WO2024108926A1 - Procédé rach pour obtenir une avance temporelle pour une transmission en liaison montante à une cellule de desserte avec de multiples points de transmission-réception - Google Patents

Procédé rach pour obtenir une avance temporelle pour une transmission en liaison montante à une cellule de desserte avec de multiples points de transmission-réception Download PDF

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Publication number
WO2024108926A1
WO2024108926A1 PCT/CN2023/094040 CN2023094040W WO2024108926A1 WO 2024108926 A1 WO2024108926 A1 WO 2024108926A1 CN 2023094040 W CN2023094040 W CN 2023094040W WO 2024108926 A1 WO2024108926 A1 WO 2024108926A1
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WIPO (PCT)
Prior art keywords
serving cell
trp
mac
wireless terminal
receiving
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Application number
PCT/CN2023/094040
Other languages
English (en)
Inventor
Fei DONG
He Huang
Jing Liu
Original Assignee
Zte Corporation
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
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Publication date
Application filed by Zte Corporation filed Critical Zte Corporation
Priority to PCT/CN2023/094040 priority Critical patent/WO2024108926A1/fr
Publication of WO2024108926A1 publication Critical patent/WO2024108926A1/fr

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Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W74/00—Wireless channel access
    • H04W74/08—Non-scheduled access, e.g. ALOHA
    • H04W74/0833—Random access procedures, e.g. with 4-step access
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W56/00—Synchronisation arrangements
    • H04W56/004—Synchronisation arrangements compensating for timing error of reception due to propagation delay
    • H04W56/0045—Synchronisation arrangements compensating for timing error of reception due to propagation delay compensating for timing error by altering transmission time
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L5/00—Arrangements affording multiple use of the transmission path
    • H04L5/003—Arrangements for allocating sub-channels of the transmission path
    • H04L5/0053—Allocation of signaling, i.e. of overhead other than pilot signals

Definitions

  • This disclosure is directed generally to wireless communication networks and particularly to Time Advance (TA) management for multipoint transmission/reception in a wireless serving cell.
  • TA Time Advance
  • the network side may require a wireless terminal to take into consideration of transmission time delay for an uplink transmission by initiating the uplink transmission by a time advance (TA) prior to a scheduled reception time by a network node.
  • the amount of TA may be determined by a signal propagation delay between the wireless terminal and the wireless network node.
  • the wireless network node may be configured to provide multiple transmit-receive-points (TRPs) for serving the wireless terminal and the TRPs may be associated with distinct TAs.
  • TRPs transmit-receive-points
  • the TAs in relation to the TRPs may need to be managed and provisioned in conjunction for achieving a desired uplink transmission timing accuracy.
  • This disclosure is directed generally to wireless communication network and particularly to Time Advance (TA) management for multipoint transmission/reception in a serving cell.
  • a TA may be initially acquired from the serving cell by a wireless terminal during a random-access procedure.
  • the various example implementations further provide manners in which the UE is informed by the serving cell of an association of the TA acquired during the RACH procedure with one or more particular TRPs of the multiple TRPs of the serving cell.
  • Additional example implementations are also provided for managing corresponding Time Alignment Timers (TATs) such that the wireless terminal and the serving cell can operates in a synchronized manner as to the validity periods of the TAs, so as to achieve accurate timing for uplink transmission.
  • TATs Time Alignment Timers
  • a method performed by a wireless terminal in communication with a serving cell may include initiating a random-access procedure with the serving cell; receiving a time advance (TA) for uplink transmissions from the wireless terminal to the serving cell; receiving an indication for identifying, among a plurality of transmit-receive-points (TRPs) , a TRP corresponding to the TA; starting or restarting a time alignment timer (TAT) corresponding to the received TA; and controlling a timing of an uplink transmission to the TRP of the serving cell based on the TA while the TAT is running.
  • TA time advance
  • TRPs transmit-receive-points
  • TAT time alignment timer
  • the random-access procedure comprises a 4-step random-access channel (RACH) procedure.
  • RACH random-access channel
  • the 4-step RACH procedure may include transmitting a RACH preamble to the serving cell; receiving a RACH Response (RAR) from the serving cell; transmitting an uplink data load according to a RACH resource scheduled by the RAR; and receiving a response message transmitted by the serving cell in response to the uplink data load.
  • RAR RACH Response
  • receiving the TA comprises extracting the TA from the RAR.
  • the uplink data load comprises a Cell-Radio-Network-Temporary-Identification (C-RNTI) MAC Control Element (C-RNTI MAC CE) .
  • C-RNTI Cell-Radio-Network-Temporary-Identification
  • C-RNTI MAC CE MAC Control Element
  • receiving the indication comprises extracting from the response message the indication for identifying the TRP corresponding to the TA.
  • the response message comprises an enhanced absolute Time-Advance-Comment MAC CE (TAC MAC CE) or a new type of MAC CE.
  • TAC MAC CE enhanced absolute Time-Advance-Comment MAC CE
  • the enhanced absolute TAC MAC CE or the new type of MAC CE comprises a single or multi-bit field for indicating the TRP corresponding to the TA.
  • a channel property of downlink control channel for receiving the response message is used for determining the indication of the TRP corresponding to the TA.
  • the channel property comprises an association of the downlink control channel with a plurality of COntrol Resource SETs (CORSETs) .
  • an association of the downlink control channel with a CORESET having a first identification indicates an association of the TA with a first TRP whereas an association of the downlink control channel with a CORESET having a second identification indicates an association of the TA with a second TRP.
