Initial access methods, and terminal devices and network devices

Abstract

The present application relates to initial access methods, and terminal devices and network devices. A method comprises: a terminal device measuring downlink synchronization signals sent by a plurality of network devices; and on the basis of measurement results, the terminal device selecting, from among the downlink synchronization signals sent by the plurality of network devices, downlink synchronization signal sent by one or more network devices. By means of the present application, a terminal device can make selection to access a plurality of network devices during initial access, thereby implementing UE-centric initial access.

Description

Initial access method, terminal device and network device TECHNICAL FIELD

[0001] The present application relates to the field of communication, and more particularly, to an initial access method, a terminal device and a network device. BACKGROUND

[0002] In the initial access of New Radio (NR), a UE always selects one Synchronization Signal and Physical Broadcast Channel Block (SSB) to perform initial access. In this way, the UE can only access one base station, i.e., only access one Transmission Reception Point (TRP). When a network (NW) is ready to use multiple TRPs to serve a UE, the UE needs to be configured with a dedicated RRC configuration to enable the multiple TRPs to serve the UE.

[0003] How to enable a UE to select and access multiple TRPs as early as possible in the initial access process, so as to implement a UE-centric initial access and a multi-TRP transmission scheme, is a technical problem to be solved.

[0004] SUMMARY

[0005] Embodiments of the present application provide an initial access method, a terminal device and a network device.

[0006] Embodiments of the present application provide an initial access method, comprising:

[0007] The terminal device measures downlink synchronization signals transmitted by multiple network devices.

[0008] The terminal device selects, according to a measurement result, a downlink synchronization signal transmitted by one or more network devices from among the downlink synchronization signals transmitted by the multiple network devices.

[0009] Embodiments of the present application provide an initial access method, comprising:

[0010] The network device transmits a downlink synchronization signal to a terminal device.

[0011] The network device receives a PRACH transmitted by the terminal device.

[0012] The network device determines a downlink synchronization signal selected by the terminal device according to a time-frequency domain position occupied by the PRACH and an association between the downlink synchronization signal and the time-frequency domain position occupied by the PRACH.

[0013] The embodiment of the present application provides a terminal device, comprising:

[0014] The first processing module is used for measuring downlink synchronization signals sent by a plurality of network devices; and selecting downlink synchronization signals sent by one or more network devices from the downlink synchronization signals sent by the plurality of network devices according to a measurement result.

[0015] The embodiment of the present application provides a network device, comprising:

[0016] The second transceiver is used for sending downlink synchronization signals to a terminal device and receiving a PRACH sent by the terminal device.

[0017] The second processing module is used for determining the downlink synchronization signals selected by the terminal device according to a time-frequency domain position occupied by the PRACH and an association relationship between the downlink synchronization signals and the time-frequency domain position occupied by the PRACH.

[0018] The embodiment of the present application provides a terminal device, comprising a transceiver, a processor and a memory. The memory is used for storing a computer program, the transceiver is used for communicating with other devices, and the processor is used for calling and running the computer program stored in the memory, so that the terminal device executes the initial access method.

[0019] The embodiment of the present application provides a network device, comprising a transceiver, a processor and a memory. The memory is used for storing a computer program, the transceiver is used for communicating with other devices, and the processor is used for calling and running the computer program stored in the memory, so that the network device executes the initial access method.

[0020] The embodiment of the present application provides a chip, which is used for implementing the initial access method.

[0021] Specifically, the chip comprises a processor, which is used for calling and running a computer program from a memory, so that a device installed with the chip executes the initial access method.

[0022] The embodiment of the present application provides a computer readable storage medium, which is used for storing a computer program, and when the computer program is run by a device, the device executes the initial access method.

[0023] The embodiment of the present application provides a computer program product, which comprises computer program instructions, and the computer program instructions make a computer execute the initial access method.

[0024] The embodiment of the present application provides a computer program, which, when run on a computer, makes the computer execute the initial access method.

[0025] In the initial access method provided in the embodiments of the present application, the UE measures downlink synchronization signals sent by multiple network devices, and selects to access downlink synchronization signals sent by one or more network devices according to the measurement result, so as to realize that the terminal device selects to access multiple network devices in the initial access process, and realizes UE-centered initial access. BRIEF DESCRIPTION OF DRAWINGS

[0026] FIG. 1 exemplarily shows a communication system 100.

[0027] FIG. 2 is a schematic diagram of a 5G network architecture.

[0028] FIG. 3 is a schematic diagram of a process of measuring and acquiring system information in an NR initial access stage.

[0029] FIG. 4 is a schematic diagram of a Cell Free MIMO scenario.

[0030] FIG. 5 is a schematic flowchart of an initial access method 500 according to an embodiment of the present application.

[0031] FIG. 6 is a schematic flowchart of an initial access method 600 according to an embodiment of the present application.

[0032] FIG. 7 is a schematic diagram of an SSB transmission scheme of Multi-TRP in the embodiments of the present application.

[0033] FIG. 8 is a schematic diagram of a manner of transmitting SIB 1 by using an SFN scheme in the embodiments of the present application.

[0034] FIG. 9 is a schematic diagram of a transmission scheme of PRACH in the embodiments of the present application.

[0035] FIG. 10 is a schematic diagram of multiple multiplexing manners of downlink synchronization signals in the embodiments of the present application.

[0036] FIG. 11 is a schematic diagram of a multiplexing manner of downlink synchronization signals in the embodiments of the present application.

[0037] FIG. 12 is a schematic diagram of downlink synchronization signals and Multi-TRP sending in the embodiments of the present application.

[0038] FIG. 13 is a schematic block diagram of a terminal device 1300 according to an embodiment of the present application.

[0039] FIG. 14 is a schematic block diagram of a terminal device 1400 according to an embodiment of the present application.

[0040] FIG. 15 is a schematic block diagram of a network device 1500 according to an embodiment of the present application.

[0041] FIG. 16 is a schematic structural diagram of a communication device 1600 according to an embodiment of the present application.

[0042] FIG. 17 is a schematic structural diagram of a chip 1700 according to an embodiment of the present application.

[0043] FIG. 18 is a schematic block diagram of a communication system 1800 according to an embodiment of the present application. DETAILED DESCRIPTION

[0044] The technical solutions in the embodiments of the present application will be described below with reference to the accompanying drawings in the embodiments of the present application.

[0045] The technical solutions in the embodiments of the present application can be applied to various communication systems, for example: a Long Term Evolution (LTE) system, an Advanced long term evolution (LTE-A) system, a New Radio (NR) system, an evolved system of the NR system, a LTE-based access to unlicensed spectrum (LTE-U) system, a NR-based access to unlicensed spectrum (NR-U) system, a Non-Terrestrial Networks (NTN) system, a Universal Mobile Telecommunication System (UMTS), a Wireless Local Area Networks (WLAN), a Wireless Fidelity (WiFi), a 5th-Generation (5G) system, or other communication systems, etc.

[0046] Generally, a conventional communication system supports a limited number of connections, which is easy to implement. However, with the development of communication technology, a mobile communication system will not only support traditional communication, but also support, for example, Device to Device (D2D) communication, Machine to Machine (M2M) communication, Machine Type Communication (MTC), Vehicle to Vehicle (V2V) communication, or Vehicle to everything (V2X) communication, etc. The embodiments of the present application can also be applied to these communication systems.

[0047] In an embodiment, the communication system in the embodiments of the present application can be applied to a carrier aggregation (CA) scenario, can also be applied to a dual connectivity (DC) scenario, and can also be applied to a standalone (SA) network deployment scenario.

[0048] In an embodiment, the communication system in the embodiments of the present application can be applied to an unlicensed spectrum, which can also be regarded as a shared spectrum, or can be applied to a licensed spectrum, which can also be regarded as a non-shared spectrum.

[0049] The embodiments of the present application combine network devices and terminal devices to describe various embodiments, wherein the terminal device can also be referred to as a user equipment (UE), an access terminal, a user unit, a user station, a mobile station, a mobile station, a remote station, a remote terminal, a mobile device, a user terminal, a terminal, a wireless communication device, a user agent or a user device, etc.

[0050] The terminal device can be a station (STA) in a WLAN, can be a cellular phone, a cordless phone, a Session Initiation Protocol (SIP) phone, a Wireless Local Loop (WLL) station, a Personal Digital Assistant (PDA) device, a handheld device with wireless communication function, a computing device or other processing device connected to a wireless modem, a vehicle-mounted device, a wearable device, a terminal device in a next-generation communication system such as an NR network, or a terminal device in a future evolved Public Land Mobile Network (PLMN) network, etc.

[0051] In the embodiments of the present application, the terminal device can be deployed on land, including indoor or outdoor, handheld, wearable or vehicle-mounted; can also be deployed on the water surface (such as ships, etc.); can also be deployed in the air (such as airplanes, balloons and satellites, etc.).

[0052] In the embodiments of the present application, the terminal device can be a mobile phone, a tablet computer, a computer with wireless transceiver function, a virtual reality (VR) terminal device, an augmented reality (AR) terminal device, a wireless terminal device in industrial control, a wireless terminal device in self driving, a wireless terminal device in remote medical treatment, a wireless terminal device in smart grid, a wireless terminal device in transportation safety, a wireless terminal device in smart city, or a wireless terminal device in smart home, etc.

