Method and apparatus for triggering and reporting a timing advance report in a wireless communication system

Abstract

The present disclosure relates to a 5G communication system or a 6G communication system for supporting higher data rates beyond a 4G communication system such as long term evolution (LTE). A wireless communication unit (802) comprises: a transceiver (1072) arranged to communicate with a base station (806) and receive an instruction to generate a timing advance report, TAR, (810); and a processor (1058) configured to generate the TAR (810) to be transmitted to the base station (806). The processor (1058) is arranged to determine whether or not to trigger a transmission of the TAR to the base station (806) via the transceiver (1072) in response to one of the following: receive a radio resource control, RRC, message (820) from the base station (806); initiate a RRC message.

Description

METHOD AND APPARATUS FOR TRIGGERING AND REPORTING A TIMING ADVANCE REPORT IN A WIRELESS COMMUNICATION SYSTEM

[0001] The technical field relates generally to implementing techniques to triggering and reporting a Timing Advance Report (TAR). The invention is applicable to, but not limited to, triggering and reporting TARs in non-terrestrial networks (NTNs).

[0002] 5G mobile communication technologies define broad frequency bands such that high transmission rates and new services are possible, and can be implemented not only in “Sub 6GHz” bands such as 3.5GHz, but also in “Above 6GHz” bands referred to as mmWave including 28GHz and 39GHz. In addition, it has been considered to implement 6G mobile communication technologies (referred to as Beyond 5G systems) in terahertz (THz) bands (for example, 95GHz to 3THz bands) in order to accomplish transmission rates fifty times faster than 5G mobile communication technologies and ultra-low latencies one-tenth of 5G mobile communication technologies.

[0003] At the beginning of the development of 5G mobile communication technologies, in order to support services and to satisfy performance requirements in connection with enhanced Mobile BroadBand (eMBB), Ultra Reliable Low Latency Communications (URLLC), and massive Machine-Type Communications (mMTC), there has been ongoing standardization regarding beamforming and massive MIMO for mitigating radio-wave path loss and increasing radio-wave transmission distances in mmWave, supporting numerologies (for example, operating multiple subcarrier spacings) for efficiently utilizing mmWave resources and dynamic operation of slot formats, initial access technologies for supporting multi-beam transmission and broadbands, definition and operation of BWP (BandWidth Part), new channel coding methods such as a LDPC (Low Density Parity Check) code for large amount of data transmission and a polar code for highly reliable transmission of control information, L2 pre-processing, and network slicing for providing a dedicated network specialized to a specific service.

[0004] Currently, there are ongoing discussions regarding improvement and performance enhancement of initial 5G mobile communication technologies in view of services to be supported by 5G mobile communication technologies, and there has been physical layer standardization regarding technologies such as V2X (Vehicle-to-everything) for aiding driving determination by autonomous vehicles based on information regarding positions and states of vehicles transmitted by the vehicles and for enhancing user convenience, NR-U (New Radio Unlicensed) aimed at system operations conforming to various regulation-related requirements in unlicensed bands, NR UE Power Saving, Non-Terrestrial Network (NTN) which is UE-satellite direct communication for providing coverage in an area in which communication with terrestrial networks is unavailable, and positioning.

[0005] Moreover, there has been ongoing standardization in air interface architecture / protocol regarding technologies such as Industrial Internet of Things (IIoT) for supporting new services through interworking and convergence with other industries, IAB (Integrated Access and Backhaul) for providing a node for network service area expansion by supporting a wireless backhaul link and an access link in an integrated manner, mobility enhancement including conditional handover and DAPS (Dual Active Protocol Stack) handover, and two-step random access for simplifying random access procedures (2-step RACH for NR). There also has been ongoing standardization in system architecture / service regarding a 5G baseline architecture (for example, service based architecture or service based interface) for combining Network Functions Virtualization (NFV) and Software-Defined Networking (SDN) technologies, and Mobile Edge Computing (MEC) for receiving services based on UE positions.

[0006] As 5G mobile communication systems are commercialized, connected devices that have been exponentially increasing will be connected to communication networks, and it is accordingly expected that enhanced functions and performances of 5G mobile communication systems and integrated operations of connected devices will be necessary. To this end, new research is scheduled in connection with eXtended Reality (XR) for efficiently supporting AR (Augmented Reality), VR (Virtual Reality), MR (Mixed Reality) and the like, 5G performance improvement and complexity reduction by utilizing Artificial Intelligence (AI) and Machine Learning (ML), AI service support, metaverse service support, and drone communication.

[0007] Furthermore, such development of 5G mobile communication systems will serve as a basis for developing not only new waveforms for providing coverage in terahertz bands of 6G mobile communication technologies, multi-antenna transmission technologies such as Full Dimensional MIMO (FD-MIMO), array antennas and large-scale antennas, metamaterial-based lenses and antennas for improving coverage of terahertz band signals, high-dimensional space multiplexing technology using OAM (Orbital Angular Momentum), and RIS (Reconfigurable Intelligent Surface), but also full-duplex technology for increasing frequency efficiency of 6G mobile communication technologies and improving system networks, AI-based communication technology for implementing system optimization by utilizing satellites and AI (Artificial Intelligence) from the design stage and internalizing end-to-end AI support functions, and next-generation distributed computing technology for implementing services at levels of complexity exceeding the limit of UE operation capability by utilizing ultra-high-performance communication and computing resources.

[0008] A wireless communication system a wireless communication device (such as a UE), a base station (such as a gNB or eNB or NTN or ATG) and a method of triggering and reporting a Timing Advance Report (TAR) are described. In a first aspect, a wireless communication unit comprises: a transceiver arranged to communicate with a base station and receive an instruction to generate a timing advance report, TAR, a processor configured to generate the TAR to be transmitted to the base station. The processor is arranged to determine whether or not to trigger a transmission of the TAR to the base station via the transceiver in response to one of the following: receive a radio resource control, RRC, message from the base station; initiate a RRC message.

[0009] In some optional examples, the processor may be configured to not trigger the transmission of the TAR to the base station in response to the wireless communication unit having initiated one of: a small data transmission, SDT, an early data transmission, EDT, a preconfigured uplink resource transmission, PUR, or CB-Msg3. In some optional examples, the processor may be configured to not trigger the transmission of the TAR to the base station or cancel the transmission of the TAR to the base station in response to the wireless communication unit having initiated a radio resource control, RRC, RRCEarlyDataRequest message transmission. In some optional examples, the processor may be configured to trigger the transmission of the TAR to the base station in response to the wireless communication unit having initiated one of: a transmission of RRCConnectionResumeRequest, a transmission of RRCConnectionRequest. In some optional examples, the instruction to generate the TAR may be configured in one of: a SystemInformationBlockType2 message, a SystemInformationBlockType2-NB message; wherein the wireless communication unit may not be arranged to initiate one of: an early data transmission, EDT, a preconfigured uplink resource transmission, PUR, a Contention-based Msg3 EDT; and wherein the processor may be configured to instruct a media access control, MAC, entity to trigger the transmission of the TAR to the base station. In some optional examples, the processor may only be configured to trigger the transmission of the TAR to the base station in response to one or more of the following having not been triggered: a small data transmission, SDT, an early data transmission, EDT, a preconfigured uplink resource transmission, PUR, or Contention-based Msg3 transmission, CB-Msg3. In some optional examples, the processor may be configured to trigger transmission of the TAR to the base station in response to an initiation of one of: RRCEarlyDataRequest, RRCConnectionResumeRequest. In some optional examples, the processor may be configured to trigger transmission of the TAR to the base station when the wireless communication unit is in RRC_IDLE mode of operation or in RRC_INACTIVE mode of operation in response to one of: a RRC connection resume request, a RRC connection re-establishment operation. In some optional examples, in response to a determination of whether or not to trigger the transmission of the TAR to the base station, the processor may be configured to cancel a previously created TAR trigger.

[0010] In a second aspect, a method for a wireless communication unit supporting timing advance is described. The method comprises at the wireless communication unit: receiving, from a base station, an instruction to generate a timing advance report, TAR; generating a TAR to be transmitted to the base station; determining whether or not to trigger a transmission of the TAR to the base station in response to one of the following: receiving a radio resource control, RRC, message from the base station; initiating a RRC message. In a third aspect, a wireless communication system is described that comprises a plurality of wireless communication units according to either or both of the first and second aspects configured to communicate with a plurality of base stations.

[0011] Aspects of the disclosure are to address at least the above-mentioned problems and / or disadvantages and to provide at least the advantages described below. Accordingly, an aspect of the disclosure is to provide efficient communication methods in a wireless communication system.

[0012] Further details, aspects and embodiments will be described, by way of example only, with reference to the drawings. In the drawings, similar reference numbers are used to identify like or functionally similar elements. Elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale.

[0013] FIG. 1 illustrates a known simplified non-terrestrial network (NTN) release 17 cellular architecture and NTN release 19 regenerative architecture.

[0014] FIG. 2 illustrates a known Air-To-Ground (ATG or A2G) network, where in NTN the access link is from space / sky to the ground.

[0015] FIG. 3 illustrates a known initial access procedure.

[0016] FIG. 4 illustrates a known early data transmission (EDT) procedure.

[0017] FIG. 5 illustrates a known preconfigured uplink resources (PUR) procedure.

[0018] FIG. 6 illustrates a known timing advance procedure performed in NR NTN Release 17.

[0019] FIG. 7 illustrates a timing advance MAC CE.

[0020] FIG. 8 illustrates a first example message sequence chart between a UE (MAC and RRC layers) and a base station (either eNB or gNB) that support access procedures without sending a TA report, adapted in accordance with some example embodiments.

[0021] FIG. 9 illustrates a second example message sequence chart between a UE (MAC and RRC layers) and a base station (either eNB or gNB) that support access procedures without sending a TA report, adapted in accordance with some example embodiments.

[0022] FIG. 10 illustrates a block diagram of an NTN base station communicating with a UE, adapted in accordance with some example embodiments.

[0023] FIG. 11 illustrates a 3GPPTM5G communication system with NTN base stations, adapted in accordance with some example embodiments.

[0024] FIG. 12 illustrates one example message sequence chart between a UE and a base station to ensure that there are no unexpected TAR MAC CEs triggered during a RRC procedure, in accordance with some example embodiments.

[0025] FIG. 13 illustrates one example message sequence chart between a UE and a base station to ensure that there are no unexpected TAR MAC CEs triggered during a RRC procedure, in accordance with some example embodiments.

[0026] FIG. 14 illustrates one example message sequence chart between a UE and a base station to ensure that there are no unexpected TAR MAC CEs triggered during a RRC procedure, in accordance with some example embodiments.

[0027] FIG. 15 is a block diagram of a terminal or user equipment (UE) 1500 according to an embodiment of the disclosure.

[0028] FIG. 16 is a block diagram of a base station (BS) 1600 according to an embodiment of the disclosure.

[0029] FIG.17 is a block diagram of a network entity 1700 according to an embodiment of the disclosure.

[0030] Skilled artisans will appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions and / or relative positioning of some of the elements in the figures may be exaggerated relative to other elements to help to improve understanding of various example embodiments. Also, common but well-understood elements that are useful or necessary in a commercially feasible embodiment are often not depicted in order to facilitate a less obstructed view of these various embodiments. It will be further appreciated that certain actions and / or steps may be described or depicted in a particular order of occurrence while those skilled in the art will understand that such specificity with respect to sequence is not actually required. It will also be understood that the terms and expressions used herein have the ordinary technical meaning as is accorded to such terms and expressions by persons skilled in the technical field as set forth above except where different specific meanings have otherwise been set forth herein.

[0031] In recent years, there has been a rapid development in communications technologies that are compliant with third generation partnership project (3GPPTM) standards. A 4thgeneration (4G) wireless communication standard (sometimes referred to as long term evolution (LTETM) was designed to support mobile internet and higher speeds for activities, such as video streaming and gaming. The 3GPPTMstandards then developed a fifth generation (5G) of mobile wireless communications, which provides a step change in the delivery of better and faster communications, for example powering businesses, improving communications within homes and spearheading advances such as driverless cars.

