estimation to receive and/or demodulate one or more of the control channel, data channel and/or CSI-RS, for example.

[0068] Some examples will now be described:

[0069] Example 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, by a user device from a network node, a reference signal (RS) configuration for a time/frequency tracking purpose including: a synchronization signal block (SSB) index identifying a synchronization signal block to be frequency extended to include physical resource blocks (PRBs) for a reference signal for the time/frequency tracking purpose; and information indicating physical resource blocks for the reference signal appended to the synchronization signal block to provide the frequency extended synchronization signal block, wherein the information indicates at least one of: 1) a first number of physical resource blocks for the reference signal that are above, or having subcarrier frequencies higher than, the synchronization signal block, and/or 2) a second number of physical resource blocks for the reference signal that are below, or having subcarrier frequencies lower than, the synchronization signal block; and determine, by the user device, the reference signal configuration for the time/frequency tracking purpose to receive the reference signal within the frequency extended synchronization signal block.

[0070] Example 2. The apparatus of Example 1, wherein the reference signal configuration determined by the user device comprises at least: the synchronization signal block index identifying the synchronization signal block that is frequency extended; and the physical resource blocks for the reference signal that are appended to the synchronization signal block to provide the frequency extended synchronization signal block.

[0071] Example 3. The apparatus of any of Examples 1-2, wherein the apparatus is further caused to: receive, by the user device, the reference signal.

[0072] Example 4. The apparatus of any of Examples 1-3, wherein the apparatus is caused to: perform, by the user device, time/frequency tracking based at least on part of the reference signal received via the frequency extended synchronization signal block.

[0073] Example 5. The apparatus of any of Examples 1-4, wherein the apparatus is caused to: perform, by the user device, channel estimation based at least on part of the reference signal received via the frequency extended synchronization signal block for demodulating a physical broadcast channel (PBCH).

[0074] Example 6. The apparatus of Example 5, wherein the channel estimation is performed based on part of the reference signal received via the physical resource blocks of the synchronization signal block but not the physical resource blocks appended to the synchronization signal block.

[0075] Example 7. The apparatus of any of Examples 4-6, wherein the apparatus is caused to: perform, by the user device, optimization of a channel estimation related to demodulation of at least one of a control channel, a data channel or a channel state information reference signal, based at least on the time/frequency tracking.

[0076] Example 8. The apparatus of Example 7, wherein the demodulation of the at least one of the control channel, the data channel or the channel state information reference signal is based on one or more quasi co-location between the reference signal received via the frequency extended synchronization signal block and the at least one of the control channel, the data channel or the channel state information reference signal.

[0077] Example 9. The apparatus of Example 8, wherein the quasi co-location is associated with at least one of: doppler shift, doppler spread, average delay, and/or delay spread.

[0078] Example 10. The apparatus of any of Examples 1-9, wherein the apparatus is further caused to: provide, by the user device to the network node, an indication of one or more synchronization signal blocks (SSBs), based on either transmitting a random access preamble associated with a synchronization signal block, or transmitting a report to the network node indicating one or more synchronization signal blocks.

[0079] Example 11. The apparatus of any of Examples 1-10, wherein the first number and/or the second number of physical resource blocks are provided for the reference signal on two symbols of the synchronization signal block, wherein there is an inter-symbol gap between the two symbols same as a separate tracking reference signal.

[0080] Example 12. The apparatus of Example 11, wherein the inter-symbol gap is either three or four symbols.

[0081] Example 13. The apparatus of any of Examples 5-12, wherein the part of the reference signal used for demodulating the physical broadcast channel is carried in physical resource blocks with an inter-symbol gap different from that of physical resource blocks carrying the part of the reference signal used for time/frequency tracking purpose.

[0082] Example 14. The apparatus of any of Examples 1-13, wherein the part of the reference signal carried in the physical resource blocks appended to the synchronization signal block has at least one of same subcarrier density or same subcarrier offset as the part of the reference signal carried in the physical resource blocks of the synchronization signal block.

[0083] Example 15. The apparatus of any of Examples 1-14, wherein the reference signal comprises a signal sequence mapped or allocated to resource elements of the frequency extended synchronization signal block, and wherein the resource elements in the symbols with appended physical resource blocks are mapped or allocated in a cyclic extension manner.

[0084] Example 16. The apparatus of any of Examples 1-15, wherein the first number of physical resource blocks for the reference signal and the second number of physical resource blocks of the signal are provided based on at least one of the following: the first number and the second number have different values; the first number and the second number have the same value; the first number is lower than the second number; the first number is higher than the second number; the first number is zero, and the second number is non-zero; and the first number is non-zero, and the second number is zero.

[0085] Example 17. The apparatus of any of Examples 1-16, wherein physical resource blocks for the reference signal comprise: at a first symbol of the extended synchronization signal block, the first number of physical resource blocks that are above the synchronization signal block and the second number of physical resource blocks that are below the synchronization signal block; and at a second symbol of the extended synchronization signal block that has an inter-symbol gap of three or four symbols from the first symbol, the first number of physical resource blocks that are above the synchronization signal block and the second number of physical resource blocks that are below the synchronization signal block.

