Timing alignment acquisition

Abstract

Aspects of the present disclosure relate to methods, apparatuses, and systems for supporting timing alignment acquisition. For example, an implementation provides an optimized RACH procedure that is performed for early acquisition of timing alignment (TA) information, for example, before a handover occurs. Further, the implementation enables a candidate cell for handover to identify a random access procedure as an early TA Acquisition (RACH), which can enable successful execution of the RACH procedure without the need to establish a Radio Resource Control (RRC) connection in the candidate cell.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to U.S. Provisional Application Serial No. 63 / 421,800, filed on November 2, 2022, entitled “TIMING ALIGNMENTACQUISITION,” the entire contents of which are incorporated herein by reference. Technical Field

[0003] The present disclosure relates to wireless communications, and more particularly to managing connections in wireless communications. Background Art

[0004] A wireless communication system may include one or more network communication devices (such as base stations), which may be referred to as eNodeB (eNB), next generation NodeB (gNB), or other suitable terms. Each network communication device (such as a base station) may support wireless communication of one or more user communication devices, which may also be referred to as user equipment (UE) or other suitable terms. A wireless communication system may support wireless communication with one or more user communication devices by utilizing resources of the wireless communication system (e.g., time resources (e.g., symbols, time slots, subframes, frames, etc.) or frequency resources (e.g., subcarriers, carriers). In addition, a wireless communication system may support wireless communication across various radio access technologies, including third generation (3G) radio access technology, fourth generation (4G) radio access technology, fifth generation (5G) radio access technology, and other suitable radio access technologies beyond 5G (e.g., sixth generation (6G)).

[0005] Some wireless communication systems provide methods for enabling a UE to perform handover between different cells. However, current handover implementations may be inefficient and may result in delays. Summary of the invention

[0006] The present disclosure relates to methods, apparatus, and systems that support timing alignment (TA) acquisition. For example, implementations provide an optimized random access channel (RACH) procedure that is performed for early acquisition of TA information, such as before a handover occurs. In addition, implementations enable a candidate cell for handover to identify a random access procedure as an early TA acquisition RACH, which can enable the RACH procedure to be successfully performed without establishing a radio resource control (RRC) connection in the candidate cell.

[0007] Thus, the described techniques provide an optimized handover process that reduces delays and signaling overhead that may be encountered in some wireless communication systems.

[0008] Some implementations of the methods and apparatus described herein may also include: receiving a first message including information about a cell set; initiating a random access procedure on at least one cell in the cell set based at least in part on the first message; and sending an uplink signal to at least one cell, the uplink signal including: usage information related to the random access procedure.

[0009] Some implementations of the methods and apparatus described herein may also include: receiving a first message as a downlink message on a physical downlink shared channel (PDSCH); wherein the downlink message on the PDSCH includes an RRC message; sending an uplink signal as a physical random access channel (PRACH) preamble; sending the uplink signal as a physical uplink shared channel (PUSCH) transmission scheduled by a random access response message; wherein the PUSCH transmission includes a media access control (MAC) control element (CE), and wherein the MAC-CE includes an identifier.

[0010] Some implementations of the methods and apparatus described herein may also include: wherein the PUSCH transmission includes an RRC message, and wherein the RRC message includes a field identifying usage information; wherein the random access process includes a contention-based random access process; and further comprising triggering the random access process via a MAC entity; wherein the usage information includes an indication of timing alignment acquisition, and further comprising receiving the timing alignment information based at least in part on an uplink signal; receiving an indication of whether at least one cell in a cell set supports early timing alignment acquisition; determining priority information of the cell set, and initiating a random access process based at least in part on the priority information; receiving an indication of whether at least one cell supports early timing alignment acquisition in a first message, and based at least in part on the indication, sending an uplink signal to a candidate cell to obtain timing alignment information.

[0011] Some implementations of the methods and apparatus described herein may also include generating a first message including information of a cell set, the information including information related to acquiring timing alignment information from one or more cells in the cell set; and sending the first message to a UE.

[0012] Some implementations of the methods and apparatus described herein may also include: wherein the information of the cell set includes: an indication of whether one or more cells in the cell set supports early acquisition of timing alignment; wherein the first message also includes: a priority indication for timing alignment with the cell set; and the priority indication is sent in an order corresponding to the priority order of the timing alignment information for acquiring one or more cells in the cell set.

[0013] Some implementations of the methods and apparatus described herein may also include: at the apparatus, receiving a first message from a UE, the first message including: information related to obtaining first timing alignment information; and sending a second message to the UE including second timing alignment information.

[0014] Some implementations of the methods and apparatus described herein may also include: wherein the second timing alignment information includes: an indication of whether the apparatus supports early timing alignment acquisition; and sending the second message via a system information block (SIB).

[0015] Some implementations of the methods and apparatus described herein may also include receiving a first message including instructions for performing a RACH process for acquiring timing alignment information from one or more cells in a cell set, and initiating a RACH process with one or more cells in the cell set.

[0016] Some implementations of the methods and apparatus described herein may also include: wherein the first message includes: downlink control information (DCI), the DCI including: one or more identifiers of one or more cells in the cell set; the DCI is received as part of a physical downlink control channel (PDCCH); the first message includes one or more of the following items: a synchronization signal block (SSB), a physical broadcast channel (PBCH), or a RACH mask index of one or more cells in the cell set; including initiating a RACH process using one or more of the SSB, PBCH, or RACH mask index; including receiving a second message before the first message, the second message including: candidate cell information identifying a candidate cell, the candidate cell including at least: one or more cells in the cell set; the first message includes: downlink Control information (DCI), the DCI comprising: one or more identifications of one or more cells in a cell set from a candidate cell of a second message; the DCI identifies one or more candidate cells in a cell set based at least in part on the order of the one or more cells in the cell set in the candidate cell information; obtains timing alignment information from a target cell in one or more cells in the cell set; and starts monitoring a physical downlink control channel (PDCCH) in the target cell; starts monitoring the PDCCH based at least in part on the reception of one or more of a layer 1 (L1) switching command or a layer 2 (L2) switching command; receives scheduling of uplink resources from the target cell via a dynamic uplink grant; and sends a third message indicating completion of switching to the target cell via one or more of the uplink resources.

[0017] Some implementations of the methods and apparatus described herein may also include: generating a first message that instructs the UE to perform a RACH procedure for acquiring timing alignment information from one or more cells in the set of cells; and sending the first message to the UE.

[0018] Some implementations of the methods and apparatus described herein may also include, wherein the first message includes: downlink control information (DCI), the DCI including: one or more identifiers of one or more cells in a cell set; the DCI is sent as part of a physical downlink control channel (PDCCH); the first message includes one or more of the following items: a synchronization signal block (SSB), a physical broadcast channel (PBCH), or a RACH mask index of one or more cells in the cell set; a second message is sent before the first message, the second message including: candidate cell information identifying candidate cells, the candidate cells including at least: one or more cells in the cell set; the first message includes: downlink control information (DCI), the DCI including: one or more identifiers of one or more cells in the cell set from the candidate cells of the second message; the DCI identifies one or more candidate cells in the cell set based at least in part on the order of the one or more cells in the cell set in the candidate cell information. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 An example of a wireless communication system supporting timing alignment acquisition in accordance with aspects of the present disclosure is illustrated.

[0020] Figure 2 A system 200 for an inter-gNB handover process is illustrated.

[0021] Figure 3 A system 300 for switching within an AMF and UPF is illustrated.

[0022] Figure 4 An example of an RRC message 400 supporting timing alignment acquisition in accordance with aspects of the present disclosure is illustrated.

[0023] Figure 5 An example of a system 500 that supports timing alignment acquisition in accordance with aspects of the present disclosure is illustrated.

[0024] Figure 6 Illustrated is an example of a block diagram 600 of an apparatus 602 (eg, device) that supports timing alignment acquisition in accordance with aspects of the present disclosure.

[0025] Figure 7 Illustrated is an example of a block diagram 700 of an apparatus 702 (eg, device) that supports timing alignment acquisition in accordance with aspects of the present disclosure.

[0026] Figure 8 A flow chart of a method 800 of supporting timing alignment acquisition according to aspects of the present disclosure is illustrated.

[0027] Fig. 9 A flow chart of a method 900 of supporting timing alignment acquisition according to aspects of the present disclosure is illustrated.

[0028] Fig.10 A flow chart of a method 1000 of supporting timing alignment acquisition according to aspects of the present disclosure is illustrated.

[0029] Fig.11 A flow chart of a method 1100 of supporting timing alignment acquisition in accordance with aspects of the present disclosure is illustrated.

[0030] Fig.12 A flow chart of a method 1200 of supporting timing alignment acquisition according to aspects of the present disclosure is illustrated. DETAILED DESCRIPTION

[0031] In a wireless communication system, a serving cell change may be performed when a UE moves from the coverage area of ​​one cell (e.g., a secondary cell group (SCG)) to another cell, for example, where the current serving cell does not remain a radio available option. In some implementations, the serving cell change of the UE is triggered by a layer 3 (L3) measurement and is implemented via a reconfiguration triggered by RRC signaling, with synchronization for changes in the primary cell (PCell) and the primary secondary cell (PSCell), and release addition for the secondary cell (SCell) where applicable. This situation may involve a complete layer 2 (L2) and layer 1 (L1) reset, resulting in longer delays, greater overhead, and longer interruption time than beam switching mobility. Therefore, in an attempt to reduce handover delays (e.g., avoiding performing a RACH procedure after receiving a handover command), the UE may perform a random access procedure on a candidate cell before switching to a candidate target cell to obtain early TA information. However, the current RACH procedure performed at handover is designed to move the RRC connection to a candidate target cell (eg, synchronize with the target cell and send an RRCReconfiguration Complete message to the target cell), which may also introduce delays and increased signaling overhead into the handover process.

[0032] Therefore, the present disclosure provides a technique to support timing alignment acquisition. For example, an implementation provides an optimized RACH procedure that is performed for early acquisition of TA information, for example, before a handover occurs. In addition, an implementation enables a candidate cell for handover to identify a random access procedure as an early TA acquisition RACH, which can enable the RACH procedure to be successfully performed without establishing an RRC connection in the candidate cell.

[0033] More specifically, in an implementation, message 3 of a contention-based random access procedure performed for early TA acquisition includes a new RRC message. For example, the new RRC message is used for contention resolution and notifies the network that a RACH is being performed for early TA acquisition. In at least one example, the new RRC message includes at least a portion of a UE identity (e.g., 5G-S-TMSI) (5G-S Temporary Mobile Subscription Identifier), such as to uniquely identify the UE and resolve potential contention.

[0034] In addition, in implementation, the UE includes a new MAC CE in the RACH msg3 of the early TA acquisition RACH procedure, which can be used to identify the RACH procedure as an early TA acquisition RACH procedure and can also be used for contention resolution. In at least one example, the new MAC CE includes a UE identifier. For example, the UE identifier can be a random value or part of the 5G-S-TMSI. In addition, the MAC CE can be identified by a new reserved logical channel ID.

[0035] Thus, the described techniques provide an optimized handover process that reduces delays and signaling overhead that may be encountered in some wireless communication systems.

[0036] Aspects of the present disclosure are described in the context of a wireless communication system. Aspects of the present disclosure are further illustrated and described with reference to device diagrams and flow charts.