[0032] A sixth generation　(6G) wireless communication standard is currently under development, as the planned successor to　5G, and will likely be significantly faster. Like its predecessors, 6G networks will likely be　broadband　cellular networks, in which the service area is divided into small geographical areas called　cells.6G networks are expected to be even more diverse than their predecessors and are likely to support applications beyond current mobile use scenarios, such as　virtual　and　augmented reality　(VR / AR), ubiquitous instant communications, pervasive intelligence and the　Internet of Things (IoT). It is expected that mobile network operators will adopt flexible decentralized　business models　for 6G, with local　spectrum licensing, spectrum sharing, infrastructure sharing, and intelligent automated management underpinned by　mobile edge computing,　artificial intelligence　(AI), short-packet communication and　blockchain technologies.

[0033] Non-Terrestrial Networks (NTNs) is an emerging area in 3GPPTMdiscussions for 5G that aim to provide 5G cellular coverage using space borne and / or air borne platforms, where traditional ground-based networks have difficulty in providing coverage and / or capacity. IoT NTN was a 3GPP study and work item in 3GPP release 17 to provide Non-Terrestrial Network access for E-UTRAN IoT devices (NB-IoT and LTE-M / eMTC) [RP-202689]. NR NTN was a work item in Rel-17 to specify adaptation to allow NR to function over NTN [RP-211557], which addressed solutions for transparent payload for both Geostationary and non-Geostationary network scenarios, with the UE having Global navigation satellite system (GNSS) capability and the satellite beams being both earth-fixed or earth-moving).

[0034] Subsequently, NR NTN phase 3 [RP-234078] is a 3GPP Work Item in 3GPP Release 19 aiming to enhance NR NTN with a range of enhancements, including: Downlink coverage enhancements, Uplink capacity and throughput enhancements by using Orthogonal Coverage Codes, MBS broadcast over NTN, Introduction of regenerative payload, Redcap and NTN enhancements, Terrestrial E-UTRAN to NR NTN mobility. An example of release 17 architecture and NTN release 19 regenerative architecture is illustrated in FIG. 1.

[0035] Referring to FIG. 1, a known simplified cellular architecture diagram 100 illustrates a first non-terrestrial base station / satellite 102 supporting communications within a coverage area 104, including communication support for a wireless communication unit, sometimes referred to as a terminal device, such as a user equipment UE 106. In 4G as well as 5G, the UE 106 is able to support traditional Human Type Communications (HTC) or the new emerging Machine Type Communications (MTC). The UE 106 is considered to be active when communicating and in the operational state technically known as radio resource control (RRC) connected. 4G or LTETM, which Internet of Things (IoT) (NB-IoT and LTE-M) is based on, has two RRC states; RRC connected mode and RRC idle mode. 5G / 5G new radio (NR) has three RRC states; RRC connected mode, RRC inactive mode and RRC idle mode, where RRC inactive is a newly introduced mode. RRC idle and RRC inactive operation are to a large part similar and a differentiation to large part in the procedures used to go to RRC connected mode.

[0036] The known simplified cellular architecture diagram 100 comprises a connection 120 connects the first non-terrestrial base station / satellite 102 and a second terrestrial base station 108 via a gateway 114. For RRC- idle state UEs 106, a cell re-selection process may be warranted, if the signal strength from the current serving cell (i.e., non-terrestrial base station 102) deteriorates as the UE transitions from base station 102 to 108. Similarly, a cell re-selection process is performed for 'RRC idle state UEs when the UE nears the cell edge of the current cell 104 that it is camped on, and is able to receive a signal from the neighbour base station 108. For IoT, this is a known 4G or E-UTRAN cell reselection process, which is also driven by signal strength measurements of the base stations carried out by the UE. In a similar operational manner, FIG. 1 also shows a known simplified NTN release 19 regenerative cellular architecture diagram 150 where a first non-terrestrial base station 152 is located in a satellite supporting communications within a coverage area 154, including communication support for a wireless communication unit, sometimes referred to as a terminal device, such as a user equipment UE 156. The known simplified NTN release 19 regenerative cellular architecture diagram 150 comprises a connection 170 connects the first non-terrestrial base station 152 with a core network 160 via a gateway 164.

[0037] Referring now to FIG. 2, a known Air-To-Ground (abbreviated as ATG or A2G) network is illustrated. Here, a cellular network provides connectivity in the air via base stations 208 located on the ground and connected by a core network 210. It is different from a Non-Terrestrial Network as the access link is from the ground to the UE 206 in the sky, where as in NTN the access link is from space / sky to the ground. One of the main the use cases of ATG networks as shown in FIG. 2 is to provide backhaul connectivity to access points in aircraft. A Study item was started in Rel-18 [RP-221369] in RAN4 to define requirements for coexistence between ATG and IMT terrestrial networks. Furthermore to define RRM performance requirements for ATG UE, demodulation performance requirements for ATH BS / UE, and test procedures for ATG BS conformance testing.

[0038] For Rel-17, RAN4 introduced basic support for NTN on lower frequency bands. These are the bands n254, n255 and n256, which have the following characteristics:

[0039] ● Band n254 in FDD mode: UL operating band 1610 - 1626.5 MHz, DL operating band 2483.5 - 2500 MHz;

[0040] ● Band n255 in FDD mode: UL operating band 1626.5 - 1660.5 MHz, DL operating band 1525 - 1559 MHz; and

[0041] ● Band n256 in FDD mode: UL operating band 1980 - 2010 MHz, DL operating band 2170 - 2200 MHz.

[0042] For Rel-18, RAN4 has introduced support for NTN for higher frequencies. RAN4 defined FR2-NTN as frequencies in between 17.3 to 30 GHz [38.101-5, V18.5.0], whereas FR1-NTN remains in lower band 410 MHz to 7.125 GHz. RAN4 introduced the following set of bands for FR2-NTN [38.101-5, V18.5.0]:

[0043] ● Band n510 in FDD mode: UL operating band 27500 - 30000 MHz, DL operating band 17300 - 20200 MHz;

[0044] ● Band n511 in FDD mode: UL operating band 28350 - 30000 MHz, DL operating band 17300 - 20200 MHz; and

[0045] ● Band n512 in FDD mode: UL operating band 27500 - 28350 MHz, DL operating band 17300 - 20200 MHz.

[0046] For these bands, SCS of 60 kHz and 120 kHz were introduced [38.101-5, V18.5.0]:

[0047] -------------------------- 38.101-5 V18.5.0 --------------------------

[0048]

[0049] -------------------------- 38.101-5 V18.5.0 --------------------------

[0050] In LTETM, the full timing advance of a UE, is defined as:

[0051] [1]

[0052] Where the individual components are:

[0053] ● T_s = basic time unit 1 / (15000 x 2048) = 1 / 30720000

[0054] ●NTA=TA 16

[0055] ● are NTN specific

[0056] In NR, which is the full and absolute Timing Advance of a UE, is defined as:

[0057] [2]

[0058] Where the individual components are:

[0059] ● is the basic time unit for NR = 1 / (480x103x 4096) = 1 / 1966080000

[0060] ● The which is the MAC-signalled timing advance is calculated as:

[0061] ○ which is how to calculate the timing advance when receiving the in Random Access response

[0062] ○ calculated when receiving the in a Timing Advance (TA) medium access control (MAC) control element (CE)

[0063] ● is the subcarrier spacing configuration, which can take the values [0, 1, 2, 3, 4, 5, 6] which corresponds to the Subcarrier Spacing (SCS) [15, 30, 60, 120, 240, 480, 960] kHz. In general, the higher the frequency, the higher the subcarrier spacing.

[0064] ● are NTN specific

[0065] What can be seen from the above is that in NR the granularity of values changes as the subcarrier spacing. For instance, for SCS = 15 kHz, the values of the timing advance changes that the UE applies are the valuesNTA=[...-4096, -3072, -2048, -1024, 0, 1024, 2048, ...]. For SCS = 60 kHz, the UE applies the valuesNTA=[..., -1024, -768, -512, -256, 0, 256, 512, 768, 1024, ...]. Thus, the difference between LTETMand NR is that in LTETMthe SCS is always the same and that in LTETM, the basic time unit is much smaller.

[0066] Referring now to FIG. 3 a known initial access procedure 300 is illustrated, where the initial access procedure 300 includes communications between a UE 306 and an eNB 308, with the UE starting in a RRC idle mode 310. The initial access procedure 300 starts at 320 with UE 306 determining a timing advance pre-compensation using the UE position and the satellite position. Typically, the UE position is obtained via GNSS, but other methods that do not rely on the network may also potentially be used, such as using inertial navigation system or similar. The satellite position is acquired via SIB19 and the UE also pre-compensates using TA-Common, which is the common timing advance from the satellite to the ground gateway, e.g., gateway 114 in FIG. 1, where the base station resides.

[0067] At 330, UE 306 uses the pre-compensation and sends a Msg1, which is the random access channel (RACH) preamble. The RACH preamble will represent a number between 1 and 64. The number selected by the UE 306 is random, but there exists several rules to determine the range of preambles, depending on configurations and conditions - sometimes referred to as preamble division. At 340, if the network is able to detect and determine the RACH preamble, the eNB 308 responds to the UE 306 with a Msg2 or random access response (RAR). The UE then schedules a sending of a Msg3.

[0068] At 350, the UE 306 sends Msg3, which is sent using a physical uplink shared channel (PUSCH). This message will contain the first RRC message. The RRC message depends on the specific reason why the random access procedure was triggered. For example, for initial access it will be RRCSetupRequest, for resuming it is RRCConnectionResumeRequest, for re-establishing RRC it is RRCConnectionReestablishmentRequest, for CP-EDT it is RRCEarlyDataRequest, etc. Since it is possible that two UEs select the same RAPID, there is a chance of collision. Therefore, at 360, the eNB 308 sends a Msg4 over a physical data shared channel (PDSCH), where this contention may be resolved using the Contention Resolution MAC CE. Msg4 also contains an RRC message that is a response to Msg3. This can, for instance, be RRCConnectionSetup, RRCConnectionResume, RRCConnectionReestablishment, RRCReject, RRCEarlyDataComplete etc. At 370, a Msg5 is sent from the UE 306, which is a further message that is a scheduled uplink message that would consist of the reply to the downlink RRC message in Msg4. Msg5 is sometimes not considered a part of the random access procedure, but a part of any access procedures. The RRC message carried in Msg5 may be RRCConnectionSetupComplete, RRCConnectionResumeComplete, RRCConnectionReestablishmentComplete, and so on.

[0069] Referring now to FIG. 4, a known early data transmission (EDT) procedure 400 is illustrated that includes communications between a UE 406 and an eNB 408, with the UE starting in a RRC idle mode 410. EDT is a feature that allows a UE 406 to start to transmit data already in Msg3 to an eNB 408. This is mostly for power-saving purposes where in the best case the UE 406 would be able to transmit all of its data and then be released already in Msg4. In RRC Resume, the UE 406 may not start transmitting data until after RRCResumeComplete in Msg5.

[0070] The EDT procedure 400 can be seen in FIG. 4, from the perspective of PHY layer, MAC and RRC, where the procedure starts similar to any random access procedure. The EDT procedure 400 starts at 420 with UE 406 determining a timing advance pre-compensation using the UE position and the satellite position. Typically, the UE position is obtained via GNSS, but other methods that do not rely on the network may also potentially be used, such as using inertial navigation system or similar. The satellite position is acquired via SIB19 and the UE also pre-compensates using TA-Common, which is the common timing advance from the satellite to the ground gateway, e.g., gateway 114 in FIG. 1, where the base station resides.

[0071] At 430, UE 406 uses the pre-compensation and sends a Msg1, which is the random access channel (RACH) preamble, but the UE 406 selects a RACH preamble from a specific set of preambles that indicates that the UE 406 will perform EDT. The RACH preamble will represent a number between 1 and 64. The number selected by the UE 406 is random, but there exists several rules to determine the range of preambles, depending on configurations and conditions - sometimes referred to as preamble division. At 440, if the network is able to detect and determine the RACH preamble, the eNB 408 responds to the UE 406 with a Msg2 or random access response (RAR). The UE then schedules a sending of a Msg 4.

[0072] At 450, the UE 406 sends Msg3, which is sent using a physical uplink shared channel (PUSCH). In Msg3 the UE either sends the RRCEarlyDataRequest for CP or RRCResumeRequest for UP. Since it is possible that two UEs select the same RAPID, there is a chance of collision. Therefore, at 460, the eNB 408 sends a Msg4 over a physical data shared channel (PDSCH), where this contention may be resolved using the Contention Resolution MAC CE. Msg4 also contains an RRC message that is a response to Msg3. This can, for instance, be RRCSetup, RRCConnectionResume, RRCConnectionReestablishment, RRCReject, RRCEarlyDataComplete etc.