[0053] By way of example and not limitation, in the embodiments of the present application, the terminal device can also be a wearable device. The wearable device can also be referred to as a wearable smart device, which is a general term for devices that are designed and developed by applying wearable technology to daily wear, such as glasses, gloves, watches, clothing, and shoes, etc. The wearable device is a portable device that can be directly worn on the body or integrated into the clothes or accessories of the user. The wearable device is not only a hardware device, but also has powerful functions through software support and data interaction and cloud interaction. The general wearable smart device includes devices with full functions, large size, and the ability to realize complete or partial functions without relying on a smart phone, such as smart watches or smart glasses, etc., and devices that focus on a certain type of application function and need to be used in cooperation with other devices, such as smart phones, such as various smart wristbands and smart jewelry for monitoring vital signs, etc.

[0054] In the embodiments of the present application, the network device can be a device for communicating with the mobile device, which can be an access point (AP) in a WLAN, an evolved node B (eNB or eNodeB) in LTE, or a relay station or an access point, or a vehicle-mounted device, a wearable device, and a network device in an NR network (gNB) or a future evolved PLMN network or a network device in an NTN network, etc.

[0055] By way of example and not limitation, in embodiments of the present application, a network device can have a mobile characteristic, for example, the network device can be a mobile device. Alternatively, the network device can be a satellite, a balloon station. For example, the satellite can be a low earth orbit (LEO) satellite, a medium earth orbit (MEO) satellite, a geostationary earth orbit (GEO) satellite, a high elliptical orbit (HEO) satellite, etc. Alternatively, the network device can also be a base station disposed at a location on land, water, etc.

[0056] In embodiments of the present application, a network device can serve a cell, and a terminal device communicates with the network device through a transmission resource (for example, a frequency domain resource, or a spectrum resource) used by the cell. The cell can be a cell corresponding to the network device (for example, a base station), and the cell can belong to a macro base station or a base station corresponding to a small cell. The small cell can include a metro cell, a micro cell, a pico cell, a femto cell, etc., and these small cells have the characteristics of small coverage and low transmit power, and are suitable for providing high-speed data transmission services.

[0057] FIG. 1 illustrates a communication system 100. The communication system includes one network device 110 and two terminal devices 120. In an implementation, the communication system 100 can include multiple network devices 110, and each network device 110 can include other numbers of terminal devices 120 within its coverage, which is not limited in embodiments of the present application.

[0058] In an implementation, the communication system 100 can also include a mobility management entity (MME), an access and mobility management function (AMF), and other network entities, which are not limited in embodiments of the present application.

[0059] The network device can include an access network device and a core network device. That is, the wireless communication system also includes a plurality of core networks for communicating with the access network device. The access network device can be an evolved node B (eNB or e-NodeB) macro base station, micro base station (also referred to as a "small base station"), pico base station, access point (AP), transmission point (TP), or new generation Node B (gNodeB) in a long-term evolution (LTE) system, a next radio (NR) system, or an authorized auxiliary access long-term evolution (LAA-LTE) system.

[0060] It should be understood that the devices with communication functions in the network / system in the embodiments of the present application can be referred to as communication devices. For example, the communication system shown in FIG. 1 can include network devices and terminal devices with communication functions. The network devices and terminal devices can be specific devices in the embodiments of the present application, which will not be described herein. The communication devices can also include other devices in the communication system, such as network controllers, mobile management entities, and other network entities. The embodiments of the present application do not limit the same.

[0061] Figure 2 is a schematic diagram of a 5G architecture. In the figure, a UE accesses an access network (AN) through a Uu interface to perform access layer connection and exchange access layer messages and wireless data transmission. The UE accesses an access and mobility management function (AMF) through an N1 interface to perform non-access stratum (NAS) connection and exchange NAS messages. The AMF is a mobility management function in a core network, and the SMF is a session management function in the core network. In addition to performing mobility management on the UE, the AMF is also responsible for forwarding session management related messages between the UE and the SMF. The PCF is a policy management function in the core network, and is responsible for formulating policies related to mobility management, session management, charging, and the like of the UE. The UPF is a user plane function in the core network, and performs data transmission with an external data network through an N6 interface and performs data transmission with the AN through an N3 interface.

[0062] It should be understood that the terms "system" and "network" are often used interchangeably herein. The term "and / or" herein is only used to describe the association relationship of the associated objects. For example, A and / or B can represent three cases: A exists alone, A and B exist together, and B exists alone. In addition, the character " / " herein generally represents an "or" relationship between the associated objects.

[0063] It should be understood that the "indication" mentioned in the embodiments of the present application can be direct indication, indirect indication, or an indication with an associated relationship. For example, A indicates B, which can mean that B can be obtained by A directly; or A indirectly indicates B, for example, A indicates C, and B can be obtained by C; or A and B have an associated relationship.

[0064] In the description of the embodiments of the present application, the term "corresponding" can represent a direct or indirect corresponding relationship between the two, or an associated relationship between the two, or an indication and being indicated, configuration and being configured, and the like.

[0065] In order to facilitate understanding of the technical solutions of the embodiments of the present application, the related technologies of the embodiments of the present application are described as follows. The following related technologies can be combined with the technical solutions of the embodiments of the present application in any way, and all belong to the protection scope of the embodiments of the present application.

[0066] I. NR initial access

[0067] In NR system, the initial access procedure is roughly divided into the following stages:

[0068] First stage, measurement and acquisition of system information:

[0069] In this stage, the UE after booting will search for the downlink synchronization signal block in the network (NW), i.e. the synchronization signal block (Synchronization Signal and Physical Broadcast Channel Block, SSB). For the UE, the role of measuring and acquiring system information is to obtain downlink time synchronization, determine the beam direction of uplink transmission, and decode the physical broadcast channel (Physical Broadcast Channel, PBCH) in the SSB (containing the Master Information Block (MIB) of the upper layer). The MIB contains the scheduling information of the physical downlink shared channel (Physical Downlink Shared Channel, PDSCH) carrying the system message block 1 (System Information Block 1, SIB 1). Next, the UE decodes SIB 1 according to the PDSCH scheduled by the physical downlink control channel (Physical Downlink Control Channel, PDCCH) to obtain the configuration information of the random access channel (Random Access Channel, RACH).

[0070] The UE scans and measures multiple SSBs transmitted from one network device (such as a transmission reception point (Transmission Reception Point, TRP) or an access point (Access Point, AP)), evaluates the signal quality (such as the reference signal receiving power (Reference Signal Receiving Power, RSRP)) of each SSB, and selects the SSB with the best signal quality for access. The UE uses the downlink receive spatial filter receiving the SSB as the uplink transmit spatial filter for transmitting uplink signals.

[0071] Figure 3 is a diagram of a process of measurement and system information acquisition in the initial access stage of NR. In the NR system, the beamforming technology is used in information transmission, and the energy is concentrated in a specific direction for transmission. Different directional beams can achieve omnidirectional or large sector coverage through beam scanning in the time domain. As shown in Figure 3, SSB is transmitted on a specific beam after beamforming. A group of SSBs forms an SSB burst set. Each SSB in an SSB burst set is sent successively in a beam scanning manner in the time domain, thereby achieving full-cell coverage of the synchronization signal. The SSBs in an SSB burst set are constrained within a system half-frame. In an SSB burst set, each SSB is assigned a determined and unique index, i.e., SSB index. When a UE detects a certain SSB, the position information of the SSB in an SSB burst set can be determined by identifying the SSB index, thereby determining the timing of the SSB in the system half-frame.

[0072] Second stage, random access stage:

[0073] Taking a four-step random access (4-step RACH) process as an example, the following steps are included:

[0074] (1) Random access preamble sending (Preamble as Msg. 1)

[0075] The UE selects a random access preamble (Preamble) and sends the random access preamble to a base station (i.e., TRP) on a physical random access channel (PRACH).

[0076] (2) Random access response (RAR as Msg. 2)

[0077] After the base station receives the preamble, it sends a random access response (RAR) containing timing advance (TA), uplink resource allocation (UL grant), and cell-radio network temporary identifier (C-RNTI).

[0078] (3) Radio resource control (RRC) connection request (Msg. 3)

[0079] The UE sends an RRC connection request message (RRCSetupRequest) using the uplink resource allocated in the RAR, which contains the UE identity and the reason for requesting the establishment of an RRC connection. This step is part of the contention-based random access procedure.

[0080] (4) RRC connection setup (Msg. 4)

[0081] After the base station receives the RRC connection request message, it sends an RRC connection setup message (RRCSetup) to the UE, which is used to confirm the connection request and allocate the necessary resources. This message marks the completion of the initial access procedure.

[0082] II. UE-centric transmission mode

[0083] In the current technical discussion, there is a design idea of UE-centric, and Figure 4 is a schematic diagram of a Cell Free MIMO scenario. As shown in Figure 4, in terms of geographical location, the UE is surrounded by multiple TRPs and performs multi-TRP uplink and downlink transmission. The baseband part between multiple TRPs can share information through ideal or non-ideal methods. Since the UE is served by multiple TRPs at the same time, this transmission scenario also has another name, i.e., cell-free MIMO.

[0084] In addition, in Figure 4, a unified transmission configuration indication state (TCI state) can be used to indicate the quasi co-located (QCL) relationship. Each TRP has multiple unified TCI state configurations and indication signals.

[0085] The characteristics of the cell-free MIMO technology (or Cell-Free technology) are as follows:

[0086] (1) User-centric design: Cell-Free technology places users at the core of network design, and each user equipment (UE) can be served by multiple TRPs around it, rather than being connected to only one TRP like traditional cellular networks.

