Random access method and device

Abstract

The embodiment of the invention provides a random access method and device, relates to the technical field of communication, and aims to reduce the influence on the ongoing service of terminal equipment, improve the service quality and improve the user experience. The method comprises the following steps: the terminal equipment sends a random access lead code; the terminal equipment receives a random access response message, wherein the random access response message carries a time advance TA value; and under the condition that the TA value is greater than the first preset threshold, the terminal equipment retransmits the random access lead code.

Description

[0001] This application claims the priority of a Chinese patent application with the application number 202311820749.6 and the invention title "A Method and an Electronic Device for Improving the Performance of an Electronic Device" filed with the National Intellectual Property Administration on December 26, 2023, the entire content of which is incorporated herein by reference. Technical Field

[0002] Embodiments of this application relate to the field of communication technologies, and in particular, to a random access method and apparatus. Background Art

[0003] When a terminal device camps on a serving cell, it can receive a handover command from a network device (e.g., a base station) corresponding to the serving cell and initiate a random access on a target cell according to the handover command. The random access process may include the following steps: S1. The terminal device sends a random access preamble to a network device (e.g., a base station) corresponding to the target cell. S2. The network device corresponding to the target cell sends a random access response (RAR) to the terminal device. Thus, the terminal device can access the target cell.

[0004] However, after the terminal device accesses the target cell and sends uplink data on the target cell, there may be a problem that the network side cannot correctly decode the uplink data sent by the terminal device, which affects the services being carried out by the terminal device (e.g., the call being made by the terminal device may have no sound), reducing the user experience. Summary of the Invention

[0005] Embodiments of this application provide a random access method and apparatus to reduce the impact on the services being carried out by the terminal device, improve the service quality, and thus improve the user experience.

[0006] To achieve the above object, the embodiments of this application adopt the following technical solutions:

[0007] In a first aspect, embodiments of this application provide a random access method, including: the terminal device sends a random access preamble; the terminal device receives a random access response message, and a time advance (TA) value is carried in the random access response message; in a case where the TA value is greater than a first preset threshold, the terminal device retransmits the random access preamble.

[0008] Based on the method provided by the embodiments of this application, the terminal device can retransmit the random access preamble (Msg1) to request a new TA value and ignore the received excessive TA value. It can avoid the problem that the network side issues an excessive TA value, which affects the services being carried out by the terminal device (e.g., voice services or data services), and can improve the user experience.

[0009] In a possible implementation, the method further includes: when the TA value in the received random access response message is greater than a second preset threshold after the terminal device retransmits the random access preamble for the Nth time, the terminal device stops retransmitting the random access preamble; where N is an integer greater than or equal to 1. In this way, scenarios where the TA value required by the terminal device is relatively large (for example, the TA value actually required by the terminal device should be greater than the second preset threshold) can be accommodated. The terminal device can adjust the transmission timing of the uplink frame according to the relatively large TA value during subsequent uplink transmission processes.

[0010] In a possible implementation, before the terminal device transmits the random access preamble, the method further includes: when the terminal device camps on a first cell, the terminal device receives a radio resource control (RRC) connection reconfiguration message from a first network device, where the first network device is the network device corresponding to the first cell, and the RRC connection reconfiguration message carries first information for instructing the terminal device to switch to a second cell; the terminal device transmitting the random access preamble includes: the terminal device transmitting the random access preamble to a second network device according to the first information, where the second network device is the network device corresponding to the second cell. That is, the terminal device can transmit the random access preamble to the second network device (the network device corresponding to the second cell) according to the first information in the RRC connection reconfiguration message to switch to the second cell.

[0011] In a possible implementation, the method further includes: when the TA value in the received random access response message is greater than a second preset threshold after the terminal device retransmits the random access preamble for the Nth time, the terminal device sends an RRC connection reconfiguration complete message to the first network device; after the terminal device sends the RRC connection reconfiguration complete message to the first network device, the terminal device determines that a radio link failure (RLF) occurs in the second cell; the terminal device sends an RRC connection re-establishment message to a third network device, where the third network device is the network device corresponding to a third cell, and the third cell is different from the second cell. After the terminal device sends the RRC connection reconfiguration complete message to the first network device, during the communication process between the terminal device and the second cell, the terminal device can adjust the transmission timing of the uplink frame according to the relatively large TA value (i.e., the TA value greater than the second preset threshold). However, during the communication process between the terminal device and the second cell, the terminal device may experience an RLF. In this case, the terminal device can send an RRC connection re-establishment message to the third network device (the network device corresponding to the third cell) to establish an RRC connection with the network device corresponding to the third cell. This can avoid problems that affect the services (such as voice services or data services) being carried out by the terminal device and improve the user experience.

[0012] In a possible implementation, the terminal device determines that a radio link failure (RLF) occurs in the second cell, including: the terminal device determines that the uplink bit error rate of the terminal device in the second cell exceeds a third preset threshold. Wherein, the uplink bit error rate is an index for measuring the accuracy of uplink data transmission within a specified time. Uplink bit error rate = number of bit errors in uplink transmission / total number of bits transmitted in uplink transmission * 100%.

[0013] In a possible implementation, the method further includes: when the TA value in the received random access response message is greater than a second preset threshold after the terminal device retransmits the random access preamble for the Nth time, the terminal device determines that a radio link failure (RLF) occurs in the second cell; the terminal device sends an RRC connection re-establishment message to a third network device, where the third network device is the network device corresponding to the third cell, and the third cell is different from the second cell. That is, the situation where the TA value in the received random access response message is greater than the second preset threshold after the terminal device retransmits the random access preamble for the Nth time can trigger RLF. In this case, the terminal device can send an RRC connection re-establishment message to the third network device (the network device corresponding to the third cell) to establish an RRC connection with the network device corresponding to the third cell. This can avoid the problem of affecting the services (such as voice services or data services) being carried out by the terminal device and improve the user experience.

[0014] In a possible implementation, when the terminal device sends a random access preamble, it is in a high-speed moving state. The terminal device being in a high-speed moving state includes that the displacement of the terminal device within a preset time period is greater than a first preset threshold, and / or the average speed / acceleration of the terminal device within the preset time period is greater than a second preset threshold.

[0015] In a possible implementation, the first cell is a high-speed rail cell or a subway cell. Since the terminal device is usually in a high-speed moving state when camping on a high-speed rail cell or a subway cell. After the network side receives the random access preamble (Msg1) sent by the terminal device in a high-speed moving state, there will be a probabilistic situation where the calculation of the TA value is deviated, resulting in an overly large TA value carried in Msg2. Based on the method provided in the embodiments of the present application, the terminal device can retransmit the random access preamble (Msg1) to request a new TA value and ignore the received overly large TA value. This can avoid the problem of the network side sending an overly large TA value and affecting the services (such as voice services or data services) being carried out by the terminal device and improve the user experience.