[0086] Example 18. A method comprising: receiving, by a user device from a network node, a reference signal (RS) configuration for a time/frequency tracking purpose including: a synchronization signal block (SSB) index identifying a synchronization signal block to be frequency extended to include physical resource blocks (PRBs) for a reference signal for the time/frequency tracking purpose; and information indicating physical resource blocks for the reference signal appended to the synchronization signal block to provide the frequency extended synchronization signal block, wherein the information indicates at least one of: 1) a first number of physical resource blocks for the reference signal that are above, or having subcarrier frequencies higher than, the synchronization signal block, and/or 2) a second number of physical resource blocks for the reference signal that are below, or having subcarrier frequencies lower than, the synchronization signal block; and determining, by the user device, the reference signal configuration for the time/frequency tracking purpose to receive the reference signal within the frequency extended synchronization signal block.

[0087] Example 19. The method of Example 18, wherein the reference signal configuration determined by the user device comprises at least: the synchronization signal block index identifying the synchronization signal block that is frequency extended; and the physical resource blocks for the reference signal that are appended to the synchronization signal block to provide the frequency extended synchronization signal block.

[0088] Example 20. The method of any of Examples 18-19, further comprising: receiving, by the user device, the reference signal.

[0089] Example 21. The method of any of Examples 18-20, further comprising: performing, by the user device, time/frequency tracking based at least on part of the reference signal received via the frequency extended synchronization signal block. [0090] Example 22. The method of any of Examples 18-21, comprising: performing, by the user device, channel estimation based at least on part of the reference signal received via the frequency extended synchronization signal block for demodulating a physical broadcast channel (PBCH).

[0091] Example 23. The method of Example 22, wherein the channel estimation is performed based on part of the reference signal received via the physical resource blocks of the synchronization signal block but not the physical resource blocks appended to the synchronization signal block.

[0092] Example 24. The method of any of Examples 21-23, wherein the apparatus is caused to: performing, by the user device, optimization of a channel estimation related to demodulation of at least one of a control channel, a data channel or a channel state information reference signal, based at least on the time/frequency tracking.

[0093] Example 25. The method of Example 24, wherein the demodulation of the at least one of the control channel, the data channel or the channel state information reference signal is based on one or more quasi co-location between the reference signal received via the frequency extended synchronization signal block and the at least one of the control channel, the data channel or the channel state information reference signal.

[0094] Example 26. The method of Example 25, wherein the quasi co-location is associated with at least one of: doppler shift, doppler spread, average delay, and/or delay spread.

[0095] Example 27. The method of any of Examples 18-26, further comprising: providing, by the user device to the network node, an indication of one or more synchronization signal blocks (SSBs), based on either transmitting a random access preamble associated with a synchronization signal block, or transmitting a report to the network node indicating one or more synchronization signal blocks.

[0096] Example 28. The method of any of Examples 18-27, wherein the first number and/or the second number of physical resource blocks are provided for the reference signal on two symbols of the synchronization signal block, wherein there is an inter-symbol gap between the two symbols same as a separate tracking reference signal.

[0097] Example 29. The method of Example 28, wherein the inter-symbol gap is either three or four symbols.

[0098] Example 30. The method of any of Examples 22-29, wherein the part of the reference signal used for demodulating the physical broadcast channel is carried in physical resource blocks with an inter-symbol gap different from that of physical resource blocks carrying the part of the reference signal used for time/frequency tracking purpose.

[0099] Example 31. The method of any of Examples 18-30, wherein the part of the reference signal carried in the physical resource blocks appended to the synchronization signal block has at least one of same subcarrier density or same subcarrier offset as the part of the reference signal carried in the physical resource blocks of the synchronization signal block.

[0100] Example 32. The method of any of Examples 18-31, wherein the reference signal comprises a signal sequence mapped or allocated to resource elements of the frequency extended synchronization signal block, and wherein the resource elements in the symbols with appended physical resource blocks are mapped or allocated in a cyclic extension manner.

[0101] Example 33. The method of any of Examples 18-32, wherein the first number of physical resource blocks for the reference signal and the second number of physical resource blocks of the signal are provided based on at least one of the following: the first number and the second number have different values; the first number and the second number have the same value; the first number is lower than the second number; the first number is higher than the second number; the first number is zero, and the second number is non-zero; and the first number is non-zero, and the second number is zero.

[0102] Example 34. The method of any of Examples 18-33, wherein physical resource blocks for the reference signal comprise: at a first symbol of the extended synchronization signal block, the first number of physical resource blocks that are above the synchronization signal block and the second number of physical resource blocks that are below the synchronization signal block; and at a second symbol of the extended synchronization signal block that has an inter-symbol gap of three or four symbols from the first symbol, the first number of physical resource blocks that are above the synchronization signal block and the second number of physical resource blocks that are below the synchronization signal block.

[0103] Example 35. A non-transitory computer-readable storage medium comprising instructions stored thereon that, when executed by at least one processor, are configured to cause a computing system to: receive, by a user device from a network node, a reference signal (RS) configuration for a time/frequency tracking purpose including: a synchronization signal block (SSB) index identifying a synchronization signal block to be frequency extended to include physical resource blocks (PRBs) for a reference signal for the time/frequency tracking purpose; and information indicating physical resource blocks for the reference signal appended to the synchronization signal block to provide the frequency extended synchronization signal block, wherein the information indicates at least one of: 1) a first number of physical resource blocks for the reference signal that are above, or having subcarrier frequencies higher than, the synchronization signal block, and/or 2) a second number of physical resource blocks for the reference signal that are below, or having subcarrier frequencies lower than, the synchronization signal block; and determine, by the user device, the reference signal configuration for the time/frequency tracking purpose to receive the reference signal within the frequency extended synchronization signal block.