[0087] (2) Network architecture: This technology is implemented through a large number of distributed TRPs and a powerful central processing unit (CPU), and the signals collected by the TRPs are sent to the CPU for unified processing.

[0088] (3) Elimination of cell boundaries: Unlike traditional cell division, Cell-Free networks do not have explicit cell boundaries, meaning users can enjoy a more consistent service experience anywhere.

[0089] The key advantages of cell-free MIMO technology are as follows:

[0090] (1) Higher signal quality: Since multiple TRPs serve a UE, Cell-Free technology can provide more stable and high-quality signals.

[0091] (2) Interference management: Cell-Free networks effectively reduce interference by jointly processing signals from multiple TRPs, improving overall network performance.

[0092] (3) Scalability: This network architecture is designed to be very flexible, allowing easy expansion as the number of users increases without sacrificing performance.

[0093] (4) Advanced signal processing: Cell-Free technology uses the latest signal processing algorithms, including channel estimation, data reception, and transmission, to ensure efficient data transmission.

[0094] In NR initial access, the UE always selects one SSB for initial access. In this way, the UE can only access one base station, i.e., one TRP. When the NW is ready to use multiple TRPs to serve the UE, the UE needs to be configured with a dedicated RRC to enable multiple TRPs to serve the UE. For example, the multi-TRP repetition of PDSCH / PUSCH supported in NR. The disadvantage of this is that before the NW configures the multi-TRP transmission scheme, the UE can only work in single-TRP mode, and the link performance of the cell edge UE is not good.

[0095] If the UE can select and access multiple TRPs as early as possible during the initial access process, then the UE-centered initial access and multi-TRP transmission scheme can be realized.

[0096] The present application designs a UE-centric initial access scheme. In the embodiments of the present application, a UE measures and selects downlink synchronization signals (such as SSBs) from multiple network devices (such as TRPs / APs), the UE sends PRACH to multiple TRPs / APs for initial access, and the NW determines which TRPs / APs the UE requests to access according to the association relationship between the time-frequency domain position occupied by the PRACH and the downlink synchronization signals. Subsequently, the NW instructs the UE to access part or all of the TRPs / APs requested by the UE. Through such design, the UE can access multiple network devices (such as TRPs / APs) in the initial access stage, use multiple network devices to serve the UE, form a UE-centric network (instead of a single TRP / AP-centric network), provide better UE-centric uplink and downlink transmission for the UE as early as possible, and thus improve the UE experience and smooth the performance difference between the cell edge and the cell center.

[0097] It should be noted that in the embodiments of the present application, a "spatial transmit filter" can be used to represent a "beam". The embodiments of the present application can use a downlink reference signal (such as CSI-RS or SSB) to associate a transmit beam. In the beam indication process, a TCI state (which contains a downlink reference signal) can be used to refer to a transmit beam. In addition, the embodiments of the present application use TRP to represent the radio frequency transmission and reception part of the base station.

[0098] FIG. 5 is a schematic flowchart of an initial access method 500 according to an embodiment of the present application. The method can optionally be applied to the systems shown in FIGS. 1-4, but is not limited thereto. The method includes at least part of the following content.

[0099] S510, a terminal device measures downlink synchronization signals sent by multiple network devices;

[0100] S520, the terminal device selects, according to the measurement result, downlink synchronization signals sent by one or more network devices from the downlink synchronization signals sent by the multiple network devices.

[0101] In some embodiments, the network device includes a TRP.

[0102] In some embodiments, the downlink synchronization signal includes an SSB.

[0103] For example, the UE measures downlink synchronization signals transmitted by multiple network devices, and according to the measurement results, can select a downlink synchronization signal with a RSRP greater than or equal to a predetermined threshold from the downlink synchronization signals transmitted by the multiple network devices. For a single network device, the user can select one or more downlink synchronization signals of the network device. For example, the user measures downlink synchronization signals transmitted by 3 network devices, each network device transmits 4 downlink synchronization signals, and the 3 network devices transmit a total of 12 downlink synchronization signals; the user selects a downlink synchronization signal with a RSRP greater than or equal to a predetermined threshold from the 12 downlink synchronization signals according to the measurement results, and the user can select one or more downlink synchronization signals; if the user selects multiple downlink synchronization signals, the multiple downlink synchronization signals can be transmitted by one network device or multiple network devices (for example, part of the downlink synchronization signals are transmitted by network device 1 and the other part of the downlink synchronization signals are transmitted by network device 2).

[0104] In some embodiments, the terminal device can also determine the time-frequency domain position corresponding to the selected downlink synchronization signal according to the association between the downlink synchronization signal and the time-frequency domain position occupied by the PRACH, and transmit the PRACH at the time-frequency domain position.

[0105] The terminal device can implicitly report the selected downlink synchronization signal to the network device by transmitting the PRACH at the time-frequency domain position associated with the selected downlink synchronization signal, i.e., the terminal device can report one or more network devices serving the terminal device. After receiving the PRACH, the network device can determine the selected downlink synchronization signal of the terminal device according to the time-frequency domain position of the PRACH and the association between the downlink synchronization signal and the time-frequency domain position occupied by the PRACH.

[0106] In some examples, the terminal device can receive a system message transmitted by multiple network devices, decode the system message to obtain the association between the downlink synchronization signal and the time-frequency domain position occupied by the PRACH. For example, the system message can include SIB 1. For the system message, each network device can broadcast it in the covered area. In some examples, the scheme for multiple network devices to transmit the system message can be a single frequency network (SFN) based scheme, i.e., multiple network devices transmit the same system message on the same time-frequency resource; accordingly, the terminal device receives the system message transmitted by multiple network devices includes that the terminal device receives the system message transmitted by multiple network devices on the same time-frequency resource. By using the SFN transmission scheme, no additional configuration is required for the UE, and better downlink coverage can be provided.

[0107] In the NR system, the SSBs in a SSB burst set can be identified by SSB indexes. Therefore, the association between the downlink synchronization signal and the time-frequency domain location occupied by the PRACH can include an association between the SSB index and a random access channel occasion (RO) occupied by the PRACH.

[0108] The association between the SSB index and the RO can be one-to-one, one-to-many, or many-to-one. For example, one SSB index is associated with one RO, or one SSB index is associated with multiple ROs, or multiple SSB indexes are associated with one RO.

[0109] For the 6th Ggeneration Mobile Networks (6G) and later systems, the downlink synchronization signal may no longer use the structure of the SSB, and the identification of the downlink synchronization signal may no longer use the SSB Index. In this scenario, the association between the downlink synchronization signal and the time-frequency domain location occupied by the PRACH can include an association between the index information of the downlink synchronization signal and the time-frequency domain location occupied by the PRACH. In an example, the time-frequency domain location occupied by the PRACH can be an RO.

[0110] For the 6G and later systems, the transmission of the downlink synchronization signal may use multiple multiplexing methods, such as a transmission method using Frequency Division Multiplexing (FDM) + Time Division Multiplexing (TDM). In this scenario, the index information of the downlink synchronization signal can include at least one of a time-domain index and a frequency-domain index.

[0111] In an example, the frequency-domain index includes at least one of:

[0112] a synchronization signal (SS) resource identification (ID);

[0113] a synchronization signal resource index (Index);

[0114] a synchronization signal port number.

[0115] The association between the downlink synchronization signal and the time-frequency domain position occupied by the PRACH can be one-to-one, one-to-many, or many-to-one. For example, the index information of one downlink synchronization signal is associated with one time-frequency domain position occupied by the PRACH; or the index information of one downlink synchronization signal is associated with multiple time-frequency domain positions occupied by the PRACH; or the index information of multiple downlink synchronization signals is associated with one time-frequency domain position occupied by the PRACH.

[0116] After the network device receives the PRACH from the terminal device at different time-frequency domain positions, the network device can determine the downlink synchronization signal selected by the terminal device according to the association between the downlink synchronization signal and the time-frequency domain position occupied by the PRACH. Thus, the network device can indicate all or part of the downlink synchronization signal selected by the terminal device to the terminal device according to the request of the terminal device, and the downlink synchronization signal indicated by the network device can be used by the terminal device subsequently. For example, the network device can add information indicating the downlink synchronization signal in the RAR to indicate all or part of the downlink synchronization signal selected by the terminal device.

[0117] In some embodiments, the terminal device receives the RAR sent by the network device, and the RAR indicates all or part of the downlink synchronization signal selected by the terminal device.

[0118] In some examples, the RAR includes at least one of the following:

[0119] SSB index (SSB Index);

[0120] Index information of the downlink synchronization signal;

[0121] TCI state associated with the downlink synchronization signal.

[0122] In an example, the TCI state associated with the downlink synchronization signal can include the SSB index.

[0123] In an example, the index information of the downlink synchronization signal includes at least one of a time domain index and a frequency domain index. The frequency domain index includes at least one of an SS resource ID, an SS resource Index, and a synchronization signal port number.

[0124] Through the above scheme, the UE can select multiple network devices to serve the UE in the initial access stage, forming a UE-centered network (instead of a single network device-centered network), thereby improving the UE experience and smoothing the performance difference between the cell edge and the cell center.

[0125] The embodiment of the present application also provides an initial access method, which can be applied to a network device, such as a TRP. FIG. 6 is a schematic flowchart of an initial access method 600 according to an embodiment of the present application. The method can be optionally applied to the systems shown in FIGS. 1-4, but is not limited thereto. The method comprises at least part of the following content.