[0073] Referring now to FIG. 5, a known preconfigured uplink resources (PUR) procedure 500 that includes communications between a UE 506 and an eNB 508. From a perspective of the physical (PHY) layer, MAC layer and radio resource control (RRC), the PUR procedure 500 starts at 510, where the UE 506 may optionally send a request to request that the UE 506 to be configured with PUR. This request contains the requested number of PUR occasions, the periodicity and offset as well as the Transport Block Size (TBS), i.e., the size of the allocation for PUR. At 520, if the network (i.e., eNB 508), determines that the UE 506 shall go to RRC idle and that it would be beneficial for the UE 506 to be configured with PUR, then the network releases the UE 506 and configures pur-Config in the RRCConnectionRelease message. Here, the PUR configuration contains the parameters that gives the PUR resource, such as: periodicity and offset, the startSFN, the start subframe, the number of PUR occasions, the PUR-RNTI, the pur-TimeAlignmentTimer, and RSRP threshold, a response window timer, the configurations for MPDCCH, PDSCH, PUCCH and PUSCH and the PDSCH frequency hopping.

[0074] At 530, the UE 506 suspends the RRC connection and moves to RRC idle. Subsequently, at 540, traffic arrives in the uplink buffer. In an NTN, at 550, the UE 506 would at least have to self-precompensate the Timing advance. Here, the UE 506 may potentially also have to acquire the GNSS position, as well as acquire SIB31, to ensure that it has the most updated satellite ephemeris. At 560, the UE 506 uses the configured PUR-resources and performs uplink transmission using PUSCH. Here, a control plane solution is that the PUR message consists of the RRC message RRCEarlyDataRequest, which contains the transparent NAS container which may contain data or NAS signalling, whereas in an user plane solution the PUR message consists of the RRCConnectionResumeRequest as well as uplink data from any of the radio bearers that triggered the PUR. At 570, the eNB 508 responds to the to the PUR of the UE 506. Here, a control plane solution is that the response may consist of (i) a Layer 1 acknowledgement, (ii) a Timing Advance MAC CE command that updates the TA or (iii) an RRCEarlyDataComplete. If none of these are received, the UE 506 considers the procedure to not be completed. Here, in an user plane solution, the response consists of the RRCConnectionRelease message that successfully completes the PUR transmission. The response may also include downlink data transmissions.

[0075] It is understood that Small Data Transmissions (SDT) may be considered to be the 5G NR-equivalent of Early Data transmissions. SDT is similar to how UP EDT works in that the RRC resumes and the data is sent in Msg3 along with the RRCResumeRequest. SDT may also allow for transmissions from RRC inactive without any RACH, in which case the resources are pre-configured.

[0076] It is known that contention-based Msg3 or contention-based EDT is an enhancement currently being discussed for Rel-19 IoT NTN, where the UE may be allowed to skip transmitting Msg1 and receiving Msg2 and directly transmit Msg3, which may include data. Thus, this is expected to be similar to current EDT, but with no Msg1 / Msg2 transmitted. It is envisaged that this can be done in a non-terrestrial network as the UE self pre-compensates for the timing advance, thereby potentially reducing the need for Msg1 / Msg2. This is also different from other previous solutions where the Msg1 / Msg2 is skipped because the Msg3 transmission will be contention-based, meaning that the Msg3 transmit opportunity is not pre-configured to a UE. This means that there may still be collisions.

[0077] It has also been agreed that the contention-based Msg3 may be transmitted in a Diversity Slotted Aloha (DSA) scheme, where the UE transmits multiple times in a set of randomly selected resources. In other words, a window of resources is configured and the UE randomly selects individual resources within this window and transmits. This can be seen to have significant performance gains compared to only transmitting a single time (this is termed Slotted Aloha).

[0078] In NR Release 15 and in LTETM, the timing advance is signalled in a Timing Advance Command (TAC) by the network. Once received the UE applies the TA. In this manner, the timing is always fully controlled by the network.

[0079] Timing Advance reporting is a feature introduced for NR NTN in Release 17. This is introduced because in NR NTN, the UE largely performs self pre-compensation of the Timing Advance. In other words, the UE autonomously estimates and applies the timing advance. Thus, for the network to know what timing advance the UE applies, the UE can be configured to report its timing advance, under certain conditions.

[0080] Referring now to FIG. 6, a first condition is shown whereby, upon indication from upper layers to trigger the report, the known timing advance reporting procedure 600 (with communications between a UE 606 and a gNB 608) includes the following. At 610, the gNB 608 configures a TA report. It is known that the timing advance reporting procedure 600 can be initiated after a set of RRC procedures, such as RRC setup, Handover (RRC Reconfiguration with Sync), RRC Re-establishment, RRC Connection resume. Therefore, at 620, the UE initiates a RRC procedure. At 630, the UE 606 transmits a Msg1 + Msg2 to the gNB 608, to which the gNB 608 responds at 640. At 650, the UE 606 sends a Msg3 that includes a TAR MAC CE.

[0081] FIG. 6 also shows a second condition, where at 660 the gNB 608 configures the UE 606 with a threshold ('offsetThresholdTA'). At 670, the UE 606 responds to the gNB 608 with a first TAR MAC CE that includes a first timing advance (TA1). At 680, if the UE 606 determines that a variation between the current Timing Advance value and the last reported TA is larger than the configured threshold (offsetThresholdTA), the UE 606 sends at 690 a second TAR MAC CE that includes a second timing advance (TA2). It is known that this may also be triggered whenoffsetThresholdTAis configured and a Timing Advance Report has not been sent.

[0082] Referring now to FIG. 7, the timing advance (TA) MAC CE 700 is illustrated for completeness, with the Timing Advance field in the TAR MAC CE being a 14-bit field stretching over two octets, and with the 'R' fields being reserved fields.

[0083] In light of the above, the inventors have recognised and appreciated that Timing Advance Reporting is a crucial feature in NR NTN, IoT NTN and ATG. It has been agreed since Release 17, that the UE will send the Timing Advance Report MAC CE during RRC establishment, RRC resume, RRC re-establishment or during handovers. However, these procedures are not the only procedures that invoke some of the establishment procedures. For instance, eMTC and NB-IoT EDT and PUR triggers establishment procedures, and 5G NR SDT also triggers establishment procedures. Thus, it is not clear whether the Timing Advance Report is to be sent for these cases. It is on one hand important that both the network and UE are clear on when to trigger the TA report, as any irregularities may result in difficulties in implementation. For instance, in some cases a network algorithm may rely on the TAR MAC CE being received. On the other hand, in some of these cases it is not expected that TAR MAC CE would be useful, as EDT, PUR and SDT may only transmit a single uplink message, and thus the network would not require the Timing Advance Report. The Timing advance report occupies 3 bytes of data, which may in some cases be considered significant (and wasteful), especially during early access procedures. Hence, an improved approach is needed.

[0084] As explained above, the TAR MAC CE may be triggered in two cases relating to the offset threshold. One is when the offset threshold is configured, and the other case is when the timing advance is larger than the offset threshold from the previously reported value. However, one issue here, as identified by the inventors, is that this introduces a 'state' to the reporting, which is not accounted for in current procedures. This 'state' needs to be made clear in order to have predictable procedures. Otherwise, the triggering of the TAR MAC CE may not occur when the network may expect that it occurs. This leads to potential degradation of the usefulness of the TA report.

[0085] The inventors have recognised and appreciated that there are several considerations for triggering and reporting the Timing Advance Report. As herein described, the term “Contention-based Msg3 transmission” or “CB-Msg3” is intended to encompass transmitting the first message of the “Contention-based Msg3 procedures”, or the full procedures. Due to similarities to the random access procedures, this message may also be referred to as “Msg3”, since it is an access procedure without the random access procedure, i.e., without Msg1 and Msg2.

[0086] Although examples herein described are mainly directed to using gNBs (5G NR), it is envisaged that some of the approaches described below are equally applicable to eNBs or NG-RAN (5G NR), or even 6G RAN. It is also envisaged that the examples herein described may also apply to a eMTC / LTE-M UE, or 5G NR UE, or E-UTRAN UE. It is also envisaged that the examples herein described may also apply to Air-to-Ground (ATG) communication as this also supports Timing Advance reporting.

[0087] It is also envisaged that the approaches described below apply equally to eNBs, gNBs, NG-RAN or NG-eNB. Hence, it is envisaged that the terms are to be considered interchangeably. For instance, in some cases the below description may be for an eNB, but it may also apply for NG-eNB (eNB is connected to EPC, while NG-eNB is connected to 5GC). In some cases below, there may also be methods explicitly for an NG-eNB, en-gNB, gNB, or NG-RAN.

[0088] It is also envisaged that an E-UTRAN (cell) is (in a loose sense) the base station of an eMTC / LTE-M cell. Thus, the term 'E-UTRAN' should be considered, in one example, an 'IoT NTN base station'. In 3GPPTMso far, only IoT is supported for LTE NTN and not ordinary non-IoT LTE NTN. It should be noted that examples herein described are not limited to IoT NTN E-UTRAN as it is envisaged that “ordinary” non-IoT LTE NTN are also supported. It is also envisaged that the approaches described herein are also applicable if non-Standalone NTN is supported, i.e., EN-DC (E-UTRAN-NR Dual Connectivity) is supported in the future. Similarly, it is also envisaged that the approaches described herein are also applicable for mobility from terrestrial, non-NTN, base stations.

[0089] Example embodiments are described with reference to radio access networks, which term encompasses and is considered to be equivalent to and interchangeable with communication cells, namely the facilitation of communications within a cell that may access other parts of the communication system as a whole. In some examples described herein it is envisaged that a wireless communication unit (such as a UE) does not trigger TA reports during RRC establishments in certain circumstances.

[0090] In a first example, it is envisaged that the wireless communication unit (such as a UE) may be configured to not trigger a TA report when the UE performs Early Data Transmissions (EDT), Preconfigured Uplink Resources transmissions (PUR) or CB-Msg3. In some examples, this approach may be achieved in a number of ways. For example, one condition may be that the wireless communication unit has initiated one of: SDT, EDT, PUR or CB-Msg3, then the wireless communication unit will not trigger a TA report. A further condition may be that the wireless communication unit has triggered certain RRC messages, such asRRCEarlyDataRequest, which causes the wireless communication unit to not trigger a TA report. Alternatively, it is envisaged that the wireless communication unit may only trigger a TA report under conditions where SDT, EDT, PUR or CB-Msg3 has not been triggered (as illustrated in specification example 1 towards the end of this document). The inventors have recognised that this is useful, because in many cases for SDT, EDT, PUR or CB-Msg3 the wireless communication unit will not move to RRC connected, so the TA report is not likely to be useful for the network. This means that the TA report would only occupy an unnecessary number of bits.

[0091] In a second example, it is envisaged that the wireless communication unit may be configured to trigger a TA report when the wireless communication unit initiates transmission ofRRCConnectionResumeRequestor when the wireless communication unit initiates transmission ofRRCConnectionRequest. In this example, the wireless communication unit may be configured conversely to not trigger the TA report or cancel the trigger of the TA report when certain RRC messages are initiated, such asRRCEarlyDataRequest.

[0092] In a third example, it is envisaged that the wireless communication unit may be configured to trigger a TA report when the wireless communication unit performs Small Data Transmission (SDT), Early Data Transmissions (EDT), Preconfigured Uplink Resources (PUR) transmissions or CB-Msg3 transmissions. In this example, it is envisaged that the wireless communication unit may, for instance, either rely on the existing configuration to trigger the TAR MAC CE (as seen in specification Example 2 below), i.e., the configurationTA-Report, or it may be configured separately in a new configuration. This configuration may determine whether the wireless communication unit shall trigger a TA report for SDT, EDT, PUR and CB-Msg3. In some examples, it is envisaged that this may be one indication for all of the cases (SDT, EDT, PUR and CB-Msg3) or that separate indications are employed. In a further example, it is envisaged that the wireless communication unit may also be configured to trigger a TA report specifically for certain RRC messages, such asRRCEarlyDataRequestorRRCConnectionResumeRequest.