[0037] Figure 1 An example of a wireless communication system 100 supporting timing alignment acquisition according to various aspects of the present disclosure is illustrated. The wireless communication system 100 may include one or more network entities 102, one or more UEs 104, a core network 106, and a packet data network 108. The wireless communication system 100 may support various radio access technologies. In some implementations, the wireless communication system 100 may be a 4G network, such as an LTE network or an advanced LTE (LTE-A) network. In some other implementations, the wireless communication system 100 may be a 5G network, such as an NR network. In other implementations, the wireless communication system 100 may be a combination of a 4G network and a 5G network, or other suitable radio access technologies, including the Institute of Electrical and Electronics Engineers (IEEE) 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802.20. The wireless communication system 100 may support radio access technologies other than 5G. In addition, the wireless communication system 100 may support technologies such as time division multiple access (TDMA), frequency division multiple access (FDMA), or code division multiple access (CDMA).

[0038] One or more network entities 102 may be dispersed throughout a geographic area to form a wireless communication system 100. One or more of the network entities 102 described herein may be or include or may be referred to as a network node, a base station, a network element, a RAN, a base transceiver station, an access point, a NodeB, an eNodeB (eNB), a next generation NodeB (gNB), or other suitable terms. The network entity 102 and the UE 104 may communicate via a communication link 110, which may be a wireless or wired connection. For example, the network entity 102 and the UE 104 may perform wireless communication (e.g., receive signaling, send signaling) via a Uu interface.

[0039] The network entity 102 may provide a geographic coverage area 112 for which the network entity 102 supports services (e.g., voice, video, packet data, messaging, broadcast, etc.) for one or more UEs 104 within the geographic coverage area 112. For example, the network entity 102 and the UE 104 may support wireless communications of signals associated with services (e.g., voice, video, packet data, messaging, broadcast, etc.) according to one or more radio access technologies. In some implementations, the network entity 102 may be mobile, for example, a satellite associated with a non-terrestrial network. In some implementations, different geographic coverage areas 112 associated with the same or different radio access technologies may overlap, but different geographic coverage areas 112 may be associated with different network entities 102. The information and signals described herein may be represented using any of a variety of different technologies and techniques. For example, data, instructions, commands, information, signals, bits, symbols, and chips that may be referenced throughout the description may be represented by voltages, currents, electromagnetic waves, magnetic fields or particles, optical fields or particles, or any combination thereof.

[0040] One or more UEs 104 may be dispersed throughout the geographic area of ​​the wireless communication system 100. UE 104 may include or may be referred to as a mobile device, a wireless device, a remote device, a remote unit, a handheld device, a subscriber device, or some other suitable term. In some implementations, UE 104 may be referred to as a unit, a station, a terminal, or a client, etc. Additionally or alternatively, UE 104 may be referred to as an Internet of Things (IoT) device, an Internet of Everything (IoE) device, or a machine type communication (MTC) device, etc. In some implementations, UE 104 may be stationary in the wireless communication system 100. In some other implementations, UE 104 may be mobile in the wireless communication system 100.

[0041] One or more UEs 104 may be devices of different forms or with different capabilities. Figure 1 Some examples of UE 104 are illustrated in FIG. Figure 1As shown in FIG. 1 , a UE 104 can communicate with various types of devices, such as a network entity 102, another UE 104, or a network device (e.g., a core network 106, a packet data network 108, a relay device, an integrated access and backhaul (IAB) node, or another network device), such as Figure 1 Additionally or alternatively, the UE 104 can support communications with other network entities 102 or UEs 104 that can act as relays in the wireless communication system 100.

[0042] The UE 104 may also be capable of supporting wireless communications directly with other UEs 104 via a communication link 114. For example, the UE 104 may support wireless communications directly with another UE 104 via a device-to-device (D2D) communication link. In some implementations, such as vehicle-to-vehicle (V2V) deployments, V2X deployments, or cellular V2X deployments, the communication link 114 may be referred to as a sidelink. For example, the UE 104 may support wireless communications directly with another UE 104 via a PC5 interface.

[0043] The network entity 102 may support communication with the core network 106 or with another network entity 102 or both. For example, the network entity 102 may interface with the core network 106 via one or more backhaul links 116 (e.g., via S1, N2, N2 or another network interface). The network entities 102 may communicate with each other via the backhaul links 116 (e.g., via X2, Xn, or another network interface). In some implementations, the network entities 102 may communicate directly with each other (e.g., between the network entities 102). In some other implementations, the network entities 102 may communicate with each other or indirectly (e.g., via the core network 106). In some implementations, one or more network entities 102 may include subcomponents, such as access network entities, which may be examples of access node controllers (ANCs). The ANC may communicate with one or more UEs 104 via one or more other access network transport entities (which may be referred to as radio heads, smart radio heads, or transport reception points (TRPs)).

[0044] In some implementations, the network entity 102 may be configured in a decomposed architecture that may be configured to utilize a protocol stack that is physically or logically distributed between two or more network entities 102, such as an integrated access backhaul (IAB) network, an open RAN (O-RAN) (e.g., a network configuration sponsored by the O-RAN Alliance), or a virtualized RAN (vRAN) (e.g., a cloud RAN (C-RAN)). For example, the network entity 102 may include one or more of the following: a central unit (CU), a distributed unit (DU), a radio unit (RU), a RAN intelligent controller (RIC) (e.g., a near real-time RIC (near real-time (RT) RIC), a non-real-time RIC (non-RT RIC)), a service management and orchestration (SMO) system, or any combination thereof.

[0045] The RU may also be referred to as a radio head, a smart radio head, a remote radio head (RRH), a remote radio unit (RRU), or a transmission reception point (TRP). In a decomposed RAN architecture, one or more components of the network entity 102 may be collocated, or one or more components of the network entity 102 may be located at distributed locations (e.g., separate physical locations). In some implementations, one or more network entities 102 of the decomposed RAN architecture may be implemented as virtual units (e.g., virtual CU (VCU), virtual DU (VDU), virtual RU (VRU)).

[0046] The functional split between the CU, DU, and RU can be flexible, and different functions can be supported according to the functions performed at the CU, DU, or RU (e.g., network layer functions, protocol layer functions, baseband functions, radio frequency functions, and any combination thereof). For example, a functional split of the protocol stack can be adopted between the CU and the DU, so that the CU can support one or more layers of the protocol stack and the DU can support one or more different layers of the protocol stack. In some implementations, the CU can host upper protocol layer (e.g., Layer 3 (L3), Layer 2 (L2)) functions and signaling (e.g., RRC, Service Data Adaptation Protocol (SDAP), Packet Data Convergence Protocol (PDCP)). The CU can be connected to one or more DUs or RUs, and one or more DUs or RUs can host lower protocol layers, such as Layer 1 (L1) (e.g., physical (PHY) layer) or L2 (e.g., radio link control (RLC) layer, MAC layer) functions and signaling, and each can be at least partially controlled by the CU.

[0047] Additionally or alternatively, a functional split of the protocol stack may be employed between the DU and the RU such that the DU may support one or more layers of the protocol stack and the RU may support one or more different layers of the protocol stack. The DU may support one or more different cells (e.g., via one or more RUs). In some implementations, the functional split between the CU and the DU or between the DU and the RU may be within the protocol layer (e.g., some functions of the protocol layer may be performed by one of the CU, the DU, or the RU, while other functions of the protocol layer may be performed by a different one of the CU, the DU, or the RU).

[0048] The CU may be further functionally split into CU control plane (CU-CP) and CU user plane (CU-UP) functions. The CU may be connected to one or more DUs via a medium-range communication link (e.g., F1, F1-c, F1-u), and the DU may be connected to one or more RUs via a fronthaul communication link (e.g., an open fronthaul (FH) interface). In some implementations, the medium-range communication link or the fronthaul communication link may be implemented according to interfaces (e.g., channels) between layers of a protocol stack supported by a corresponding network entity 102 communicating via such a communication link.

[0049] The core network 106 may support user authentication, access authorization, tracking, connection, and other access, routing, or mobility functions. The core network 106 may be an evolved packet core (EPC) or a 5G core (5GC), which may include control plane entities that manage access and mobility (e.g., mobility management entity (MME), access and mobility management function (AMF)), and user plane entities that route packets or interconnections to external networks (e.g., serving gateway (S-GW), packet data network (PDN) gateway (P-GW), or user plane function (UPF)). In some implementations, the control plane entity may manage non-access stratum (NAS) functions, such as mobility, authentication, and bearer management (e.g., data bearer, signal bearer, etc.) of one or more UEs 104 served by one or more network entities 102 associated with the core network 106.

[0050] The core network 106 may communicate with the packet data network 108 via one or more backhaul links 116 (e.g., via S1, N2, N2, or another network interface). The packet data network 108 may include an application server 118. In some implementations, one or more UEs 104 may communicate with the application server 118. The UE 104 may establish a session (e.g., a protocol data unit (PDU) session, etc.) with the core network 106 via the network entity 102. The core network 106 may use the established session (e.g., the established PDU session) to route traffic (e.g., control information, data, etc.) between the UE 104 and the application server 118. The PDU session may be an example of a logical connection between the UE 104 and the core network 106 (e.g., one or more network functions of the core network 106).

[0051] In the wireless communication system 100, the network entity 102 and the UE 104 may use the resources of the wireless communication system 100 (e.g., time resources (e.g., symbols, time slots, subframes, frames, etc.) or frequency resources (e.g., subcarriers, carriers)) to perform various operations (e.g., wireless communication). In some implementations, the network entity 102 and the UE 104 may support different resource structures. For example, the network entity 102 and the UE 104 may support different frame structures. In some implementations, such as in 4G, the network entity 102 and the UE 104 may support a single frame structure. In some other implementations, such as in 5G and other suitable radio access technologies, the network entity 102 and the UE 104 may support various frame structures (i.e., multiple frame structures). The network entity 102 and the UE 104 may support various frame structures based on one or more digital technologies.

[0052] One or more digital technologies may be supported in the wireless communication system 100, and the digital technologies may include subcarrier spacing and cyclic prefixes. A first digital technology (e.g., μ = 0) may be associated with a first subcarrier spacing (e.g., 15kHz) and a normal cyclic prefix. A first digital technology (e.g., μ = 0) associated with a first subcarrier spacing (e.g., 15kHz) may utilize one slot per subframe. A second digital technology (e.g., μ = 1) may be associated with a second subcarrier spacing (e.g., 30kHz) and a normal cyclic prefix. A third digital technology (e.g., μ = 2) may be associated with a third subcarrier spacing (e.g., 60kHz) and a normal cyclic prefix or an extended cyclic prefix. A fourth digital technology (e.g., μ = 3) may be associated with a fourth subcarrier spacing (e.g., 120kHz) and a normal cyclic prefix. A fifth digital technology (e.g., μ = 4) may be associated with a fifth subcarrier spacing (e.g., 240kHz) and a normal cyclic prefix.

[0053] The time intervals of resources (e.g., communication resources) can be organized according to frames (also referred to as radio frames). Each frame can have a duration, for example, a duration of 10 milliseconds (ms). In some implementations, each frame can include multiple subframes. For example, each frame can include 10 subframes, and each subframe can have a duration, for example, a duration of 1 ms. In some implementations, each frame can have the same duration. In some implementations, each subframe of a frame can have the same duration.