[0126] S610, the network device sends a downlink synchronization signal to the terminal device;

[0127] S620, the network device receives a PRACH sent by the terminal device;

[0128] S630, the network device determines the downlink synchronization signal selected by the terminal device according to a time-frequency domain position occupied by the PRACH and an association relationship between the downlink synchronization signal and the time-frequency domain position occupied by the PRACH.

[0129] The network device can comprise a TRP.

[0130] In an example, the downlink synchronization signal comprises an SSB.

[0131] In a future-oriented network (such as a 6G network) scenario, the network device can be a TRP or other device; the downlink synchronization signal can be an SSB or other signal, which is not listed here.

[0132] In some embodiments, the network device further sends a RAR to the terminal device, and the RAR indicates all or part of the downlink synchronization signals selected by the terminal device.

[0133] A plurality of network devices respectively perform the initial access method shown in FIG. 6 to determine the downlink synchronization signal selected by the terminal device, and determine part or all of the plurality of downlink synchronization signals selected by the terminal device for subsequent access of the terminal device, so that the terminal device can be served by the plurality of network devices in the initial access stage, forming a network centered on the terminal device (rather than a single network device).

[0134] The RAR can comprise at least one of the following:

[0135] an SSB index;

[0136] index information of the downlink synchronization signal;

[0137] a TCI state associated with the downlink synchronization signal.

[0138] The index information of the downlink synchronization signal can comprise at least one of a time domain index and a frequency domain index; the frequency domain index can comprise at least one of the following:

[0139] synchronization signal resource identifier;

[0140] synchronization signal resource index;

[0141] synchronization signal port number.

[0142] In some embodiments, the association between the downlink synchronization signal and the time-frequency domain location occupied by the PRACH includes an association between an SSB index and an RO occupied by the PRACH.

[0143] The association can be one-to-one, one-to-many, or many-to-one. For example, one SSB index is associated with one RO; or one SSB index is associated with multiple ROs; or multiple SSB indexes are associated with one RO.

[0144] In some embodiments, the association between the downlink synchronization signal and the time-frequency domain location occupied by the PRACH includes an association between index information of the downlink synchronization signal and the time-frequency domain location occupied by the PRACH.

[0145] The time-frequency domain location can include an RO.

[0146] The association can be one-to-one, one-to-many, or many-to-one. For example, one SSB index is associated with one RO; or one SSB index is associated with multiple ROs; or multiple SSB indexes are associated with one RO.

[0147] In the association, the index information of the downlink synchronization signal can include at least one of a time domain index and a frequency domain index. The frequency domain index can include at least one of:

[0148] synchronization signal resource identifier;

[0149] synchronization signal resource index;

[0150] synchronization signal port number.

[0151] In addition, each network device can send a system message to the terminal device, to provide the terminal device with an association between a downlink synchronization signal and a time-frequency domain position occupied by the PRACH. When sending the system message to one terminal device, the scheme for sending the system message by the multiple network devices can be an SFN-based scheme, that is, the multiple network devices send the same system message on the same time-frequency resource; correspondingly, the terminal device receiving the system message sent by the multiple network devices comprises: the terminal device receiving the system message sent by the multiple network devices on the same time-frequency resource. By using the SFN transmission scheme, no additional configuration is needed for the UE, and better downlink coverage can be provided.

[0152] Specific examples of the network device performing the method 600 of the embodiment can be referred to the related description of the network device, for example, the TRP, in the method 500 described above. For brevity, the description is not repeated here.

[0153] The embodiment is described in detail below with reference to the accompanying drawings.

[0154] Embodiment 1

[0155] In this embodiment, according to the setting of NR initial access, an initial access scheme for a UE to select and access multiple network devices (i.e., TRPs) is given. The scheme includes the following stages:

[0156] First stage: Transmission and measurement of SSB

[0157] In NR, the downlink synchronization signal is contained in the SSB, and the SSB contains the primary synchronization signal (PSS) and the secondary synchronization signal (SSS). In addition, the SSB also contains a PBCH. In FR1, one SSB burst set can contain 4 or 8 SSBs. In FR2, one SSB burst set can contain up to 64 SSBs.

[0158] SSBs in NR are transmitted in a TDM manner in time domain. For example, in one SSB burst set in FR2, SSBs in different time domain locations are distinguished by SSB index, whose value ranges from SSB index #0 to SSB index #63. The SSB index can be explicitly expressed by 3 bits of the payload of PBCH, and another 3 bits can be implicitly expressed by 8 different DMRS sequences. A UE can determine the SSB index of one SSB by the above two pieces of information, and then perform time domain synchronization within a system half frame according to the time domain location of different SSB indexes in a system half frame specified in the protocol.

[0159] Considering the actual deployment scenario of multiple TRPs, multiple TRPs share all SSB indexes in a system half frame. For example, TRP #1 uses SSB indexes #0 to #15, TRP #2 uses SSB indexes #16 to #31, TRP #3 uses SSB indexes #32 to #47, and TRP #4 uses SSB indexes #48 to #63. Although TDM SSBs will occupy a large amount of beam scanning time, UEs can synchronize different TRPs.

[0160] A UE measures SSBs from multiple TRPs and selects one or more strongest SSB indexes from TRPs that meet a condition for downlink synchronization and subsequent access. In some embodiments, the "condition met" can refer to the SSB-RSRP of the SSB being greater than or equal to a predefined threshold.

[0161] Figure 7 is a schematic diagram of a SSB transmission scheme of a multi-TRP (Multi-TRP) system according to an embodiment of the present application. As shown in Figure 7, the multi-TRP system includes three APs / TRPs, i.e., AP / TRP #1, AP / TRP #2 and AP / TRP #3. A SSB burst set includes 12 SSBs, and the indexes of the 12 SSBs are SSB index #1 to #12, respectively. In the SSB burst set, AP / TRP #1 transmits SSBs in four different directions, and the indexes of the four SSBs are SSB index #1, #2, #3 and #4, respectively. AP / TRP #2 transmits SSBs in four different directions, and the indexes of the four SSBs are SSB index #5, #6, #7 and #8, respectively. AP / TRP #3 transmits SSBs in four different directions, and the indexes of the four SSBs are SSB index #9, #10, #11 and #12, respectively. A UE receives the SSBs transmitted by the three APs / TRPs. In this embodiment, the SSB grouping based on TRP can be implemented by the NW.

[0162] Second stage, transmission and decoding of system information:

[0163] For system information, such as SIB 1 in NR, although it is a cell-specific system information, the NW needs to broadcast it in the covered area. Specifically, for any SSB index (corresponding to a downlink coverage direction), the NW schedules PDSCH through PDCCH to carry SIB 1.

[0164] This embodiment can use a multi-TRP transmission scheme to broadcast system information. In some embodiments, the multi-TRP transmission scheme is a SFN-based transmission scheme, i.e., multiple TRPs transmit the same PDCCH and PDSCH (carrying SIB 1) scheduled by the PDCCH on the same time and frequency domain resources. Figure 8 is a schematic diagram of a SIB 1 transmission scheme using a SFN scheme according to an embodiment of the present application. As shown in Figure 8, multiple APs / TRPs transmit the same system information on the same time and frequency resources.

[0165] The technical advantage of the SFN scheme is that no additional configuration is needed for the UE, and the transmission scheme is relatively transparent to the receiver of the UE. Compared with the single-TRP transmission scheme, the SFN transmission scheme can provide better downlink coverage.

[0166] From the system information, the UE can decode the configuration information of RACH in initial access, which includes the time-frequency domain location information of PRACH transmission, and the association information between SSB index and RO occupied by PRACH transmission. In the NR system, the association between SSB index and RO can be one-to-one, one-to-many, or many-to-one; for example, one SSB index is associated with one RO, or one SSB index is associated with multiple ROs, or multiple SSB indexes are associated with one RO.

[0167] The third stage is UE-centered PRACH transmission:

[0168] The UE transmits PRACH to the TRP corresponding to the selected SSB; for example, transmits PRACH on the RO corresponding to the selected SSB, so that the network side knows which SSBs are selected by the UE and which TRPs correspond to the SSBs selected by the UE. In the UE-centered scenario, the UE can select multiple TRPs to serve it.

[0169] In some embodiments, when the SSB index and the RO are in a many-to-one relationship (i.e., multiple SSB indexes are associated with one RO), the UE transmitting PRACH on one RO can correspond to multiple SSBs (corresponding to one or more TRPs). The transmit spatial filter of each PRACH of the UE corresponds to the receive spatial filter of the SSB selected by the UE.

[0170] In some other embodiments, when the SSB index and the RO are in a one-to-one relationship, the UE selects N (N is a positive integer) SSBs, determines N ROs corresponding to the N SSBs according to the association relationship, and transmits N times of PRACH on the N ROs. The transmit spatial filter of each PRACH of the UE corresponds to the receive spatial filter of the SSB selected by the UE.

[0171] In some other embodiments, when the SSB index and the RO are in a one-to-many relationship (i.e., one SSB index is associated with multiple ROs), the UE selects N (N is a positive integer) SSBs, determines one RO from the multiple ROs associated with each SSB, a total of N ROs, and transmits N times of PRACH on the N ROs. The transmit spatial filter of each PRACH of the UE corresponds to the receive spatial filter of the SSB selected by the UE.