[0016] In a possible implementation, the second cell is a high-speed rail cell or a subway cell. When the terminal device is preparing to hand over to a high-speed rail cell or a subway cell, the terminal device may be in a high-speed moving state. After the network side receives the random access preamble (Msg1) sent by the terminal device in the high-speed moving state, there may be a situation where the calculation of the TA value is deviated probabilistically, resulting in an overly large TA value carried in Msg2. Based on the method provided in the embodiments of the present application, the terminal device can retransmit the random access preamble (Msg1) to request a new TA value and ignore the received overly large TA value. It is possible to avoid the problem that the network side issues an overly large TA value and affects the services being carried out by the terminal device (such as voice services or data services), and the user experience can be improved.

[0017] In a possible implementation, the terminal device retransmitting the random access preamble to the second network device includes: the terminal device discards the random access response message and retransmits the random access preamble to the second network device. This situation can be understood as the terminal device ignoring the overly large TA value (i.e., the TA value greater than the first preset threshold) in Msg2 sent by the network device corresponding to the second cell for the first time and re-requesting the TA value from the network device corresponding to the second cell.

[0018] In a possible implementation, when the terminal device is camped on the first cell, receiving the radio resource control (RRC) connection reconfiguration message from the first network device includes: when the terminal device is camped on the first cell and performing a first service, receiving the RRC connection reconfiguration message from the first network device, where the first service includes a voice service or a data service.

[0019] In a possible implementation, the method further includes one or more of the following: the third cell is a high-speed rail cell or a subway cell; or, the first cell is a Long-Term Evolution (LTE) cell and the second cell is an LTE cell; or, the first cell is a New Radio (NR) cell and the second cell is an NR cell; or, the first cell is an LTE cell and the second cell is an NR cell; or, the first cell is an NR cell and the second cell is an LTE cell; or, the third cell is an LTE cell or an NR cell. That is, the terminal device switching from the first cell to the second / third cell can be an intra-system cell handover or an inter-system cell handover.

[0020] The present application provides some embodiments to improve the performance of the terminal and reduce the probability of service anomalies occurring on the terminal.

[0021] In a second aspect, an embodiment of the present application provides a method for improving the performance of a terminal device, including:

[0022] The terminal device sends a Msg1 message for initiating a random access process to the network side;

[0023] The terminal device receives a random access response message Msg2 sent by the network side, and the Msg2 message carries a time advance (TA) value.

[0024] When the TA value is greater than a first preset threshold, the terminal device retransmits the Msg1 message.

[0025] In some embodiments, when the TA value is greater than a first preset threshold, the terminal device retransmitting the Msg1 message includes:

[0026] When the TA value is greater than a first preset threshold, the terminal device discards the Msg2 message and retransmits the Msg1 message.

[0027] In some embodiments, before the terminal device sends a Msg1 message for initiating a random access procedure to the network side, the method further includes:

[0028] When the terminal device is camped on a first cell (such as the original cell shown in Figure 7 or Figure 8 ), the terminal device receives an RRC connection reconfiguration message (such as the RRCConnectionReconfiguration shown in Figure 7 or Figure 8 ) sent by the base station corresponding to the first cell. The RRC connection reconfiguration message carries first information, and the first information (such as the mobilityControlInfo shown in Figure 7 or Figure 8 , mobility control information) is used to instruct the terminal device to switch to a second cell (for example, the first information may carry information such as the cell ID and / or frequency point of the second cell);

[0029] The terminal device sending a Msg1 message for initiating a random access procedure to the network side includes:

[0030] The terminal device sends the Msg1 message to the base station corresponding to the second cell according to the first information.

[0031] In some embodiments, when the terminal device is camped on the first cell and receives an RRC connection reconfiguration message sent by the base station corresponding to the first cell, it includes:

[0032] When the terminal device is camped on the first cell and moving at high speed, the terminal device receives an RRC connection reconfiguration message sent by the base station corresponding to the first cell.

[0033] In some embodiments, the first cell is a high-speed rail cell. The second cell may be a high-speed rail cell or a non-high-speed rail cell. A high-speed rail cell may refer to a specific cell set along a high-speed rail line.

[0034] In some embodiments, the network modes of the first cell and the second cell are the same or different. For example, the first cell is an LTE cell and the second cell is an LTE cell; or, the first cell is an NR cell and the second cell is an NR cell; or, the first cell is an LTE cell and the second cell is an NR cell; or, the first cell is an NR cell and the second cell is an LTE cell.

[0035] In some embodiments, the method further includes:

[0036] After the terminal device retransmits the Msg1 message for the Nth time, when the TA value in the received Msg2 message is greater than a second preset threshold, the terminal device completes the random access procedure according to the Msg2 message (it can be understood that the random access procedure may include more messages in addition to Msg1 and Msg2), and then successfully accesses the second cell (such as Figure 8 the target cell shown in Figure 8 The RRC Connection Reconfiguration Complete message shown in

[0037] In some embodiments, the value of the second preset threshold may be the same as or different from the value of the first preset threshold.

[0038] In a third aspect, a terminal device is provided, including: a processor and a memory; the memory stores computer-executable instructions; the processor executes the computer-executable instructions stored in the memory, so that the terminal device executes the method described in any possible implementation manner of the first aspect or the second aspect.

[0039] In a fourth aspect, a chip system is provided, including at least one processor and a communication interface, the communication interface and the at least one processor are interconnected by a line, and the at least one processor is configured to run a computer program or instruction to execute the method described in any possible implementation manner of the first aspect or the second aspect.

[0040] In a fifth aspect, an embodiment of the present application provides a computer-readable storage medium, and the computer-readable storage medium stores a computer program. When the computer program is executed by a processor, the method described in any possible implementation manner of the first aspect or the second aspect is implemented.

[0041] In a sixth aspect, an embodiment of the present application provides a computer program product, which includes a computer program. When the computer program runs, it causes a computer to execute the method described in any possible implementation manner of the first aspect or the second aspect.