[0054] Additionally or alternatively, the time intervals of resources (e.g., communication resources) can be organized according to time slots. For example, a subframe may include a certain number (e.g., quantity) of time slots. Each time slot may include a certain number (e.g., quantity) of symbols (e.g., orthogonal frequency division multiplexing (OFDM) symbols). In some implementations, the number (e.g., quantity) of time slots of a subframe may depend on the digital technology. For a normal cyclic prefix, a time slot may include 14 symbols. For an extended cyclic prefix (e.g., applicable to a 60kHz subcarrier spacing), a time slot may include 12 symbols. For a normal cyclic prefix and an extended cyclic prefix, the relationship between the number of symbols per time slot, the number of time slots per subframe, and the number of time slots per frame may depend on the digital technology. It should be understood that the identification of a first digital technology (e.g., μ=0) associated with a first subcarrier spacing (e.g., 15kHz) may be used interchangeably between a subframe and a time slot.

[0055] In the wireless communication system 100, the electromagnetic (EM) spectrum can be divided into various categories, frequency bands, frequency channels, etc. based on frequency or wavelength. For example, the wireless communication system 100 can support one or more operating frequency bands, such as frequency range names FR1 (410 MHz-7.125 GHz), FR2 (24.25 GHz-52.6 GHz), FR3 (7.125 GHz-24.25 GHz), FR4 (52.6 GHz-114.25 GHz), FR4a or FR4-1 (52.6 GHz-71 GHz), and FR5 (114.25 GHz-300 GHz). In some implementations, the network entity 102 and the UE 104 can perform wireless communications on one or more operating frequency bands. In some implementations, FR1 can be used by the network entity 102 and the UE 104 and other equipment or devices for cellular communication services (e.g., control information, data). In some implementations, FR2 can be used by the network entity 102 and the UE 104 and other equipment or devices for short-range, high data rate capabilities.

[0056] FR1 may be associated with one or more digital technologies (e.g., at least three digital technologies). For example, FR1 may be associated with: a first digital technology (e.g., μ=0) including a subcarrier spacing of 15 kHz; a second digital technology (e.g., μ=1) including a subcarrier spacing of 30 kHz; a third digital technology (e.g., μ=2) including a subcarrier spacing of 60 kHz. FR2 may be associated with one or more digital technologies (e.g., at least 2 digital technologies). For example, FR2 may be associated with: a third digital technology (e.g., μ=2) including a subcarrier spacing of 60 kHz; a fourth digital technology (e.g., μ=3) including a subcarrier spacing of 120 kHz.

[0057] Based on the implementation of the timing alignment acquisition, the network entity 102a determines that the UE 104 is to implement a handover to a different cell, and sends a cell information message 120 to the UE 104. For example, the cell information message 120 includes cell information of different candidate cells for the handover, including information of cells associated with the network entity 102b. Therefore, the UE 104 receives the cell information message 120, and based at least in part on the cell information message 120, the UE 104 initiates a random access procedure 122 for performing a handover to the network entity 102b. As part of the random access procedure 122, the UE 104 sends a usage information message 124 to the network entity 102b. In at least one implementation, the usage information message 124 includes an indication for receiving early (e.g., before the handover) TA information from the network entity 102b. Therefore, the UE 104 can receive the early TA information from the network entity 102b and can participate in the handover from the network entity 102a to the network entity 102b.

[0058] In some wireless communication systems, conditional PSCell change (CPC) / conditional PSCell addition (CPA), CPC / CPA configures the UE to release the CPC / CPA configuration upon completion of random access to the target PSCell. Therefore, if CPC / CPA is not reconfigured and reinitialized from the network in advance, the UE may not have the opportunity to perform subsequent CPC / CPA. This may increase the delay of cell changes and increase signaling overhead, such as in the case of frequent changes of SCG when operating FR2. Therefore, multi-RAT (MR) dual connectivity (DC) (MR-DC) with selective activation of cell groups is intended to enable subsequent CPC / CPA after the SCG change without reconfiguring and reinitializing CPC / CPA preparation from the network. This can reduce the signaling overhead and interruption time of SCG changes.

[0059] Currently, conditional handover (CHO) and MR-DC cannot be configured at the same time. This limits the usefulness of these two features when configured in MR-DC. However, this alone may not be enough to optimize MR-DC mobility because when the UE accesses the target PCell, the radio link quality of the conditionally configured PSCell may be insufficient or may not be the best candidate PSCell, and this may affect the UE throughput. To mitigate this throughput impact, some implementations of CHO+MRDC may consider CHO, including multiple candidate SCGs for the target master cell group (MCG) and CPC / CPA.

[0060] Except for some wireless communication systems, network-controlled mobility can be applied to UEs in RRC_CONNECTED state and can be divided into two types of mobility: cell-level mobility and beam-level mobility. Beam-level mobility can include: intra-cell beam-level mobility and inter-cell beam-level mobility.

[0061] Figure 2 A system 200 for an inter-gNB handover procedure is illustrated. In various scenarios, cell-level mobility involves triggering explicit RRC signaling, such as for handover. For an inter-gNB handover, the signaling procedure may consist of at least the basic components shown in system 200, as described below:

[0062] 1. The source gNB initiates a handover and sends a handover request through the Xn interface.

[0063] 2. The target gNB performs admission control and provides the new RRC configuration as part of the Handover Request Acknowledgement.

[0064] 3. The source gNB provides the RRC configuration to the UE by forwarding the RRCReconfiguration message received in the Handover Request Acknowledgement. The RRCReconfiguration message includes at least a cell identifier (ID) and information required to access the target cell, so that the UE can access the target cell without reading system information. For some cases, the information required for contention-based and contention-free random access may be included in the RRCReconfiguration message. The access information to the target cell may include beam-specific information (if any).

[0065] 4. The UE moves the RRC connection to the target gNB and responds with RRCReconfigurationComplete. In implementation, user data may also be sent in step 4 if authorization allows.

[0066] In a dual active protocol stack (DAPS) handover scenario, the UE may continue to receive downlink user data from the source gNB until the source cell is released, and may continue to send uplink user data to the source gNB until a successful random access procedure is performed to the target gNB. In addition, the source and target PCells may be used during a DAPS handover. Carrier aggregation (CA), DC, supplementary uplink (SUL), multiple TRPs, Ethernet header compression (EHC), CHO, unified data fusion (UDC), NR sidelink configuration, and V2X sidelink configuration may be released by the source gNB before the handover command is sent to the UE, and may not be configured by the target gNB until the DAPS handover is completed, for example, at the earliest in the same message that releases the source PCell.

[0067] The handover mechanism triggered by RRC may involve the UE resetting at least the MAC entity and re-establishing the RLC, except for DAPS handover, where upon receiving the handover command, the UE may:

[0068] -Create a MAC entity for the target;

[0069] - Establishing an RLC entity and an associated Dedicated Traffic Channel (DTCH) logical channel for the target for each Data Radio Bearer (DRB) configured with DAPS;

[0070] - for each DRB configured with DAPS, reconfigure the PDCP entity with separate Security and Robust Header Compression (ROHC) functionality for the source and the target, and

[0071] Associating them with the RLC entities configured by the source and target respectively;

[0072] - Prior to the release of the source, the remaining source configuration is preserved.

[0073] In some wireless communication systems, RRC managed switching may be supported, including with and without PDCP entity re-establishment. For DRBs using RLC Acknowledged Mode (AM) mode, PDCP may be re-established with a security key change, or a data recovery procedure may be initiated without a key change. For DRBs using RLC Unacknowledged Mode (UM) mode, PDCP may be re-established with a security key change, or may remain intact without a key change. For SRBs, PDCP may remain intact, discarding its stored PDCP PDU / SDU without a key change, or may be re-established with a security key.

[0074] When the target gNB uses the same DRB configuration as the source gNB, data forwarding, in-sequence delivery, and duplicate avoidance during handover can succeed. Timer-based handover failure procedures can be supported in NR. RRC connection re-establishment procedures can be used to recover from handover failures, except for certain CHO or DAPS handover scenarios:

[0075] - When DAPS handover fails, if the source link has not been released, the UE can fall back to the source cell configuration, resume the connection with the source cell, and report the DAPS handover failure via the source without triggering RRC connection re-establishment.

[0076] -When the initial CHO execution attempt fails or handover fails, the UE may perform cell selection, and if the selected cell is a CHO candidate cell, and if the network configures the UE to attempt CHO after handover / CHO failure, the UE may attempt CHO execution once, otherwise a re-establishment may be performed.

[0077] In some scenarios, the handover of the Integrated Access and Backhaul (IAB) Mobile Termination (MT) in standalone mode follows the same procedure as the UE. The handover of IAB-MT is part of the intra-CU topology adaptation procedure after the backhaul has been established. Modifications to the configuration of the Backhaul Adaptation Protocol (BAP) sublayer and higher protocol layers above the BAP sublayer may be implemented.

[0078] In some wireless communication scenarios, beam-level mobility does not require triggering explicit RRC signaling. For example, beam-level mobility can be within a cell or between cells, and the latter is called inter-cell beam management (ICBM). For ICBM, the UE can receive or send UE-specific channels / signals via a TRP associated with a physical cell identity (PCI) different from the serving cell, while non-UE-specific channels or signals can be received via a TRP associated with the PCI of the serving cell. The gNB can provide the UE with a measurement configuration via RRC signaling, which contains the configuration of synchronization signal / physical broadcast channel (SS / PBCH) block (SSB) / channel state information (CSI) resources and resource sets, reports and triggering status for triggering channel and interference measurements, and reports. In the case of ICBM, the measurement configuration may include SSB resources associated with a PCI different from the PCI of the serving cell. Beam-level mobility can then be handled at a low level through physical layer and MAC layer control signaling, and RRC may not need to know which beam is being used at a given point in time.

[0079] In some scenarios, SSB-based beam-level mobility is based on the SSB associated with the initial downlink (DL) bandwidth part (BWP) and can be configured for the initial DL BWP and for the DL BWP containing the SSP associated with the initial DL BWP. For other DL BWPs, beam-level mobility can be performed based on CSI reference signals (RS).

[0080] Figure 3 A system 300 for intra-AMF and UPF handover is illustrated. In some scenarios, intra-NR RAN handover performs the preparation and execution phases of the handover procedure without the involvement of the 5GC, for example, preparation messages are exchanged directly between gNBs. During the handover completion phase, resource release at the source gNB may be triggered by the target gNB. System 300 depicts a handover scenario where neither the AMF nor the UPF is changed:

[0081] 0. The UE context within the source gNB contains information about roaming and access restrictions, which was provided at connection establishment or at the last timing advance update.

[0082] 1. The source gNB configures the measurement procedure for the UE and the UE reports according to the measurement configuration.

[0083] 2. The source gNB decides to hand over the UE based on the MeasurementReport and Radio Resource Management (RRM) information.

[0084] 3. The source gNB issues a Handover Request message to the target gNB to pass a transparent RRC container with the information necessary to prepare the handover on the target side. This information includes at least: the target cell ID, KgNB*, the cell radio network temporary identifier (C-RNTI) of the UE in the source gNB, the RRM configuration including the UE inactive time, the basic access stratum (AS) configuration including antenna information and DL carrier frequency, the current QoS flow to DRB mapping rules applied to the UE, SIB1 from the source gNB, UE capabilities of different RATs, PDU session related information, and may include UE report measurement information, which includes beam related information (if available). PDU session related information includes: slice information, and (multiple) QoS flow level QoS profiles. The source gNB may also request DAPS handover of one or more DRBs. In some scenarios, after issuing the Handover Request, the source gNB does not reconfigure the UE, including performing reflective QoS flow to DRB mapping.