[0172] By transmitting PRACH on the RO associated with the SSB index, the NW can know the N SSB indexes selected by the UE, i.e., corresponding to one or more TRPs (such as N TRPs), by the RO on which the UE transmits PRACH.

[0173] Figure 9 is a schematic diagram of a transmission scheme of PRACH in an embodiment of the present application. In the example shown in Figure 9, three network devices (such as APs / TRPs) transmit SSBs respectively, and the three network devices include AP / TRP #1, AP / TRP #2 and AP / TRP #3; in a system half-frame, each AP / TRP transmits four SSBs in four different directions in turn. The UE receives and measures the SSBs transmitted by the three APs / TRPs, and selects three SSBs according to the measurement results of the SSBs received from the three APs / TRPs, the three SSBs being transmitted by different APs / TRPs respectively. The UE transmits PRACH on the RO associated with the selected SSBs according to the selected SSBs and the association relationship between SSB indexes and ROs, and the transmission spatial filter of each PRACH of the UE corresponds to the reception spatial filter of the selected SSB; the PRACH transmitted by the UE can be received by different APs / TRPs respectively. In the example shown in Figure 9, each AP / TRP can receive one PRACH, and can determine the index of the SSB selected by the UE according to the RO where the PRACH is located.

[0174] Fourth stage, indication of access TRP:

[0175] When the NW receives the PRACH from the UE on the corresponding RO resource, the index of the SSB selected by the UE can be determined according to the association relationship between the SSB index and the RO. The NW can indicate all or part of the SSB indexes selected by the UE to the UE for subsequent use according to the request of the UE. In some embodiments, the NW adds the index information of the SSB in the subsequent RAR, which includes all or part of the SSB indexes selected by the UE.

[0176] For subsequent Msg.3 uplink transmission and / or Msg.4 downlink reception, a multi-TRP transmission scheme can be used, which is not described here.

[0177] Embodiment 2:

[0178] In this embodiment, a multi-TRP selection and access scheme is designed for the initial access scheme of a future-oriented network (such as a 6G network). Since the future-oriented network may be designed based on NR for the initial access scheme, this embodiment no longer uses the assumption completely compatible with NR (such as the design of SSB). This embodiment includes the following stages:

[0179] First stage, transmission and measurement of downlink synchronization reference signal:

[0180] The downlink synchronization signal in the future-oriented network (such as a 6G network) system can no longer use the structure of the SSB in the NR, therefore, the downlink synchronization signal in this embodiment is used as a broad concept, and it should be noted that other signals that are the same as or correspond to the function of the downlink synchronization signal also belong to the technical scope of this embodiment.

[0181] In some embodiments, the downlink synchronization signal (DownLink Synchronization Signals, DL SS) in the new system (such as a 6G system) can use a more time-saving multiplexing mode for transmission, such as frequency division multiplexing (FDM), time division multiplexing (SDM), code division multiplexing (CDM), or a combination of multiple multiplexing modes, as shown in FIG. 10.

[0182] For example, the transmission of the downlink synchronization signal can use the FDM+TDM transmission mode, and FIG. 11 is a schematic diagram of a downlink synchronization signal multiplexing mode according to an embodiment of the present application. Considering that the main function of the downlink synchronization signal is downlink synchronization, therefore, the downlink synchronization signals transmitted at the same time have the same time domain index, similar to the SSB index of the TDM transmission in the NR. Specifically, the different synchronization signals measured by the UE at the same time all represent the same system time, so that the problem of inconsistent downlink time is not caused. This way can enable the UE to complete the beam scanning of the downlink synchronization signal in a shorter time, reducing the latency of the initial access of the UE.

[0183] Considering the TDM+FDM multiplexing mode in the multi-TRP scenario, this embodiment designs a signaling structure of the downlink synchronization signal hierarchy.

[0184] In some embodiments, at a specific time, a TRP transmits multiple downlink synchronization signals (part of FDM). The downlink synchronization signals have the same time domain index. The downlink synchronization signals can be represented by different resource IDs, different resource indexes (index), or different synchronization signal ports (SS Port) in the frequency domain. Each resource ID / resource index / synchronization signal port corresponds to a downlink beam direction, that is, corresponds to a transmit spatial filter. FIG. 12 is a schematic diagram of a downlink synchronization signal and multi-TRP (multi-TRP) transmission according to an embodiment of the present application, in the example shown in FIG. 12, multiple TRPs (such as TRP#1 and TRP#2 and more TRPs) share all the TDM+FDM multiplexed synchronization signals. It should be noted that in the example shown in FIG. 12, the downlink beam direction is taken as an example for introduction by using the synchronization signal port (SS Port); this embodiment can also use resource ID, resource index, etc. to correspond to the downlink beam direction.

[0185] UE measures downlink synchronization signals from multiple TRPs. When the link quality (e.g., L1-RSRP) of a certain resource ID / resource index / synchronization signal port is higher than a certain pre-defined threshold, the UE can select the corresponding resource ID / resource index / synchronization signal port of the synchronization signal as a usable downlink beam direction (i.e., downlink receive spatial filter). In order to implement UE-centric network, the UE can select N downlink synchronization signals from N TRPs, where N is greater than or equal to 1.

[0186] In addition, in some embodiments, the UE can select more than one beam direction for one TRP, for example, the UE selects 2 downlink beam directions (i.e., 2 ports) of TRP #1. Finally, the UE can select N beam directions, but the number of TRPs is less than N.

[0187] Second stage, transmission and decoding of system messages:

[0188] For subsequent system messages, such as SIB 1, the NW can use multi-TRP transmission. This stage is similar to the implementation of the second stage in Embodiment 1. The NW needs to broadcast in the covered area. Specifically, for any SSB (corresponding to a downlink coverage direction), the NW schedules PDSCH through PDCCH to carry SIB 1.

[0189] This embodiment can use multi-TRP transmission to broadcast system messages. In some embodiments, the multi-TRP transmission scheme is an SFN-based scheme, i.e., multiple TRPs transmit the same PDCCH and scheduled PDSCH (carrying SIB 1) on the same time and frequency domain resources. The way of transmitting SIB 1 using the SFN scheme in this embodiment can refer to FIG. 8 in Embodiment 1, which will not be described here.

[0190] The technical advantage of the SFN scheme is that no additional configuration is needed for the UE, and the transmission scheme is relatively transparent to the UE receiver. Compared with the single-TRP transmission scheme, the SFN transmission scheme can provide better downlink coverage.

[0191] From the system messages, the UE can decode the configuration information of RACH in initial access, which includes time-frequency domain location information of PRACH transmission, and index information of downlink synchronization signals and association information between the time-frequency domain location occupied by PRACH transmission. In some embodiments, the index information of the downlink synchronization signal can include at least one of the time domain index and the frequency domain index; in an example, the frequency domain index can include at least one of the synchronization signal resource identifier, the synchronization signal resource index, and the synchronization signal port number.

[0192] In some embodiments, the association between the index information (time domain index and / or frequency domain index) of the downlink synchronization signal and the time-frequency domain location of the PRACH can be one-to-one, one-to-many, or many-to-one; for example, one index information of the downlink synchronization signal is associated with one time-frequency domain location, or one index information of the downlink synchronization signal is associated with multiple time-frequency domain locations, or multiple index information of the downlink synchronization signal is associated with one time-frequency domain location.

[0193] The third stage is the PRACH transmission from the UE perspective:

[0194] From the system message, the UE can decode the configuration information of the RACH in the initial access, including the time-frequency domain location information (such as the configuration of the RO) of the PRACH, the multiple preambles (Preamble) that can be selected for the RO, and the association information between the downlink synchronization signal and the time-frequency domain location of the PRACH.

[0195] In some embodiments, the port number and / or time domain index of the downlink synchronization signal are associated with the RO. For example, one port number and one time domain index of one downlink synchronization signal are associated with one RO.

[0196] In some other embodiments, the resource ID and / or time domain index of the downlink synchronization signal are associated with the RO. For example, one resource ID and one time domain index of one downlink synchronization signal are associated with one RO.

[0197] In some other embodiments, the resource index and / or time domain index of the downlink synchronization signal are associated with the RO. For example, one resource index and one time domain index of one downlink synchronization signal are associated with one RO.

[0198] When the UE decodes the system message, it obtains the association between the downlink synchronization signal and the time-frequency domain location of the PRACH. Next, the UE transmits the PRACH to the TRP at the time-frequency domain location associated with the selected downlink synchronization signal. In the UE-centric scenario, the UE can naturally select multiple TRPs to serve it. Similarly, the UE can select one or more beams from one TRP to serve it.

[0199] The UE transmits the PRACH to the TRP corresponding to the selected downlink synchronization signal; for example, the PRACH is transmitted on the time-frequency domain resource corresponding to the selected downlink synchronization signal, so that the network side knows which downlink synchronization signal is selected by the UE and which TRP corresponds to the downlink synchronization signal selected by the UE. In the UE-centric scenario, the UE can select multiple TRPs to serve it.

[0200] In some embodiments, when the downlink synchronization signal and the time-frequency domain resource are in a many-to-one relationship (i.e., the index information of multiple downlink synchronization signals is associated with one time-frequency domain resource), the UE sends one PRACH on one time-frequency domain resource, which can correspond to multiple downlink synchronization signals (corresponding to one or more TRPs). The transmit spatial filter of each PRACH of the UE corresponds to the receive spatial filter of the selected SSB.