[0104] Example 36. An apparatus comprising: means for receiving, by a user device from a network node, a reference signal (RS) configuration for a time/frequency tracking purpose including: a synchronization signal block (SSB) index identifying a synchronization signal block to be frequency extended to include physical resource blocks (PRBs) for a reference signal for the time/frequency tracking purpose; and information indicating physical resource blocks for the reference signal appended to the synchronization signal block to provide the frequency extended synchronization signal block, wherein the information indicates at least one of: 1) a first number of physical resource blocks for the reference signal that are above, or having subcarrier frequencies higher than, the synchronization signal block, and/or 2) a second number of physical resource blocks for the reference signal that are below, or having subcarrier frequencies lower than, the synchronization signal block; and means for determining, by the user device, the reference signal configuration for the time/frequency tracking purpose to receive the reference signal within the frequency extended synchronization signal block.

[0105] Example 37. 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: transmit, by a network node to a user device, a reference signal (RS) configuration for a time/frequency tracking purpose including: a synchronization signal block index identifying the selected synchronization signal block to be frequency extended to include physical resource blocks (PRBs) for a reference signal for the time/frequency tracking purpose; and information indicating physical resource blocks for the reference signal appended to the synchronization signal block to provide the frequency extended synchronization signal block, wherein the information indicates at least one of: 1) a first number of physical resource blocks for the reference signal that are above, or having subcarrier frequencies higher than, the synchronization signal block, and/or 2) a second number of physical resource blocks for the reference signal that are below, or having subcarrier frequencies lower than, the synchronization signal block. [0106] Example 38. The apparatus of Example 37, wherein the apparatus is further caused to: receive, by the network node from a user device, an indication of one or more synchronization signal blocks (SSBs), based on either receiving from the user device a random access preamble associated with a synchronization signal block, or receiving a report from the user device indicating one or more synchronization signal blocks; select, by the network node, one of the one or more indicated synchronization signal blocks, wherein the synchronization signal block that is extended comprises the selected synchronization signal block.

[0107] Example 39. A method comprising: transmitting, by a network node to a user device, a reference signal (RS) configuration for a time/frequency tracking purpose including: a synchronization signal block index identifying the selected synchronization signal block to be frequency extended to include physical resource blocks (PRBs) for a reference signal for the time/frequency tracking purpose; and information indicating physical resource blocks for the reference signal appended to the synchronization signal block to provide the frequency extended synchronization signal block, wherein the information indicates at least one of: 1) a first number of physical resource blocks for the reference signal that are above, or having subcarrier frequencies higher than, the synchronization signal block, and/or 2) a second number of physical resource blocks for the reference signal that are below, or having subcarrier frequencies lower than, the synchronization signal block.

[0108] Example 40. 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, by a user device from a network node, a reference signal (RS) configuration for a time/frequency tracking purpose including: a synchronization signal block (SSB) index identifying a synchronization signal block to be frequency extended to include physical resource blocks (PRBs) for a reference signal for the time/frequency tracking purpose; and information indicating physical resource blocks for the reference signal appended to the synchronization signal block to provide the frequency extended synchronization signal block, wherein the information indicates at least one of: 1) a first number of physical resource blocks for the reference signal that are above, or having subcarrier frequencies higher than, the synchronization signal block, and/or 2) a second number of physical resource blocks for the reference signal that are below, or having subcarrier frequencies lower than, the synchronization signal block; determine, by the user device, the reference signal configuration for the time/frequency tracking purpose to receive the reference signal within the frequency extended synchronization signal block; and receive, by the user device, the reference signal.

[0109] Example 41. The apparatus of Example 40, wherein the apparatus is further caused to: perform, by the user device, time/frequency tracking based at least on part of the reference signal received via the frequency extended synchronization signal block.

[0110] Example 42. The apparatus of any of Examples 40-41, wherein the reference signal configuration determined by the user device comprises at least: the synchronization signal block index identifying the synchronization signal block that is frequency extended; and the physical resource blocks for the reference signal that are appended to the synchronization signal block to provide the frequency extended synchronization signal block.

[0111] Example 43. The apparatus of any of Examples 40-42, wherein the apparatus is caused to: perform, by the user device, channel estimation based at least on part of the reference signal received via the frequency extended synchronization signal block for demodulating a physical broadcast channel (PBCH).

[0112] Example 44. The apparatus of Example 43, wherein the channel estimation is performed based on part of the reference signal received via the physical resource blocks of the synchronization signal block but not the physical resource blocks appended to the synchronization signal block.

[0113] Example 45. The apparatus of any of Examples 43-44, wherein the apparatus is caused to: perform, by the user device, optimization of a channel estimation related to demodulation of at least one of a control channel, a data channel or a channel state information reference signal, based at least on the time/frequency tracking.

[0114] Example 46. The apparatus of Example 45, wherein the demodulation of the at least one of the control channel, the data channel or the channel state information reference signal is based on one or more quasi co-location between the reference signal received via the frequency extended synchronization signal block and the at least one of the control channel, the data channel or the channel state information reference signal.

[0115] Example 47. The apparatus of Example 46, wherein the quasi co-location is associated with at least one of: doppler shift, doppler spread, average delay, and/or delay spread.

[0116] Example 48. The apparatus of any of Examples 40-47, wherein the apparatus is further caused to: provide, by the user device to the network node, an indication of one or more synchronization signal blocks (SSBs), based on either transmitting a random access preamble associated with a synchronization signal block, or transmitting a report to the network node indicating one or more synchronization signal blocks.