[0042] It can be understood that the terminal device provided in the above third aspect, the chip system provided in the fourth aspect, the computer storage medium provided in the fifth aspect, and the computer program product provided in the sixth aspect are all used to execute the method described in any implementation manner of the first aspect or the second aspect. Therefore, the beneficial effects that can be achieved can refer to the beneficial effects of any possible implementation manner in the above first aspect or the second aspect, and will not be elaborated here. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 FIG. 9 is a signal interaction schematic diagram of related technologies;

[0044] Figure 2 FIG. 13 is a schematic diagram of a network architecture provided by an embodiment of the present application;

[0045] Figure 3 FIG. 17 is another schematic diagram of a network architecture provided by an embodiment of the present application;

[0046] Figure 4 FIG. 21 is a schematic diagram of a voice call scenario provided by an embodiment of the present application;

[0047] Figure 5 FIG. 25 is a signal interaction schematic diagram applicable to a random access method provided by an embodiment of the present application;

[0048] Figure 6 FIG. 29 is a schematic diagram of the format of a RAR message provided by an embodiment of the present application;

[0049] Figure 7 FIG. 33 is another signal interaction schematic diagram provided by an embodiment of the present application;

[0050] Figure 8 FIG. 37 is another signal interaction schematic diagram provided by an embodiment of the present application;

[0051] Figure 9 FIG. 41 is a schematic diagram of the hardware structure of a terminal device provided by an embodiment of the present application;

[0052] Figure 10 FIG. 45 is a software structure block diagram of a terminal device provided by an embodiment of the present application;

[0053] Figure 11 FIG. 49 is a schematic diagram of the structure of a chip system provided by an embodiment of the present application. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0054] In order to make the description of the following embodiments clear and concise, a brief introduction to the relevant concepts or technologies is first given:

[0055] 1. Cell: A cell is an area within the wireless coverage of a network device (e.g., a base station). In this area, a terminal device can reliably communicate with the network device through wireless signals. It can be understood that the coverage of each network device can be divided into one or more cells, and each cell can correspond to one or more frequency points. It can also be understood that each cell is an area formed by the coverage of one or more frequency points.

[0056] In some embodiments of the present application, different cells may correspond to the same network device. For example, the network device to which the first cell belongs and the network device to which the second cell belongs may be the same network device. That is, the first cell and the second cell may be managed by the same base station. In this case, the first cell and the second cell may be referred to as being co-located.

[0057] In some embodiments of the present application, different cells may correspond to different network devices. For example, the network device to which the first cell belongs and the network device to which the second cell belongs may be different network devices. That is, the first cell and the second cell may be managed by different base stations. Alternatively, the first cell and the second cell may be managed by the same base station, but the radio frequency processing units corresponding to the first cell and the second cell are different radio frequency processing units in the same base station.

[0058] 2. Adjacent cell: It can also be called adjacent cell or neighboring cell. It refers to the area within the wireless coverage of the network equipment that is adjacent to the current serving cell, has a physical location association and transmits signals on the same frequency or different frequencies. In other words, the adjacent cell refers to the cell that is connected or adjacent to the current serving cell. In layman's terms, the adjacent cell can be understood as the "surrounding cell" of the current serving cell.

[0059] 3. Cell Handover (HO): Cell handover refers to the process of migrating the communication link between a terminal device and a current network device to another network device in mobile communications. In a wireless communication system, when a terminal device moves from one cell to another or approaches another cell, a cell handover is required to maintain uninterrupted communication of the terminal device.

[0060] Cell switching can be intra-site switching or inter-site switching, and this application does not impose specific restrictions on this. Intra-site switching means that the original cell (or source cell) and the target cell belong to the same network device (for example, a base station). Inter-site switching means that the source cell and the target cell belong to different network devices (for example, a base station).

[0061] In this application, the original cell refers to the cell that provides services to the terminal device before cell handover, and the target cell refers to the cell that provides services to the terminal device after cell handover.

[0062] In some scenarios, the terminal device can receive a handover command on the currently camped cell (i.e., the original cell), and initiate random access on the target cell according to the handover command. The random access process may include the following steps: S1. The terminal device selects a preamble index and a physical random access channel (PRACH) resource for transmitting the preamble, and transmits a random access preamble on this resource. S2. The base station sends a random access response to the terminal device. Thus, the terminal device can access the target cell.

[0063] However, after the terminal device accesses the target cell, there may be a problem that the uplink data sent by the terminal device on the target cell cannot be normally decoded on the network side, resulting in too high uplink bit error rate of the terminal device, affecting the normal services of the terminal device (for example, it may cause no sound in the ongoing call of the terminal device), and reducing the user experience.

[0064] For example, when the terminal device camps on a high-speed rail cell or a subway cell (i.e., the original cell is a high-speed rail cell or a subway cell), the terminal device can receive a handover message (such as an RRC connection reconfiguration message) from the network device corresponding to the high-speed rail cell or the subway cell, and this handover message is used to instruct the terminal device to hand over to the target cell. As Figure 1As shown in the figure, after receiving a handover message from the original cell, the terminal device can initiate random access on the target cell according to the handover message, that is, it can send a random access preamble (the random access preamble can also be referred to as Msg1) to the network device corresponding to the target cell. After receiving the random access preamble sent by the terminal device, the network device corresponding to the target cell can calculate a timing advance (TA) value based on the random access preamble, and can send a random access response message (the random access response message can also be referred to as Msg2) carrying the TA value to the terminal device. After receiving the random access response message (Msg2), the terminal device can adjust the transmission timing of the uplink data according to the TA value carried in Msg2. However, when the terminal device camps on a high-speed rail cell or a subway cell, it is usually in a high-speed moving state. After receiving the random access preamble (Msg1) sent by the terminal device in a high-speed moving state, the network device corresponding to the target cell will probabilistically have a deviation in the calculation of the TA value, resulting in an overly large TA value carried in Msg2. If the terminal device uses an overly large TA value to adjust the transmission timing of the uplink data in the target cell, it will cause a large deviation in the time domain of the uplink data, affecting the network side's decoding of the uplink data, thereby affecting the ongoing services of the terminal device (for example, the user suddenly experiences a silent call drop during high-speed rail travel), and reducing the user experience.

[0065] The embodiments of the present application provide a random access method to reduce the impact on the ongoing services of the terminal device, improve the service quality, and thus improve the user experience.

[0066] To better understand a communication method and related devices provided by the embodiments of the present application, the network architecture of the embodiments of the present application will be described below.

[0067] The network architecture of the embodiments of the present application may include at least two cells (for example, the first cell and the second cell) and at least one terminal device.