[0093] Referring now to FIG. 8, a first example message sequence chart 800, between a UE RRC function 802 and a UE MAC function 804 and a base station 806 (either eNB or gNB or NTN or ATG) that support access procedures without sending a TA report, is illustrated in accordance with some example embodiments. Initially, the UE is configured with a TA report at 810. At 820, the UE RRC 802 indicated to the UE MAC 804 to trigger a TA report. At 830, the UE RRC 802 then determines to perform SDT, EDT, PUR or CB-Msg3. At 840, the UE RRC 802 may then decide to cancel the TA report (after the TA report has been triggered) sent to UE MAC 804, due to any of the aforementioned reasons. At 850, the UE RRC 802 submits the RRC message to lower layers, including the UE MAC 804. At 860, the UE MAC 804 and base station 806 are able to access the procedures without sending the TA report. In this manner, UE RRC 802 may indicate to UE MAC 804 to trigger the TA report, but then later the TA report may be cancelled. As shown, this can for instance be done before the UE RRC 802 message is submitted to the lower layers.

[0094] Referring now to FIG. 9, a second example message sequence chart 900, between a UE RRC function 802 and a UE MAC function 804 and a base station 806 (either eNB or gNB or NTN or ATG) that support access procedures without sending a TA report, is illustrated in accordance with some example embodiments. Initially, the UE is configured with a TA report at 910. At 920, the UE RRC 802 indicated to the UE MAC 804 to trigger a TA report. At 930, the UE RRC 802 then determines to perform SDT, EDT, PUR or CB-Msg3. In this second example, at 940, the UE RRC 802 moves straight to submitting the RRC message to lower layers, including the UE MAC 804. At 950, the UE MAC 804 determines to cancel the TA report. Thereafter, the UE MAC 804 and base station 806 are able to access the procedures without sending the TA report. Again, the UE RRC 802 may indicate to UE MAC 804 to trigger the TA report, but then later the TA report may be cancelled. Here, the UE MAC 804 may also potentially cancel a TA report. For instance, the UE RRC 802 may first indicate to the UE MAC 804 to trigger the TA report, which may then be cancelled. For instance, UE MAC 804 may for instance cancel the TA report if CB-Msg3 is triggered. This can for instance mean that normal EDT may include a TA report, whilst CB-Msg3 does not include the TA report.

[0095] In some examples, it is envisaged that this may be differentiated for Control Plane (CP) CIoT optimization and User Plane (UP) CIoT optimization. For instance, it is envisaged that the TA report may be triggered for UP EDT, but not for CP EDT. It may also be differentiated that NB-IoT does or does not trigger the TA report in some of the scenarios.

[0096] In some examples, it is envisaged that the wireless communication unit may also be configured to decide whether to include the TA report and whether there are enough bits allocated when the wireless communication unit / UE is scheduled, or when the PDU is being constructed. As such, a new TA report configuration may be introduced, which configures the wireless communication unit to include a TA report if the size of the uplink grant, pre-configured uplink grant, TBS or similar allows for both data and TA report to be sent.

[0097] In some examples, it is envisaged that the TAR MAC CE may be taken into account when calculating the data volume used for determining whether to perform the SDT, EDT, PUR or CB-Msg3 procedure. This can, for instance, be done by considering whether (or not) the TA report is configured.

[0098] In some examples, it is envisaged that, for pre-configured uplink or for SDT, the wireless communication unit may be configured as part of the preconfigured uplink or the SDT configuration whether to trigger TA report. This can be configured via broadcasted or dedicated configuration. The dedicated configuration can be included in a release message, which releases the wireless communication unit to RRC idle, RRC idle with suspended RRC connection or to RRC inactive. If the TA report is not configured, then either it may be considered that the wireless communication unit shall not trigger the TA report, or that the wireless communication unit shall rely on other configurations to determine whether to send the TA report, such as the broadcastedTA-Reportconfiguration. In other words, the wireless communication unit sends the TA report if the SDT or PUR configuration indicates it, or if not configured in SDT or PUR configuration, then the wireless communication unit follows theTA-Reportconfiguration that broadcasted.

[0099] Referring now to FIG. 10, more detailed block diagrams of an eNB or gNB TN or NTN wireless base station 806 and a wireless communication unit (such as a UE 802) are illustrated, where the respective communications units have been adapted in accordance with some example embodiments.

[0100] The eNB or gNB TN or NTN wireless base station 806 contains an antenna 1002, for receiving transmissions, coupled to an antenna switch or duplexer 1004 that provides isolation between receive and transmit chains within the eNB or gNB TN or NTN wireless base station 806. One or more receiver chains, as known in the art, include receiver front-end circuitry 1006 (effectively providing reception, filtering and intermediate or base-band frequency conversion). The receiver front-end circuitry 1006 is coupled to a signal processor 1008 (generally realized by a digital signal processor (DSP)). A skilled artisan will appreciate that the level of integration of receiver circuits or components may be, in some instances, implementation-dependent.

[0101] The controller 1014 maintains overall operational control of the eNB or gNB TN or NTN wireless base station 806. The controller 1014 is also coupled to the receiver front-end circuitry 1006 and the signal signal processor 1008. In some examples, the controller 1014 is also coupled to a frequency generation circuit 1017 and a memory device 1016 that selectively stores operating regimes, such as decoding / encoding functions, synchronization patterns, code sequences, and the like. A timer 1018 is operably coupled to the controller 1014 to control the timing of operations (e.g., transmission or reception of time-dependent signals) within the eNB or gNB TN or NTN wireless base station 806.

[0102] As regards the transmit chain, this essentially includes an input interface 1020, coupled in series through transmitter / modulation circuitry 1022 and a power amplifier 1024 to the antenna 1002, antenna array, or plurality of antennas. The transmitter / modulation circuitry 1022 and the power amplifier 1024 are operationally responsive to the controller 1014. The signal processor 1008 in the transmit chain may be implemented as distinct from the signal processor in the receive chain. Alternatively, a single processor may be used to implement a processing of both transmit and receive signals, as shown in FIG. 10. Clearly, the various components within the eNB or gNB TN or NTN wireless base station 806 can be realized in discrete or integrated component form, with an ultimate structure therefore being an application-specific or design selection.

[0103] The processor 1008 and transceiver (e.g., transmitter / modulation circuitry 1022 and receiver front-end circuitry 1006) of the eNB or gNB TN or NTN wireless base station 806 are configured to operate differently with regard to the triggering and reporting of a Timing Advance Report to a served wireless communication unit, such as a UE, according to at least one of the operations described in one of FIG. 8, FIG. 9 or FIG. 12.

[0104] FIG. 10 also shows a high-level block diagram of the wireless communication unit (a user equipment UE in 3GPP parlance) 802 contains an antenna 1052, for receiving transmissions, coupled to an antenna switch or duplexer 1054 that provides isolation between receive and transmit chains within the wireless communication unit 802. One or more receiver chains, as known in the art, include receiver front-end circuitry 1056 (effectively providing reception, filtering and intermediate or base-band frequency conversion). The receiver front-end circuitry 1056 is coupled to a signal processor 1058 (generally realized by a digital signal processor (DSP)). A skilled artisan will appreciate that the level of integration of receiver circuits or components may be, in some instances, implementation-dependent.

[0105] The controller 1064 maintains overall operational control of the wireless communication unit 802. The controller 1064 is also coupled to the receiver front-end circuitry 1056 and the signal processor 1058. In some examples, the controller 1064 is also coupled to a frequency generation circuit 1067 and a memory device 1066 that selectively stores operating regimes, such as decoding / encoding functions, synchronization patterns, code sequences, and the like. The processor 1058 and transceiver (e.g., transmitter / modulation circuitry 1072 and receiver front-end circuitry 1056) of the wireless communication unit 802 are configured to communicate with the eNB or gNB TN or NTN wireless base station 806 on a frequency that is set by frequency generation circuit 1067. A timer 1068 is operably coupled to the controller 1064 to control the timing of operations (e.g., transmission or reception of time-dependent signals) within the wireless communication unit 802.

[0106] As regards the transmit chain, this essentially includes an input interface 1070, coupled in series through transmitter / modulation circuitry 1072 and a power amplifier 1074 to the antenna 1052, antenna array, or plurality of antennas. The transmitter / modulation circuitry 1072 and the power amplifier 1074 are operationally responsive to the controller 1064.

[0107] The signal processor 1058 in the transmit chain may be implemented as distinct from the signal processor in the receive chain. Alternatively, a single processor may be used to implement a processing of both transmit and receive signals, as shown in FIG. 10. Clearly, the various components within the wireless communication unit 802 can be realized in discrete or integrated component form, with an ultimate structure therefore being an application-specific or design selection.

[0108] In accordance with some examples, the processor 1058 and transceiver (e.g., transmitter / modulation circuitry 1072) of the wireless communication unit 806 are configured to not trigger a TA report when the wireless communication unit 802 performs Early Data Transmissions (EDT), Preconfigured Uplink Resources transmissions (PUR) or CB-Msg3. In some examples, this approach may be achieved in a number of ways. For example, one condition may be that the wireless communication unit 802 has initiated one of: SDT, EDT, PUR or CB-Msg3, then the UE will not trigger a TA report. A further condition may be that the UE has triggered certain RRC messages, such asRRCEarlyDataRequest, which causes the wireless communication unit 802 to not trigger a TA report. Alternatively, it is envisaged that the wireless communication unit 802 may only trigger a TA report under conditions where SDT, EDT, PUR or CB-Msg3 has not been triggered, according to at least one of the operations in accordance with the approach described in one of FIG. 8, FIG. 9 or FIG. 12.

[0109] In accordance with some examples, it is envisaged that the processor 1058 and transceiver (e.g., transmitter / modulation circuitry 1072) of the wireless communication unit 806 are configured to trigger a TA report when the wireless communication unit initiates transmission ofRRCConnectionResumeRequestor when the wireless communication unit initiates transmission ofRRCConnectionRequest. In this example, the wireless communication unit may be configured conversely to not trigger the TA report or cancel the trigger of the TA report when certain RRC messages are initiated, such asRRCEarlyDataRequest.

[0110] In accordance with some examples, it is envisaged that the processor 1058 and transceiver (e.g., transmitter / modulation circuitry 1072) of the wireless communication unit 806 may be configured to trigger a TA report when the wireless communication unit performs Small Data Transmission (SDT), Early Data Transmissions (EDT), Preconfigured Uplink Resources (PUR) transmissions or CB-Msg3 transmissions. In this example, it is envisaged that the wireless communication unit may, for instance, either rely on the existing configuration to trigger the TAR MAC CE (as seen in specification Example 2 below), i.e., the configurationTA-Report, or it may be configured separately in a new configuration. This configuration may determine whether the wireless communication unit shall trigger a TA report for SDT, EDT, PUR and CB-Msg3. In some examples, it is envisaged that this may be one indication for all of the cases (SDT, EDT, PUR and CB-Msg3) or that separate indications are employed. In a further example, it is envisaged that the wireless communication unit may also be configured to trigger a TA report specifically for certain RRC messages, such asRRCEarlyDataRequestorRRCConnectionResumeRequest.

[0111] Thus, in accordance with examples herein described, a wireless communication unit comprises a processor, operably coupled to the transceiver and arranged to perform one or more of the following: (i) not trigger TA reports during RRC establishments in certain circumstances (for example Early Data Transmissions, Preconfigured Uplink Resources transmissions or CB-Msg3, or when the wireless communication unit has triggered certain RRC messages, such asRRCEarlyDataRequest, (ii) only trigger TA reports under conditions where SDT, EDT, PUR or CB-Msg3 has not been triggered; (iii) trigger a TA report when the wireless communication unit initiates transmission ofRRCConnectionResumeRequestor when the wireless communication unit initiates transmission ofRRCConnectionRequest; (iv) not trigger the TA report or cancel the trigger of the TA report when certain RRC messages are initiated, such asRRCEarlyDataRequest; (v)trigger a TA report specifically for certain RRC messages, such asRRCEarlyDataRequestorRRCConnectionResumeRequest;(vi) cancel any previously created trigger.

[0112] Referring now to FIG. 11, part of a wireless communication system 1100 is shown in outline, in accordance with one example embodiment. In this example embodiment, the wireless communication system 1100 is compliant with, and contains network elements capable of operating over, a 4thgeneration (4G), a 5thgeneration (5G) or 6thgeneration (6G) wireless communication system, which are currently under discussion in the third Generation Partnership Project (3GPPTM). The wireless communication system 1100 architecture consists of radio access network (RAN) and core network (CN) elements (not shown), with the core network elements being coupled to external networks (named Packet Data Networks (PDNs)), such as the Internet or a corporate network.