  • the TAT is started or restarted when the TAT associated with the indicated TRP is not running.
  • the TAT is started or restarted at a first symbol of an end of a downlink control channel for receiving the response message.
  • the TAT is started or restarted with a time value reduced by an amount from receiving the RAR and the first symbol of the end of the downlink control channel for receiving the response message.
  • the TAT is started or restarted when the enhanced absolute TAC MAC CE or the new type of MAC CE is received.
  • the random-access procedure comprises a 2-step RACH procedure.
  • the 2-step RACH procedure may include transmitting a RACH preamble and an uplink data load to the serving cell; and receiving a response message from the serving cell.
  • the uplink data load comprises a C-RNTI MAC CE.
  • receiving the TA comprises extracting the TA from the response message.
  • the response message comprises an enhanced absolute TAC MAC CE.
  • the enhanced absolute TAC MAC CE comprises a single or multi-bit field for indicating the TRP corresponding to the TA.
  • a method performed by a wireless network node in communication with a wireless terminal in a serving cell may include providing a random-access configuration to the wireless terminal; and interacting with the wireless terminal in a random-access procedure initiated by the wireless terminal to: determine a time advance (TA) for uplink transmissions from the wireless terminal to the serving cell; transmit the TA to the wireless terminal; and transmit an indication to the wireless terminal for identifying, among a plurality of transmit-receive-points (TRPs) of the serving cell, a TRP corresponding to the TA.
  • TRPs transmit-receive-points
  • the wireless terminal or network node of any one of the methods above is disclosed.
  • the wireless terminal or network node may include a processor and a memory, wherein the processor is configured to read computer code from the memory to cause the wireless terminal to perform the method of any one of the methods above.
  • a a non-transitory computer-readable program medium with computer code stored thereupon is further disclosed.
  • the computer code when executed by a processor of the wireless terminal or network node of any one of the methods above, is configured to cause the processor to implement any one of the methods above.
  • FIG. 1 illustrates an example wireless communication network including a wireless access network, a core network, and data networks.
  • FIG. 2 illustrates an example wireless access network including a plurality of mobile stations/terminals or User Equipments (UEs) and a wireless access network node in communication with one another via an over-the-air radio communication interface.
  • UEs User Equipments
  • FIG. 3 shows an example radio access network (RAN) architecture.
  • RAN radio access network
  • FIG. 4 shows an example communication protocol stack in a wireless access network node or wireless terminal device including various network layers.
  • FIG. 5 illustrates an example random access procedure involving four basic messaging steps between a UE and a wireless access network node.
  • FIG. 6 illustrates an example random access procedure involving two basis message steps for obtaining a TA and a TRP thereof.
  • FIG. 7 illustrates a format of an example advanced absolute Time Advance Command Media Access Control-Element (TAC MAC CE) .
  • TAC MAC CE advanced absolute Time Advance Command Media Access Control-Element
  • FIG. 8 illustrates an example random access procedure involving four basis message steps for obtaining a TA and a TRP thereof.
  • FIG. 9 illustrates an example procedure for TCI state activation or update in a single DCI based multiple TRP scenario.
  • FIG. 10 illustrates an example DL MAC CE structure for activation of TCI states.
  • the technology and examples of implementations and/or embodiments described in this disclosure can be used to configure and manage time advance in multipoint transmit-receive environment in wireless communication networks.
  • the technology and examples of implementations and/or embodiments described in this disclosure can further be used to activate and/or update a Transmission Configuration Indicator (TCI) state in multipoint transmit-receive environment in wireless communication networks.
  • TCI Transmission Configuration Indicator
  • the term “over-the-air interface” is used interchangeably with “air interface” or “radio interface” in this disclosure.
  • the term “exemplary” is used to mean “an example of” and unless otherwise stated, does not imply an ideal or preferred example, implementation, or embodiment. Section headers are used in the present disclosure to facilitate understanding of the disclosed implementations and are not intended to limit the disclosed technology in the sections only to the corresponding section.
  • this disclosure is directed generally to wireless communication networks and particularly to Time Advance (TA) management for multipoint transmission/reception in a wireless serving cell.
  • TA Time Advance
  • each of the mTRP may be associated with a TA for uplink transmission from the wireless terminal to the wireless serving cell.
  • the TAs of these multiple TRPs may be distinct.
  • an association between a TRP and a TA may be provided to the wireless terminal.
  • the TA may be initially acquired by the wireless terminal through a random-access procedure with the wireless serving cell.
  • Various embodiments of this disclosure provide example manners in which an association of the acquired TA with one or more particular TRPs of the wireless serving cell provided for servicing the wireless terminal may be signaled, explicitly or implicitly during the random-access procedure.
  • this disclosure is directed to TCI state management for single Downlink Control Information (DCI) based multiple transmission/reception point in a wireless serving cell.
  • DCI Downlink Control Information
  • mTRP Transmission/Reception Points
  • each TRP transmission including Uplink (UL) transmission and/or downlink (DL) transmission
  • DL downlink
  • each TRP transmission may be associated with a beam (including DL beam and/or UL beam) indicated by the TCI state (including DL transmission configuration state and UL transmission configuration state) .
  • one or more TCI states for the serving cell may first be activated by using a DL MAC CE from NW, and then DCI may be used to update/indicate an actual TCI state for the TRP transmission with the TCI state codepoint in the DCI.