[0085] 4. Admission control may be performed by the target gNB. If slice information is sent to the target gNB, slice-aware admission control may be performed. If a PDU session is associated with an unsupported slice, the target gNB may reject such a PDU session.

[0086] 5. The target gNB prepares for the handover with L1 / L2 and sends a Handover Request Acknowledgement to the source gNB, which includes a transparent container, which will be sent to the UE as an RRC message to perform the handover. The target gNB also indicates whether the DAPS handover is accepted. Note 2: Data forwarding can be initiated after the source gNB receives the Handover Request Acknowledgement, or after the transmission of the Handover Command is initiated in the downlink.

[0087] NOTE 3: For DRBs configured with DAPS, downlink PDCP SDUs shall be forwarded with the sequence number (SN) assigned by the source gNB until the SN allocation is handed over to the target gNB in ​​step 8b, for which normal data forwarding follows the specified procedure.

[0088] 6. The source gNB triggers Uu handover by sending an RRCReconfiguration message to the UE, which contains information for accessing the target cell: at least the target cell ID, the new C-RNTI, and the target gNB security algorithm identifier for the selected security algorithm. It may also include: dedicated RACH resource set, association between RACH resources and (multiple) SSBs, association between RACH resources and (multiple) UE-specific CSI-RS configurations, common RACH resources, and system information of the target cell. Note 4: For DRBs configured with DAPS, the source gNB may not stop sending downlink packets until a handover success message is received from the target gNB in ​​step 8a.

[0089] Note 4a: CHO may not be configured simultaneously with DAPS switching.

[0090] 7a. For DRBs configured with DAPS, the source gNB sends an Early State Transfer message. The DL COUNT value conveyed in the Early State Transfer message indicates the PDCP SN and Hyperframe Number (HFN) of the first PDCP Service Data Unit (SDU) that the source gNB forwards to the target gNB. The source gNB does not stop allocating SNs to downlink PDCP SDUs until the source gNB sends the SN State Transfer message to the target gNB in ​​step 8b.

[0091] 7. For DRBs that are not configured with DAPS, the source gNB sends an SN Status Transfer message to the target gNB to convey the uplink PDCP SN receiver status and downlink PDCP SN transmitter status of the DRBs (i.e., RLC AM) for which PDCP status preservation is applicable. The uplink PDCP SN receiver status includes at least the PDCP SN of the first lost uplink (UL) PDCP SDU and may include a bitmap of the reception status of out-of-sequence UL PDCP SDUs that the UE needs to retransmit in the target cell (if any). The downlink PDCP SN transmitter status indicates the next PDCP SN that the target gNB can assign to a new PDCP SDU that does not yet have a PDCP SN.

[0092] Note 5: In case of DAPS handover, the uplink PDCP SN receiver state and downlink PDCP SN transmitter state of DRBs with RLC-AM and not configured with DAPS may be transferred through the SN STATUS TRANSFER message in step 8b instead of step 7.

[0093] NOTE 6: For DRBs configured with DAPS, the source gNB may additionally send (multiple) Early State Transfer messages between step 7 and step 8b to inform the discarding of the forwarded PDCP SDUs. The target gNB may not send the forwarded downlink PDCP SDUs to the UE whose count is less than the communicated DL count value and discard them if transmission has not been attempted.

[0094] 8. The UE synchronizes with the target cell and completes the RRC handover procedure by sending an RRCReconfigurationComplete message to the target gNB. In case of DAPS handover, the UE does not detach from the source cell after receiving the RRCReconfiguration message. The UE releases the source resources and configuration and stops DL / UL reception / transmission with the source after receiving an explicit release from the target node.

[0095] Note 6a: From the RAN perspective, a DAPS handover is considered complete only after the UE releases the source cell as explicitly requested by the target node. RRC is suspended and no subsequent handover or inter-RAT handover can be initiated until the source cell is released.

[0096] 8a / 8b: In case of DAPS handover, the target gNB sends a handover success message to the source gNB to inform the UE that it has successfully accessed the target cell. In return, the source gNB sends an SN state transfer message for the DRBs configured with DAPS, the description in step 7 applies to these DRBs, and normal data forwarding follows the specified process.

[0097] NOTE 7: If configured with DAPS, then in step 8b, the uplink PDCP SN receiver status and downlink PDCP SN transmitter status are also transmitted in the SN STATUS TRANSFER message for the DRB with RLC-UM.

[0098] NOTE 8: For DRBs configured with DAPS, the Source gNB shall not stop delivering uplink QoS flows to the UPF until it sends an SN STATUS TRANSFER message in step 8b. The Target gNB shall not forward QoS flows of successfully received in-sequence uplink PDCP SDUs to the UPF until it receives an SN STATUS TRANSFER message in which the UL HFN and the first missing SN in the Uplink PDCP SN Receiver Status indicate the start of uplink PDCP SDUs to be delivered to the UPF. The Target gNB shall not deliver any uplink PDCP SDUs with an UL Count lower than the provided value.

[0099] 9. The target gNB sends a Path Switch Request message to the AMF to trigger the 5GC to switch the DL data path to the target gNB and establish an NG-C interface instance towards the target gNB.

[0100] 10. 5GC switches the DL data path to the target gNB. The UPF sends an “end marker” packet to the source gNB on the old path or paths for each PDU session / tunnel, and any U-Plane / Transport Network Layer (TNL) resources may then be released to the source gNB.

[0101] 11.AMF confirms the Path Switch Request message with a Path Switch Request Confirm message.

[0102] 12. After receiving the Path Switch Request Confirmation message from the AMF, the target gNB sends a UE Context Release to inform the source gNB of the handover success. The source gNB may then release the radio and C-plane related resources associated with the UE context. Any ongoing data forwarding may continue.

[0103] Depending on the scenario, if both types of measurements are available, the RRM configuration may include both beam measurement information associated with (multiple) SSBs (for layer 3 mobility) and the reported (multiple) CSI-RS of the (multiple) cells. In addition, if CA is configured, the RRM configuration may include a list of the best cells for which measurement information is available on each frequency. And, the RRM measurement information may also include beam measurements of the listed cells belonging to the target gNB.

[0104] The generic RACH configuration for beams in the target cell may be associated only with the SSB(s). The network may have dedicated RACH configurations associated with the SSB(s) and / or have dedicated RACH configurations associated with the CSI-RS(s) within the cell. The target gNB may include one of the following RACH configurations in the handover command to enable the UE to access the target cell:

[0105] i) General RACH configuration;

[0106] ii) Common RACH configuration + dedicated RACH configuration associated with SSB;

[0107] iii) Common RACH configuration + dedicated RACH configuration associated with CSI-RS.

[0108] In some scenarios, a dedicated RACH configuration allocates (multiple) RACH resources and a quality threshold for their use. When dedicated RACH resources are provided, the UE may prioritize them and as long as the quality threshold of these dedicated resources is met, the UE will not switch to contention-based RACH resources. The order for accessing dedicated RACH resources may depend on the UE implementation.

[0109] After receiving a handover command requesting a DAPS handover, the UE may suspend the source cell SRB, stop sending and receiving any RRC control plane signaling to the source cell, and establish an SRB for the target cell. After successfully performing a DAPS handover, the UE may release the source cell SRB configuration upon receiving a source cell release indication from the target cell. When the DAPS handover to the target cell fails and the source cell link is available, the UE may revert to the source cell configuration and resume the source cell SRB for control plane signaling transmission.

[0110] In various scenarios (e.g., for L1 / L2 mobility), the UE maintains the TA for the candidate cell before handover to reduce handover delay. For example, the UE obtains the TA of the candidate cell before receiving the L1 / L2 handover command from the source cell. Then, if the UE receives the L1 / L2 handover command from the source cell, the UE can perform handover to the candidate cell without performing a random access (RA) procedure on the candidate cell.

[0111] For example, to avoid performing the RA procedure on the candidate cell after receiving the L1 / L2 handover command, the TA of the candidate cell may be acquired before receiving the L1 / L2 handover command. One of the options considered is that the UE performs a random access procedure (RACH) on the candidate cell to acquire uplink timing related information before the actual handover.

[0112] Therefore, the present disclosure provides a solution for an optimized RACH procedure that is performed for early acquisition of TA information, for example, before a handover occurs.

[0113] In implementation, the UE triggers a random access procedure (RACH) on a candidate cell in response to receiving candidate cell information from a source cell (e.g., a source gNB). For example, the candidate cell information is provided to the UE from the source cell (e.g., a current serving gNB) in an RRC message. In the present disclosure, a message that provides a UE with a configuration applicable to a candidate cell to which the UE may switch may be referred to as a candidate cell information message, but this should not be construed as limiting, and such messages may be referred to using additional or alternative terminology.

[0114] In at least one example, the candidate cell information message includes configuration information of the candidate cell set. For example, the RRC layer of the UE triggers and / or initiates a RACH process in one of the candidate cells (e.g., instructs the MAC layer to start a random access process), and the candidate cell information message provides configuration information for it, in order to obtain uplink timing synchronization in the candidate cell, such as obtaining a TA from the candidate cell. Depending on the implementation, a new RACH trigger (e.g., reception of candidate cell information) is introduced.

[0115] In an implementation, the UE (e.g., the RRC layer of the UE) may trigger a RACH procedure to perform early TA acquisition for each of the candidate cells for which configuration information is provided in a candidate cell information message. In at least one example, the order in which the RRC layer may initiate the RACH procedure on the candidate cells may correspond to the order in which the candidate cell configurations are signaled from the network. For example, the UE first initiates the RACH procedure on the candidate cell for which the configuration information is first signaled within the candidate cell information message. In alternative or additional examples, the order in which the UE and / or the RRC layer initiate the RACH procedure on the candidate cells depends on the UE implementation.

[0116] In an implementation, the candidate cell information message includes one or more signaling fields that indicate which candidate cells the UE will acquire early uplink timing synchronization for by initiating a RACH procedure. For example, the UE may acquire early TA only for a subset of candidate cells for which configuration is provided within the candidate cell information message, for example, multiple candidate cells may share the same uplink timing, such as by belonging to the same timing alignment group. In at least one example, the configuration information of the candidate cell includes a field and / or signaling indicating whether the UE is to acquire early timing synchronization for the candidate cell. In at least one example, the field may be a 1-bit flag and / or a Boolean value.

[0117] In an implementation, the UE uses a random access preamble in a reserved random access preamble set when performing a random access procedure to perform early acquisition of uplink timing synchronization on a candidate cell. For example, the implementation includes a random access preamble set and / or PRACH resources reserved and / or configured for early TA acquisition RACH attempts in a candidate cell. For example, a RACH configuration including a reserved RACH preamble set and / or PRACH resources is broadcast by the candidate cell in system information. In another alternative or additional example, RACH information for early TA acquisition is provided to the UE within a candidate cell information message. The use of reserved RACH preambles and / or PRACH resources can enable the network to identify the purpose of the RACH procedure earlier based on the received preambles and / or PRACH resources, and can also reduce the probability of contention and / or conflict.

[0118] In an implementation, the candidate cell information includes information indicating whether the candidate cell supports early TA acquisition. For example, the configuration information provided for the candidate cell includes information indicating whether the UE is allowed to perform a RACH procedure in the candidate cell to achieve early uplink timing synchronization. Alternatively or additionally, the candidate cell may broadcast (e.g., in system information) whether RACH for early TA acquisition is supported in the cell.