[0201] In some other embodiments, when the downlink synchronization signal and the time-frequency domain resource are in a one-to-one relationship, the UE selects N (N is a positive integer) downlink synchronization signals, determines N time-frequency domain resources corresponding to the N downlink synchronization signals, and sends N PRACHs on the N time-frequency domain resources. The transmit spatial filter of each PRACH of the UE corresponds to the receive spatial filter of the selected downlink synchronization signal.

[0202] In some other embodiments, when the downlink synchronization signal and the time-frequency domain resource are in a one-to-many relationship (i.e., the index information of one downlink synchronization signal is associated with multiple time-frequency domain resources), the UE selects N (N is a positive integer) downlink synchronization signals, determines one time-frequency domain resource from the multiple time-frequency domain resources associated with each downlink synchronization signal, and determines N time-frequency domain resources in total, and sends N PRACHs on the determined N time-frequency domain resources. The transmit spatial filter of each PRACH of the UE corresponds to the receive spatial filter of the selected downlink synchronization signal.

[0203] In some embodiments, the UE sends one PRACH to the TRP of each selected downlink synchronization signal. The UE sends at most N PRACHs, corresponding to N different TRPs. The transmit spatial filter of each PRACH corresponds to the receive spatial filter of the selected downlink synchronization signal. In this embodiment, the transmission scheme of the PRACH can refer to the example shown in FIG. 9 in Embodiment 1, which will not be described here.

[0204] Fourth stage, indication of access TRP:

[0205] When the NW receives multiple PRACHs from the UE on the corresponding time-frequency domain resources, it can infer the multiple TRPs selected by the UE and the corresponding downlink transmission beams according to the association relationship. Next, the NW comprehensively considers the load conditions of the multiple TRPs deployed by it, and indicates the selected TRP or part of the TRP to serve the UE.

[0206] In some embodiments, the NW indicates the index information (e.g., time domain index and / or frequency domain index) of the downlink reference synchronization signals corresponding to all or part of the PRACH in the subsequent RAR. The UE accesses the multiple TRPs at the earliest time according to the indication in the RAR. The signaling (e.g., Msg.3 and Msg.4) interaction in the initial access stage after the RAR can use the multi-TRP transmission mode.

[0207] In some other embodiments, the NW can more indirectly indicate the indication information of the TRP selected by the UE, such as using a unified TCI state. The NW indicates the TCI state corresponding to all or part of the downlink synchronization signals. The UE accesses the multiple TRPs according to the indicated TCI state.

[0208] It should be noted that in the case where the UE does not enter the RRC connected state, the TCI state indicated by the NW is notified to the UE in the SIB 1. Therefore, the UE already knows the correspondence between the TCI state and the synchronization signal, such as the spatial domain relationship of QCL-TypeD (TypeD), before sending the RACH.

[0209] The present application also proposes a terminal device, and FIG. 13 is a schematic block diagram of a terminal device 1300 according to an embodiment of the present application. The terminal device 1300 can include:

[0210] A first processing module 1310 is configured to measure downlink synchronization signals sent by multiple network devices, and select, according to a measurement result, downlink synchronization signals sent by one or more network devices from among the downlink synchronization signals sent by the multiple network devices.

[0211] The present application also proposes a terminal device, and FIG. 14 is a schematic block diagram of a terminal device 1400 according to an embodiment of the present application. The terminal device 1400 can include a first processing module 1310 and a first transceiver module 1420. The first processing module 1310 is further configured to determine, according to an association relationship between the downlink synchronization signals and time-frequency domain positions occupied by the PRACH, a time-frequency domain position corresponding to the selected downlink synchronization signal.

[0212] The first transceiver module 1420 is configured to send the PRACH at the time-frequency domain position.

[0213] In some embodiments, the first transceiver module 1420 is further configured to receive an RAR sent by the network device, the RAR indicating all or part of the downlink synchronization signals selected by the terminal device.

[0214] In some embodiments, the downlink synchronization signals include SSBs.

[0215] In some embodiments, the association between the downlink synchronization signal and the time-frequency domain location occupied by the PRACH includes:

[0216] an association between an SSB index and an RO occupied by the PRACH.

[0217] In some embodiments, the association includes:

[0218] one SSB index is associated with one RO; or,

[0219] one SSB index is associated with multiple ROs; or,

[0220] multiple SSB indexes are associated with one RO.

[0221] In some embodiments, the association between the downlink synchronization signal and the time-frequency domain location occupied by the PRACH includes:

[0222] an association between index information of a downlink synchronization signal and the time-frequency domain location occupied by the PRACH.

[0223] In some embodiments, the time-frequency domain location includes an RO.

[0224] In some embodiments, the association includes:

[0225] one index information of a downlink synchronization signal is associated with one time-frequency domain location occupied by the PRACH; or,

[0226] one index information of a downlink synchronization signal is associated with multiple time-frequency domain locations occupied by the PRACH; or,

[0227] multiple index information of downlink synchronization signals is associated with one time-frequency domain location occupied by the PRACH.

[0228] In some embodiments, the RAR contains at least one of:

[0229] an SSB index;

[0230] index information of a downlink synchronization signal;

[0231] an association for indicating a TCI state of a downlink synchronization signal.

[0232] In some embodiments, the index information of the downlink synchronization signal includes at least one of a time domain index and a frequency domain index.

[0233] In some embodiments, the frequency domain index includes at least one of:

[0234] a synchronization signal resource identifier;

[0235] synchronization signal resource index;

[0236] synchronization signal port number.

[0237] In some embodiments, the first transceiver 1420 is further configured to receive the system information transmitted by the plurality of network devices.

[0238] The first processing module 1310 is further configured to decode the system information to obtain the association between the downlink synchronization signals and the time-frequency domain positions occupied by the PRACH.

[0239] In some embodiments, the first transceiver 1420 is configured to receive the system information transmitted by the plurality of network devices on the same time-frequency resource.

[0240] In some embodiments, the network device comprises a transmission reception point (TRP).

[0241] The terminal device 1300 and the terminal device 1400 of the embodiments of the present application can realize the corresponding functions of the terminal device in the foregoing method embodiments. The corresponding processes, functions, implementation manners, and beneficial effects of the various modules (sub-modules, units, or components, etc.) in the terminal device 1300 and the terminal device 1400 can be referred to the corresponding description in the foregoing method embodiments, which will not be described here. It should be noted that the functions described with respect to the various modules (sub-modules, units, or components, etc.) in the terminal device 1300 and the terminal device 1400 of the embodiments of the present application can be realized by different modules (sub-modules, units, or components, etc.), or can be realized by the same module (sub-module, unit, or component, etc.).

[0242] FIG. 15 is a schematic block diagram of a network device 1500 according to an embodiment of the present application. The network device 1500 can comprise:

[0243] The second transceiver 1510 is configured to transmit a downlink synchronization signal to a terminal device, and receive a PRACH transmitted by the terminal device.

[0244] The second processing module 1520 is configured to determine a downlink synchronization signal selected by the terminal device according to the time-frequency domain position occupied by the PRACH and the association between the downlink synchronization signals and the time-frequency domain positions occupied by the PRACH.

[0245] In some embodiments, the second transceiver 1510 is further configured to,

[0246] transmit a RAR to the terminal device, the RAR indicating all or part of the downlink synchronization signals selected by the terminal device.

[0247] In some embodiments, the downlink synchronization signal comprises a synchronization signal block (SSB).

[0248] In some embodiments, the association between the downlink synchronization signal and the time-frequency domain location occupied by the PRACH includes:

[0249] an association between an SSB index and an RO occupied by the PRACH.

[0250] In some embodiments, the association includes:

[0251] one SSB index is associated with one RO; or,

[0252] one SSB index is associated with multiple ROs; or,

[0253] multiple SSB indexes are associated with one RO.

[0254] In some embodiments, the association between the downlink synchronization signal and the time-frequency domain location occupied by the PRACH includes:

[0255] an association between index information of a downlink synchronization signal and the time-frequency domain location occupied by the PRACH.

[0256] In some embodiments, the time-frequency domain location includes an RO.

[0257] In some embodiments, the association includes:

[0258] one index information of a downlink synchronization signal is associated with one time-frequency domain location occupied by the PRACH; or,

[0259] one index information of a downlink synchronization signal is associated with multiple time-frequency domain locations occupied by the PRACH; or,

[0260] multiple index information of downlink synchronization signals are associated with one time-frequency domain location occupied by the PRACH.

[0261] In some embodiments, the RAR contains at least one of:

[0262] an SSB index;

[0263] index information of a downlink synchronization signal;

[0264] a TCI state indicating an associated downlink synchronization signal.

[0265] In some embodiments, the index information of the downlink synchronization signal includes at least one of a time domain index and a frequency domain index.

[0266] In some embodiments, the frequency domain index includes at least one of:

[0267] a synchronization signal resource identifier;

[0268] Synchronization signal resource index;

[0269] Synchronization signal port number.

[0270] In some embodiments, the network device comprises a TRP.

[0271] The network device 1500 of the embodiments of the present application can realize the corresponding functions of the network device in the foregoing method embodiments. The corresponding processes, functions, implementation manners, and beneficial effects of each module (sub-module, unit, or component, etc.) in the network device 1500 can be referred to the corresponding description in the foregoing method embodiments, which will not be described here. It should be noted that the functions described with respect to each module (sub-module, unit, or component, etc.) in the network device 1500 of the embodiments of the present application can be realized by different modules (sub-modules, units, or components, etc.), or can be realized by the same module (sub-module, unit, or component, etc.).