  • An example wireless communication network may include wireless terminal devices or user equipment (UE) 110, 111, and 112, a carrier network 102, various service applications 140, and other data networks 150.
  • the wireless terminal devices or UEs may be alternatively referred to as wireless terminals.
  • the carrier network 102 may include access network nodes 120 and 121, and a core network 130.
  • the carrier network 110 may be configured to transmit voice, data, and other information (collectively referred to as data traffic) among UEs 110, 111, and 112, between the UEs and the service applications 140, or between the UEs and the other data networks 150.
  • the access network nodes 120 and 121 may be configured as various wireless access network nodes (WANNs, alternatively referred to as wireless base stations) to interact with the UEs on one side of a communication session and the core network 130 on the other.
  • WANNs wireless access network nodes
  • the term “access network” may be used more broadly to refer a combination of the wireless terminal devices 110, 111, and 112 and the access network nodes 120 and 121.
  • a wireless access network may be alternatively referred to as Radio Access Network (RAN) .
  • the core network 130 may include various network nodes configured to control communication sessions and perform network access management and traffic routing.
  • the service applications 140 may be hosted by various application servers deployed outside of but connected to the core network 130.
  • the other data networks 150 may also be connected to the core network 130.
  • the UEs may communicate with one another via the wireless access network.
  • UE 110 and 112 may be connected to and communicate via the same access network node 120.
  • the UEs may communicate with one another via both the access networks and the core network.
  • UE 110 may be connected to the access network node 120 whereas UE 111 may be connected to the access network node 121, and as such, the UE 110 and UE 111 may communicate to one another via the access network nodes 120 and 121, and the core network 130.
  • the UEs may further communicate with the service applications 140 and the data networks 150 via the core network 130. Further, the UEs may communicate to one another directly via side link communications, as shown by 113.
  • FIG. 2 further shows an example system diagram of the wireless access network 120 including a WANN 202 serving UEs 110 and 112 via the over-the-air interface 204.
  • the wireless transmission resources for the over-the-air interface 204 include a combination of frequency, time, and/or spatial resource.
  • Each of the UEs 110 and 112 may be a mobile or fixed terminal device installed with mobile access units such as SIM/USIM modules for accessing the wireless communication network 100.
  • the UEs 110 and 112 may each be implemented as a terminal device including but not limited to a mobile phone, a smartphone, a tablet, a laptop computer, a vehicle on-board communication equipment, a roadside communication equipment, a sensor device, a smart appliance (such as a television, a refrigerator, and an oven) , or other devices that are capable of communicating wirelessly over a network.
  • each of the UEs such as UE 112 may include transceiver circuitry 206 coupled to one or more antennas 208 to effectuate wireless communication with the WANN 120 or with another UE such as UE 110.
  • the transceiver circuitry 206 may also be coupled to a processor 210, which may also be coupled to a memory 212 or other storage devices.
  • the memory 212 may be transitory or non-transitory and may store therein computer instructions or code which, when read and executed by the processor 210, cause the processor 210 to implement various ones of the methods described herein.
  • the WANN 120 may include a wireless base station or other wireless network access point capable of communicating wirelessly via the over-the-air interface 204 with one or more UEs and communicating with the core network 130.
  • the WANN 120 may be implemented, without being limited, in the form of a 2G base station, a 3G nodeB, an LTE eNB, a 4G LTE base station, a 5G NR base station of a 5G gNB, a 5G central-unit base station, or a 5G distributed-unit base station.
  • Each type of these WANNs may be configured to perform a corresponding set of wireless network functions.
  • the WANN 202 may include transceiver circuitry 214 coupled to one or more antennas 216, which may include an antenna tower 218 in various forms, to effectuate wireless communications with the UEs 110 and 112.
  • the transceiver circuitry 214 may be coupled to one or more processors 220, which may further be coupled to a memory 222 or other storage devices.
  • the memory 222 may be transitory or non-transitory and may store therein instructions or code that, when read and executed by the one or more processors 220, cause the one or more processors 220 to implement various functions of the WANN 120 described herein.
  • Data packets in a wireless access network may be transmitted as protocol data units (PDUs) .
  • the data included therein may be packaged as PDUs at various network layers wrapped with nested and/or hierarchical protocol headers.
  • the PDUs may be communicated between a transmitting device or transmitting end (these two terms are used interchangeably) and a receiving device or receiving end (these two terms are also used interchangeably) once a connection (e.g., a radio link control (RRC) connection) is established between the transmitting and receiving ends.
  • RRC radio link control
  • Any of the transmitting device or receiving device may be either a wireless terminal device such as device 110 and 120 of FIG. 2 or a wireless access network node such as node 202 of FIG. 2. Each device may both be a transmitting device and receiving device for bi-directional communications.
  • the core network 130 of FIG. 1 may include various network nodes geographically distributed and interconnected to provide network coverage of a service region of the carrier network 102. These network nodes may be implemented as dedicated hardware network nodes. Alternatively, these network nodes may be virtualized and implemented as virtual machines or as software entities. These network nodes may each be configured with one or more types of network functions which collectively provide the provisioning and routing functionalities of the core network 130.
  • FIG. 3 illustrates an example RAN 340 in communication with a core network 310 and wireless terminals UE1 to UE7.
  • the RAN 340 may include one or more various types of wireless base station or WANNs 320 and 321 which may include but are not limited to gNB, eNodeB, NodeB, or other type of base stations.
  • the RAN 340 may be backhauled to the core network 310.