[0068] Exemplarily, please refer to Figure 2 , Figure 2 which is a schematic diagram of a network architecture provided by the embodiments of the present application. As Figure 2 shown, the network architecture may include a terminal device, a first cell belonging to network device a, a second cell belonging to network device b, and a third cell belonging to network device c. As Figure 2 shown, the cell where the terminal device currently camps may be the first cell. The movement trajectory of the terminal device may be from the first cell to the second cell / third cell. Among them, the second cell and the third cell may be neighboring cells (i.e., adjacent cells) of the first cell. The terminal device may be located on a train (for example, high-speed rail or subway). The first cell, the second cell, and the third cell may be high-speed rail cells or subway cells.

[0069] It can be understood that the network architecture provided in the embodiments of the present application may further include more cells, and the present application does not limit this. In some embodiments of the present application, a network device may correspond to one or more cells. The first cell, the second cell, and the third cell may belong to the same network device. That is to say, network device a, network device b, and network device c may be the same network device. In this case, the terminal device performs handover within the network device. Optionally, the first cell, the second cell, and the third cell may belong to network devices that are not completely the same. That is to say, network device a, network device b, and network device c may be network devices that are not completely the same. The first cell, the second cell, and the third cell belonging to network devices that are not completely the same may specifically include: at most two of the network devices to which the first cell belongs, the network device to which the second cell belongs, and the network device to which the third cell belongs are the same.

[0070] Please refer to Figure 3 , Figure 3 which is another schematic diagram of the network architecture exemplarily provided in the embodiments of the present application. As Figure 3 shown, this network architecture may include a terminal device, LTE, NR, a core network, and IMS or the Internet. The following is a specific introduction thereto:

[0071] (1) Terminal device: It can be a device that includes a wireless transceiver function and can cooperate with a network device (such as a base station) to provide communication services for users. The terminal device can be a mobile phone, or a wearable device (such as a smart watch), etc.

[0072] (2) LTE: It can be understood as the radio access network of the fourth-generation (4 th generation, 4G) mobile communication system. In the LTE network (i.e., the so-called 4G network), due to the evolution relationship, the access network part is called the Evolved UMTS Terrestrial Radio Access Network (E-UTRAN). In the present application, the meaning of LTE is the same as the meaning of E-UTRAN, both referring to the access network part of the 4G network. The terminal device can access LTE through a 4G base station. Among them, the 4G base station can be an evolved NodeB (eNB or eNodeB) in long term evolution (LTE).

[0073] (3) NR: It can be understood as the fifth-generation (5 thThe radio access network of a (5G) mobile communication system. In a 5G network, the access network part is called the Next Generation Radio Access Network (NG-RAN or NG RAN). In this application, the meaning of NR is the same as that of NG-RAN (or NG RAN), both referring to the access network part of a 5G network. A terminal device can access NR through a 5G base station. Among them, the 5G base station can be the next-generation base station (gNodeB, gNB) in new radio (NR). The base station in NR can also be called a transmission reception point (TRP).

[0074] It can be understood that both LTE and NR are access networks. The access network is responsible for using a certain wired or wireless connection and communication technology to converge a large number of end users level by level into the core network (also called the backbone network) to achieve connection with the network. The access network is the edge part of the entire network, the part closest to the user, and is usually also called "the last mile".

[0075] (4) Core network: Its main functions are to provide user connection, user management, and bearer for services, and to provide an interface to an external network as a bearer network. The establishment of user connection includes functions such as mobility management (MM), call management (CM), switching / routing, and announcement recording (combining intelligent network services to complete the connection relationship to intelligent network peripheral devices).

[0076] It can be understood that the core network of a 4G network is an evolved packet core (EPC) network. The EPC network is the core network of a 4G mobile communication network. It belongs to the category of the core network, has traditional capabilities of a mobile network such as user subscription data storage, mobility management, and data exchange, and can provide users with an ultra-high-speed Internet experience. The core network of a 5G network is 5G Core (which can be abbreviated as 5GC). 5GC will use general network function virtualization devices to replace the dedicated communication devices of a 4G network.

[0077] It should be noted that Figure 3The core network in the shown network architecture can be obtained by fusing the EPC and 5GC. That is to say, the core network in this network architecture can include both the network elements in the EPC and the network elements in the 5GC. For example, the core network in this network architecture can include network elements such as the access and mobility management function (AMF) network element, the mobility management entity (MME) network element, the serving gateway (SGW) network element, the packet data network gateway (PGW) network element, the session management function (SMF) network element, the user plane function (UPF) network element, the unified data management (UDM) network element, and the home subscriber server (HSS) network element, etc.

[0078] In some embodiments of the present application, the core network in this network architecture can include a converged network element obtained from the network elements in the EPC and the network elements in the 5GC. For example, SMF + PGW-C, UPF + PGW-U, UDM + HSS, etc. Among them, PGW-C is the control plane node of the PGW network element, and PGW-U is the user plane node of the PGW network element.

[0079] In some embodiments of the present application, Figure 3 The core network in the shown network architecture can include a proxy session border control (PSBC) network element, which is a co-located network element integrating session border control (SBC), proxy call session control function (Proxy-CSCF, P-CSCF), access transfer control function (ATCF), and access transfer gateway (ATGW). As an SBC network element, it connects the IMS core network / softswitch network to the external user access area, completes the service access of IMS / softswitch users, realizes the interworking of user services in different network environments, ensures the security of the IMS / softswitch network, supports QoS management, CAC traffic control, media management, CDR media call detail list, and other functions.

[0080] Each network element in the core network can also be referred to as a functional entity, which can be either a network component implemented on dedicated hardware, a software instance running on dedicated hardware, or an instance of a virtualized function on a suitable platform.

[0081] It should be understood that the names of all network elements in this application are only for illustration. In future communications, such as in 6G, they can also be called other names, or in future communications, such as in 6G, the network elements involved in this application can also be replaced by other entities or devices with the same functions, etc., and this application does not make any limitations in this regard. A unified explanation is made here and will not be repeated later. Optionally, various network elements in the embodiments of this application can be communication devices, or chips or chip systems that can be used in such communication devices, etc., and the embodiments of this application do not make any limitations in this regard.

[0082] It can be understood that Figure 3 The core network in the shown network architecture may also include other devices, network elements, network entities or network subsystems, such as a policy control function (PCF) network element, and this application does not make any restrictions in this regard. It should be noted that this application does not make any restrictions on the distribution method of each network element in the core network. The specific distribution method can refer to relevant technical documents, and this application will not expand on this here.

[0083] (5) IMS is a network architecture that provides voice and multimedia communication services (such as voice, video, and text messages, etc.) based on the Internet Protocol (IP) network. IMS can achieve secure and reliable multimedia communication between different devices on different networks. The architecture model provides a unified infrastructure and common mechanisms for controlling, operating, routing, and managing sessions, as well as for implementing authentication, authorization, and accounting control. The IMS specification includes widely used recommendations of the Internet Engineering Task Force (IETF). For example, the Session Initialization Protocol (SIP) for session control signaling.