[0119] In an implementation, a message 3 of a contention-based random access procedure (e.g., a PUSCH scheduled by a random access response (RAR)) performed for early TA acquisition includes an RRC message. For example, a RACH message 3 (e.g., an UL message scheduled by a random access response message) includes an RRC message, which can be used for contention resolution and / or to notify the network that a RACH is performed for early TA acquisition. In at least one example, the RRC message is a message sent on an UL common control channel (CCCH), such as (multiple) UL CCCH SDUs. In an implementation, the RRC message can have a size of, for example, 48 bits. In at least one example, the RRC message includes at least a portion of a UE identity (e.g., a 5G-S-TMSI) to uniquely identify the UE and resolve potential contention. In at least one example, a RestblishmentUE-Identity and / or a shortMAC-I can be included as the UE identity. When the gNB receives the RRC message, the gNB can know the UE identity and the purpose of the RACH attempt (e.g., early TA acquisition), and can react and / or respond accordingly. In another or alternative example, the RACH msg3 for the early TA acquisition RACH procedure is an RRCSetupRequest message, and in an example implementation, an EstablishmentCause value (eg, one of the alternate values) may be used to identify the early TA acquisition RACH.

[0120] In an implementation, message 3 does not contain data for a data radio bearer (DRB), such as user plane data. For example, only (multiple) SDUs of SRBs may be included in RACH message 3. In at least one example, logical channel restrictions are applied to message 3 of a RACH procedure initiated for early TA acquisition, for example, multiplexing (multiple) SDUs of DRBs / (multiple) LCHs in RACH message 3 is not allowed. In at least one example, when a TB is generated for RACH message 3, the UE considers that the data radio bearer is suspended. In at least one example, for the case where RACH is performed for early TA acquisition, the UE is not allowed to multiplex MAC CEs (e.g., buffer status report (BSR) MAC CE or power headroom report (PHR) MAC CE) within RACH message 3.

[0121] Figure 4 An example of an RRC message 400 supporting timing alignment acquisition according to aspects of the present disclosure is illustrated. For example, the RRC message 400 may be used to resolve contention and / or inform the network that RACH is performed for early TA acquisition.

[0122] Figure 5 An example of a system 500 that supports timing alignment acquisition according to aspects of the present disclosure is illustrated. In the system 500, at 502, the UE 104 sends an RRCSetupRequest message to the network entity 102 to indicate the purpose of early TA acquisition from the network entity 102. For example, the network entity 102 represents a candidate gNB. Therefore, at 504, the network entity 102 sends an RRCRelease message or an RRCReject message to the UE 104 in response to receiving the RRCSetupRequest message.

[0123] Depending on the implementation, for a case where a contention-based RACH access (CBRA) RACH is performed to acquire early uplink timing synchronization on a candidate cell and an RRCSetupRequest message (e.g., with a new EstablishmentCause) is used as RACH Msg3, there may be no need to signal (e.g., a DL message in Msg 4, nor is there a need to signal an RRCConnectionSetupComplete message in the uplink) in response to receipt of an RRCConnectionSetup message in response to RACH Msg3 to complete the RRC connection establishment.

[0124] For example, according to at least one example, the gNB does not include an RRCConnectionSetup message, such as a contention resolution message, in RACH Msg4. In addition, the UE may not send an RRCConnectionSetupComplete message in response to successful contention resolution and RACH process completion. For example, the candidate gNB sends an RRCRelease or RRCReject message as part of RACH Msg4. For example, a contention resolution identification MAC CE is included in RACH Msg4, such as for the case where the UE includes an RRCSetupRequest message in RACHMsg3.

[0125] In implementation, if the UE performing CBRA for early TA acquisition does not have a valid C-RNTI, the contention resolution message (RACH Msg4) may be addressed using a temporary C-RNTI (TC-RNTI) (which may be received in a RACH response message), and the associated DL shared channel (SCH) may contain a contention resolution message, such as a contention resolution identity MAC CE. After transmission of RACH message 3, the MAC layer at the UE may start the ra-ContentionResolutionTimer. The value of the contention resolution timer may be provided by RACH-ConfigCommon. After starting the timer, the UE may start monitoring the physical downlink control channel (PDCCH) to obtain downlink control information (DCI) format 1_0, where the CRC is scrambled with the corresponding TC-RNTI. After reception of the PDSCH, the timer stops.

[0126] If the decoded MAC PDU contains a contention resolution identifier that matches the CCCH SDU sent in message 3 (e.g., within a contention resolution identifier MAC CE), the contention resolution may be considered successful. In an implementation, the UE may stop monitoring the PDCCH from the candidate cell on which the early TA acquisition RACH procedure is performed in response to successful contention resolution. In addition, the UE may consider the early TA acquisition procedure to be successfully completed. In response to PDSCH reception (RACH Msg4), the UE may send a hybrid automatic repeat request (HARQ) feedback on a physical uplink control channel (PUCCH). As described above, for scenarios involving early TA acquisition, the UE may not send an RRCConnectionSetupComplete message. In at least one example, the candidate gNB sends an RRCRelease or RRCReject message as part of RACH Msg4 (e.g., RACH Msg4 also includes a contention resolution identifier MAC CE) to complete the early TA acquisition RACH procedure.

[0127] In implementation, the UE includes a MAC CE in RACH msg3 of an early TA acquisition RACH procedure, which is used to identify the RACH procedure as an early TA acquisition RACH procedure and is also used for contention resolution. In at least one example, the MAC CE contains a UE identity, and the UE identity can be, for example, a random value or part of a 5G-S-TMSI. The MAC CE can be identified by a newly reserved logical channel ID. In at least one example, the size of the new MAC CE is 48 bits. For the case where the UE includes a new MAC CE in RACH Msg3 of a CBRA RACH procedure performed for early TA acquisition, the UE can start monitoring the PDCCH for DCI format 1_0 at the transmission of RACH Msg3, where the CRC is scrambled with the corresponding TC-RNTI. After reception of the PDSCH (RACHMsg4), the UE can check whether the decoded MAC PDU contains a contention resolution identification MAC CE that matches the new MAC CE sent in message 3. In response to a match, the UE can consider that the contention resolution is successful and can also consider that the early TA acquisition procedure is successfully completed. The UE may stop monitoring the PDCCH on the candidate cell.

[0128] In an implementation, message 3 does not include data other than MAC CE. For example, (multiple) SDUs (e.g., user plane data) of DRB or (multiple) SRB are not included in RACH Msg3. In at least one example, logical channel restrictions are applied to message 3 of a RACH procedure initiated for early TA acquisition. For example, multiplexing (multiple) SDUs of RB / (multiple) LCH in RACH message 3 is not allowed. In at least one example, when a TB is generated for RACH message 3, the UE considers (multiple) data / signaling radio bearers to be suspended. In at least one example, for a scenario in which RACH is performed for early TA acquisition, the UE is not allowed to multiplex (multiple) other MAC CEs (e.g., BSR MAC CE or PHR MAC CE) within RACH message 3.

[0129] In an implementation, the UE includes a C-RNTI MAC CE in the RACH msg3 of an early TA acquisition RACH procedure used for contention resolution. In at least one example, the UE receives the C-RNTI of the candidate cell from its current serving cell / gNB in ​​the candidate cell information message. The UE may set the C-RNTI field in the C-RNTI MAC CE to a value received in the candidate cell information message, such as the C-RNTI of the MAC entity of the candidate cell. According to at least one implementation, the C-RNTI MAC CE for early TA acquisition is different from the C-RNTI MAC CE used in the legacy specification. The new C-RNTI MAC CE may also be used to identify the RACH procedure as an early TA acquisition RACH procedure. The new C-RNTI MAC CE may be identified by a newly reserved logical channel (LCH) ID. In the case where the UE has been allocated a C-RNTI, contention resolution may be handled by addressing the UE on the PDCCH using the C-RNTI. When its C-RNTI is detected on the PDCCH, the UE may declare that the RA attempt is successful and contention resolution related information on the DL-SCH may not be required, e.g. (RACH Msg4). Alternatively or additionally, the UE may multiplex the C-RNTI MAC CE and an additional new MAC CE within the RACH Msg3 of the early TA acquisition RACH procedure. The new MAC CE may have a fixed size of zero bits and may be used to identify the RACH procedure as an early TA acquisition RACH procedure. The new MAC CE may be identified by a reserved logical channel ID (LCID).

[0130] In an implementation, RACH message 3 does not contain data other than (multiple) MAC CEs. For example, (multiple) SDUs (e.g., user plane data) of DRBs and / or (multiple) SRBs are not included in RACH Msg3. In at least one example, logical channel restrictions are applied to message 3 of a RACH procedure initiated for early TA acquisition, for example, (multiple) SDUs of RBs / (multiple) LCHs are not allowed to be multiplexed in RACH message 3. In at least one example, when a TB is generated for RACH message 3, the UE considers (multiple) data / signaling radio bearers to be suspended. In at least one example, for a scenario in which RACH is performed for early TA acquisition, the UE is not allowed to multiplex (multiple) other MAC CEs (e.g., BSR MAC CE or PHR MAC CE) within RACH message 3.

[0131] In implementation, the candidate gNB sends the RRCRelease message as RACH Msg4, for example, in response to receiving RACH Msg3, which identifies the RACH procedure as early TA acquisition RACH, so as to complete the early TA acquisition RACH procedure.

[0132] In implementation, after successful contention resolution, the UE may discard the TC-RNTI received in the early TA acquisition RACH procedure, for example, within a RACH response message. In at least one example, for the case where Msg3 does not include a C-RNTI MAC CE, the UE does not set the C-RNTI of the candidate cell to the TC-RNTI value. Alternatively or additionally, the UE may set the C-RNTI of the candidate cell to the value of the received TC-RNTI and store the C-RNTI value in its context.

[0133] In an implementation, the UE applies the TA command received in the early TA acquisition RACH process (e.g., within a RACH response message) and uses the acquired uplink timing to transmit HARQ feedback for RACH msg3 and / or RACH Msg 4. In at least one example, the UE transmits the N of the candidate cells to the UE. TA The value is set to the TA value received in the RACH response message. For example, the UE maintains N for each candidate cell in which the Early TA Acquisition RACH procedure is successfully completed (eg, an Early TA is acquired). TA value. According to at least one implementation, the UE starts the timer in response to receiving a TA command in a RACH response message of an early TA acquisition RACH procedure. While the timer is running, the UE may consider itself to be uplink synchronized with the candidate cell. In at least one example, the timer is associated with the candidate cell and is set to a value signaled by the source cell / current serving cell. In at least one example, the timer configuration is signaled in a candidate cell information message. In another example, the timer that controls the validity of the early TA may be common to all candidate cells and may be signaled in an RRC reconfiguration message that configures one or more candidate cells; for example, the value of the timer is the same as T304 configured by the source cell.

[0134] In implementation, the UE notifies the current serving cell / gNB that it has successfully acquired uplink timing synchronization with the candidate cell. After performing and successfully completing the Early TA Acquisition RACH procedure, the UE may send information to its current serving cell / gNB to indicate that it has successfully acquired TA from the candidate cell. In an example implementation, a new MAC CE is used to notify the gNB about the TA acquisition success. Alternatively or additionally, the RRC measurement report includes the measurement result of the corresponding measurement identifier and indicates whether the early TA has been acquired for at least one of the cells belonging to the corresponding measurement object.