  • the WANNs 320 may further include multiple separate access network nodes in the form of a Central Unit (CU) 322 and one or more Distributed Unit (DU) 324 and 326.
  • CU Central Unit
  • DU Distributed Unit
  • the CU 322 is connected with DU1 324 and DU2 326 via various interfaces, for example, an F1 interface.
  • the F1 interface may further include an F1-C interface and an F1-U interface, which may be used to carry control plane information and user plane data, respectively.
  • the CU may be a gNB Central Unit (gNB-CU)
  • the DU may be a gNB Distributed Unit (gNB-DU) .
  • gNB-CU gNB Central Unit
  • gNB-DU gNB Distributed Unit
  • the UEs may be connected to the network via the WANNs 320 over an air interface.
  • the UEs may be served by at least one cell. Each cell is associated with a coverage area. These cells may be alternatively referred to as serving cells. The coverage areas between cells may partially overlap.
  • Each UE may be actively communicating with at least one cell while may be potentially connected or connectable to more than one cell.
  • UE1, UE2, and UE3 may be served by cell1 330 of the DU1
  • UE4 and UE5 may be served by cell2 332 of the DU1
  • UE6 and UE7 may be served by cell3 associated with DU2.
  • a UE may be served simultaneously by two or more cells.
  • Each of the UE may be mobile and the signal strength and quality from the various cells at the UE may depend on the UE location and mobility.
  • the cells shown in FIG. 3 may be alternatively referred to as serving cells.
  • the serving cells may be grouped into serving cell groups (CGs) .
  • a serving cell group may be either a Master CG (MCG) or Secondary CG (SCG) .
  • MCG Master CG
  • SCG Secondary CG
  • a primary cell in a MSG for example, may be referred to as a PCell
  • PScell Primary cell in a SCG
  • Secondary cells in either an MCG or an SCG may be all referred to as SCell.
  • the primary cells including PCell and PScell may be collectively referred to as spCell (special Cell) .
  • serving cells may be referred to as serving cells or cells.
  • the term “cell” and “serving cell” may be used interchangeably in a general manner unless specifically differentiated.
  • the term “serving cell” may refer to a cell that is serving, will serve, or may serve the UE. In other words, a “serving cell” may not be currently serving the UE. While the various embodiment described below may at times be referred to one of the types of serving cells above, the underlying principles apply to all types of serving cells in both types of serving cell groups.
  • FIG. 4 further illustrates a simplified view of the various network layers involved in transmitting user-plane PDUs from a transmitting device 402 to a receiving device 404 in the example wireless access network of FIGs. 1-3.
  • FIG. 4 is not intended to be inclusive of all essential device components or network layers for handling the transmission of the PDUs.
  • FIG. 4 illustrates that the data packaged by upper network layers 420 at the transmitting device 402 may be transmitted to corresponding upper layer 430 (such as radio resource control or RRC layer) at the receiving device 304 via Packet Data Convergence Protocol layer (PDCP layer, not shown in FIG.
  • PDCP layer Packet Data Convergence Protocol layer
  • Radio link control (RLC) layer 422 and of the transmitting device the physical (PHY) layers of the transmitting and receiving devices and the radio interface, as shown as 406, and the media access control (MAC) layer 434 and RLC layer 432 of the receiving device.
  • Various network entities in each of these layers may be configured to handle the transmission and retransmission of the PDUs.
  • the upper layers 420 may be referred as layer-3 or L3, whereas the intermediate layers such as the RLC layer and/or the MAC layer and/or the PDCP layer (not shown in FIG. 4) may be collectively referred to as layer-2, or L2, and the term layer-1 is used to refer to layers such as the physical layer and the radio interface-associated layers.
  • the term “low layer” may be used to refer to a collection of L1 and L2, whereas the term “high layer” may be used to refer to layer-3.
  • the term “lower layer” may be used to refer to a layer among L1, L2, and L3 that are lower than a current reference layer.
  • Control signaling may be initiated and triggered at each of L1 through L3 and within the various network layers therein. These signaling messages may be encapsulated and cascaded into lower layer packages and transmitted via allocated control or data over-the-air radio resources and interfaces.
  • the term “layer” generally includes various corresponding entities thereof.
  • a MAC layer encompasses corresponding MAC entities that may be created.
  • the layer-1 for example, encompasses PHY entities.
  • the layer-2 for another example encompasses MAC layers/entities, RLC layers/entities, service data adaptation protocol (SDAP) layers and/or PDCP layers/entities.
  • SDAP service data adaptation protocol
  • UEs may be in communication with the WANNs 120 and 121 using wireless network communication resources allocated by the WANNs.
  • wireless network communication resources may include but are not limited to radio frequency carrier frequencies and time slots.
  • wireless access network may be more efficiently implemented at least partially using random access.
  • a user mobile station may request access to network communication resources at random times and as needed.
  • Network resources and synchronization information may be made available and assigned by the WANNs upon random access request by a user mobile station.
  • requests for random access by the mobile stations may be transmitted via one or more random access communication resources or random-access channels (RACH) .
  • RACH random-access channels
  • Random access communication resources configuration may be included in random access channel configuration messages (e.g., an RRC message) ) generated by the WANNs.
  • the RACH configuration messages may be broadcasted by the WANNs to the user mobile stations.
  • a user mobile station may select a RACH among all RACHs that are available according a RACH configuration message for transmitting a random-access request to the WANNs.