[0117] Example 49. The apparatus of any of xamples 40-48, wherein the first number and/or the second number of physical resource blocks are provided for the reference signal on two symbols of the synchronization signal block, wherein there is an inter-symbol gap between the two symbols same as a separate tracking reference signal.

[0118] Example 50. The apparatus of Example 49, wherein the inter-symbol gap is either three or four symbols.

[0119] Example 51. The apparatus of any of Examples 43-50, wherein the part of the reference signal used for demodulating the physical broadcast channel is carried in physical resource blocks with an inter-symbol gap different from that of physical resource blocks carrying the part of the reference signal used for time/frequency tracking purpose.

[0120] Example 52. The apparatus of any of Examples 40-51, wherein the part of the reference signal carried in the physical resource blocks appended to the synchronization signal block has at least one of same subcarrier density or same subcarrier offset as the part of the reference signal carried in the physical resource blocks of the synchronization signal block.

[0121] Example 53. The apparatus of any of Examples 40-52, wherein the reference signal comprises a signal sequence mapped or allocated to resource elements of the frequency extended synchronization signal block, and wherein the resource elements in the symbols with appended physical resource blocks are mapped or allocated in a cyclic extension manner.

[0122] Example 54. The apparatus of any of Examples 40-53, wherein the first number of physical resource blocks for the reference signal and the second number of physical resource blocks of the signal are provided based on at least one of the following: the first number and the second number have different values; the first number and the second number have the same value; the first number is lower than the second number; the first number is higher than the second number; the first number is zero, and the second number is non-zero; and the first number is non-zero, and the second number is zero.

[0123] Example 55. The apparatus of any of Examples 40-54, wherein physical resource blocks for the reference signal comprise: at a first symbol of the extended synchronization signal block, the first number of physical resource blocks that are above the synchronization signal block and the second number of physical resource blocks that are below the synchronization signal block; and at a second symbol of the extended synchronization signal block that has an inter-symbol gap of three or four symbols from the first symbol, the first number of physical resource blocks that are above the synchronization signal block and the second number of physical resource blocks that are below the synchronization signal block.

[0124] Example 56. A method comprising: receiving, by a user device from a network node, a reference signal (RS) configuration for a time/frequency tracking purpose including: a synchronization signal block (SSB) index identifying a synchronization signal block to be frequency extended to include physical resource blocks (PRBs) for a reference signal for the time/frequency tracking purpose; and information indicating physical resource blocks for the reference signal appended to the synchronization signal block to provide the frequency extended synchronization signal block, wherein the information indicates at least one of: 1) a first number of physical resource blocks for the reference signal that are above, or having subcarrier frequencies higher than, the synchronization signal block, and/or 2) a second number of physical resource blocks for the reference signal that are below, or having subcarrier frequencies lower than, the synchronization signal block; determining, by the user device, the reference signal configuration for the time/frequency tracking purpose to receive the reference signal within the frequency extended synchronization signal block; and receiving, by the user device, the reference signal.

[0125] Example 57. The method of example 56, further comprising: performing, by the user device, time/frequency tracking based at least on part of the reference signal received via the frequency extended synchronization signal block.

[0126] Example 58. The method of any of Examples 56-57, wherein the reference signal configuration determined by the user device comprises at least: the synchronization signal block index identifying the synchronization signal block that is frequency extended; and the physical resource blocks for the reference signal that are appended to the synchronization signal block to provide the frequency extended synchronization signal block.

[0127] Example 59. The method of any of Examples 56-58, comprising: performing, by the user device, channel estimation based at least on part of the reference signal received via the frequency extended synchronization signal block for demodulating a physical broadcast channel (PBCH).

[0128] Example 60. The method of Example 59, wherein the channel estimation is performed based on part of the reference signal received via the physical resource blocks of the synchronization signal block but not the physical resource blocks appended to the synchronization signal block. [0129] Example 61. The method of any of Examples 58-60, comprising: performing, by the user device, optimization of a channel estimation related to demodulation of at least one of a control channel, a data channel or a channel state information reference signal, based at least on the time/frequency tracking.

[0130] Example 62. The method of Example 61, wherein the demodulation of the at least one of the control channel, the data channel or the channel state information reference signal is based on one or more quasi co-location between the reference signal received via the frequency extended synchronization signal block and the at least one of the control channel, the data channel or the channel state information reference signal.

[0131] Example 63. A non-transitory computer-readable storage medium comprising instructions stored thereon that, when executed by at least one processor, are configured to cause a computing system to: receive, by a user device from a network node, a reference signal (RS) configuration for a time/frequency tracking purpose including: a synchronization signal block (SSB) index identifying a synchronization signal block to be frequency extended to include physical resource blocks (PRBs) for a reference signal for the time/frequency tracking purpose; and information indicating physical resource blocks for the reference signal appended to the synchronization signal block to provide the frequency extended synchronization signal block, wherein the information indicates at least one of: 1) a first number of physical resource blocks for the reference signal that are above, or having subcarrier frequencies higher than, the synchronization signal block, and/or 2) a second number of physical resource blocks for the reference signal that are below, or having subcarrier frequencies lower than, the synchronization signal block; determine, by the user device, the reference signal configuration for the time/frequency tracking purpose to receive the reference signal within the frequency extended synchronization signal block; and receive, by the user device, the reference signal.