[0135] In an implementation, the DCI signals the UE to perform a random access procedure on a candidate cell for early TA acquisition. According to at least one implementation, the DCI includes a new field that identifies for which cell the UE will perform a RACH procedure and acquire uplink timing synchronization. The new DCI may be sent after the serving gNB sends a candidate cell information message to the UE. In at least one example, the current PDCCH order (e.g., DCI format 1_0) contains the following information.

[0136] DCI format 1_0 is used for random access procedures initiated by PDCCH commands, and all remaining fields are set as follows:

[0137] - Random access preamble index - 6 bits, according to ra-PreambleIndex in clause 5.1.2 of [8, TS38.321]

[0138] -UL / SUL indicator - 1 bit. If the value of "Random Access Preamble Index" is not all zeros, and if the UE is configured with supplementaryUplink in the cell's ServingCellConfig, this field indicates which UL carrier in the cell is to be used to send PRACH according to Table 7.3.1.1.1-1; otherwise, this field is reserved.

[0139] - SS / PBCH Index - 6 bits. If the value of "Random Access Preamble Index" is not all zeros, this field indicates the SS / PBCH that should be used to determine the RACH opportunity for PRACH transmission; otherwise, this field is reserved.

[0140] -PRACH Mask Index - 4 bits. If the value of "Random Access Preamble Index" is not all zeros, this field indicates the RACH opportunity associated with the SS / PBCH indicated by the "SS / PBCH Index" transmitted by the PRACH according to [8, TS38.321] Section 5.1.1; otherwise, this field is reserved

[0141] - Reserved bits - 12 bits for operation in cells with shared spectrum channel access; otherwise 10 bits

[0142] In implementation, some of the reserved bits may be used to signal cell identification information, for example, information identifying which candidate cell(s) the UE will perform a random access procedure on to obtain early TA information. Therefore, when the UE receives a DCI indicating that a RACH is to be performed on one of the candidate cells, the UE uses the SSB / PBCH index and RACH mask index of the indicated candidate cell.

[0143] In implementation, the DCI cell identifier may be an identifier of a candidate cell provided in a candidate cell information message. For example, the candidate cells are identified based on the order in which their candidate cell configurations are provided in the candidate cell information message. For example, an identifier set to 0 refers to the first candidate cell whose configuration information is provided in the candidate cell information message.

[0144] In an implementation, the UE performs a contention-free random access procedure on a candidate cell to acquire early TA information. Dedicated RACH information (e.g., PRACH preamble and PRACH resources) for contention-free RACH access (CFRA) may be provided to the UE in the candidate cell information. In response to receipt of the preamble transmission for early TA acquisition, the gNB may send a response message including the TA information. According to at least one implementation, a new RAR format may be used as a response message. For example, a new MAC payload of the random access response includes only a TA command field in one example. In at least one example, the new MAC payload of the RAR does not include an UL grant field or a TC-RNTI.

[0145] In an alternative or additional implementation, for the case where RAR reception is successful, in response to a PRACH transmission for early TA acquisition, the UE may ignore the UL grant received in the legacy RAR. In addition, the UE may not perform an UL transmission scheduled by the RAR for early TA acquisition CFRA RACH. In at least one example, in response to a successful random access response reception, the UE deems the early TA acquisition procedure to be successfully completed.

[0146] In an implementation, uplink resources (e.g., PUSCH resources) in the candidate cell are provided to the UE before switching to the candidate cell. According to at least one implementation, when the UE has moved to the candidate cell, in response to receiving a handover command (e.g., an L1 / L2 handover command) on the allocated uplink resources in the candidate cell, the UE sends a message indicating that the handover is complete. In at least one example, the uplink resources are configured as authorized uplink resources (e.g., configured grant (CG)-PUSCH resources) that are periodically configured for the candidate cell. In at least one example, the message sent on the allocated uplink resources is an RRC message, such as an RRCReconfigurationComplete message and / or a HandoverComplete message. According to at least one implementation, the uplink resources (e.g., CG-PUSCH resources) in the candidate cell are provided in a candidate cell information message. For example, when the candidate target gNB confirms successful reception of the RRC message (e.g., RRCReconfigurationComplete message), the UE autonomously deactivates the configured CG-PUSCH resources. In at least one example, the preconfigured CG-PUSCH resources are used only to transmit RRC messages, such as the first message after a handover. In at least one example, the UE does not send other data on the CG-PUSCH resources, except for the MAC CE. In at least one example, in response to the receipt of the L1 / L2 handover command, the CG-PUSCH resources are considered valid PUSCH resources.

[0147] In an implementation, the UE transmits an uplink signal on the candidate target cell in response to receipt of the L1 / L2 handover command. In at least one example, the uplink signal is a sounding reference signal (SRS) transmission. For example, when the UE moves to the target candidate cell, the SRS transmission is performed by the UE and notifies the candidate cell (e.g., the new serving cell) that the UE has performed a handover. After detecting / receiving the uplink signal / SRS transmission, the gNB may schedule the UE PUSCH resources for transmission of an RRC message, such as a handover complete message.

[0148] In an implementation, for a scenario where the UE has acquired uplink timing synchronization for the target cell (e.g., where early TA is successfully acquired), the UE begins monitoring the PDCCH in the target cell in response to receipt of the L1 / L2 handover command. In response to having sent the L1 / L2 handover command (e.g., from the source cell), the target cell may schedule uplink resources to the UE via a dynamic uplink grant, which will be used by the UE to transmit an RRCReconfigurationComplete message, e.g., indicating completion of the handover. In at least one example, the source cell notifies the target cell of the transmission of the L1 / L2 handover command to the UE, e.g., successful transmission.

[0149] Thus, in summary, implementations described in this disclosure provide aspects of early TA acquisition, including new aspects of the RACH procedure, including:

[0150] ●After receiving the candidate target cell information, the UE triggers RACH to obtain the TA from the candidate cell:

[0151] ○RACH process can be triggered by RRC

[0152] ■TA acquisition priority order (the order in which neighboring cell information is provided)

[0153] ●Reserve RACH resources to identify early TAs to obtain RACH;

[0154] The cell (e.g., gNB) indicates whether it supports and / or enables early TA acquisition, such as in the SIB and / or candidate target cell message;

[0155] ●Content of message 3:

[0156] ○ If the UE does not have the C-RNTI of the candidate cell:

[0157] ■Introduction of new RRC messages for early TA acquisition of RACH and contention resolution;

[0158] ■ A new MAC CE may be used instead of RRC messages to identify early TA acquisition and for contention resolution;

[0159] ○ If the UE has been provisioned with a C-RNTI for the candidate cell:

[0160] ■New C-RNTI MAC CE (new reserved LCID) to identify early TA to obtain RACH

[0161] ●UE behavior after successful contention resolution:

[0162] ○ T-CRNTI can be issued after successful contention resolution

[0163] ■Discard T-CRNTI; or

[0164] ■Do not set C-RNTI to T-CRNTI

[0165] ○ Or store T-CRNTI for later switching;

[0166] ■Target cell configuration can be published through network process

[0167] ○ TA can be maintained for candidate cells;

[0168] ■New N for each candidate target cell TA value:

[0169] ● Timing Alignment Timer (TAT): The current TAT value may be retrieved from the Candidate Cell Information message and / or may be used, for example, if instructed to do so in the RRC reconfiguration message configuring one or more candidate cells;

[0170] ●PDCCH command, used to obtain TA from the target cell, such as new DCI content.

[0171] ●CFRA: UL Grant in RAR can be ignored, and TA information and RAPID are included in the new RAR format.

[0172] Figure 6 An example of a block diagram 600 of a device 602 (e.g., an apparatus) supporting timing alignment acquisition according to aspects of the present disclosure is illustrated. The device 602 may be an example of a UE 104 as described herein. The device 602 may support wireless communications with one or more network entities 102, UEs 104, or any combination thereof. The device 602 may include components for bidirectional communications, including components for sending and receiving communications (such as a processor 604, a memory 606, a transceiver 608, and an I / O controller 610). These components may be in electronic communication or otherwise coupled (e.g., operatively, communicatively, functionally, electronically, electrically) via one or more interfaces (e.g., a bus).

[0173] The processor 604, the memory 606, the transceiver 608, or various combinations thereof or various components thereof may be examples of means for performing various aspects of the present disclosure described herein. For example, the processor 604, the memory 606, the transceiver 608, or various combinations thereof or components thereof may support methods for performing one or more of the operations described herein.

[0174] In some implementations, the processor 604, the memory 606, the transceiver 608, or various combinations or components thereof may be implemented in hardware (e.g., in a communication management circuit system). The hardware may include a processor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof, which is configured to or otherwise supports components for performing the functions described in the present disclosure. In some implementations, the processor 604 and the memory 606 coupled to the processor 604 may be configured to perform one or more functions described herein (e.g., by executing instructions stored in the memory 606 by the processor 604). For example, in the context of the UE 104, the transceiver 608 and the processor 604 coupled to the transceiver 608 are configured to cause the UE 104 to perform various described operations and / or combinations thereof.

[0175] For example, according to examples disclosed herein, the processor 604 and / or the transceiver 608 may support wireless communications at the device 602. For example, the processor 604 and / or the transceiver 608 may be configured to and / or otherwise support a component for: receiving a first message including information of a set of cells; initiating a random access procedure on at least one cell in the set of cells based at least in part on the first message; and sending an uplink signal to the at least one cell, the uplink signal including: usage information related to the random access procedure.

[0176] In addition, in some implementations, the processor is configured to cause the device to: receive a first message on the PDSCH as a downlink message; the downlink message on the PDSCH includes an RRC message; the processor is configured to cause the device to: send an uplink signal as a PRACH preamble code; the processor is configured to cause the device to: send an uplink signal as a PUSCH transmission scheduled by a random access response message; the PUSCH transmission includes a MAC control element (CE), and the MAC-CE includes an identifier; the PUSCH transmission includes an RRC message, and the RRC message includes: a field for identifier usage information; the random access process includes: a contention-based random access process.

[0177] In addition, in some implementations, the processor is configured to cause the device to: trigger a random access process via a MAC entity of the device; use information including an indication of timing alignment acquisition, and the processor is configured to cause the device to: receive timing alignment information based at least in part on an uplink signal; the processor is configured to cause the device to: receive an indication of whether at least one cell in a cell set supports early timing alignment acquisition; the processor is configured to cause the device to: determine priority information of the cell set, and initiate a random access process based at least in part on the priority information; the processor is configured to cause the device to: receive an indication of whether at least one cell supports early timing alignment acquisition in a first message, and based at least in part on the indication, send an uplink signal to a candidate cell to obtain timing alignment information.

[0178] According to examples disclosed herein, a processor 604 of a device 602 (such as UE 104) may support wireless communications. The processor 604 includes at least one controller coupled to at least one memory, and the at least one controller is configured and / or operable to cause the processor to: receive a first message including information of a cell set; initiate a random access procedure on at least one cell in the cell set based at least in part on the first message; and send an uplink signal to at least one cell, the uplink signal including: usage information related to the random access procedure. In addition, the at least one controller is configured and / or operable to cause the processor to perform one or more other operations described herein, such as with reference to UE 104 and / or device 602.

[0179] According to examples disclosed herein, a processor 604 of a device 602, such as a UE 104, may support wireless communications. The processor 604 includes at least one controller coupled to at least one memory, the at least one controller being configured and / or operable to cause the processor to: receive a first message including instructions for the UE to perform a RACH procedure for acquiring timing alignment information from one or more cells in a cell set; and initiate a RACH procedure with one or more cells in the cell set.