[0084] The Internet generally refers to the Internet, also known as the international network, which refers to the huge network formed by connecting networks with each other. These networks are connected by a set of common protocols to form a logically single huge international network. From the perspective of network communication, the Internet is a data communication network that connects computer networks in various countries, regions, and institutions around the world with the Transmission Control Protocol (TCP) / Internet Protocol.

[0085] It should be noted thatFigure 3 In the network architecture shown, it is not limited to only including the devices and networks shown in the figure, and may also include other devices not shown in the figure. This application will not give further examples one by one.

[0086] Figure 2 The network devices a, b, and c in Figure 3 belong to LTE or NR in Figure 2 For example, the network devices a, b, and c can be 4G base stations (e.g., eNB) or 5G base stations (e.g., gNB).

[0087] Please refer to Figure 4 , Figure 4 which is a schematic diagram of a voice call scenario provided by an embodiment of this application. As Figure 4 shown, the terminal device 100 can transmit voice data to the terminal device 200 through the network device_1, IMS, and network device_2. Among them, the network device_1 is the network device corresponding to the cell where the terminal device 100 currently camps, and the network device_2 is the network device corresponding to the cell where the terminal device 200 currently camps. In some embodiments of this application, the network device_1 and the network device_2 can be the same network device. In some embodiments of this application, the terminal device 100 can be the party initiating the voice call to request a voice call with the terminal device 200. In still other embodiments of this application, the terminal device 200 can be the party initiating the voice call to request a voice call with the terminal device 100.

[0088] The network device in the embodiment of this application can be a device used to communicate with the terminal device. For example, the network device can be a base station.

[0089] Figure 2 The terminal device in Figure 4 can be the terminal device 100 or the terminal device 200 in Figure 2 The network devices a, b, and c in Figure 4 can be the network device_1 or the network device_2 in Figure 2 The first cell, the second cell, and the third cell in

[0090] The technical solutions of the embodiments of this application can be applied to various communication systems, such as: Global System for Mobile Communication (GSM) system, Code Division Multiple Access (CDMA) system, Wideband Code Division Multiple Access (WCDMA) system, General Packet Radio Service (GPRS), LTE system, LTE Frequency Division Duplex (FDD) system, LTE Time Division Duplex (TDD) system, Universal Mobile Telecommunications System (UMTS) system, Enhanced Data Rate for GSM Evolution (EDGE) system, Worldwide Interoperability for Microwave Access (WiMAX) system. The technical solutions of the embodiments of this application can also be applied to other communication systems, such as Public Land Mobile Network (PLMN) system, etc. The embodiments of this application do not make any limitation thereto.

[0091] The terminal device in the embodiments of this application can also be referred to as a terminal, user equipment (UE), user terminal, mobile station (MS), mobile terminal (MT), etc. The terminal device can be a handheld terminal, laptop computer, subscriber unit, cellular phone, smart phone, wireless data card, personal digital assistant (PDA) computer, tablet computer, wireless modem, handheld device, laptop computer, cordless phone, or wireless local loop (WLL) station, machine type communication (MTC) terminal, wearable device (such as a smart watch, smart bracelet, pedometer, etc.), vehicle-mounted device (such as a car, bicycle, electric vehicle, airplane, ship, train, high-speed train, etc.), virtual reality (VR) device, augmented reality (AR) device, wireless terminal in industrial control, smart home device (such as a refrigerator, TV, air conditioner, electricity meter, etc.), intelligent robot, workshop device, wireless terminal in self-driving, wireless terminal in remote medical surgery, wireless terminal in smart grid, wireless terminal in transportation safety, wireless terminal in smart city, wireless terminal in smart home, flying device (such as an intelligent robot, drone), or wireless terminal in a 5G network or future communication network, etc. The embodiments of this application do not make specific limitations on this.

[0092] The network device in the embodiments of this application may be a device for communicating with a terminal device. For example, the network device may be a base transceiver station (BTS) in a GSM system or a CDMA system, may also be a NodeB (NB) in a WCDMA system, may also be an eNB or eNodeB in an LTE system, may also be a radio controller in a cloud radio access network (CRAN) scenario, or the network device may be a relay station, an access point, a vehicle-mounted device, a wearable device, and a network device in a future 5G network or a network after 5G, or a network device in a future evolved PLMN network, etc. For example, a transmission point (TRP or TP) in an NR system, a base station (gNB) in an NR system, one or a group (including multiple antenna panels) of antenna panels of a base station in a 5G system, etc. The embodiments of this application do not make any limitations in this regard.

[0093] Optionally, the base stations in the embodiments of this application may include various forms of base stations, such as: macro base stations, micro base stations (also referred to as small stations), relay stations, access points, gNBs, transmission points (TRP), transmitting points (TP), mobile switching centers, and devices that undertake the functions of base stations in device-to-device (D2D), vehicle-to-everything (V2X), and machine-to-machine (M2M) communications, etc. The embodiments of this application do not make specific limitations in this regard.

[0094] The embodiments of this application do not particularly limit the specific structure of the execution entity of the method provided in the embodiments of this application. As long as it can run a program recording the code of the method provided in the embodiments of this application to communicate according to the method provided in the embodiments of this application. For example, the execution entity of the method provided in the embodiments of this application may be a terminal device or a network device, or a functional module in a terminal device or a network device that can call and execute the program.

[0095] Next, the technical solutions in the embodiments of the present application will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present application. Among them, in the description of the embodiments of the present application, unless otherwise specified, " / " means "or". For example, A / B may represent A or B; "and / or" in the text is only a description of the association relationship of the associated objects, indicating that there can be three relationships. For example, A and / or B may represent: A exists alone, A and B exist simultaneously, and B exists alone. In addition, in the description of the embodiments of the present application, "a plurality" means two or more than two.

[0096] It should be understood that the terms "first", "second", etc. in the specification, claims and drawings of the present application are used to distinguish different objects, rather than to describe a specific order. In addition, the terms "comprising" and "having" and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product or device that includes a series of steps or units is not limited to the listed steps or units, but optionally further includes steps or units not listed, or optionally further includes other steps or units inherent to these processes, methods, products or devices.

[0097] Referring to "embodiment" in the present application means that the specific features, structures or characteristics described in conjunction with the embodiment can be included in at least one embodiment of the present application. The appearance of this phrase in various positions in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment mutually exclusive with other embodiments. Those skilled in the art explicitly and implicitly understand that the embodiments described in the present application can be combined with other embodiments.