[0113] As illustrated, the CN is operably connected to two NodeBs (eNB 1110 and gNB 1112), with respective, coverage areas (or cells) 1180, 1185. A plurality of wireless communication units 1125 communicate with the serving eNB 1110 or gNB 1112. In accordance with example embodiments, at least one eNB 1110, gNB 1112 and at least one UE 1170, 1175 (amongst other elements) have been adapted to support the concepts hereinafter described.

[0114] In this example, the main components of the RAN include a TN eNB 1110 and an NTN eNB 1112, in a form of a satellite, which perform many standard base station functions and are connected to the CN via an S1 interface / feeder link and to the wireless communication units 1125 via a Uu interface. A wireless communication system will typically have a large number of such infrastructure elements, including a number of terrestrial base stations where, for clarity purposes, only a limited number are shown in FIG. 11. Each of the TN eNB 1110 and the NTN gNB 1112 are able to control and manage the radio resource related functions for a plurality of wireless communication units 1125. Each of the wireless communication units 1125 comprise a transceiver unit operably coupled to signal processor (with one wireless communication unit illustrated in such detail for clarity purposes only). The system comprises many other wireless communication units 1125 and eNBs 1110 and gNBs 1112, which for clarity purposes are not shown.

[0115] In accordance with examples herein described, the wireless communication system comprises a first base station, such as NTN eNB 810, supporting a first network and a second base station, such as gNB wireless base station 812 supporting a second terrestrial network, and a plurality of wireless communication units 825, 870, 875 that are configured to trigger and report a Timing Advance Report as described herein. In accordance with examples herein described, a wireless communication system comprises a base station supporting a network and a plurality of wireless communication units, wherein the network may be a non-terrestrial network, NTN or a terrestrial network, TN. At least one wireless communication unit of the plurality of wireless communication units comprises a transceiver having a transmitter and a receiver for communicating with the base station. The at least one wireless communication unit comprises a processor, operably coupled to the transceiver and arranged to perform one or more of the following: (i) not trigger TA reports during RRC establishments in certain circumstances (for example Early Data Transmissions, Preconfigured Uplink Resources transmissions or CB-Msg3, or when the at least one wireless communication unit has triggered certain RRC messages, such asRRCEarlyDataRequest, (ii) only trigger TA reports under conditions where SDT, EDT, PUR or CB-Msg3 has not been triggered; (iii) trigger a TA report when the at least one wireless communication unit initiates transmission ofRRCConnectionResumeRequestor when the at least one wireless communication unit initiates transmission ofRRCConnectionRequest; (iv) not trigger the TA report or cancel the trigger of the TA report when certain RRC messages are initiated, such asRRCEarlyDataRequest; (v)trigger a TA report specifically for certain RRC messages, such asRRCEarlyDataRequestorRRCConnectionResumeRequest;(vi) cancel any previously created trigger. In some examples, corresponding operations performed by the base station are described.

[0116] In some examples described herein, it is envisaged that the wireless communication unit may consider the state ofany last reported value, orany previously reported TA reportto be 'flushed', 'reset' or that 'no value or TA report is considered to have been reported' in some cases. These cases can, for instance, be when the MAC is reset, when MAC is reconfigured, or when MAC is resumed, or during RRC Resume or RRC re-establishment. This can for instance mean that when the MAC is reset, for instance during RRC Resume procedure, that it is not considered that there is a TA report or any TA values reported previously. This can be seen in specification example 3 and 4. This can then ensure that there are no unexpected TAR MAC CEs triggered during the RRC resume procedure or RRC re-establishment procedure.

[0117] Referring now to FIG. 12, one example message sequence chart 1200 between a UE 802 and a base station 806 is illustrated, that aims to ensure that there are no unexpected TAR MAC CEs triggered during a RRC procedure through considering whether any state related to the TA report is flushed, reset or released, in accordance with some example embodiments. Here, at 1210, a UE 802 is configured with 'offsetThresholdTA'. At 1220, the UE 802 sends a TAR MAC CE reporting message that includes a first TA1 to the gNB 806. Thereafter, the UE 802 performs a MAC reset whereby the UE 802 considers no last-reported TA value and / or previously reported TA report (i.e., the TA1 has been 'flushed'). During the RRC re-establishment procedures, the previously or last reported values may remain.

[0118] Referring now to FIG. 13, one example message sequence chart 1300 between a UE 802 and a base station 806 is illustrated, to ensure that there are no unexpected TAR MAC CEs triggered during a RRC procedure, in accordance with some example embodiments. Here, at 1310, a UE 802 is configured with 'offsetThresholdTA'. At 1320, the UE 802 sends a TAR MAC CE reporting message that includes a first TA1 to the gNB 806. Thereafter, at 1330, the gNB 806 sends a message to the UE 802 that releases the UE 802 to an RRC_INACTIVE state or RRC is suspended. At 1340, the UE 802 enters an an RRC_INACTIVE state or moves to RRC_IDLE with a suspended RRC. At 1350. RRC is subsequently resumed between the UE 802 and the gNB 806. At 1360, the MAC is resumed at the UE 802. At 1370, if the UE 802 determines that the TA2-TA1 is larger than the offsetThresholdTA, a TAR is triggered. At 1380, the UE 802 sends a TAR MAC CE reporting message that includes a second TA2 to the gNB 806.

[0119] Referring now to FIG. 14, a further example message sequence chart 1400 between a UE 802 and a base station 806 is illustrated, to ensure that there are no unexpected TAR MAC CEs triggered during a RRC procedure, in accordance with some example embodiments. Here, at 1410, a UE 802 is configured with 'offsetThresholdTA'. At 1420, the UE 802 sends a TAR MAC CE reporting message that includes a first TA1 to the gNB 806. Thereafter, at 1430, the gNB 806 sends a message to the UE 802 that releases the UE 802 to an RRC_INACTIVE state or RRC is suspended. At 1440, the UE 802 enters an RRC_INACTIVE state or moves to RRC_IDLE with a suspended RRC. At 1450. RRC is subsequently resumed between the UE 802 and the gNB 806. At 1460, the MAC is resumed at the UE 802. At 1470, the gNB 806 re-configures the UE 802 with the offsetThresholdTA, and a TAR is not triggered due to the TAR MAC CE that was previously sent to the gNB 806.

[0120] FIG. 15 is a block diagram of a terminal or user equipment (UE) 1500 according to an embodiment of the disclosure.

[0121] The terminal is an electronic device capable of wireless communication and having various form factors, examples of the terminal may include a UE, a mobile station (MS), a cellular phone, a smartphone, a computer, a tablet, a wearable device, an Internet of Things (IoT) device, or any other device / system capable of performing wireless communication with a base station (BS) and / or another terminal through a wireless channel.

[0122] Referring to FIG. 15, the UE 1500 may include at least one transceiver (hereinafter, referred to as simply “transceiver”) 1501, at least one processor (hereinafter, referred to as simply “processor”) 1502, and at least one memory (hereinafter, referred to as simply “memory”) 1503. According to at least one or a combination of methods corresponding to the embodiments described in the present disclosure, the transceiver 1501, the processor 1502, and the memory 1503 of the UE 1500 may operate. However, components of the UE 1500 are not limited to the example components illustrated in FIG. 15. In another embodiment, the UE 1500 may further include additional components in addition to the above-mentioned components, or some components may be omitted. Further, in some embodiments, any combination of the transceiver 1501, the processor 1502, or the memory 1503 may be integrated in the form of one component.

[0123] The transceiver 1501 may be a communication circuit or communication circuitry that enables the UE 1500 to perform wireless communication with a node or an entity of a network. For example, the transceiver 1501 may enable the UE 1500 to transmit or receive a signal to or from a BS through cellular communication, or to transmit or receive a signal to or from another UE through cellular communication. For example, the transceiver 1501 may support at least one of various cellular communication technologies including 3rd generation (3G), 4th generation (4G), long term evolution (LTE), 5th generation (5G) NR, 6th generation (6G), and various cellular wireless communication technologies supported by the transceiver (1501) may include all subsequent generations of evolved wireless communications.

[0124] According to an embodiment, the UE 1500 may include a plurality of transceivers. For example, in the case of supporting evolved-universal terrestrial radio access-new radio (E-UTRA-NR) dual connectivity (EN-DC), the UE 1500 may include a first transceiver supporting the 4G LTE wireless communication and a second transceiver supporting the 5G NR wireless communication. According to another embodiment, in the case of supporting NR-dual connectivity (NR-DC), the UE 1500 may include a plurality of transceivers supporting the 5G NR wireless communication. According to still another embodiment, in the case of supporting near field wireless communication, the UE 1500 may separately include a transceiver supporting at least one standard in the group of wireless communication protocol standards as defined in the protocol standards for Bluetooth®, wireless local area network (WLAN) network (including institute of electrical and electronics engineers (IEEE) 802.11-2016 standard or its amendments, e.g., 802.11ah, 802.11ad, 802.11ay, 802.11ax, 802.11az, 802.11ba, and 802.11be, without being limited thereto).

[0125] According to an embodiment, the transceiver 1501 may include various circuit structures used to transmit or receive signals to or from a BS through a wireless channel. The signals may include control information and data. For example, the transceiver 1501 may include a radio frequency (RF) transmitter for up-converting and amplifying the frequency of a transmitted signal and an RF receiver for low-noise-amplifying a received signal and down-converting the frequency thereof. The transceiver 1501 may output a signal received through a wireless channel to the processor 1502 and may transmit, through a wireless channel, a signal output from the processor 1502.

[0126] The processor 1502 may control general operations of the UE 1500 according to embodiments of the disclosure. The processor 1502 may be implemented by one or more integrated circuit (or circuitry) (IC) chips and may execute various data processing operations. The processor 1502 may include at least one electric circuit, and may execute instructions (or a program, codes, data, etc.) stored in the memory 1503, individually, collectively or in any combination thereof. Further, the processor 1502 may include a single-core processor or multi-core processor, and may include a processor assembly including a plurality of processing circuits (circuitry) according to a specific implementation scheme.

[0127] The processor 1502 may be electrically, operatively, and / or communicatively coupled to the transceiver 1501 to control the transceiver 1501.

[0128] The processor 1502 may include at least one processor (or processing circuitry), and the at least one processor may perform the following operations individually, collectively or in any combination thereof. For example, the processor 1502 may include a communication processor (CP) configured to control communication operations and an application processor (AP) configured to control execution of an upper layer (for example, an application layer). In a specific embodiment, at least a part of the processor 1502 may be included in one chip (or IC) and the other part of the processor 1502 may be included in another chip (or IC). Otherwise, at least one processor may be included in another component, for example, the transceiver 1501 or the memory 1503.

[0129] The processor 1502 may perform or control or cause an operation of the UE 1500 for executing at least one or a combination of methods according to embodiments of the disclosure. For example, the processor 1502 may control operations of the UE 1500 for processing a downlink signal received from a BS or generating and transmitting an uplink signal to a BS. To this end, the processor 1502 may execute a computer program, codes, or instructions stored in the memory 1503, so as to control other components of the UE 1500 to enable execution of various operations.

[0130] The memory 1503 corresponds to a hardware storage device capable of temporarily or permanently storing information and may include one or more storage media. For example, the memory 1503 may include a memory assembly including one or more storage media. For example, the one or more storage media may include permanent memory, such as a hard drive, flash memory, or read-only memory (ROM), semipermanent memory, such as random access memory (RAM), cache memory, or a combination thereof.

[0131] The memory 1503 may be electrically, operatively, and / or communicatively coupled to the processor 1502 and may be accessed by the processor 1502.

[0132] The memory 1503 may store a computer program, codes, or instructions executable by the processor 1502. According to an embodiment, a computer program, codes, or instructions executable by the processor 1502 may be either stored in a single memory device or separated and distributedly stored in two or more memory devices. By executing the instructions stored in the memory 1503, the processor 1502 may perform various functions according to an embodiment of the disclosure.

[0133] According to an embodiment of the disclosure, operations of the UE 1500 may be caused to be performed based on execution of instructions (or a computer program or codes) stored in the memory 1503 by at least one processor (or processing circuitry) configured to execute the same individually, collectively, or in any combination thereof, based on processing circuitry that is not configured to execute instructions, and / or based on components of processing circuitry that is not configured to execute instructions.

[0134] FIG. 16 is a block diagram of a base station (BS) 1600 according to an embodiment of the disclosure.

[0135] The BS 1600 may perform wireless communication with at least one user equipment (UE) located within the area of the BS 1600 through a wireless channel. The BS 1600 may perform communication with a node or an entity of a network through wired or wireless communication.