  • channel is used herein to broadly refer to network transmission resources, including but not limited to any combination of transmission carrier frequencies and time slots.
  • random access may be contention based or contention free, referred to as CBRA (Contention-Based Random Access) or CFRA (Contention-Free Random Access) , respectively.
  • CBRA Contention-Based Random Access
  • CFRA Contention-Free Random Access
  • random access communication resources such as a RACH may be UE-dedicated
  • CBRA Contention-Free Random Access
  • FIG. 5 illustrates an example implementation of a CBRA request and allocation procedure 500.
  • the contention-based RACH procedure starts at step 1 (502) in which the WANN 501 performs optimization for RACH configuration to obtain an optimized RACH configuration.
  • the optimization of the RACH configuration may involve designing RACH preambles according to various network operational parameters available at the WANN for optimizing RACH efficiency and for reducing potential contention among user mobile stations.
  • the WANN may broadcast the optimized RACH configuration via, for example, a predetermined control channel.
  • the optimized RACH configuration may be broadcasted in step 2 (504) as part of the synchronization signal and physical broadcast channel block (SSB) .
  • SSB physical broadcast channel block
  • the user mobile station 503 receives the optimized RACH configuration broadcasted by the MANN 501.
  • the user mobile station selects a random-access preamble from the plurality of random-access preambles indicated as available in the optimized RACH configuration and communicates the selection to the MANN, as shown by 513.
  • the MANN receives the preamble selection from the user mobile station and provides response to the mobile station at step 4 (506) .
  • the response 506, referred to as Random Access Response (RAR) may include network resources allocated for the mobile station for transmission to the MANN and time advance (TA) information (to be described in further detail below) .
  • RAR Random Access Response
  • TA time advance
  • the mobile station receives the response at step 5 (514) and extracts from the RAR 506, for example, the allocated network resources and TA.
  • the mobile station then prepares its transmitter to schedule transmission and transmits information using, for example, the allocated network resources to the MANN and the TA, as shown by 515.
  • the random access by the mobile station is then determined to be established if no network resource contention from other user mobile stations is present. Otherwise, the WANN proceeds to resolving the contention in step 6 (508) before the random access by the user mobile station 503 is either allowed to be established or disallowed to make the allocated network resources available to some other contending user mobile station.
  • the CBRA implementation of FIG. 5 may be referred to as a 4-step process.
  • the four steps refer to the transmission of messages 513 (preamble from mobile station to WANN) , 506 (Random Access Response (RAR) from the WANN to the mobile station) , 515 (scheduled transmission of data from the mobile station to the WANN) , and 508 (for contention resolution) .
  • RAR Random Access Response
  • 515 scheduled transmission of data from the mobile station to the WANN
  • 508 for contention resolution
  • a 2-step rather than a 4-step RACH procedure may be used.
  • the Msg 1 and Msg 3 described above may be combined to include both a RACH preamble and uplink data load, referred to as MSGA, and the Msg 2 and Msg 4 above may be combined into one response message, referred to as MSGB.
  • the UE may retry the 2-step procedure or fall back to the 4-step procedure if there was contention and the transmission failed.
  • a timing of an uplink transmission may be controlled according to a Time Advance (TA) .
  • TA Time Advance
  • the time advance for each UE with respect to a base station helps ensure that uplink transmissions from all UEs are synchronized when received by the base station.
  • the TA for a particular UE in communication with a base station via a serving cell is essentially dependent on a transmission propagation delay which is directly related to a path length from the UE to the base station (for example, the DU above) .
  • a UE generally needs to acquire and maintain its TA in relation to a base station to which it communicates in order to effectively control the timing of its uplink signal transmission using any allocated uplink transmission resources.
  • the TA may be initially communicated from the base station to the UE during a random-access process in a Random-Access Response (RAR) after a random-access request by the UE.
  • RAR Random-Access Response
  • a time advance may be also communicated to the UE via a MAC Control Element (MAC CE) including a Timing Advance Command (TAC) , e.g., for TA updates.
  • MAC CE MAC Control Element
  • TAC Timing Advance Command
  • mTRP Multiple Transmit-Receive Points
  • RX-TX transmission-reception
  • the mTRP technology allow the wireless network and/or a UE to transmit/receive the multiple radio/data streams simultaneously.
  • mTRP transmissions may be characterized in two types. One type may be multi-DCI based mTRP transmission, in which each TRP transmission is respectively scheduled by one DCI. The other type may be single-DCI based mTRP transmission, in which all TRP transmissions are of a given time window are scheduled by one DCI.
  • a serving cell for a UE may be provided with one or more antenna panels from the network side. Each antenna panel may provide a UL/DL transmission with multiple beams. A beam may be used as a TRP.
  • mTRP service may be provided by the serving cell to the UE via two or more beams from the same or different antennal panels at the same time.
  • mTRP provided by the same serving cell may be referred to as intra-cell mTRP.
  • the serving cell without handover, may rely on TRP of a neighboring cell to provide mTRP service to the UE.
  • a TRP in the serving cell and another TRP from its neighboring cell may together be used to provide mTRP service to the UE.
  • Such situation may be referred to as inter-cell mTRP.
  • Such neighboring cells for example, may be managed by the same DU or by DUs managed by the same CU. While it may be allowed to have all TRPs that the serving cell uses for providing the mTRP service to a UE provided from its neighboring, with none from its own cell, such situation may nevertheless be preferably avoided by initiating a handover of the service to one of the neighboring cells.