[0180] For example, according to examples disclosed herein, the processor 604 and / or the transceiver 608 may support wireless communications at the device 602. For example, the processor 604 and / or the transceiver 608 may be configured to and / or otherwise support a component for: receiving a first message including instructions for performing a RACH procedure for acquiring timing alignment information from one or more cells in a set of cells; and initiating a RACH procedure with one or more cells in the set of cells.

[0181] In addition, in some implementations, the first message includes: downlink control information (DCI), the DCI including: one or more identifiers of one or more cells in the cell set; the DCI is received as part of a physical downlink control channel (PDCCH); the first message includes one or more of the following items: a synchronization signal block (SSB), a physical broadcast channel (PBCH), or a RACH mask index of one or more cells in the cell set; using one or more of the SSB, PBCH, or RACH mask index to initiate a RACH process; at least one processor is configured to cause the UE to receive a second message before the first message, the second message including: candidate cell information identifying a candidate cell, the candidate cell including at least: one or more cells in the cell set; the first message includes: downlink control information (DCI), The DCI includes: one or more identifications of one or more cells in a cell set from a candidate cell of a second message; the DCI identifies one or more candidate cells in a cell set based at least in part on the order of one or more cells in the cell set in the candidate cell information; obtains timing alignment information from a target cell in one or more cells in the cell set; and starts monitoring a physical downlink control channel (PDCCH) in the target cell; at least one processor is configured to enable the UE to: start monitoring the PDCCH based at least in part on the reception of one or more of a layer 1 (L1) switching command or a layer 2 (L2) switching command; receive scheduling of uplink resources from the target cell via a dynamic uplink grant; and send a third message indicating completion of switching to the target cell via one or more of the uplink resources.

[0182] The processor 604 may include an intelligent hardware device (e.g., a general purpose processor, a DSP, a CPU, a microcontroller, an ASIC, an FPGA, a programmable logic device, a discrete gate or transistor logic component, a discrete hardware component, or any combination thereof). In some implementations, the processor 604 may be configured to operate a memory array using a memory controller. In some other implementations, the memory controller may be integrated into the processor 604. The processor 604 may be configured to execute computer-readable instructions stored in a memory (e.g., a memory 606) to cause the device 602 to perform various functions of the present disclosure.

[0183] The memory 606 may include random access memory (RAM) and read-only memory (ROM). The memory 606 may store computer-readable computer executable code, which includes instructions that, when executed by the processor 604, cause the device 602 to perform various functions described herein. The code may be stored in a non-transitory computer-readable medium such as a system memory or another type of memory. In some implementations, the code may not be directly executed by the processor 604, but may cause a computer (e.g., when compiled and executed) to perform the functions described herein. In some implementations, the memory 606 may include a basic I / O system (BIOS), which may control basic hardware or software operations, such as interaction with peripheral components or devices.

[0184] I / O controller 610 can manage input and output signals of device 602. I / O controller 610 can also manage peripheral devices that are not integrated into device 602. In some implementations, I / O controller 610 can represent a physical connection or port to an external peripheral device. In some implementations, I / O controller 610 can utilize an operating system, such as Or other known operating systems. In some implementations, I / O controller 610 can be implemented as part of a processor such as processor 608. In some implementations, a user can interact with device 602 via I / O controller 610 or via hardware components controlled by I / O controller 610.

[0185] In some implementations, the device 602 may include a single antenna 612. However, in some other implementations, the device 602 may have more than one antenna 612 (e.g., multiple antennas), including multiple antenna panels or antenna arrays, which are capable of concurrently sending or receiving multiple wireless transmissions. The transceiver 608 can communicate bidirectionally via one or more antennas 612, wired or wireless links, as described herein. For example, the transceiver 608 can represent a wireless transceiver and can communicate bidirectionally with another wireless transceiver. The transceiver 608 may also include a modem for modulating packets, providing the modulated packets to one or more antennas 612 for transmission, and demodulating packets received from one or more antennas 612.

[0186] Figure 7An example of a block diagram 700 of a device 702 (e.g., an apparatus) supporting timing alignment acquisition in accordance with aspects of the present disclosure is illustrated. The device 702 may be an example of a network entity 102 as described herein. The device 702 may support wireless communications with one or more network entities 102, UEs 104, or any combination thereof. The device 702 may include components for bidirectional communications, including components for sending and receiving communications (such as a processor 704, a memory 706, a transceiver 708, and an I / O controller 710). These components may be in electronic communication or otherwise coupled (e.g., operatively, communicatively, functionally, electronically, electrically) via one or more interfaces (e.g., a bus).

[0187] The processor 704, the memory 706, the transceiver 708, or various combinations thereof, or various components thereof may be examples of means for performing various aspects of the present disclosure described herein. For example, the processor 704, the memory 706, the transceiver 708, or various combinations thereof, or components thereof may support methods for performing one or more of the operations described herein.

[0188] In some implementations, the processor 704, the memory 706, the transceiver 708, or various combinations or components thereof may be implemented in hardware (e.g., in a communication management circuit system). The hardware may include a processor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof, which is configured to or otherwise supports means for performing the functions described in the present disclosure. In some implementations, the processor 704 and the memory 706 coupled to the processor 704 may be configured to perform one or more functions described herein (e.g., by executing instructions stored in the memory 706 by the processor 704). For example, in the context of the network entity 102, the transceiver 708 and the processor 704 coupled to the transceiver 708 are configured to cause the network entity 102 to perform various described operations and / or combinations thereof.

[0189] For example, according to examples disclosed herein, the processor 704 and / or the transceiver 708 may support wireless communications at the device 702. For example, the processor 704 and / or the transceiver 708 may be configured to or otherwise support a component for: generating a first message including information of a cell set, the information including: information related to obtaining timing alignment information from one or more cells in the cell set; and sending the first message to a UE.

[0190] In addition, in some implementations, the information of the cell set includes: an indication of whether one or more cells in the cell set supports early acquisition of timing alignment; the first message also includes: a priority indication for timing alignment with the cell set; the processor is configured to cause the device to: send the priority indication in an order corresponding to the priority order for acquiring the timing alignment information for one or more cells in the cell set.

[0191] In another example, according to examples disclosed herein, the processor 704 and / or the transceiver 708 may support wireless communication at the device 702. For example, the processor 704 and / or the transceiver 708 may be configured to or otherwise support a component for: receiving a first message from a UE, the first message including information related to acquiring first timing alignment information; and sending a second message including second timing alignment information to the UE.

[0192] Furthermore, in some implementations, the second timing alignment information includes: an indication of whether the apparatus supports early timing alignment acquisition; and the processor is configured to cause the apparatus to: send the second message via the SIB.

[0193] In another example, for example, the processor 704 and / or the transceiver 708 may be configured to or otherwise support a component for: generating a first message instructing the UE to perform a RACH process for acquiring timing alignment information from one or more cells in a cell set; and sending the first message to the UE.

[0194] In addition, in some implementations, the first message includes: downlink control information (DCI), which includes: one or more identifiers of one or more cells in the cell set; the DCI is sent as part of a physical downlink control channel (PDCCH); the first message includes one or more of the following items: a synchronization signal block (SSB), a physical broadcast channel (PBCH), or a RACH mask index of one or more cells in the cell set; a second message is sent before the first message, and the second message includes: candidate cell information identifying candidate cells, and the candidate cells include at least: one or more cells in the cell set; the first message includes: downlink control information (DCI), which includes: one or more identifiers of one or more cells in the cell set from the candidate cells of the second message; the DCI identifies one or more candidate cells in the cell set based at least in part on the order of one or more cells in the cell set in the candidate cell information.

[0195] The processor 704 may include an intelligent hardware device (e.g., a general purpose processor, a DSP, a CPU, a microcontroller, an ASIC, an FPGA, a programmable logic device, a discrete gate or transistor logic component, a discrete hardware component, or any combination thereof). In some implementations, the processor 704 may be configured to operate a memory array using a memory controller. In some other implementations, the memory controller may be integrated into the processor 704. The processor 704 may be configured to execute computer-readable instructions stored in a memory (e.g., a memory 706) to cause the device 702 to perform various functions of the present disclosure.

[0196] The memory 706 may include random access memory (RAM) and read-only memory (ROM). The memory 706 may store computer-readable computer executable code, which includes instructions that, when executed by the processor 704, cause the device 702 to perform various functions described herein. The code may be stored in a non-transitory computer-readable medium such as a system memory or another type of memory. In some implementations, the code may not be directly executed by the processor 704, but may cause a computer (e.g., when compiled and executed) to perform the functions described herein. In some implementations, the memory 706 may include a basic I / O system (BIOS), which may control basic hardware or software operations, such as interaction with peripheral components or devices.

[0197] I / O controller 710 can manage input and output signals of device 702. I / O controller 710 can also manage peripheral devices that are not integrated into device 702. In some implementations, I / O controller 710 can represent a physical connection or port to an external peripheral device. In some implementations, I / O controller 710 can utilize an operating system, such as Or other known operating systems. In some implementations, I / O controller 710 can be implemented as part of a processor such as processor 706. In some implementations, a user can interact with device 702 via I / O controller 710 or via hardware components controlled by I / O controller 710.

[0198] In some implementations, the device 702 may include a single antenna 712. However, in some other implementations, the device 702 may have more than one antenna 712 (e.g., multiple antennas), including multiple antenna panels or antenna arrays, which are capable of concurrently sending or receiving multiple wireless transmissions. The transceiver 708 can communicate bidirectionally via one or more antennas 712, wired or wireless links, as described herein. For example, the transceiver 708 can represent a wireless transceiver and can communicate bidirectionally with another wireless transceiver. The transceiver 708 may also include a modem for modulating packets, providing the modulated packets to one or more antennas 712 for transmission, and demodulating packets received from one or more antennas 712.

[0199] Figure 8 A flow chart of a method 800 for supporting timing alignment acquisition according to aspects of the present disclosure is illustrated. The operations of the method 800 may be implemented by the apparatus described herein or components thereof. For example, the operations of the method 800 may be implemented by reference to Figures 1 to 7 The UE 104 described herein performs. In some implementations, the device may execute a set of instructions to control the functional elements of the device to perform the described functions. Additionally or alternatively, the device may use dedicated hardware to perform various aspects of the described functions.

[0200] At 802, the method may include: receiving a first message including information of a cell set. The operations of 802 may be performed according to the examples described herein. In some implementations, aspects of the operations of 802 may be performed by reference to Figure 1 The device is used to perform the above.

[0201] At 804, the method may include initiating a random access procedure on at least one cell in the set of cells based at least in part on the first message. The operations of 804 may be performed according to examples described herein. In some implementations, aspects of the operations of 804 may be described with reference to Figure 1 The device is used to perform the above.

[0202] At 806, the method may include: sending an uplink signal to at least one cell, the uplink signal including: usage information related to the random access process. The operations of 806 may be performed according to the examples described herein. In some implementations, aspects of the operations of 806 may be described by reference to Figure 1 The device is used to perform the above.

[0203] Fig. 9 A flow chart of a method 900 for supporting timing alignment acquisition according to aspects of the present disclosure is illustrated. The operations of the method 900 may be implemented by the apparatus described herein or components thereof. For example, the operations of the method 900 may be implemented by reference to Figures 1 to 7The network entity 102 performs. In some implementations, the device may execute a set of instructions to control the functional elements of the device to perform the described functions. Additionally or alternatively, the device may use dedicated hardware to perform various aspects of the described functions.