[0136] Referring to FIG. 16, the BS 1600 may include at least one transceiver (hereinafter, referred to as simply “transceiver”) 1601, at least one processor (hereinafter, referred to as simply “processor”) 1602, and at least one memory (hereinafter, referred to as simply “memory”) 1603. According to at least one or a combination of methods corresponding to the embodiments described in the present disclosure, the transceiver 1601, the processor 1602, and the memory 1603 of the BS 1600 may operate. However, components of the BS 1600 are not limited to the example components illustrated in FIG. 16. In another embodiment, the BS 1600 may further include additional components in addition to the above-mentioned components, or some components may be omitted. Further, in some embodiments, any combination of the transceiver 1601, the processor 1602, or the memory 1603 may be integrated in the form of one component.

[0137] The transceiver 1601 may be a communication circuit or communication circuitry that enables the BS 1600 to perform wireless communication with a node or an entity of a network. For example, the transceiver 1601 may enable the BS 1600 to transmit or receive a signal to or from the UE 1500 through cellular communication, or to transmit or receive a signal to or from another network entity through wireless communication. For example, the transceiver 1601 may support various cellular communication technologies including 3rd generation (3G), 4th generation (4G), long term evolution (LTE), 5th generation (5G) NR, 6th generation (6G), and various cellular wireless communication technologies supported by the transceiver (1601) may include all subsequent generations of evolved wireless communications.. According to an embodiment, the transceiver 1601 may include various circuit structures used to transmit or receive signals to or from a UE through a wireless channel. The signals may include control information and data. For example, the transceiver 1601 may include a radio frequency (RF) transmitter for up-converting and amplifying the frequency of a transmitted signal and an RF receiver for low-noise-amplifying a received signal and down-converting the frequency thereof. The transceiver 1601 may output a signal received through a wireless channel to the processor 1602 and may transmit, through a wireless channel, a signal output from the processor 1602.

[0138] Meanwhile, according to an embodiment of the present disclosure, the BS 1600 may perform communication with a node or an entity of a network through wired or wireless communication. For example, the BS 1600 may perform wired or wireless communication with an adjacent BS, or a node or an entity of a core network through a backhaul network. Although not illustrated in FIG. 16, when the BS 1600 performs wired communication, the BS 1600 may further include a separate network interface for wired communication in addition to the transceiver 1601. The network interface may be referred to as network interface circuitry or communication interface circuitry.

[0139] The processor 1602 may control general operations of the BS 1600 according to embodiments of the disclosure. The processor 1602 may be implemented by one or more integrated circuit (or circuitry) (IC) chips and may execute various data processing operations. The processor 1602 may include at least one electric circuit, and may execute instructions (or a program, codes, data, etc.) stored in the memory 1603, individually, collectively or in any combination thereof. Further, the processor 1602 may include a single-core processor or multi-core processor, and may include a processor assembly including a plurality of processing circuits (circuitry) according to a specific implementation scheme.

[0140] The processor 1602 may be electrically, operatively, and / or communicatively coupled to the transceiver 1601 to control the transceiver 1601.

[0141] The processor 1602 may include at least one processor (or processing circuitry), and the at least one processor may perform the following operations individually, collectively or in any combination thereof. In a specific embodiment, at least a part of the processor 1602 may be included in one chip (or IC) and the other part of the processor 1602 may be included in another chip (or IC). Otherwise, at least one processor may be included in another component, for example, the transceiver 1601 or the memory 1603.

[0142] The processor 1602 may perform or control or cause an operation of the BS 1600 for executing at least one or a combination of methods according to embodiments of the disclosure. For example, the processor 1602 may control operations of the BS 1600 for generating and transmitting a downlink signal to a UE or processing an uplink signal received from a UE. Otherwise, the BS 1600 may transmit or receive a signal to or from a neighboring BS, transfer a signal received from a UE to an upper node of the network, or transmit a signal transferred from an upper node of the network to a UE. To this end, the processor 1602 may execute a computer program, codes, or instructions stored in the memory 1603, so as to control other components of the BS 1600 to enable execution of various operations.

[0143] The memory 1603 corresponds to a hardware storage device capable of temporarily or permanently storing information and may include one or more storage media. For example, the memory 1603 may include a memory assembly including one or more storage media. For example, the one or more storage media may include permanent memory, such as a hard drive, flash memory, or read-only memory (ROM), semipermanent memory, such as random access memory (RAM), cache memory, or a combination thereof.

[0144] The memory 1603 may be electrically, operatively, and / or communicatively coupled to the processor 1602 and may be accessed by the processor 1602.

[0145] The memory 1603 may store a computer program, codes, or instructions executable by the processor 1602. According to an embodiment, a computer program, codes, or instructions executable by the processor 1602 may be either stored in a single memory device or separated and distributedly stored in two or more memory devices. By executing the instructions stored in the memory 1603, the processor 1602 may perform various functions according to an embodiment of the disclosure.

[0146] According to an embodiment of the disclosure, operations of the BS 1600 may be caused to be performed based on execution of instructions (or a computer program or codes) stored in the memory 1603 by at least one processor (or processing circuitry) configured to execute the same individually, collectively, or in any combination thereof, based on processing circuitry that is not configured to execute instructions, and / or based on components of processing circuitry that is not configured to execute instructions.

[0147] The UE or the base station may perform various communication procedures related to the control plane or the user plane by cooperating with one or more network entities based on wireless communication. For example, the UE may communicate with a network entity (for example, an Access and Mobility Management Function (AMF), a Session Management Function (SMF), rtc.) via the base station, or the base station may perform at least one communication procedure by directly transmitting and receiving signals to / from, or relaying signals between, the network entities.

[0148] The structure of the above-described network entity will be described in more detail with reference to the drawings.

[0149] FIG.17 is a block diagram of a network entity 1700 according to an embodiment of the disclosure.

[0150] The network entity 1700 may include an entity (apparatus, device, or server, etc.) that performs one or more network functions (NFs) or a part of a network function constituting a core network (e.g., a 5th generation (5G) core (5GC)) in a communication system. In this case, multiple NFs may be implemented within a single network entity, or a single NF may be distributed and implemented across a plurality of network entities. In addition, when an NF is implemented within the network entity, the NF may be implemented in the form of software, and in such a case, a program for operating the NF may be stored in memory of the network entity 1700.

[0151] A single NF may be implemented by one or more instances, which may be deployed on the same network entity or distributed across multiple network entities to operate. The instance may be a software unit that logically executes a specific network function, and may be implemented in a form that is decoupled from physical hardware resources. Further, one or more NFs may be implemented in the form of one network slice to operate to satisfy specifications required by a particular service.

[0152] The NF may include at least one of an access and mobility management function (AMF), a session management function (SMF), a local session management function (L-SMF), a user plane function (UPF), a local user plane function (L-UPF), a policy control function (PCF), a unified data management (UDM), a unified data repository (UDR), a network exposure function (NEF), a network repository function (NRF), an application function (AF), a network slice selection function (NSSF), a network data analytics function (NWDAF), a network slice admission control function (NSACF), an authentication server function (AUSF), or a data network (DN), etc.

[0153] Referring to FIG. 17, the network entity 1700 may include at least one network interface 1701, at least one processor 1702 (hereinafter, “processor”), and at least one memory 1703 (hereinafter, “memory”). As described above, a NF may be implemented in the form of a physical device such as the network entity 1700, or may be virtualized and executed in the form of an instance. When implemented as an instance, the NF need not necessarily include physical components as illustrated in FIG. 17. In such a case, the instance may be logically represented as comprising one or more logical functional elements.

[0154] According to at least one or a combination of methods corresponding to the embodiments described in the present disclosure, the network interface 1701, the processor 1702, and the memory 1703 of the network entity 1700 may operate. However, components of the network entity 1700 are not limited to the example components illustrated in FIG. 17. In another embodiment, the network entity 1700 may further include additional components in addition to the above-mentioned components, or some components may be omitted. Further, in an embodiment, the network interface 1701, the processor 1702, or the memory 1703 may be integrated in the form of one component.

[0155] The network interface 1701 is a collective term for a transmitter part of the network entity 1700 and a receiver part of the network entity 1700, and may be a communication circuit for transmitting or receiving a signal to or from a user equipment (UE), a base station (BS), or another network entity. Here, the communication circuit may include both a communication circuit for wireless communication and a communication circuit for a wired communication. For example, the network interface 1701 may include a circuit, logic, hardware, etc., configured to exchange a control plane message or a user plane message with a UE, a BS, or other core network entities through wireless communication or wired communication. The network interface 1701 may operate using various protocols (e.g., non-access stratum (NAS) protocol). The network interface 1701 may also be referred to, for convenience of description or depending on implementation, as communication circuitry, network interface circuitry, or a communication interface circuitry.

[0156] The processor 1702 may control general operations of the network entity 1700 according to embodiments of the disclosure. The processor 1702 may be implemented by one or more integrated circuit (or circuitry) (IC) chips and may execute various data processing operations. The processor 1702 may include at least one electric circuit, and may execute instructions (or a program, codes, data, etc.) stored in the memory 1703, individually, collectively or in any combination thereof. Further, the processor 1702 may include a single-core processor or multi-core processor, and may include a processor assembly including a plurality of processing circuits (circuitry) according to a specific implementation scheme. Further, it should be noted that, according to another embodiment, in a case where NF is implemented in the form of an instance, the network function may be not necessarily configured by physical hardware.

[0157] According to an embodiment, the processor 1702 may be electrically, operatively, and / or communicatively coupled to the network interface 1701 to control the network interface 1701.

[0158] The processor 1702 may include at least one processor (or processing circuitry), and the at least one processor may perform the following operations individually, collectively or in any combination thereof. In a specific embodiment, at least a part of the processor 1702 may be included in one chip (or IC) and the other part of the processor 1702 may be included in another chip (or IC). Otherwise, at least one processor may be included in another component, for example, the network interface 1701 or the memory 1703.

[0159] The processor 1702 may perform or control or cause an operation of the network entity 1700 for executing at least one or a combination of methods according to embodiments of the disclosure. For example, the processor 1702 may control operations of the network entity 1700 for exchanging a control plane message or a user plane message with a UE, a BS, or other core network entities through wireless or wired communication, using various protocols (e.g., NAS protocol). To this end, the processor 1702 may execute a computer program, codes, or instructions stored in the memory 1703, so as to control other components of the network entity 1700 to enable execution of various operations.

[0160] The memory 1703 corresponds to a hardware storage device capable of temporarily or permanently storing information and may include one or more storage media. For example, the memory 1703 may include a memory assembly including one or more storage media. For example, the one or more storage media may include permanent memory, such as a hard drive, flash memory, or read-only memory (ROM), semipermanent memory, such as random access memory (RAM), cache memory, or a combination thereof.

[0161] The memory 1703 may be electrically, operatively, and / or communicatively coupled to the processor 1702 and may be accessed by the processor 1702.

[0162] The memory 1703 may store a computer program, codes, or instructions executable by the processor 1702. According to an embodiment, a computer program, codes, or instructions executable by the processor 1702 may be either stored in a single memory device or separated and distributedly stored in two or more memory devices. By executing the instructions stored in the memory 1703, the processor 1702 may perform various functions according to an embodiment of the disclosure.

[0163] According to an embodiment of the disclosure, operations of the network entity 1700 may be caused to be performed based on execution of instructions (or a computer program or codes) stored in the memory 1703 by at least one processor (or processing circuitry) configured to execute the same individually, collectively, or in any combination thereof, based on processing circuitry that is not configured to execute instructions, and / or based on components of processing circuitry that is not configured to execute instructions.

[0164] In some examples described herein, it is envisaged that the wireless communication unit may consider that a previously reported Timing Advance value or a last reported value may be from a previous connection when the wireless communication unit was connected to the same cell. This may for instance be specific to RRC resume and / or RRC re-establishment. For instance, the wireless communication unit may consider that a previously reported Timing Advance value may have been reported with the same cell if the RRC connection was suspended and the cell did not change to another cell. The previously reported Timing Advance value or last reported Timing Advance value may thus be considered to be flushed when the wireless communication unit changes the cell. This may require that the state related to the TA reporting is maintained when the wireless communication unit for instance when MAC is reset.

[0165] In some examples described herein, it is envisaged that there may for instance be a distinction between apreviously reported Timing Advance valueand thelast reported Timing Advance value. In other words, for the triggering of the TAR MAC CE at the point when the wireless communication unit is configured with the offset threshold, the wireless communication unit may consider that nothing has been reported in the past. In the case of triggering the TA report when the timing advance is larger than the offset threshold compared to previously reported timing advance value, the wireless communication unit may consider that the previously reported timing advance value can be maintained from previous RRC connections.