[0132] Example 64. An apparatus comprising: means for receiving, by a user device from a network node, a reference signal (RS) configuration for a time/frequency tracking purpose including: a synchronization signal block (SSB) index identifying a synchronization signal block to be frequency extended to include physical resource blocks (PRBs) for a reference signal for the time/frequency tracking purpose; and information indicating physical resource blocks for the reference signal appended to the synchronization signal block to provide the frequency extended synchronization signal block, wherein the information indicates at least one of: 1) a first number of physical resource blocks for the reference signal that are above, or having subcarrier frequencies higher than, the synchronization signal block, and/or 2) a second number of physical resource blocks for the reference signal that are below, or having subcarrier frequencies lower than, the synchronization signal block; means for determining, by the user device, the reference signal configuration for the time/frequency tracking purpose to receive the reference signal within the frequency extended synchronization signal block; and means for receiving, by the user device, the reference signal.

[0133] FIG. 6 is a block diagram of a wireless station (e.g., AP, BS or user device/UE, or other network node) 1500 according to an example embodiment. The wireless station 1500 may include, for example, one or more (e.g., two as shown in FIG. 6) RF (radio frequency) or wireless transceivers 1502 A, 1502B, where each wireless transceiver includes a transmitter to transmit signals and a receiver to receive signals. The wireless station also includes a processor or control unit/entity (controller) 1504 to execute instructions or software and control transmission and receptions of signals, and a memory 1506 to store data and/or instructions.

[0134] Processor 1504 may also make decisions or determinations, generate frames, packets or messages for transmission, decode received frames or messages for further processing, and other tasks or functions described herein. Processor 1504, which may be a baseband processor, for example, may generate messages, packets, frames or other signals for transmission via wireless transceiver 1502 (1502A or 1502B). Processor 1504 may control transmission of signals or messages over a wireless network, and may control the reception of signals or messages, etc., via a wireless network (e.g., after being down-converted by wireless transceiver 1502, for example). Processor 1504 may be programmable and capable of executing software or other instructions stored in memory or on other computer media to perform the various tasks and functions described above, such as one or more of the tasks or methods described above. Processor 1504 may be (or may include), for example, hardware, programmable logic, a programmable processor that executes software or firmware, and/or any combination of these. Using other terminology, processor 1504 and transceiver 1502 together may be considered as a wireless transmitter/receiver system, for example.

[0135] In addition, referring to FIG. 6, a controller (or processor) 1508 may execute software and instructions, and may provide overall control for the station 1500, and may provide control for other systems not shown in FIG. 6, such as controlling input/output devices (e.g., display, keypad), and/or may execute software for one or more applications that may be provided on wireless station 1500, such as, for example, an email program, audio/video applications, a word processor, a Voice over IP application, or other application or software.

[0136] In addition, a storage medium may be provided that includes stored instructions, which when executed by a controller or processor may result in the processor 1504, or other controller or processor, performing one or more of the functions or tasks described above.

[0137] According to another example embodiment, RF or wireless transceiver(s) 1502A/1502B may receive signals or data and/or transmit or send signals or data. Processor 1504 (and possibly transceivers 1502A/1502B) may control the RF or wireless transceiver 1502 A or 1502B to receive, send, broadcast or transmit signals or data.

[0138] The embodiments are not, however, restricted to the system that is given as an example, but a person skilled in the art may apply the solution to other communication systems. Another example of a suitable communications system is the 5G concept. It is assumed that network architecture in 5G will be quite similar to that of the LTE-advanced. 5G is likely to use multiple input - multiple output (MIMO) antennas, many more base stations or nodes than the LTE (a so-called small cell concept), including macro sites operating in co-operation with smaller stations and perhaps also employing a variety of radio technologies for better coverage and enhanced data rates.

[0139] It should be appreciated that future networks will most probably utilise network functions virtualization (NFV) which is a network architecture concept that proposes virtualizing network node functions into “building blocks” or entities that may be operationally connected or linked together to provide services. A virtualized network function (VNF) may comprise one or more virtual machines running computer program codes using standard or general type servers instead of customized hardware. Cloud computing or data storage may also be utilized. In radio communications this may mean node operations may be carried out, at least partly, in a server, host or node operationally coupled to a remote radio head. It is also possible that node operations will be distributed among a plurality of servers, nodes or hosts. It should also be understood that the distribution of labour between core network operations and base station operations may differ from that of the LTE or even be non-existent.

[0140] Embodiments of the various techniques described herein may be implemented in digital electronic circuitry, or in computer hardware, firmware, software, or in combinations of them. Embodiments may be implemented as a computer program product, i.e., a computer program tangibly embodied in an information carrier, e.g., in a machine-readable storage device or in a propagated signal, for execution by, or to control the operation of, a data processing apparatus, e.g., a programmable processor, a computer, or multiple computers. Embodiments may also be provided on a computer readable medium or computer readable storage medium, which may be a non-transitory medium. Embodiments of the various techniques may also include embodiments provided via transitory signals or media, and/or programs and/or software embodiments that are downloadable via the Internet or other network(s), either wired networks and/or wireless networks. In addition, embodiments may be provided via machine type communications (MTC), and also via an Internet of Things (IOT).

[0141] 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, distribution medium, or computer readable medium, which may be any entity or device capable of carrying the program. Such carriers include a record medium, computer memory, read-only memory, photoelectrical and/or electrical carrier signal, telecommunications signal, and software distribution package, for example. Depending on the processing power needed, the computer program may be executed in a single electronic digital computer or it may be distributed amongst a number of computers.