  • Each of the TRP may be associated with its own uplink TA depending on the signal path of the corresponding beam from the UE to the TRP.
  • a subset, e.g., two or more, of the TRPs may be actually configured to provide mTRP service to the UE for uplink transmission at the same time.
  • the subset of active TRPs for providing mTRP service by the serving cell to the UE may change or switch over time.
  • the UE may be configured with TA Groups (TAG) to manage uplink TAs.
  • TAG TA Groups
  • Each TAG may be associates with a TA value to apply for uplink transmission.
  • the UE may be configured to simultaneously manage multiple TAGs identified by TAG IDs in order to maintain multiple TAs.
  • TRP single TRP
  • a cell may be associated with one TAG while each TAG may be associated with multiple cells having similar TAs.
  • the UE may obtain a TAG ID from a scheduling message and/or configuration from a serving cell for uplink transmission and use the corresponding TA that is maintained either via initial acquisition or subsequent update from the network.
  • a serving cell may potentially use multiple TRP to serve the UE.
  • the multiple TRPs may be characterized by distinct TAs and thus the TRPs of the serving cell may need to be associated with multiple TAGs.
  • a cell may need to be associated with multiple TAGs in order for the UE to correctly apply the TA when mTRP service is provided.
  • a timer referred to as Time Alignment Timer (TAT)
  • TAT Time Alignment Timer
  • the TAT may start or restart when, for example, the corresponding TA is configured or updated from the base station.
  • Management of the TAT is also critical in that the UE and the base station should be at a consensus as to the length the TAT, its association with a TA and/or TAG, and the manner and conditions in which it is started/restarted or becomes expired.
  • TAT expires, it suggests that the prior TA associated with this TAT has become stale and invalid, a new or updated TA is usually needed and may be provided via a RACH procedure or via MAC layer updates.
  • a TA may be acquired from the network during a RACH procedure.
  • a RACH procedure as described above, may be initiated from the UE after RACH configuration is provided by the network.
  • a RACH process may be ordered by the network via, for example, PDCCH order, referred to as PDCCH ordered RACH.
  • TA value configuration for uplink transmission as a result of the RACH procedure may be included in and transmitted to the UE as part of the Random-Access Response (RAR) described above.
  • RAR Random-Access Response
  • the UE may request random-access to the serving cell according to the RACH configuraiton as normal and obtain TA for one TRP of the serving cell in order to establish uplink/downlink communication with the serving cell.
  • TAs for other TRPs may be obtained in various manners, such as through time advance control MAC CE or through SRS.
  • a RACH procedure by a UE to access the serving cell may be started, as shown above in FIG. 5, by the UE sending to the serving cell a RACH preamble (after RACH configuration information has been received at UE) .
  • the base station upon receiving the preamble via a particular TRP at the base station, may perform estimate of a TA based on, for example, the received preamble.
  • the TA value so estimated may then be included in an RAR and sent to the UE in response to receiving the RACH preamble.
  • An RAR is usually specific to the received RACH preamble, thus only contains the one particular TA. In a single TRP situation, there would be no ambiguity as to which TRP the TA contained the RAR should be associated with.
  • the UE may not be able to ascertain an association of the received TA with the particular TRP among the several active TRPs.
  • one serving cell when one serving cell is configured with two or more TRPs (hence, there may be two or more distinct TAs and/or TAGs configured for one serving cell) and a single TA is received in a RAR during a RACH procedure by the UE, it may be critical to provide a mechanism for the UE to identify the TRP associated with the received TA.
  • the various example implementations of this disclosure below provide manners in which the UE is informed of the association of the TA received during the RACH procedure with one or more particular TRPs of the multiple TRPs of the serving cell. Additional example implementations are also provided for managing the corresponding TATs such that the UE and the base station can operates in a synchronized manner as to the validity periods of the TAs.
  • An example 2-step RACH procedure 600 is shown in FIG. 6 that may be utilized to convey not only the TA but also the TRP associated with the TA from the base station 604 to the UE 602, so that the UE 602 can properly manage timing advance when performing uplink transmission.
  • the 2-step RACH procedure 600 may include the following steps.
  • the term “2-step” should not be confused with the 4 steps listed below.
  • STEP 2 and STEP 3 represent the two steps of the 2-step RACH procedure.
  • ⁇ STEP 1 The UE 602 determines that a 2-step RACH procedure should be initiated
  • ⁇ STEP 2 As shown by 610, the UE 602 transmits the preamble and the corresponding PUSCH (the combination is referred to as MSGA 610, as described above) to base station (the network, or NW 604) , in which a C-RNTI MAC CE is included.
  • the base station or NW 604 correspondingly receives the MSGA 610 from the UE 602;
  • ⁇ STEP 3 The base station or NW 604 sends an MSGB 620 to the UE 602, in which, an enhanced absolute Time Advance Command (TAC) MAC Control Element (CE) (or a legacy TAC MAC CE) is included.
  • TAC Time Advance Command
  • CE MAC Control Element
  • the UE 602 correspondingly receive the enhanced absolute TAC MAC CE;
  • ⁇ STEP 4 The UE 602 apply the TA value received from STEP 2 to a TRP identified according to the enhanced absolute TAC MAC CE if the corresponding TAT is not running, and then start or restart the corresponding TAT, as shown by 630
  • the UE 602 may choose a RACH preamble configured by the base station.
  • the RACH preamble may be UE-specific or non-UE-specific.