[0166] In some examples described herein, it is envisaged that, when the wireless communication unit is re-configured with offsetThresholdTA or if MAC is resumed (when the offset threshold is resumed), the wireless communication unit will trigger a TA report. In other words, if the wireless communication unit has already been configured with an offset threshold, the wireless communication unit will be configured to trigger a TA report when the wireless communication unit is re-configured with the offset threshold. This can be seen in specification example 5. It is envisaged that this may be performed under the condition that the UE did not report the TAR MAC CE during a Msg3, or that TA-report was not configured. In some examples, this may be important to ensure that the TA report can be triggered when the timing advance value is larger than the offset threshold, as otherwise there may not be considered to be a last reported timing advance value, thus not making it possible to trigger the TAR MAC CE.

[0167] In some examples described herein, it is envisaged that the wireless communication unit only considers the state for the current RRC connection, which may also include the access attempt. This means that the wireless communication unit only considers if the wireless communication unit has previously reported Timing Advance value to the current Serving Cell for the current RRC connection, or current RRC connection and access attempt or access procedures. Similarly, the wireless communication unit only considers the variation between the current Timing Advance value and the last reported Timing Advance of the current RRC connection. An example of this can be found in specification example 5.

[0168] In some examples described herein, it is envisaged that the wireless communication unit may consider whether (or not) a TAR MAC CE was triggered and sent in a Msg3, or whether (or not) the TA-report (UE configured to send TAR MAC CE in Msg3) in System information or in dedicated configuration was configured. For instance, when the offset threshold TA is resumed or re-configured, then the wireless communication unit may consider whether either the TAR MAC CE was sent in a Msg3 or whether (or not) TA-report was configured. For instance, the “flush”, “reset” or release of a previously reported Timing Advance value or the last reported Timing Advance value may be based on whether a TAR MAC CE was sent in a Msg3 or whether TA-report was configured.

[0169] It is also envisaged that the above operation may be configurable, for instance via either a broadcasted or dedicated configuration.

[0170] In some examples described herein, it is envisaged that the wireless communication unit may report its capabilities on any of the above, e.g., capability to include TA report for SDT, EDT, PUR and CB-Msg3.

[0171] Implementation examples

[0172] Example #1

[0173] Changes indicated in bold for LTE and NR specifications:

[0174] -------------------------- Example --------------------------

[0175] 5.3.3.2 Initiation

[0176] The UE initiates the procedure when upper layers request establishment or resume of an RRC connection while the UE is in RRC_IDLE or when upper layers request resume of an RRC connection or RRC layer requests resume of an RRC connection for, e.g. RNAU or reception of RAN paging while the UE is in RRC_INACTIVE.

[0177] ...

[0178] Except for NB-IoT, upon initiating the procedure, if connected to EPC or 5GC, the UE shall:

[0179] ...

[0180] 1> if UE supports timing advance reporting andta-Reportis included inSystemInformationBlockType2and the UE is not initiating EDT according to 5.3.3.1b or PUR according to 5.3.3.1c:

[0181] 2> instruct the associated MAC entity to trigger Timing Advance reporting;

[0182] ...

[0183] For NB-IoT, upon initiation of the procedure, the UE shall:

[0184] ...

[0185] 1> if UE supports timing advance reporting andta-Reportis included inSystemInformationBlockType2-NBand the UE is not initiating EDT according to 5.3.3.1b or PUR according to 5.3.3.1c:

[0186] 2> instruct the associated MAC entity to trigger Timing Advance reporting;...

[0187] -------------------------- Example --------------------------

[0188] -------------------------- Example --------------------------

[0189] 5.3.13.2 Initiation

[0190] The UE initiates the procedure when upper layers or AS (when responding to RAN paging, upon triggering RNA updates while the UE is in RRC_INACTIVE, upon requesting multicast reception as specified in clause 5.3.13.1d, for NR sidelink communication / discovery / V2X sidelink communication as specified in clause 5.3.13.1a, for requesting configuration for SRS for positioning, for activation of preconfigured Positioning SRS in RRC_INACTIVE, upon receivingRRCReleasemessage includingresumeIndication) requests the resume of a suspended RRC connection or requests the resume for initiating SDT as specified in clause 5.3.13.1b.

[0191] The UE shall ensure having valid and up to date essential system information as specified in clause 5.2.2.2 before initiating this procedure.

[0192] Upon initiation of the procedure, the UE shall:

[0193] ...

[0194] 1> if conditions for initiating SDT in accordance with 5.3.13.1b are fulfilled:

[0195] 2> consider the resume procedure is initiated for SDT;

[0196] 2> start timer T319a when the lower layers first transmit the CCCH message;

[0197] 2> consider SDT procedure is ongoing;

[0198] 1> else:

[0199] 2> start timer T319;

[0200] 2> instruct the MAC entity to stop thecg-SDT-TimeAlignmentTimer, if it is running;

[0201] 1> ifta-Reportorta-ReportATGis configured with valueenabled,andthe UE supports TA reportingand the UE is not initiating SDT procedure:

[0202] 2> indicate TA report initiation to lower layers;

[0203] 1> set the variablependingRNA-Updatetofalse;

[0204] 1> releasesuccessHO-Configfrom the UE Inactive AS context, if stored;

[0205] 1> releasesuccessPSCell-Configconfigured by the PCell from the UE Inactive AS context, if stored;

[0206] 1> releasesuccessPSCell-Configconfigured by the PSCell from the UE Inactive AS context, if stored;

[0207] 1> initiate transmission of theRRCResumeRequestmessage orRRCResumeRequest1in accordance with 5.3.13.3

[0208] -------------------------- Example --------------------------

[0209] Example #2

[0210] Changes indicated in bold for LTE and NR specifications:

[0211] -------------------------- Example --------------------------

[0212]

[0213] -------------------------- Example --------------------------

[0214] -------------------------- Example --------------------------

[0215]

[0216] -------------------------- Example --------------------------

[0217] Example #3

[0218] Changes indicated in bold for LTE and NR specifications:

[0219] -------------------------- Example --------------------------

[0220] 5.9 MAC Reset

[0221] If a reset of the MAC entity is requested by upper layers, the MAC entity shall:

[0222] - initialize Bj for each logical channel to zero;

[0223] - except forpur-TimeAlignmentTimer,if configured,stop (if running) all timers;

[0224] - except forpur-TimeAlignmentTimer,if configured,consider alltimeAlignmentTimersas expired and perform the corresponding actions in clause 5.2;

[0225] - set the NDIs for all uplink HARQ processes to the value 0;

[0226] - stop, if any, ongoing RACH procedure;

[0227] - discard explicitly signalledra-PreambleIndexandra-PRACH-MaskIndex, if any;

[0228] - flush Msg3 buffer;

[0229] - cancel, if any, triggered Scheduling Request procedure;

[0230] - cancel, if any, triggered Buffer Status Reporting procedure;

[0231] - cancel, if any, triggered Power Headroom Reporting procedure;

[0232] - cancel, if any, triggered Recommended bit rate query procedure;

[0233] - cancel, if any, triggered Timing Advance Reporting procedure;

[0234] - cancel, if any, triggered GNSS Validity Duration Reporting procedure;

[0235] - flush the soft buffers for all DL HARQ processes;

[0236] - for each DL HARQ process, consider the next received transmission for a TB as the very first transmission;

[0237] - release, if any, Temporary C-RNTI;

[0238] - clear, if any, Differential Koffset.

[0239] -consider that for Timing Advance Reporting, no Timing Advance value has been reported previously

[0240] If a partial reset of the MAC entity is requested by upper layers, for a serving cell, the MAC entity shall for the serving cell:

[0241] - set the NDIs for all uplink HARQ processes to the value 0;

[0242] - flush all UL HARQ buffers;

[0243] - stop all runningdrx-ULRetransmissionTimers;

[0244] - stop all running UL HARQ RTT timers;

[0245] - stop, if any, ongoing RACH procedure;

[0246] - discard explicitly signalledra-PreambleIndexandra-PRACH-MaskIndex, if any;

[0247] - flush Msg3 buffer;

[0248] - release, if any, Temporary C-RNTI.

[0249] -------------------------- Example --------------------------

[0250] Example #4

[0251] Changes indicated in bold for LTE:

[0252] -------------------------- Example --------------------------

[0253] 5.4.9 Timing Advance Reporting

[0254] The UE may be configured to report information about timing advance during a Random Access procedure and in RRC_CONNECTED Mode.

[0255] The Timing Advance reporting procedure is used in a non-terrestrial network to provide the eNB with an estimate of the UE's Timing Advance, see TTAin TS 36.211 [7] clause 8.1.

[0256] Timing Advance reporting shall be triggered if any of the following events occur:

[0257] - if triggered by upper layers;

[0258] - upon configuration ofoffsetThresholdTAby upper layers, if the UE has not previously reported Timing Advance value to current Serving Cell;

[0259] - if the variation between current information about Timing Advance and the last reported information about Timing Advance is equal to or larger thanoffsetThresholdTA, if configured.

[0260] NOTE:The UE considers there to not be any previously reported Timing Advance value after MAC is reset or RRC resume.

[0261] -------------------------- Example --------------------------

[0262] Example #5

[0263] Changes indicated in bold for LTE (but same change may be applicable for NR):

[0264] -------------------------- Example --------------------------

[0265] 5.4.9 Timing Advance Reporting

[0266] The UE may be configured to report information about timing advance during a Random Access procedure and in RRC_CONNECTED Mode.

[0267] The Timing Advance reporting procedure is used in a non-terrestrial network to provide the eNB with an estimate of the UE's Timing Advance, see TTAin TS 36.211 [7] clause 8.1.

[0268] Timing Advance reporting shall be triggered if any of the following events occur:

[0269] - if triggered by upper layers;

[0270] - upon configurationor resumptionofoffsetThresholdTAby upper layers, if the UE has not previously reported Timing Advance value to current Serving Cell;

[0271] - if the variation between current information about Timing Advance and the last reported information about Timing Advance is equal to or larger thanoffsetThresholdTA, if configured.

[0272] -------------------------- Example --------------------------

[0273] In various embodiments according to the disclosure, A wireless communication unit (802) comprises: a transceiver (1072) arranged to communicate with a base station (806) and receive an instruction to generate a timing advance report, TAR, (810); a processor (1058) configured to generate the TAR, (810) to be transmitted to the base station (806); wherein the processor (1058) is arranged to determine whether or not to trigger a transmission of the TAR to the base station (806) via the transceiver (1072) in response to one of the following: receive a radio resource control, RRC, message (820) from the base station (806); initiate a RRC message.

[0274] In an embodiment, the processor (1058) is configured to not trigger the transmission of the TAR to the base station (806) in response to the wireless communication unit (802) having initiated one of: a small data transmission, SDT, an early data transmission, EDT, a preconfigured uplink resource transmission, PUR, or CB-Msg3.

[0275] In an embodiment, the processor (1058) is configured to not trigger the transmission of the TAR to the base station (806) or cancel (840) the transmission of the TAR to the base station (806) in response to an initiation by the wireless communication unit (802) of a radio resource control, RRC, RRCEarlyDataRequest message transmission.

[0276] In an embodiment, the processor (1058) is configured to trigger the transmission of the TAR to the base station (806) in response to the wireless communication unit (802) having initiated one of: a transmission of RRCConnectionResumeRequest, a transmission of RRCConnectionRequest.

[0277] In an embodiment, wherein the instruction to generate the TAR is configured in one of: a SystemInformationBlockType2 message, a SystemInformationBlockType2-NB message; wherein the wireless communication unit (802) is not arranged to initiate one of: an early data transmission, EDT, a preconfigured uplink resource transmission, PUR, a Contention-based Msg3 EDT; wherein the processor (1058) is configured to instruct a media access control, MAC, entity to trigger the transmission of the TAR to the base station (806).

[0278] In an embodiment, the processor (1058) is only configured to trigger the transmission of the TAR to the base station (806) in response to one or more of the following having not been triggered: a small data transmission, SDT, an early data transmission, EDT, a preconfigured uplink resource transmission, PUR, or Contention-based Msg3 transmission, CB-Msg3.

[0279] In an embodiment, the processor (1058) is configured to trigger transmission of the TAR to the base station (806) in response to an initiation of one of: RRCEarlyDataRequest, RRCConnectionResumeRequest.