[0098] For ease of understanding, the random access method provided in the embodiments of the present application will be specifically introduced below in conjunction with the accompanying drawings.

[0099] As Figure 5 shown, the embodiments of the present application provide a random access method, including:

[0100] 501. The terminal device camps on the first cell to perform the first service.

[0101] That is, the current serving cell of the terminal device is the first cell. The first cell may also be referred to as the original cell / source cell of the terminal device.

[0102] The terminal device can camp on the first cell to perform the first service. The first service may include a voice service or a data service. The voice service includes a telephone service (for example, making a call). The data service may include services such as web browsing, online games, or video / short video playback, which are not specifically limited in the present application.

[0103] In some embodiments, when the signal strength of the first cell is lower than a preset threshold, the terminal device may report an A2 event to the network device corresponding to the first cell, so that the network device can configure an event for the user to perform a handover.

[0104] Among them, the events for handover may include the following events:

[0105] A3 event: It indicates that the signal quality of the neighboring cell is better than that of the first cell, and is used to determine whether the terminal device should hand over to the neighboring cell.

[0106] A4 event: It indicates that the signal quality of the neighboring cell is better than an absolute threshold, and is used to determine whether the terminal device should hand over to the neighboring cell.

[0107] A5 event: It indicates that the signal quality of the first cell is worse than an absolute threshold 1 and the signal quality of the neighboring cell is better than an absolute threshold 2, and is used to determine whether the terminal device should hand over to the neighboring cell.

[0108] Among them, the A3 - A5 events are three events used by the LTE system or NR system for intra - system measurement.

[0109] B1 event: It indicates that the signal quality of the neighboring cell is better than an absolute threshold, and is used to measure a high - priority RAT cell.

[0110] B2 event: It indicates that the signal quality of the first cell is worse than an absolute threshold 1 and the signal quality of the neighboring cell is better than an absolute threshold 2, and is used for measurement of the same or lower - priority RAT cells.

[0111] Among them, the B1 event and the B2 event are two events used by the LTE system or NR system for inter - system measurement.

[0112] When the terminal device is in the connected state, the network device corresponding to the first cell (for example, a base station) may configure events for handover (such as A3 event, A4 event, A5 event, B1 event, B2 event, etc.) for the terminal device. The terminal device reports the measurement results to the network device corresponding to the first cell according to the configured events. The network device corresponding to the first cell may send an RRC connection reconfiguration message to the terminal device according to the measurement results to instruct the terminal device to hand over to the second cell.

[0113] 502. The terminal device receives the RRC connection reconfiguration message sent by the network device corresponding to the first cell.

[0114] When the terminal device is camped on the first cell, it may receive the RRC connection reconfiguration message (RRC Connection Reconfiguration) sent by network device a. Among them, network device a is the network device corresponding to the first cell (the first network device), and may be, for example, a base station.

[0115] Among them, the first information is carried in the RRC connection reconfiguration message, and the first information is used to instruct the terminal device to switch to the second cell. The second cell may be referred to as the target cell of the terminal device. To distinguish it from the following third cell (the third cell involved in step 511), the second cell may be referred to as the target cell 1 of the terminal device, and the following third cell may be referred to as the target cell 2 of the terminal device.

[0116] Among them, the first information may include the mobilityControlInfo cell. The mobilityControlInfo cell is used to instruct the terminal device to switch to the second cell.

[0117] Exemplarily, the mobilityControlInfo cell may include fields such as the ID of the second cell, carrier frequency, bandwidth, the identifier of the terminal device, and parameters of each physical channel.

[0118] In some embodiments, when the terminal device is camped on the first cell to perform a first service (for example, voice service or data service), the terminal device may receive an RRC connection reconfiguration message from the network device corresponding to the first cell.

[0119] In some embodiments, when the terminal device is camped on the first cell, the terminal device may be in a high-speed moving state. The terminal device being in a high-speed moving state includes that the displacement of the terminal device in a preset time period is greater than a first preset threshold, and / or the average speed / acceleration of the terminal device in a preset time period is greater than a second preset threshold.

[0120] Exemplarily, the terminal device may detect the acceleration / speed of the terminal device in the horizontal direction through an acceleration sensor. The terminal device may obtain the geographical location of the terminal device through a positioning system (GPS or Beidou system), and determine the displacement of the terminal device according to the geographical locations at different times.

[0121] In a possible case, the terminal device's judgment of its own state based on the data collected by the acceleration sensor may be misjudged. For example, if the terminal device is moving in a uniform straight line and the acceleration sensor detects that the acceleration of the terminal device in the horizontal direction is 0, the state of the terminal device cannot be accurately judged. In this case, the terminal device may simultaneously determine whether the terminal device is in a high-speed moving state through the acceleration sensor and the positioning system. For example, when it is detected that the data output by the positioning system changes greatly in a recent period of time and the acceleration value is zero or less than the threshold, it is determined that the terminal device is in a high-speed moving state.

[0122] In some embodiments, the first cell is a high-speed rail cell or a subway cell.

[0123] Among them, the high-speed rail cell can also be referred to as a high-speed rail communication cell, which refers to a cell covering the high-speed rail track. The subway cell can also be referred to as a subway communication cell, which refers to a cell covering the subway tunnel.

[0124] In some embodiments, the terminal device can determine whether a cell (e.g., the first cell) is an LTE high-speed rail cell through the highSpeedFlag field in the SIB message (e.g., SIB2). Alternatively, the terminal device can determine whether a cell is an NR high-speed rail cell through the highSpeedMeasFlag field in the SIB message (e.g., SIB1).

[0125] In some other embodiments, the terminal device can obtain the geographical location information (e.g., longitude and latitude information) of the first cell through a positioning system (e.g., GPS or Beidou system), and determine whether the first cell is a high-speed rail cell or a subway cell according to the geographical location information of the first cell. For example, the terminal device can compare the geographical location information of the first cell with the geographical location information corresponding to the high-speed rail line or subway line. If the geographical location information of the first cell matches the geographical location information corresponding to the high-speed rail line or subway line (i.e., the geographical location information corresponding to the high-speed rail line or subway line includes the geographical location information of the first cell), it is determined that the first cell is a high-speed rail cell or a subway cell. Among them, the geographical location information corresponding to the high-speed rail line or subway line can be obtained by the terminal device from the network device, or can be stored in the terminal device in advance. The embodiments of the present application do not make specific limitations.