  • the C-RNTI MAC CE Cell-Radio Network Temporary Identifier MAC Control Element
  • the UE network identifier may be provided to the base station via MSGA.
  • the enhanced absolute TAC MAC CE may be included in the MSGB 620 transmitted from the base station or NW 604 to the UE 602.
  • the enhanced absolute TAC MAC CE may be a separately identifiable MAC CE in comparison to a legacy TAC MAC CE.
  • the enhanced absolute TAC MAC CE may be constructed according an example 700 shown in FIG. 7. Each of the horizontal division shown in FIG. 7 represents one bit, whereas each vertical division represents on octave.
  • FIG. 7 indicates that the example enhanced absolute TAC MAC CE may include several reserved bits and a Timing Advance Command (TAC) .
  • TAC Timing Advance Command
  • the TAC may occupy 12 bits and may represent quantification of TA in, for example, predefined time units or predefined index in a predefined table.
  • the field labeled as “TRP Indicator” may be used for indication to the UE an identification of the TRP associated with the TA indicated in the TAC field. While a single bit is shown in FIG. 1 as the TRP Indicator (thereby capable of identifying one of two TRPs) , more bits of the enhanced absolute TAC MAC CE may be used as the TRP Indicator.
  • additional reserved bits may be used for TRP indication, when there are more than two possible TRPs and thus more than 1 bit is needed for TRP identification.
  • the two or more bits may be used to indicate the tag-Id instead of one TRP indicator bit for the present TAC.
  • the base station upon receiving the MSGA from the UE, would be able to determine the identify of the UE requesting the random access, and may determine or obtain a TA corresponding to one of the TRPs allocated to the UE.
  • the base station may transmit in the MSGB a legacy TAC MAC CE to provide the TA in the TAC field therein (legacy TAC MAC CE does not include TRP identification field, which is not needed in this case) , and the association of the included TA and the single TRP for the UE would be implicit.
  • the base station may include in the MSGB an enhanced absolute TAC MAC CE to provide the TA in the TAC field therein and to also provide an identification of the TRP associated with the included TA.
  • An example 4-step RACH procedure 800 is shown in FIG. 8 that may be utilized to convey not only the TA but also the TRP associated with the TA from the base station 804 to the UE 802, so that the UE 802 can properly manage timing advance when performing uplink transmission.
  • the 4-step RACH procedure 800 may include the following steps.
  • the term “4-step” should not be confused with the 6 steps listed below.
  • STEP 2, STEP 3, STEP 4, and STEP 5 represent the four essential steps of the 4-step RACH procedure.
  • ⁇ STEP 1 The UE 802 determines the 4-step RACH procedure should be initiated
  • the UE 802 may transmit the preamble 810 to the base station or NW 804.
  • the base station or NW 804 correspondingly receives the preamble 810 from the UE 802;
  • the base station or NW 804 may then send an RAR 820 in response to receiving the preamble 810 from the UE 802.
  • the UE 802 may correspondingly receive the RAR 820 from the base station or NW 804, and obtain a TA value as included in the RAR 820 and apply the TA value to the subsequent UL transmission (including, e.g., Msg. 3 830 in STEP 4) ;
  • the UE 802 may send the Msg. 3 830 to the base station or NW 804 after receiving the RAR 820.
  • the UE 802 may include a C-RNTI MAC CE in Msg. 3 830. Further, the timing of the uplink transmission of the Msg. 3 830 may rely on the uplink grant and TA included in the RAR 820 as received in STEP 3;
  • the base station or NW 804 may then send Msg. 4 840 to the UE 802.
  • the UE 802 may correspondingly receive the Msg. 4 840.
  • UE may identify the TRP corresponding to the TA included in the RAR of STEP 3;
  • the UE 802 may apply the TA value obtained from the RAR 820 in STEP 2 to the TRP as identified according to the indication in Msg. 4 840, and start/restart the TAT corresponding to the obtained TA.
  • the UE 802 may choose a RACH preamble configured by the base station.
  • the RACH preamble may be UE-specific or non-UE-specific but is mostly non-UE-Specific.
  • the base station 804 may not be able determine the originating UE when receiving the preamble and thus may not be able to have sufficient information to include a UE specific TA in the RAR in STEP 3 above.
  • the base station may then include an TA estimated according the preamble received by the receiving TRP but with out the TRP indication information in the RAR.
  • the base station may indicate to the UE the TRP associated with the TA included in the RAR:
  • a MAC CE may be included in the MSG. 4 in STEP 5.
  • the MAC CE may be an enhanced TAC MAC CE described above, which include a single or multi-bit TRP or TAG indication field.
  • the MAC CE may be a new type of MAC CE for indicating the TRP for which the TA value in RAR is.
  • the MAC CE may only include the subheader without any payload, in the case of a serving cell is configured with only two TRP/TAG Id. If such MAC CE is present in the MSG. 4, it means that the TA value obtained in the RAR is for one certain TRP (e.g. the first TRP) . Otherwise, it means that the TA value obtained in the RAR is for the other TRP (e.g. the second TRP) .
  • the start/restart timing of the TAT may be implemented in various example manners.
  • the start/restart/timing refers to when TAT should start or restart after the TA is obtained.
  • the TAT may be started/restarted at different time points at or after the RAR is received and the TA is obtained.
  • the TAT may be started if the TAT associated with the indicated TRP is not running.
  • the UE may start/restart the TAT at the first symbol of the end of the PDCCH reception for MSG. 4.