[0280] In an embodiment, the processor (1058) is configured to trigger transmission of the TAR to the base station (806) when the wireless communication unit (802) is in RRC_IDLE mode of operation or in RRC_INACTIVE mode of operation in response to one of: a RRC connection resume request, a RRC connection re-establishment operation.

[0281] In an embodiment, in response to a determination of whether or not to trigger the transmission of the TAR to the base station (806), the processor (1058) is configured to cancel a previously created TAR trigger.

[0282] In various embodiments according to the disclosure, A method for a wireless communication unit (802) supporting timing advance, the method comprising at the wireless communication unit (802): receiving, from a base station (806), an instruction to generate a timing advance report, TAR, (810); generating a TAR (810) to be transmitted to the base station (806); determining whether or not to trigger a transmission of the TAR to the base station (806) in response to one of the following: receiving a radio resource control, RRC, message (820) from the base station (806); initiating a RRC message.

[0283] In an embodiment, the method further comprises: determining to not trigger the transmission of the TAR to the base station (806) in response to the wireless communication unit (802) having initiated one of: a small data transmission, SDT, an early data transmission, EDT, a preconfigured uplink resource transmission, PUR, or CB-Msg3.

[0284] In an embodiment, the method further comprises: transmitting a radio resource control, RRC, RRCEarlyDataRequest message; determining, in response thereto, to not trigger the transmission of the TAR to the base station (806) or cancel (840) the transmission of the TAR to the base station (806).

[0285] In an embodiment, the method further comprises: triggering the transmission of the TAR to the base station (806) in response to the wireless communication unit (802) having initiated one of: a transmission of RRCConnectionResumeRequest, a transmission of RRCConnectionRequest.

[0286] In an embodiment, the instruction to generate the TAR is configured in one of: a SystemInformationBlockType2 message, a SystemInformationBlockType2-NB message, and in response to the instruction, the method further comprises; preventing initiation of one of: an early data transmission, EDT, a preconfigured uplink resource transmission, PUR, a Contention-based Msg3 EDT; and instructing a media access control, MAC, entity to trigger the transmission of the TAR to the base station (806).

[0287] In an embodiment, the method further comprises: only triggering the transmission of the TAR to the base station (806) in response to one or more of the following having not been triggered: a small data transmission, SDT, an early data transmission, EDT, a preconfigured uplink resource transmission, PUR, or Contention-based Msg3 transmission, CB-Msg3.

[0288] In an embodiment, the method further comprises: triggering transmission of the TAR to the base station (806) in response to an initiation of one of: RRCEarlyDataRequest, RRCConnectionResumeRequest.

[0289] In an embodiment, the method further comprises: triggering transmission of the TAR to the base station (806) when the wireless communication unit (802) is in RRC_IDLE mode of operation or in RRC_INACTIVE mode of operation in response to one of: a RRC connection resume request, a RRC connection re-establishment operation.

[0290] In an embodiment, the method further comprises: determining whether or not to trigger the transmission of the TAR to the base station (806), and in response thereto cancelling a previously created TAR trigger.

[0291] In various embodiments according to the disclosure, A wireless communication system comprises a plurality of wireless communication units (802) according to the methods disclosed herewith to communicate with a plurality of base stations (806).

[0292] In particular, it is envisaged that the aforementioned inventive concept can be applied by a semiconductor manufacturer to any integrated circuit comprising a signal processor configured to perform any of the aforementioned operations. Furthermore, the inventive concept can be applied to any circuit that is able to configure, process, encode and / or decode signals for wireless distribution. It is further envisaged that, for example, a semiconductor manufacturer may employ the inventive concept in a design of a stand-alone device, such as a digital signal processor, or application-specific integrated circuit (ASIC) and / or any other sub-system element.

[0293] It will be appreciated that, for clarity purposes, the above description has described example embodiments with reference to different functional units and processors. However, it will be apparent that any suitable distribution of functionality between different functional units or processors, for example with respect to the signal processor may be used without detracting from the concepts described herein. For example, functionality illustrated to be performed by separate processors or controllers may be performed by the same processor or controller. Hence, references to specific functional units are only to be seen as references to suitable means for providing the described functionality, rather than indicative of a strict logical or physical structure or organization.

[0294] Aspects may be implemented in any suitable form including hardware, software, firmware or any combination of these. Example embodiments may optionally be implemented, at least partly, as computer software running on one or more data processors and / or digital signal processors or configurable module components such as FPGA devices. Thus, the elements and components of an embodiment may be physically, functionally and logically implemented in any suitable way. Indeed, the functionality may be implemented in a single unit, in a plurality of units or as part of other functional units.

[0295] Although the concepts have been described in connection with some embodiments, it is not intended to be limited to the specific form set forth herein. Rather, the scope is limited only by the accompanying claims. Additionally, although a feature may appear to be described in connection with particular embodiments, one skilled in the art would recognize that various features of the described embodiments may be combined in other examples. In the claims, the term 'comprising' does not exclude the presence of other elements or steps.

[0296] Furthermore, although individually listed, a plurality of means, elements or method steps may be implemented by, for example, a single unit or processor. Additionally, although individual features may be included in different claims, these may possibly be advantageously combined, and the inclusion in different claims does not imply that a combination of features is not feasible and / or advantageous. Also, the inclusion of a feature in one category of claims does not imply a limitation to this category, but rather indicates that the feature is equally applicable to other claim categories, as appropriate.

[0297] Thus, examples have been described that provide improved mobility of communication units from terrestrial base stations or base stations such as NTN airborne gNBs, eNBs, to NTN base stations, such as satellite base stations. In accordance with examples herein described, a number of approaches are provided to enable the network to request or ensure that the UE performs measurements on terrestrial frequencies if indicated to do so, wherein the aforementioned disadvantages with prior art arrangements have been substantially alleviated.

[0298] Meanwhile, although specific embodiments of the present disclosure have been described in detail, various modifications may be made without departing from the scope of the present disclosure. Therefore, the scope of the present disclosure should not be limited to the described embodiments, but should be defined by the claims and equivalents thereof.

[0299] Abbreviations / Definitions

[0300] In the present disclosure, the following acronyms / definitions are used.

[0301] 3GPP 3rdGeneration Partnership Project

[0302] 6G 6thGeneration

[0303] 5G 5thGeneration

[0304] 5GC 5G Core

[0305] 5GS 5G System

[0306] ACK Acknowledge

[0307] AM Acknowledged Mode

[0308] AMF Access and Mobility management Function

[0309] AS Access Stratum

[0310] BL Bandwidth-reduced Low-complexity

[0311] CA Carrier Aggregation

[0312] CCCH Common Control Channel

[0313] CDMA Code Division Multiple Access

[0314] CE Coverage Enhancement

[0315] CIoT Cellular IoT

[0316] CN Core Network

[0317] C-RNTI Cell RNTI

[0318] CS Circuit Switched

[0319] DC Dual Connectivity

[0320] DCCH Dedicated Control Channel

[0321] DRB Data Radio Bearer

[0322] EDGE Enhanced Data rates for Global Evolution

[0323] EDT Early Data Transmission

[0324] eMTC enhanced Machine Type Communication

[0325] EN E-UTRAN NR

[0326] eNB Base Station

[0327] EPC Evolved Packet Core

[0328] EPS Evolved Packet System

[0329] E-UTRA Evolved Universal Terrestrial Radio Access

[0330] E-UTRAN Evolved Universal Terrestrial Radio Access Network

[0331] GEO Geosynchronous Equatorial Orbit

[0332] GERAN GSM EDGE Radio Access Network

[0333] gNB 5G Base Station

[0334] GSM Groupe Special Mobile

[0335] HAPS High Altitude Platform Station

[0336] HARQ Hybrid Automatic Repeat Request

[0337] ID Identity / Identification

[0338] IE Information Element

[0339] IoT Internet of Things

[0340] LEO Lower Earth Orbit

[0341] LTE Long Term Evolution

[0342] LTE-M LTE Machine Type Communication

[0343] MAC Medium Access Control

[0344] MCG Master Cell Group

[0345] MEO Medium Earth Orbit

[0346] MME Mobility Management Entity

[0347] NAS Non Access Stratum

[0348] NB Narrow Band

[0349] BS Base Station

[0350] NG Next Generation

[0351] NR New Radio

[0352] NTN Non-Terrestrial Network

[0353] PCell Primary Cell

[0354] PDCP Packet Data Convergence Protocol

[0355] PDU Protocol Data Unit

[0356] PSCell Primary and Secondary Cells

[0357] RAN Radio Access Network

[0358] RAT Radio Access Technology

[0359] RB Radio Bearer

[0360] RLC Radio Link Control

[0361] RLF Radio Link Failure

[0362] RNTI Radio Network Temporary Identifier

[0363] ROHC Robust Header Compression

[0364] RRC Radio Resource Control

[0365] S1 Interface between RAN and CN

[0366] SAP Service Access Point

[0367] SCG Secondary Cell Group

[0368] SIB System Information Block

[0369] SRB Signalling Radio Bearer

[0370] S-TMSI Short TMSI

[0371] TAU Tracking Area Update

[0372] TM Transparent Mode

[0373] TMSI Temporary Mobile Subscriber Identity

[0374] TN Terrestrial Network

[0375] TS Technical Specification

[0376] Txxx Timer xxx

[0377] UE User Equipment

[0378] UP User Plane

[0379] X2 / Xn Interface between RAN nodes

Claims

1.A method performed by a user equipment (UE) in a wireless communication system, the method comprising:receiving, from a base station, a system information block (SIB) including information indicating a timing advance (TA) reporting; andinstructing an associated medium access control (MAC) entity to trigger TA reporting in a random access (RA) procedure based on the information.2.The method of claim 1,wherein the instructing of the associated MAC entity to trigger TA reporting is based on that the UE is not performing contention based (CB)-Msg3-early data transmission (EDT).3.The method of claim 1,wherein the instructing of the associated MAC entity to trigger TA reporting is based on a preconfigured uplink resource (PUR) transmission.4.The method of claim 1,wherein the information is related to non terrestrial network configuration, andwherein the instruction of the associated MAC entity to trigger TA reporting is based on a small data transmission (SDT).5.A method performed by a base station in a wireless communication system, the method comprising:transmitting, to a user equipment (UE), a system information block (SIB) including information indicating a timing advance (TA) reporting; andreceiving, from the UE, a TA report in a random access (RA) procedure based on the information.6.The method of claim 5,wherein the receiving of the TA report is based on that the UE is not performing contention based (CB)-Msg3-early data transmission (EDT).7.The method of claim 5,wherein the receiving of the TA report is based on a preconfigured uplink resource (PUR) transmission from the UE.8.The method of claim 5,wherein the information is related to non terrestrial network configuration, andwherein the receiving of the TA report is based on a small data transmission (SDT) from the UE.9.A user equipment (UE) comprising:at least one transceiver;at least one processor communicatively coupled to the at least one transceiver; andat least one memory, communicatively coupled to the at least one processor, storing instructions executable by the at least one processor individually or in any combination to cause the UE to:receive, from a base station, a system information block (SIB) including information indicating a timing advance (TA) reporting; andinstruct an associated medium access control (MAC) entity to trigger TA reporting in a random access (RA) procedure based on the information.10.The UE of claim 9,wherein the instructing of the associated MAC entity to trigger TA reporting is based on that the UE is not performing contention based (CB)-Msg3-early data transmission (EDT).11.The UE of claim 9,wherein the instructing of the associated MAC entity to trigger TA reporting is based on a preconfigured uplink resource (PUR) transmission.12.The UE of claim 9,wherein the information is related to non terrestrial network configuration, andwherein the instruction of the associated MAC entity to trigger TA reporting is based on a small data transmission (SDT).13.A base station comprising:at least one transceiver;at least one processor communicatively coupled to the at least one transceiver; andat least one memory, communicatively coupled to the at least one processor, storing instructions executable by the at least one processor individually or in any combination to cause the base station to:transmit, to a user equipment (UE), a system information block (SIB) including information indicating a timing advance (TA) reporting; andreceive, from the UE, a TA report in a random access (RA) procedure based on the information.14.The base station of claim 13,wherein the receiving of the TA report is based on that the UE is not performing contention based (CB)-Msg3-early data transmission (EDT).15.The base station of claim 13,wherein the receiving of the TA report is based on a preconfigured uplink resource (PUR) transmission from the UE.

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