[0126] In some embodiments, before / after the terminal device switches to the second cell, the terminal device can be in a high-speed moving state.

[0127] In some embodiments, the second cell is a high-speed rail cell or a subway cell. The method for the terminal device to identify whether the second cell is a high-speed rail cell or a subway cell can refer to the method for the terminal device to identify whether the first cell is a high-speed rail cell or a subway cell, which will not be elaborated here.

[0128] In some embodiments, the first cell is an LTE cell and the second cell is an LTE cell; or, the first cell is an NR cell and the second cell is an NR cell. That is, the terminal device switching from the first cell to the second cell can be an intra-system cell switch. In some other embodiments, the first cell is an LTE cell and the second cell is an NR cell; or, the first cell is an NR cell and the second cell is an LTE cell. That is, the terminal device switching from the first cell to the second cell can be an inter-system cell switch.

[0129] 503. The terminal device sends a random access preamble to the network device corresponding to the second cell.

[0130] The terminal device may send a random access preamble to network device b (the second network device) according to the first information in the RRC connection reconfiguration message. Network device b is the network device corresponding to the second cell.

[0131] Among them, the random access preamble may be referred to as Msg1 (message 1), or simply referred to as the preamble, and this application does not make specific limitations on this.

[0132] The terminal device may send a random access preamble according to the preamble-related parameters. Among them, the preamble-related parameters include the preamble target received power (PREAMBLE RECEIVED TARGET POWER), the preamble transmission counter (PREAMBLE TRANSMISSION COUNTER), and the preamble power ramping counter (PREAMBLE POWER RAMPING COUNTER), etc. The preamble-related parameters may be configured by higher layer signaling.

[0133] The terminal device determines whether to send a random access preamble according to the preamble transmission counter. For example, the terminal device determines whether the value of the preamble transmission counter is less than a preset maximum value. If it is less than the maximum value, the terminal device may send a random access preamble.

[0134] If the terminal device determines to send a random access preamble, the terminal device may determine the transmission power of the random access preamble according to the preamble target received power and the value of the preamble power ramping counter.

[0135] Exemplarily, the transmission power of the random access preamble may be determined by Equation (1):

[0136] P PRACH，b，f，c (i)=min{P CMAX，f，c (i),P PRACH，target，f，c +PL b，f，c}} Equation (1)

[0137] Among them, P PRACH，b，f，c (i) is the maximum transmission power of the terminal device in transmission time unit i, P PRACH，target，f，c is the first preamble target received power, PL b，f，c is the path loss estimated according to the downlink reference signal, b represents the BWP serial number, f represents the carrier serial number, and c represents the serial number of the serving cell.

[0138] Among them, P PRACH，target，f，c= preambleReceivedTargetPower + DELTA PREAMBLE + (PREAMBLE POWER RAMPING COUNTER – 1) × PREAMBLE POWER RAMPING STEP

[0139] Among them, preambleReceivedTargetPower is the initial target received power of the random access preamble. DELTA PREAMBLE is the power increment determined by the format of the random access preamble or by the format of the random access preamble and the subcarrier spacing. PREAMBLE POWER RAMPING COUNTER is the preamble power increment counter, which is used to characterize the number of power increment times of the random access preamble retransmission. This value is determined based on whether the number of retransmissions of the random access preamble changes according to the transmit - side filtering coefficient or the downlink path loss reference signal resource (SSB or CSI - RS) associated with the random access preamble. PREAMBLE POWER RAMPING STEP is the power increment interval.

[0140] 504. The network device corresponding to the second cell sends a random access response message to the terminal device.

[0141] The network device corresponding to the second cell can receive the random access preamble sent by the terminal device on the corresponding PRACH resource.

[0142] After the network device corresponding to the second cell receives the random access preamble sent by the terminal device, it can calculate the timing advance (TA) value corresponding to the terminal device according to the random access preamble.

[0143] Among them, the TA value is used to indicate to the terminal device the timing advance that needs to be adjusted when transmitting on the physical uplink shared channel (PUSCH), the physical uplink control channel (PUCCH), and the sounding reference signal (SRS).

[0144] It can be understood that in a wireless communication system, the uplink frame is sent by the UE to the network device (for example, the base station), and the downlink frame is transmitted by the network device to the UE. To ensure the time - domain synchronization of the uplink frame and the downlink frame, the transmission time of the uplink frame of the terminal device needs to be adjusted. The transmission time of the uplink frame of the terminal device can be adjusted through the TA value to ensure that the uplink frame and the downlink frame achieve time - domain synchronization.

[0145] A network device may send a random access response (RAR) message to a terminal device. The random access response message may also be referred to as Msg2 (message 2). The random access response message may include a TA value.

[0146] As Figure 6 shown, the TA value may be carried in the timing advance command (TAC) field in the RAR message, and the TAC field includes 12 bits. The value range of the TA value may be 0 to 3846.

[0147] Optionally, the RAR message may also include information such as a temporary cell radio network temporary identity (TC-RNTI) and an uplink (UL) grant, which are not limited in this application.

[0148] 505. The terminal device determines whether the TA value carried in the random access response message is greater than a first preset threshold.

[0149] After receiving the random access response message (Msg2) sent by the network device corresponding to the second cell, the terminal device may parse Msg2 to obtain the TA value and determine whether the TA value carried in Msg2 is greater than the first preset threshold.

[0150] When the terminal device resides in a high-speed rail cell or a subway cell (i.e., the original cell of the terminal device is a high-speed rail cell or a subway cell), the terminal device is usually in a high-speed moving state, and the distance between the terminal device and the network device of the target cell (target cell 1, i.e., the second cell) will change greatly in a short time. As a result, when the network device of the second cell calculates the TA value of the terminal device, a large error (i.e., an anomaly) may occur. For example, the TA value of the terminal device calculated by the network device of the second cell is too large (e.g., the TA value is greater than the first preset threshold). If the terminal device uses this too-large TA value to send uplink data in the second cell, there may be a problem that the uplink data sent by the terminal device in the target cell cannot be normally decoded on the network side, resulting in too high uplink error rate of the terminal device, affecting the normal services of the terminal device (e.g., the ongoing call of the terminal device may have no sound), and reducing the user experience. Therefore, when the terminal device resides in a high-speed rail cell or a subway cell, i.e., when the first cell is a high-speed rail cell or a subway cell, for the random access process triggered by cell handover, the terminal device can increase the verification of the TA value in Msg2. That is, it is judged whether the TA value carried in the random access response message is greater than the first preset threshold. If the TA value is greater than the first preset threshold, step 506 can be executed. If the TA value is less than or equal to the first preset threshold, step 507 can be executed.