  • the UE may start/restart the TAT from a time point with a modified time length by considering the timing of the TAC reception within RAR. For example, the normal predefined time value for the TAT may be reduced by the amount between the start/restart time point and the time for receiving the RAR that was earlier.
  • the UE may start/restart the TAT when receiving an enhanced absolute TAC MAC CE and/or the new type of MAC CE designed for TRP indication.
  • FIG. 9 An example implementation for TCI state activation/update in the scenario of single-DCI based mTRP is illustrated in FIG. 9 with the following example steps:
  • STEP 1 The base station or NW 902 sends/configures RRC configuration of TCI state resource pools and TCI state model for one serving cell.
  • STEP 2 The base station or NW 902 sends a DL MAC CE (e.g. enhanced unified TCI state activation/deactivation MAC CE) to UE 904.
  • a DL MAC CE e.g. enhanced unified TCI state activation/deactivation MAC CE
  • STEP 3 The UE 904 activates the multiple sets of TCI states for the multiple TRP transmission.
  • an example structure of DL MAC CE (e.g. enhanced unified TCI state activation/deactivation MAC CE) is shown in FIG. 10 and explained as below.
  • At least one of the following information may be included:
  • ⁇ Serving cell Id To identify the serving cell where the corresponding TCI states are activated;
  • ⁇ DL BWP Id To identify the DL BWP (Bandwidth Part) where the DL and/or joint TCI state list is configured;
  • ⁇ UL BWP Id To identify the UL BWP where the UL TCI state list is configured
  • TCI State Id To identify the TCI state from the TCI state list configured in DL or UL BWP of the serving cell identified by the serving cell Id;
  • ⁇ R Reserved bit. It should be ignored by UE, and always set to zero or 1.
  • the serving cell indicated by the serving cell Id in the MAC CE is configured with joint TCI state mode and if two octets containing the TCI state Id field are present for a TCI state codepoint, the first octet containing the TCI state field corresponding to the TCI state codepoint may be for the first TRP, and the subsequent octet containing the TCI state field corresponding to the TCI state code point may be for the second TRP.
  • the serving cell indicated by serving cell Id in the MAC CE is configured with joint TCI state mode and if only one octet containing the TCI state Id field is present for a TCI state codepoint, the octet containing the TCI state Id field may be only for the first TRP.
  • the octet containing the TCI state field for the TCI state codepoint may be present in an order of ⁇ DL TCI state for the first TRP, UL TCI state for the first TRP, DL TCI state for the second TRP, UL TCI state for the second TRP... ⁇ or may be in an order of ⁇ UL TCI state for the first TRP, DL TCI state for the first TRP, UL TCI state for the second TRP, DL TCI state for the second TRP... ⁇ .
  • terms, such as “a, ” “an, ” or “the, ” may be understood to convey a singular usage or to convey a plural usage, depending at least in part upon context.
  • the term “based on” may be understood as not necessarily intended to convey an exclusive set of factors and may, instead, allow for existence of additional factors not necessarily expressly described, again, depending at least in part on context.

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  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
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Abstract

La présente divulgation concerne de manière générale des réseaux de communication sans fil et en particulier une gestion d'avance temporelle (TA) pour une transmission/réception multipoint dans une cellule de desserte sans fil. Une TA peut être initialement acquise à partir de la cellule de desserte par un terminal sans fil pendant une procédure d'accès aléatoire. Les divers modes de réalisation donnés à titre d'exemple fournissent en outre des manières selon lesquelles l'UE est informé par la cellule de desserte d'une association de la TA acquise pendant la procédure RACH avec un ou plusieurs TRP particuliers des multiples TRP de la cellule de desserte. Des modes de réalisation donnés à titre d'exemple supplémentaires sont également fournis pour gérer des temporisateurs d'alignement temporel (TAT) correspondants de telle sorte que le terminal sans fil et la cellule de desserte peuvent fonctionner de manière synchronisée quant aux périodes de validité des TA, de façon à obtenir un cadencement précis pour une transmission en liaison montante.
PCT/CN2023/094040 2023-05-12 2023-05-12 Procédé rach pour obtenir une avance temporelle pour une transmission en liaison montante à une cellule de desserte avec de multiples points de transmission-réception WO2024108926A1 (fr)

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US20180124724A1 (en) * 2016-11-01 2018-05-03 Asustek Computer Inc. Method and apparatus for identifying uplink timing advance in a wireless communication system
WO2020121497A1 (fr) * 2018-12-13 2020-06-18 株式会社Ｎｔｔドコモ Terminal utilisateur et procédé de communication sans fil
US20200351730A1 (en) * 2019-05-02 2020-11-05 Kyungmin Park Multiple Access Configuration Information
CN113647046A (zh) * 2019-03-28 2021-11-12 诺基亚技术有限公司 多传输接收点pucch设计考虑

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Publication number Priority date Publication date Assignee Title
US20180124724A1 (en) * 2016-11-01 2018-05-03 Asustek Computer Inc. Method and apparatus for identifying uplink timing advance in a wireless communication system
WO2020121497A1 (fr) * 2018-12-13 2020-06-18 株式会社Ｎｔｔドコモ Terminal utilisateur et procédé de communication sans fil
CN113647046A (zh) * 2019-03-28 2021-11-12 诺基亚技术有限公司 多传输接收点pucch设计考虑
US20200351730A1 (en) * 2019-05-02 2020-11-05 Kyungmin Park Multiple Access Configuration Information

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