[0142] Furthermore, embodiments of the various techniques described herein may use a cyber-physical system (CPS) (a system of collaborating computational elements controlling physical entities). CPS may enable the embodiment and exploitation of massive amounts of interconnected ICT devices (sensors, actuators, processors microcontrollers, . . .) embedded in physical objects at different locations. Mobile cyber physical systems, in which the physical system in question has inherent mobility, are a subcategory of cyber-physical systems. Examples of mobile physical systems include mobile robotics and electronics transported by humans or animals. The rise in popularity of smartphones has increased interest in the area of mobile cyber-physical systems. Therefore, various embodiments of techniques described herein may be provided via one or more of these technologies.

[0143] A computer program, such as the computer program(s) described above, can be written in any form of programming language, including compiled or interpreted languages, and can be deployed in any form, including as a stand-alone program or as a module, component, subroutine, or other unit or part of it suitable for use in a computing environment. A computer program can be deployed to be executed on one computer or on multiple computers at one site or distributed across multiple sites and interconnected by a communication network. [0144] Method steps may be performed by one or more programmable processors executing a computer program or computer program portions to perform functions by operating on input data and generating output. Method steps also may be performed by, and an apparatus may be implemented as, special purpose logic circuitry, e.g., an FPGA (field programmable gate array) or an ASIC (application-specific integrated circuit).

[0145] Processors suitable for the execution of a computer program include, by way of example, both general and special purpose microprocessors, and any one or more processors of any kind of digital computer, chip or chipset. Generally, a processor will receive instructions and data from a read-only memory or a random access memory or both. Elements of a computer may include at least one processor for executing instructions and one or more memory devices for storing instructions and data. Generally, a computer also may include, or be operatively coupled to receive data from or transfer data to, or both, one or more mass storage devices for storing data, e.g., magnetic, magneto-optical disks, or optical disks. Information carriers suitable for embodying computer program instructions and data include all forms of non-volatile memory, including by way of example semiconductor memory devices, e.g., EPROM, EEPROM, and flash memory devices; magnetic disks, e.g., internal hard disks or removable disks; magneto-optical disks; and CD-ROM and DVD-ROM disks. The processor and the memory may be supplemented by, or incorporated in, special purpose logic circuitry.

[0146] To provide for interaction with a user, embodiments may be implemented on a computer having a display device, e.g., a cathode ray tube (CRT) or liquid crystal display (LCD) monitor, for displaying information to the user and a user interface, such as a keyboard and a pointing device, e.g., a mouse or a trackball, by which the user can provide input to the computer. Other kinds of devices can be used to provide for interaction with a user as well; for example, feedback provided to the user can be any form of sensory feedback, e.g., visual feedback, auditory feedback, or tactile feedback; and input from the user can be received in any form, including acoustic, speech, or tactile input.

[0147] Embodiments may be implemented in a computing system that includes a back-end component, e.g., as a data server, or that includes a middleware component, e.g., an application server, or that includes a front-end component, e.g., a client computer having a graphical user interface or a Web browser through which a user can interact with an embodiment, or any combination of such back-end, middleware, or front-end components. Components may be interconnected by any form or medium of digital data communication, e.g., a communication network. Examples of communication networks include a local area network (LAN) and a wide area network (WAN), e.g., the Internet.

[0148] While certain features of the described embodiments have been illustrated as described herein, many modifications, substitutions, changes and equivalents will now occur to those skilled in the art. It is, therefore, to be understood that the appended claims are intended to cover all such modifications and changes as fall within the true spirit of the various embodiments.

Claims

WHAT IS CLAIMED IS:

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, by a user device from a network node, a reference signal (RS) configuration for a time/frequency tracking purpose including: a synchronization signal block (SSB) index identifying a synchronization signal block to be frequency extended to include physical resource blocks (PRBs) for a reference signal for the time/frequency tracking purpose; and information indicating physical resource blocks for the reference signal appended to the synchronization signal block to provide the frequency extended synchronization signal block, wherein the information indicates at least one of: 1) a first number of physical resource blocks for the reference signal that are above, or having subcarrier frequencies higher than, the synchronization signal block, and/or 2) a second number of physical resource blocks for the reference signal that are below, or having subcarrier frequencies lower than, the synchronization signal block; and determine, by the user device, the reference signal configuration for the time/frequency tracking purpose to receive the reference signal within the frequency extended synchronization signal block.

2. The apparatus of claim 1, wherein the reference signal configuration determined by the user device comprises at least: the synchronization signal block index identifying the synchronization signal block that is frequency extended; and the physical resource blocks for the reference signal that are appended to the synchronization signal block to provide the frequency extended synchronization signal block.

3. The apparatus of any of claims 1-2, wherein the apparatus is further caused to: receive, by the user device, the reference signal.

4. The apparatus of any of claims 1-3, wherein the apparatus is caused to: perform, by the user device, time/frequency tracking based at least on part of the reference signal received via the frequency extended synchronization signal block.

5. The apparatus of any of claims 1-4, wherein the apparatus is caused to: perform, by the user device, channel estimation based at least on part of the reference signal received via the frequency extended synchronization signal block for demodulating a physical broadcast channel (PBCH).

6. The apparatus of claim 5, wherein the channel estimation is performed based on part of the reference signal received via the physical resource blocks of the synchronization signal block but not the physical resource blocks appended to the synchronization signal block.