[0272] FIG. 16 is a schematic structural diagram of a communication device 1600 according to the embodiments of the present application. The communication device 1600 comprises a processor 1610. The processor 1610 can invoke and run a computer program from a memory to enable the communication device 1600 to implement the methods in the embodiments of the present application.

[0273] In an embodiment, the communication device 1600 can further comprise a memory 1620. The processor 1610 can invoke and run a computer program from the memory 1620 to enable the communication device 1600 to implement the methods in the embodiments of the present application.

[0274] The memory 1620 can be a separate device independent of the processor 1610, or can be integrated in the processor 1610.

[0275] In an embodiment, the communication device 1600 can further comprise a transceiver 1630. The processor 1610 can control the transceiver 1630 to communicate with other devices. Specifically, the transceiver 1630 can send information or data to other devices, or receive information or data sent by other devices.

[0276] The transceiver 1630 can comprise a transmitter and a receiver. The transceiver 1630 can further comprise an antenna, and the number of antennas can be one or more.

[0277] In an embodiment, the communication device 1600 can be a network device of the embodiments of the present application, and the communication device 1600 can realize the corresponding processes realized by the network device in the various methods of the embodiments of the present application. For brevity, details will not be described here.

[0278] In an embodiment, the communication device 1600 can be a terminal device of the embodiments of the present application, and the communication device 1600 can implement the corresponding procedures implemented by the terminal device in each method of the embodiments of the present application. For brevity, details are not repeated here.

[0279] FIG. 17 is a schematic structural diagram of a chip 1700 according to an embodiment of the present application. The chip 1700 includes a processor 1710, which can call and run a computer program from a memory to implement the method in the embodiments of the present application.

[0280] In an embodiment, the chip 1700 can further include a memory 1720. The processor 1710 can call and run a computer program from the memory 1720 to implement the method performed by the terminal device or the network device in the embodiments of the present application.

[0281] The memory 1720 can be a separate device independent of the processor 1710, or can be integrated in the processor 1710.

[0282] In an embodiment, the chip 1700 can further include an input interface 1730. The processor 1710 can control the input interface 1730 to communicate with other devices or chips, and specifically, can obtain information or data sent by other devices or chips.

[0283] In an embodiment, the chip 1700 can further include an output interface 1740. The processor 1710 can control the output interface 1740 to communicate with other devices or chips, and specifically, can output information or data to other devices or chips.

[0284] In an embodiment, the chip can be applied to the network device in the embodiments of the present application, and the chip can implement the corresponding procedures implemented by the network device in each method of the embodiments of the present application. For brevity, details are not repeated here.

[0285] In an embodiment, the chip can be applied to the terminal device in the embodiments of the present application, and the chip can implement the corresponding procedures implemented by the terminal device in each method of the embodiments of the present application. For brevity, details are not repeated here.

[0286] The chip applied to the network device and the terminal device can be the same chip or different chips.

[0287] It should be understood that the chip mentioned in the embodiments of the present application can also be referred to as a system-level chip, a system chip, a chip system, or a system-on-chip chip, etc.

[0288] The aforementioned processor can be a general-purpose processor, a digital signal processor (DSP), a field programmable gate array (FPGA), an application specific integrated circuit (ASIC), or other programmable logic device, a transistor logic device, a discrete hardware component, and the like. Among them, the aforementioned general-purpose processor can be a microprocessor or any conventional processor, etc.

[0289] The aforementioned memory can be a volatile memory or a non-volatile memory, or can include both volatile and non-volatile memories. Among them, the non-volatile memory can be a read-only memory (ROM), a programmable ROM (PROM), an erasable PROM (EPROM), an electrically EPROM (EEPROM), or a flash memory. The volatile memory can be a random access memory (RAM).

[0290] It should be understood that the aforementioned memory is an exemplary but non-limiting description, for example, the memory in the embodiments of the present application can also be a static RAM (SRAM), a dynamic RAM (DRAM), a synchronous DRAM (SDRAM), a double data rate SDRAM (DDR SDRAM), an enhanced SDRAM (ESDRAM), a synch link DRAM (SLDRAM), and a direct memory bus RAM (Direct Rambus RAM, DR RAM), etc. That is, the memory in the embodiments of the present application is intended to include but not limited to these and any other suitable type of memory.

[0291] FIG. 18 is a schematic block diagram of a communication system 1800 according to an embodiment of the present application. The communication system 1800 includes a terminal device 1810 and a plurality of network devices 1820.

[0292] A terminal device includes:

[0293] The first processing module is configured to measure downlink synchronization signals transmitted by a plurality of network devices, and select one or more downlink synchronization signals transmitted by a plurality of network devices according to the measurement results.

[0294] A network device includes:

[0295] The second transceiver is configured to transmit a downlink synchronization signal to a terminal device, and receive a PRACH transmitted by the terminal device.

[0296] The second processing module is configured to determine the downlink synchronization signal selected by the terminal device according to a time-frequency domain position occupied by the PRACH, and an association between the downlink synchronization signal and the time-frequency domain position occupied by the PRACH.

[0297] The terminal device 1810 can be configured to implement the corresponding functions of the terminal device in the above method, and the network device 1820 can be configured to implement the corresponding functions of the network device in the above method. For brevity, details are not repeated here.

[0298] In the above embodiments, all or part of the embodiments can be implemented by software, hardware, firmware or any combination thereof. When implemented by software, all or part of the embodiments can be implemented in the form of a computer program product. The computer program product includes one or more computer instructions. When loaded and executed by a computer, all or part of the computer program instructions generate a process or function according to the embodiments of the present application. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable devices. The computer instructions can be stored in a computer readable storage medium or transmitted from one computer readable storage medium to another computer readable storage medium, for example, the computer instructions can be transmitted from one website, computer, server or data center to another website, computer, server or data center through wired (such as coaxial cable, optical fiber, digital subscriber line (Digital Subscriber Line, DSL)) or wireless (such as infrared, wireless, microwave, etc.) mode. The computer readable storage medium can be any available medium that can be accessed by a computer or a data storage device such as a server, data center, etc. integrated with one or more available media. The available medium can be a magnetic medium (for example, floppy disk, hard disk, magnetic tape), optical medium (for example, DVD), or semiconductor medium (for example, solid state disk (Solid State Disk, SSD)) and the like.

[0299] It should be understood that the size of the sequence number of each process described above in various embodiments of the present application does not mean the order of execution, the execution order of each process should be determined by its function and inherent logic, and should not constitute any limitation on the implementation process of the embodiments of the present application.

[0300] Those skilled in the art can clearly understand that, for the convenience and brevity of the description, the specific working process of the system, device and unit described above can refer to the corresponding process in the foregoing method embodiments, which will not be repeated here.

[0301] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited to this, any person skilled in the art can easily think of changes or replacements within the technical scope disclosed by the present application, which should be covered within the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A method for initial access, comprising: a terminal device measuring downlink synchronization signals transmitted by a plurality of network devices; the terminal device selecting, according to a measurement result, downlink synchronization signals transmitted by one or more network devices from among the downlink synchronization signals transmitted by the plurality of network devices.

2. The method of claim 1, further comprising: the terminal device determining, according to an association between the downlink synchronization signals and time-frequency domain positions occupied by transmission of a physical random access channel (PRACH), a time-frequency domain position corresponding to the selected downlink synchronization signals; the terminal device transmitting the PRACH at the time-frequency domain position.

3. The method of claim 2, further comprising: the terminal device receiving a random access response (RAR) transmitted by a network device, the RAR indicating all or part of the downlink synchronization signals selected by the terminal device.

4. The method of claim 2 or 3, wherein, The downlink synchronization signals comprise synchronization signal blocks (SSBs).

5. The method of claim 4, wherein, The association between the downlink synchronization signals and the time-frequency domain positions occupied by transmission of the PRACH comprises: an association between an SSB index and a random access channel occasion (RO) occupied by transmission of the PRACH.

6. The method of claim 5, wherein, The association comprises: one SSB index is associated with one RO; or one SSB index is associated with multiple ROs; or multiple SSB indexes are associated with one RO.

7. The method of claim 2 or 3, wherein, The association between the downlink synchronization signals and the time-frequency domain positions occupied by transmission of the PRACH comprises: an association between index information of a downlink synchronization signal and a time-frequency domain position occupied by transmission of the PRACH.

8. The method of claim 7, wherein, The time-frequency domain position comprises an RO.

9. The method of claim 7 or 8, wherein, The association comprises: one index information of a downlink synchronization signal is associated with one time-frequency domain position occupied by transmission of the PRACH; or one index information of a downlink synchronization signal is associated with multiple time-frequency domain positions occupied by transmission of the PRACH; or multiple index information of downlink synchronization signals are associated with one time-frequency domain position occupied by transmission of the PRACH.

10. The method of claim 3, wherein, The RAR comprises at least one of: an SSB index; index information of a downlink synchronization signal; a transmission configuration indication (TCI) state associated with a downlink synchronization signal.

11. The method of any one of claims 7-10, wherein, The index information of the downlink synchronization signal comprises at least one of:

12. The method of claim 11, wherein, a time domain index; and a frequency domain index. The frequency domain index comprises at least one of: a synchronization signal resource identifier; a synchronization signal resource index; and a synchronization signal port number.