[0204] At 902, the method may include generating a first message including information of a cell set, the information including information related to obtaining timing alignment information from one or more cells in the cell set. The operations of 902 may be performed according to the examples described herein. In some implementations, aspects of the operations of 902 may be performed by reference to Figure 1 The device is used to perform the above.

[0205] At 904, the method may include: sending a first message to the UE. The operations of 904 may be performed according to the examples described herein. In some implementations, aspects of the operations of 904 may be described by reference to Figure 1 The device is used to perform the above.

[0206] Fig.10 A flow chart of a method 1000 for supporting timing alignment acquisition according to aspects of the present disclosure is illustrated. The operations of the method 1000 may be implemented by the apparatus described herein or components thereof. For example, the operations of the method 1000 may be implemented by reference to Figures 1 to 7 The network entity 102 performs. In some implementations, the device may execute a set of instructions to control the functional elements of the device to perform the described functions. Additionally or alternatively, the device may use dedicated hardware to perform various aspects of the described functions.

[0207] At 1002, the method may include: receiving, at an apparatus, a first message from a UE, the first message including: information related to obtaining first timing alignment information. The operations of 1002 may be performed according to examples described herein. In some implementations, aspects of the operations of 1002 may be performed by reference to Figure 1 The device is used to perform the above.

[0208] At 1004, the method may include: sending a second message including second timing alignment information to the UE. The operations of 1004 may be performed according to the examples described herein. In some implementations, aspects of the operations of 1004 may be described with reference to Figure 1 The device is used to perform the above.

[0209] Fig.11 A flowchart of a method 1100 for supporting timing alignment acquisition according to aspects of the present disclosure is illustrated. The operations of the method 1100 may be implemented by the apparatus described herein or components thereof. For example, the operations of the method 1100 may be implemented by reference to Figures 1 to 7The UE 104 described herein performs. In some implementations, the device may execute a set of instructions to control the functional elements of the device to perform the described functions. Additionally or alternatively, the device may use dedicated hardware to perform various aspects of the described functions.

[0210] At 1102, the method may include receiving a first message including instructions for performing a RACH procedure for acquiring timing alignment information from one or more cells in a set of cells. The operations of 1102 may be performed according to examples described herein. In some implementations, aspects of the operations of 1102 may be described with reference to Figure 1 The device is used to perform the above.

[0211] At 1104, the method may include initiating a RACH process with one or more cells in the cell set. The operations of 1104 may be performed according to the examples described herein. In some implementations, aspects of the operations of 1104 may be described with reference to Figure 1 The device is used to perform the above.

[0212] Fig.12 A flow chart of a method 1200 for supporting timing alignment acquisition according to aspects of the present disclosure is illustrated. The operations of the method 1200 may be implemented by the apparatus described herein or components thereof. For example, the operations of the method 1200 may be implemented by reference to Figures 1 to 7 The network entity 102 performs. In some implementations, the device may execute a set of instructions to control the functional elements of the device to perform the described functions. Additionally or alternatively, the device may use dedicated hardware to perform various aspects of the described functions.

[0213] At 1202, the method may include generating a first message that instructs the UE to perform a RACH procedure for acquiring timing alignment information from one or more cells in the cell set. The operations of 1202 may be performed according to the examples described herein. In some implementations, aspects of the operations of 1202 may be described in detail with reference to Figure 1 The device is used to perform the above.

[0214] At 1204, the method may include: sending a first message to the UE. The operations of 1204 may be performed according to the examples described herein. In some implementations, aspects of the operations of 1204 may be described by reference to Figure 1 The device is used to perform the above.

[0215] It should be noted that the methods described herein describe possible implementations, and that the operations and steps may be rearranged or otherwise modified, and other implementations are possible. Furthermore, aspects from two or more methods may be combined.

[0216] The various illustrative blocks and components described in conjunction with the disclosure herein may be implemented or executed with a general purpose processor, DSP, ASIC, CPU, FPGA or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A general purpose processor may be a microprocessor, but in an alternative, the processor may be any processor, controller, microcontroller, or state machine. The processor may also be implemented as a combination of computing devices (e.g., a combination of a DSP and a microprocessor, multiple microprocessors, one or more microprocessors combined with a DSP core, or any other such configuration).

[0217] The functions described herein may be implemented in hardware, software executed by a processor, firmware, or any combination thereof. If implemented in software executed by a processor, the functions may be stored on or sent via a computer-readable medium as one or more instructions or codes. Other examples and implementations are within the scope of this disclosure and the appended claims. For example, due to the nature of software, the functions described herein may be implemented using software executed by a processor, hardware, firmware, hard wiring, or any combination of these. Features that implement the functions may also be physically located in various locations, including being distributed so that portions of the functions are implemented in different physical locations.

[0218] Computer-readable media include both non-transient computer storage media and communication media, and communication media include any medium that facilitates transferring a computer program from one place to another. Non-transient storage media can be any available medium that can be accessed by a general or special-purpose computer. As an example and not limitation, non-transient computer-readable media can include RAM, ROM, electrically erasable programmable ROM (EEPROM), flash memory, compact disk (CD) ROM or other optical disk storage, disk storage or other magnetic storage device, or can be used to carry or store desired program code devices in the form of instructions or data structures and can be accessed by a general or special-purpose computer, or any other non-transient medium of a general or special-purpose processor.

[0219] Any connection may be appropriately referred to as a computer-readable medium. For example, if the software is sent from a website, server, or other remote source using a coaxial cable, fiber optic cable, twisted pair, digital subscriber line (DSL), or wireless technology (such as infrared, radio, and microwave), the coaxial cable, fiber optic cable, twisted pair, DSL, or wireless technology (such as infrared, radio, and microwave) is included in the definition of computer-readable medium. Disks and optical disks as used herein include CDs, laser disks, optical disks, digital versatile disks (DVDs), floppy disks, and blue-ray disks, wherein disks typically reproduce data magnetically, and optical disks reproduce data optically with lasers. Combinations of the above are also included within the scope of computer-readable media.

[0220] As used herein, including in the claims, "or" used in a list of items (e.g., a list of items beginning with a phrase such as "at least one of" or "one or more of" or "one or both of") means an inclusive list, so that, for example, a list of at least one of A, B, or C means A or B or C or AB or AC or BC or ABC (e.g., A and B and C). In addition, as used herein, the phrase "based on" should not be interpreted as a reference to a closed set of conditions. For example, an example step described as "based on condition A" may be based on both condition A and condition B without departing from the scope of the present disclosure. In other words, as used herein, the phrase "based on" should be interpreted in the same manner as the phrase "based at least in part on." In addition, as used herein, including in the claims, a "set" may include one or more elements.

[0221] When referring to a network entity, the terms "send," "receive," or "transmit" may refer to any part of a network entity of a RAN (e.g., base station, CU, DU, RU) that communicates with another device (e.g., directly or via one or more other network entities).

[0222] The descriptions described herein in conjunction with the accompanying drawings describe example configurations and do not represent all examples that may be implemented or within the scope of the claims. The term "example" as used herein means "used as an example, instance, or illustration," rather than "preferred" or "better than other examples." The detailed description includes specific details to facilitate understanding of the described techniques. However, these techniques may be practiced without these specific details. In some cases, known structures and devices are shown in block diagram form to avoid confusing the concepts of the described examples.

[0223] The description herein is provided to enable one of ordinary skill in the art to make or use the present disclosure. Various modifications to the present disclosure will be clear to one of ordinary skill in the art, and the general principles defined herein may be applied to other variations without departing from the scope of the present disclosure. Therefore, the present disclosure is not limited to the examples and designs described herein, but should conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A user equipment (UE) for wireless communication, comprising: at least one memory; as well as at least one processor, coupled to the at least one memory, and configured to cause the UE to: receiving a first message including instructions for performing a random access channel (RACH) procedure for acquiring timing alignment information from one or more cells in a set of cells; as well as The RACH process is initiated with the one or more cells in the cell set.

2. The UE according to claim 1, wherein the first message comprises: Downlink control information (DCI), the DCI comprising: one or more identities of the one or more cells in the cell set.

3. The UE of claim 2, wherein the DCI is received as part of a physical downlink control channel (PDCCH).

4. The UE according to claim 1, wherein the first message comprises one or more of the following items: a synchronization signal block (SSB), a physical broadcast channel (PBCH), or a RACH mask index of the one or more cells in the cell set.

5. The UE according to claim 4, wherein the at least one processor is configured to cause the UE to: use one or more of the SSB, the PBCH, or the RACH mask index to initiate the RACH process.

6. The UE according to claim 1, wherein the at least one processor is configured to cause the UE to: receive a second message before the first message, the second message comprising: The candidate cell information identifying the candidate cell includes at least: the one or more cells in the cell set.

7. The UE according to claim 6, wherein the first message comprises: Downlink control information (DCI), the DCI comprising: one or more identifications of the one or more cells in the set of cells from the candidate cells of the second message.

8. The UE of claim 7, wherein the DCI identifies the one or more candidate cells in the cell set based at least in part on an order of the one or more cells in the cell set in the candidate cell information.

9. The UE according to claim 1, wherein the at least one processor is configured to cause the UE to: Acquire timing alignment information from a target cell among the one or more cells in the set of cells; and Monitoring of a physical downlink control channel (PDCCH) in the target cell begins.

10. The UE of claim 9, wherein the at least one processor is configured to cause the UE to: start monitoring the PDCCH based at least in part on reception of one or more of a layer 1 (L1) handover command or a layer 2 (L2) handover command.

11. The UE of claim 9, wherein the at least one processor is configured to cause the UE to: receive scheduling of uplink resources from the target cell via a dynamic uplink grant.

12. The UE according to claim 11, wherein the at least one processor is configured to cause the UE to: send a third message indicating completion of the handover to the target cell via one or more of the uplink resources.

13. A processor for wireless communication, comprising: at least one controller coupled to at least one memory and configured to cause the processor to: receiving a first message including instructions for a user equipment (UE) to perform a random access channel (RACH) procedure for acquiring timing alignment information from one or more cells in a set of cells; as well as The RACH process is initiated with the one or more cells in the cell set.

14. The processor of claim 13, wherein the first message comprises: Downlink control information (DCI), the DCI comprising: one or more identities of the one or more cells in the cell set.

15. The processor of claim 14, wherein the DCI is received as part of a physical downlink control channel (PDCCH).

16. The processor of claim 13, wherein the first message comprises one or more of: a synchronization signal block (SSB), a physical broadcast channel (PBCH), or a RACH mask index of the one or more cells in the set of cells.

17. The processor of claim 13, wherein the at least one controller is configured to cause the processor to: receive a second message prior to the first message, the second message comprising: The candidate cell information identifying the candidate cell includes at least: the one or more cells in the cell set.

18. The processor of claim 17, wherein the first message comprises: Downlink control information (DCI), the DCI comprising: one or more identifications of the one or more cells in the set of cells from the candidate cells of the second message.

19. A method performed by a user equipment (UE), the method comprising: receiving a first message including instructions for performing a random access channel (RACH) procedure for acquiring timing alignment information from one or more cells in a set of cells; as well as The RACH process is initiated with the one or more cells in the cell set.

20. A base station for wireless communication, comprising: at least one memory; as well as at least one processor coupled to the at least one memory and configured to cause the base station to: generating a first message, the first message instructing a user equipment (UE) to perform a random access channel (RACH) procedure, the RACH procedure being used to obtain timing alignment information from one or more cells in a set of cells; as well as Sending the first message to the UE.

Images