7. The apparatus of any of claims 4-6, wherein the apparatus is caused to: perform, by the user device, optimization of a channel estimation related to demodulation of at least one of a control channel, a data channel or a channel state information reference signal, based at least on the time/frequency tracking.

8. The apparatus of claim 7, wherein the demodulation of the at least one of the control channel, the data channel or the channel state information reference signal is based on one or more quasi co-location between the reference signal received via the frequency extended synchronization signal block and the at least one of the control channel, the data channel or the channel state information reference signal.

9. The apparatus of claim 8, wherein the quasi co-location is associated with at least one of: doppler shift, doppler spread, average delay, and/or delay spread.

10. The apparatus of any of claims 1-9, wherein the apparatus is further caused to: provide, by the user device to the network node, an indication of one or more synchronization signal blocks (SSBs), based on either transmitting a random access preamble associated with a synchronization signal block, or transmitting a report to the network node indicating one or more synchronization signal blocks.

11. The apparatus of any of claims 1-10, wherein the first number and/or the second number of physical resource blocks are provided for the reference signal on two symbols of the synchronization signal block, wherein there is an inter-symbol gap between the two symbols same as a separate tracking reference signal.

12. The apparatus of claim 11, wherein the inter-symbol gap is either three or four symbols.

13. The apparatus of any of claims 5-12, wherein the part of the reference signal used for demodulating the physical broadcast channel is carried in physical resource blocks with an inter-symbol gap different from that of physical resource blocks carrying the part of the reference signal used for time/frequency tracking purpose.

14. The apparatus of any of claims 1-13, wherein the part of the reference signal carried in the physical resource blocks appended to the synchronization signal block has at least one of same subcarrier density or same subcarrier offset as the part of the reference signal carried in the physical resource blocks of the synchronization signal block.

15. The apparatus of any of claims 1-14, wherein the reference signal comprises a signal sequence mapped or allocated to resource elements of the frequency extended synchronization signal block, and wherein the resource elements in the symbols with appended physical resource blocks are mapped or allocated in a cyclic extension manner.

16. The apparatus of any of claims 1-15, wherein the first number of physical resource blocks for the reference signal and the second number of physical resource blocks of the signal are provided based on at least one of the following: the first number and the second number have different values; the first number and the second number have the same value; the first number is lower than the second number; the first number is higher than the second number; the first number is zero, and the second number is non-zero; and the first number is non-zero, and the second number is zero.

17. The apparatus of any of claims 1-16, wherein physical resource blocks for the reference signal comprise: at a first symbol of the extended synchronization signal block, the first number of physical resource blocks that are above the synchronization signal block and the second number of physical resource blocks that are below the synchronization signal block; and at a second symbol of the extended synchronization signal block that has an intersymbol gap of three or four symbols from the first symbol, the first number of physical resource blocks that are above the synchronization signal block and the second number of physical resource blocks that are below the synchronization signal block.

18. A method comprising: receiving, by a user device from a network node, a reference signal (RS) configuration for a time/frequency tracking purpose including: a synchronization signal block (SSB) index identifying a synchronization signal block to be frequency extended to include physical resource blocks (PRBs) for a reference signal for the time/frequency tracking purpose; and information indicating physical resource blocks for the reference signal appended to the synchronization signal block to provide the frequency extended synchronization signal block, wherein the information indicates at least one of: 1) a first number of physical resource blocks for the reference signal that are above, or having subcarrier frequencies higher than, the synchronization signal block, and/or 2) a second number of physical resource blocks for the reference signal that are below, or having subcarrier frequencies lower than, the synchronization signal block; and determining, by the user device, the reference signal configuration for the time/frequency tracking purpose to receive the reference signal within the frequency extended synchronization signal block.

19. The method of claim 18, wherein the reference signal configuration determined by the user device comprises at least: the synchronization signal block index identifying the synchronization signal block that is frequency extended; and the physical resource blocks for the reference signal that are appended to the synchronization signal block to provide the frequency extended synchronization signal block.

20. The method of any of claims 18-19, further comprising: receiving, by the user device, the reference signal.

21. The method of any of claims 18-20, further comprising: performing, by the user device, time/frequency tracking based at least on part of the reference signal received via the frequency extended synchronization signal block.

22. The method of any of claims 18-21, comprising: performing, by the user device, channel estimation based at least on part of the reference signal received via the frequency extended synchronization signal block for demodulating a physical broadcast channel (PBCH).

23. The method of claim 22, wherein the channel estimation is performed based on part of the reference signal received via the physical resource blocks of the synchronization signal block but not the physical resource blocks appended to the synchronization signal block.

24. The method of any of claims 21-23, wherein the apparatus is caused to: performing, by the user device, optimization of a channel estimation related to demodulation of at least one of a control channel, a data channel or a channel state information reference signal, based at least on the time/frequency tracking.

25. The method of claim 24, wherein the demodulation of the at least one of the control channel, the data channel or the channel state information reference signal is based on one or more quasi co-location between the reference signal received via the frequency extended synchronization signal block and the at least one of the control channel, the data channel or the channel state information reference signal.

26. The method of claim 25, wherein the quasi co-location is associated with at least one of: doppler shift, doppler spread, average delay, and/or delay spread.

27. The method of any of claims 18-26, further comprising: providing, by the user device to the network node, an indication of one or more synchronization signal blocks (SSBs), based on either transmitting a random access preamble associated with a synchronization signal block, or transmitting a report to the network node indicating one or more synchronization signal blocks.