14. The method of claim 13, wherein, 13. The method of any one of claims 2-12, further comprising: the terminal device receiving system messages transmitted by a plurality of network devices, and decoding the system messages to obtain the association between the downlink synchronization signals and the time-frequency domain positions occupied by transmission of the PRACH.

15. The method of any one of claims 1-14, wherein, The terminal device receiving system messages transmitted by a plurality of network devices comprises: the terminal device receiving the system messages transmitted by the plurality of network devices on the same time-frequency resources. The network device comprises a transmission reception point (TRP).

16. A method for initial access, comprising: a network device transmitting downlink synchronization signals to a terminal device; the network device receiving a PRACH transmitted by the terminal device; The network device determines the downlink synchronization signal selected by the terminal device according to the time-frequency domain position occupied by the PRACH and an association relationship between a downlink synchronization signal and a time-frequency domain position occupied by a PRACH.

17. The method of claim 16, further comprising, The network device sends a random access response (RAR) to the terminal device, the RAR indicating all or part of the downlink synchronization signals selected by the terminal device. The downlink synchronization signal comprises a synchronization signal block (SSB).

18. The method of claim 16 or 17, wherein, The association relationship between the downlink synchronization signal and the time-frequency domain position occupied by the PRACH comprises:

19. The method of claim 18, wherein, An association relationship between an SSB index and a random access channel occasion (RO) occupied by the PRACH. The association relationship comprises:

20. The method of claim 19, wherein, One SSB index is associated with one RO; or One SSB index is associated with multiple ROs; or Multiple SSB indexes are associated with one RO. The association relationship between the downlink synchronization signal and the time-frequency domain position occupied by the PRACH comprises:

21. The method of claim 16 or 17, wherein, An association relationship between index information of a downlink synchronization signal and a time-frequency domain position occupied by the PRACH. The time-frequency domain position comprises a RO.

22. The method of claim 21, wherein, The association relationship comprises:

23. The method of claim 21 or 22, wherein, Index information of one downlink synchronization signal is associated with one time-frequency domain position occupied by the PRACH; or Index information of one downlink synchronization signal is associated with multiple time-frequency domain positions occupied by the PRACH; or Index information of multiple downlink synchronization signals is associated with one time-frequency domain position occupied by the PRACH. The RAR comprises at least one of:

24. The method of claim 17, wherein, An SSB index; Index information of a downlink synchronization signal; A TCI state associated with a downlink synchronization signal. The index information of the downlink synchronization signal comprises at least one of a time domain index and a frequency domain index.

25. The method of any one of claims 21-24, wherein, The frequency domain index comprises at least one of:

26. The method of claim 25, wherein, A synchronization signal resource identifier; A synchronization signal resource index; A synchronization signal port number. The network device comprises a TRP.

27. The method of any one of claims 16-26, wherein, 28. A terminal device, comprising: A first processing module configured to measure downlink synchronization signals sent by multiple network devices; According to the measurement result, select downlink synchronization signals sent by one or more network devices from among the downlink synchronization signals sent by the multiple network devices.

29. The terminal device of claim 28, wherein the first processing module is further configured to determine a time-frequency domain position corresponding to the selected downlink synchronization signal according to an association relationship between a downlink synchronization signal and a time-frequency domain position occupied by a physical random access channel (PRACH). The terminal device further comprises a first transceiver module configured to send a PRACH at the time-frequency domain position.

30. The terminal device of claim 29, The first transceiver module is further configured to receive a random access response (RAR) sent by a network device, the RAR indicating all or part of the downlink synchronization signals selected by the terminal device. The downlink synchronization signal comprises a synchronization signal block (SSB).

31. The terminal device of claim 29 or 30, wherein, The association relationship between the downlink synchronization signal and the time-frequency domain position occupied by the PRACH comprises:

32. The terminal device of claim 31, wherein, An association relationship between an SSB index and a random access channel occasion (RO) occupied by the PRACH. ​ 33. The terminal device of claim 32, wherein, The association relationship includes: one SSB index is associated with one RO; or one SSB index is associated with multiple ROs; or multiple SSB indexes are associated with one RO.

34. The terminal device of claim 29 or 30, wherein, The association relationship between the downlink synchronization signal and the time-frequency domain position occupied by the PRACH includes: index information of the downlink synchronization signal and the time-frequency domain position occupied by the PRACH.

35. The terminal device of claim 34, wherein, The time-frequency domain position includes an RO.

36. The terminal device of claim 34 or 35, wherein, The association relationship includes: index information of one downlink synchronization signal is associated with one time-frequency domain position occupied by the PRACH; or index information of one downlink synchronization signal is associated with multiple time-frequency domain positions occupied by the PRACH; or index information of multiple downlink synchronization signals is associated with one time-frequency domain position occupied by the PRACH.

37. The terminal device of claim 30, wherein, The RAR includes at least one of the following: an SSB index; index information of a downlink synchronization signal; a TCI state used for indicating a downlink synchronization signal.

38. The terminal device of any one of claims 34-37, wherein, The index information of the downlink synchronization signal includes at least one of a time domain index and a frequency domain index.

39. The terminal device of claim 38, wherein, The frequency domain index includes at least one of the following: a synchronization signal resource identifier; a synchronization signal resource index; a synchronization signal port number.

40. The terminal device of any of claims 29-39, the first transceiver module is further configured to receive system messages transmitted by multiple network devices; the first processing module is further configured to decode the system messages to obtain the association relationship between the downlink synchronization signal and the time-frequency domain position occupied by the PRACH.

41. The terminal device of claim 40, wherein, The first transceiver module is configured to receive the system messages transmitted by the multiple network devices on the same time-frequency resource.

42. The terminal device of any one of claims 28-41, wherein, The network device includes a transmission reception point (TRP).

43. A network device, comprising: a second transceiver module configured to transmit a downlink synchronization signal to a terminal device; receive a PRACH transmitted by the terminal device; a second processing module configured to determine a downlink synchronization signal selected by the terminal device according to a time-frequency domain position occupied by the PRACH and an association relationship between the downlink synchronization signal and the time-frequency domain position occupied by the PRACH.

44. The network device of claim 43, the second transceiver module is further configured to: transmit a RAR to the terminal device, the RAR indicating all or part of the downlink synchronization signal selected by the terminal device.

45. The network device of claim 43 or 44, wherein, The downlink synchronization signal includes an SSB.

46. The network device of claim 45, wherein, The association relationship between the downlink synchronization signal and the time-frequency domain position occupied by the PRACH includes: an association relationship between an SSB index and an RO occupied by the PRACH.

47. The network device of claim 46, wherein, The association relationship includes: one SSB index is associated with one RO; or one SSB index is associated with multiple ROs; or multiple SSB indexes are associated with one RO.

48. The network device of claim 43 or 44, wherein, The association relationship between the downlink synchronization signal and the time-frequency domain position occupied by the PRACH includes: index information of the downlink synchronization signal and the time-frequency domain position occupied by the PRACH.

49. The network device of claim 48, wherein, The time-frequency domain position includes an RO.

50. The network device of claim 48 or 49, wherein, The association relationship includes: The index information of one downlink synchronization signal is associated with a time-frequency domain position occupied by one PRACH; or The index information of one downlink synchronization signal is associated with a time-frequency domain position occupied by multiple PRACHs; or The index information of multiple downlink synchronization signals is associated with a time-frequency domain position occupied by one PRACH.

51. The network device of claim 44, wherein, The RAR contains at least one of the following: an SSB index; index information of a downlink synchronization signal; a TCI state used for indicating an associated downlink synchronization signal.

52. The network device of any of claims 48-51, wherein, The index information of the downlink synchronization signal includes at least one of a time domain index and a frequency domain index.

53. The network device of claim 52, wherein, The frequency domain index includes at least one of the following: a synchronization signal resource identifier; a synchronization signal resource index; a synchronization signal port number.

54. The network device of any of claims 43-53, wherein, The network device includes a TRP.

55. A terminal device comprising: a transceiver, a processor and a memory, the memory being configured to store a computer program, the transceiver being configured to communicate with other devices, and the processor being configured to invoke and run the computer program stored in the memory, so that the terminal device performs the method according to any one of claims 1 to 15.

56. A network device comprising: a transceiver, a processor and a memory, the memory being configured to store a computer program, the transceiver being configured to communicate with other devices, and the processor being configured to invoke and run the computer program stored in the memory, so that the network device performs the method according to any one of claims 16 to 27.

57. A chip comprising: a processor configured to invoke and run a computer program from a memory, so that a device installed with the chip performs the method according to any one of claims 1 to 15.

58. A chip comprising: a processor configured to invoke and run a computer program from a memory, so that a device installed with the chip performs the method according to any one of claims 16 to 27.

59. A computer readable storage medium configured to store a computer program, which, when executed by a device, causes the device to perform the method according to any one of claims 1 to 15.

60. A computer readable storage medium configured to store a computer program, which, when executed by a device, causes the device to perform the method according to any one of claims 16 to 27.

61. A computer program product comprising computer program instructions, which cause a computer to perform the method according to any one of claims 1 to 15.

62. A computer program product comprising computer program instructions, which cause a computer to perform the method according to any one of claims 16 to 27.

63. A computer program, which causes a computer to perform the method according to any one of claims 1 to 15.

64. A computer program, which causes a computer to perform the method according to any one of claims 16 to 27.

65. A communication system comprising: a terminal device configured to perform the method according to any one of claims 1 to 15; and a network device configured to perform the method according to any one of claims 16 to 27.

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