28. The method of any of claims 18-27, wherein the first number and/or the second number of physical resource blocks are provided for the reference signal on two symbols of the synchronization signal block, wherein there is an inter-symbol gap between the two symbols same as a separate tracking reference signal.

29. The method of claim 28, wherein the inter-symbol gap is either three or four symbols.

30. The method of any of claims 22-29, wherein the part of the reference signal used for demodulating the physical broadcast channel is carried in physical resource blocks with an inter-symbol gap different from that of physical resource blocks carrying the part of the reference signal used for time/frequency tracking purpose.

31. The method of any of claims 18-30, wherein the part of the reference signal carried in the physical resource blocks appended to the synchronization signal block has at least one of same subcarrier density or same subcarrier offset as the part of the reference signal carried in the physical resource blocks of the synchronization signal block.

32. The method of any of claims 18-31, wherein the reference signal comprises a signal sequence mapped or allocated to resource elements of the frequency extended synchronization signal block, and wherein the resource elements in the symbols with appended physical resource blocks are mapped or allocated in a cyclic extension manner.

33. The method of any of claims 18-32, wherein the first number of physical resource blocks for the reference signal and the second number of physical resource blocks of the signal are provided based on at least one of the following: the first number and the second number have different values; the first number and the second number have the same value; the first number is lower than the second number; the first number is higher than the second number; the first number is zero, and the second number is non-zero; and the first number is non-zero, and the second number is zero.

34. The method of any of claims 18-33, wherein physical resource blocks for the reference signal comprise: at a first symbol of the extended synchronization signal block, the first number of physical resource blocks that are above the synchronization signal block and the second number of physical resource blocks that are below the synchronization signal block; and at a second symbol of the extended synchronization signal block that has an intersymbol gap of three or four symbols from the first symbol, the first number of physical resource blocks that are above the synchronization signal block and the second number of physical resource blocks that are below the synchronization signal block.

35. A non-transitory computer-readable storage medium comprising instructions stored thereon that, when executed by at least one processor, are configured to cause a computing system to: receive, by a user device from a network node, a reference signal (RS) configuration for a time/frequency tracking purpose including: a synchronization signal block (SSB) index identifying a synchronization signal block to be frequency extended to include physical resource blocks (PRBs) for a reference signal for the time/frequency tracking purpose; and information indicating physical resource blocks for the reference signal appended to the synchronization signal block to provide the frequency extended synchronization signal block, wherein the information indicates at least one of: 1) a first number of physical resource blocks for the reference signal that are above, or having subcarrier frequencies higher than, the synchronization signal block, and/or 2) a second number of physical resource blocks for the reference signal that are below, or having subcarrier frequencies lower than, the synchronization signal block; and determine, by the user device, the reference signal configuration for the time/frequency tracking purpose to receive the reference signal within the frequency extended synchronization signal block.

36. An apparatus comprising: means for receiving, by a user device from a network node, a reference signal (RS) configuration for a time/frequency tracking purpose including: a synchronization signal block (SSB) index identifying a synchronization signal block to be frequency extended to include physical resource blocks (PRBs) for a reference signal for the time/frequency tracking purpose; and information indicating physical resource blocks for the reference signal appended to the synchronization signal block to provide the frequency extended synchronization signal block, wherein the information indicates at least one of: 1) a first number of physical resource blocks for the reference signal that are above, or having subcarrier frequencies higher than, the synchronization signal block, and/or 2) a second number of physical resource blocks for the reference signal that are below, or having subcarrier frequencies lower than, the synchronization signal block; and means for determining, by the user device, the reference signal configuration for the time/frequency tracking purpose to receive the reference signal within the frequency extended synchronization signal block.

37. 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: transmit, by a network node to a user device, a reference signal (RS) configuration for a time/frequency tracking purpose including: a synchronization signal block index identifying the selected synchronization signal block to be frequency extended to include physical resource blocks (PRBs) for a reference signal for the time/frequency tracking purpose; and information indicating physical resource blocks for the reference signal appended to the synchronization signal block to provide the frequency extended synchronization signal block, wherein the information indicates at least one of: 1) a first number of physical resource blocks for the reference signal that are above, or having subcarrier frequencies higher than, the synchronization signal block, and/or 2) a second number of physical resource blocks for the reference signal that are below, or having subcarrier frequencies lower than, the synchronization signal block.

38. The apparatus of claim 37, wherein the apparatus is further caused to: receive, by the network node from a user device, an indication of one or more synchronization signal blocks (SSBs), based on either receiving from the user device a random access preamble associated with a synchronization signal block, or receiving a report from the user device indicating one or more synchronization signal blocks; select, by the network node, one of the one or more indicated synchronization signal blocks, wherein the synchronization signal block that is extended comprises the selected synchronization signal block.

39. A method comprising: transmitting, by a network node to a user device, a reference signal (RS) configuration for a time/frequency tracking purpose including: a synchronization signal block index identifying the selected synchronization signal block to be frequency extended to include physical resource blocks (PRBs) for a reference signal for the time/frequency tracking purpose; and information indicating physical resource blocks for the reference signal appended to the synchronization signal block to provide the frequency extended synchronization signal block, wherein the information indicates at least one of: 1) a first number of physical resource blocks for the reference signal that are above, or having subcarrier frequencies higher than, the synchronization signal block, and/or 2) a second number of physical resource blocks for the reference signal that are below, or having subcarrier frequencies lower than, the synchronization signal block.