[0151] 506. In the case where the TA value is greater than the first preset threshold, the terminal device retransmits the random access preamble to the network device corresponding to the second cell.

[0152] In the case where the TA value is greater than the first preset threshold, the terminal device can discard the random access response message (Msg2) sent by the network device corresponding to the second cell and retransmit the random access preamble to the network device corresponding to the second cell. This situation can be understood as that the terminal device ignores the too-large TA value (i.e., the TA value greater than the first preset threshold) in the Msg2 sent by the network device corresponding to the second cell for the first time and requests the TA value from the network device corresponding to the second cell again.

[0153] Since the situation where the TA value carried in Msg2 is too large is a probabilistic phenomenon, in order to reduce the probability that the TA value carried in Msg2 is too large, the terminal device can ignore the received too-large TA value and retransmit Msg1 to request a new TA value, so as to obtain a normal TA value. So that the terminal device can send uplink frames according to the normal TA value, thereby avoiding the continuous high uplink error rate problem of the terminal device, avoiding affecting voice services or data services, and improving the user experience. Among them, the normal TA value is the TA value within a reasonable value range. For example, the normal TA value is less than or equal to the first preset threshold.

[0154] 507. When the TA value is less than or equal to the first preset threshold, the terminal device sends an RRC connection reconfiguration complete message to the network device corresponding to the second cell.

[0155] When the TA value carried in the random access response message (Msg2) is less than or equal to the first preset threshold, the terminal device does not need to discard the random access response message (Msg2). The terminal device can send an RRC connection reconfiguration complete message to the network device corresponding to the second cell. The RRC connection reconfiguration complete message can indicate that the terminal device has completed the random access process.

[0156] Since the TA value is less than or equal to the first preset threshold, it is considered that the TA value is in a reasonable value range (i.e., the TA value is a normal TA value). In this way, the terminal device can send uplink frames according to the normal TA value, thereby avoiding the problem of continuous high uplink error rate of the terminal device, avoiding affecting voice services or data services, and improving the user experience.

[0157] In the embodiment of this application, after step 506, step 508 may further be included.

[0158] 508. The network device corresponding to the second cell sends a random access response message to the terminal device.

[0159] After the network device corresponding to the second cell receives the random access preamble retransmitted by the terminal device for the first time (i.e., the random preamble sent by the terminal device in step 506), it can retransmit the random access response message to the terminal device.

[0160] After the network device corresponding to the second cell retransmits the random access response message to the terminal device, when the terminal device receives the retransmitted random access response message and determines that the TA value carried in the retransmitted random access response message is greater than the first preset threshold, step 506 can be executed again. Steps 506 and 508 can be looped N times, where N is an integer greater than or equal to 1.

[0161] In this way, the terminal device ignores the received excessive TA values multiple times (for example, N times), retransmits Msg1 to request a new TA value, so as to obtain a normal TA value. This enables the terminal device to send uplink frames according to the normal TA value, thereby avoiding the problem of continuous high uplink error of the terminal device, avoiding affecting voice services or data services, and improving the user experience.

[0162] 509. After the terminal device retransmits the random access preamble for the Nth time and the TA value in the random access response message received from the network device corresponding to the second cell is greater than the second preset threshold, the terminal device no longer retransmits the random access preamble to the network device corresponding to the second cell.

[0163] Exemplarily, assume N is 2. In step 505, if the terminal device determines that the TA value carried in the random access response message is greater than the first preset threshold, the terminal device may retransmit the random access preamble (e.g., preamble 1) to the network device corresponding to the second cell for the first time. After the network device receives the random access preamble (e.g., preamble 1) retransmitted by the terminal device for the first time, it may retransmit the random access response message (e.g., random access response message 1) to the terminal device. After the terminal device receives this random access response message (e.g., random access response message 1), if it determines that the TA value carried in the random access response message is greater than the second preset threshold, it may retransmit the random access preamble (e.g., preamble 2) to the network device corresponding to the second cell for the second time. After the network device receives the random access preamble retransmitted by the terminal device for the second time, it may retransmit the random access response message (e.g., random access response message 2) to the terminal device. After the terminal device receives this random access response message (e.g., random access response message 2), if it determines that the TA value carried in the random access response message is greater than the second preset threshold, it no longer retransmits the random access preamble to the network device corresponding to the second cell for the third time.

[0164] In this way, it is possible to be compatible with the scenario where the TA value actually required by the terminal device in the second cell is relatively large (e.g., the TA value actually required by the terminal device in the second cell should be greater than the second preset threshold), that is, after the terminal device retransmits the random access preamble for the Nth time and the TA value in the random access response message received from the network device corresponding to the second cell is still greater than the second preset threshold, the relatively large TA value can no longer be ignored. And adjust the transmission timing of the uplink frame according to this relatively large TA value during the subsequent uplink transmission process.

[0165] In some embodiments, after the terminal device retransmits the random access preamble for the Nth time, if the TA value in the random access response message sent by the network device corresponding to the second cell received by the terminal device is greater than the second preset threshold, the terminal device may record the correspondence between the terminal device receiving an excessive TA value (the TA value is greater than the first preset threshold or the second preset threshold) in the second cell and the second cell. Thus, when the terminal device needs to switch to the second cell next time, it can directly use the excessive TA value indicated by the network device corresponding to the second cell without frequently retransmitting the random access preamble. In this way, it can not only be compatible with the scenario where the TA value actually required by the terminal device in the second cell is relatively large (for example, the TA value actually required by the terminal device in the second cell should be greater than the second preset threshold), but also save the information interaction time, and can avoid the problem that the uplink data sent by the terminal device subsequently cannot be normally decoded by the network side, thus avoiding affecting the normal services of the terminal device.

[0166] In some embodiments, the value of the second preset threshold may be the same as the value of the first preset threshold; in other embodiments, the value of the second preset threshold may be different from the value of the first preset threshold.

[0167] After the terminal device retransmits the random access preamble for the Nth time, the terminal device may send an RRC connection reconfiguration complete message to the network device corresponding to the second cell. The RRC connection reconfiguration complete message may indicate that the terminal device has completed the random access process.

[0168] Optionally, the method provided in the embodiments of the present application may further include the following steps:

[0169] 510. The terminal device determines that an RLF occurs in the second cell.

[0170] In some embodiments, after the terminal device retransmits the random access preamble for the Nth time, if the TA value in the random access response message sent by the network device corresponding to the second cell received by the terminal device is greater than the second preset threshold, the terminal device determines that a radio link failure (RLF) occurs in the second cell. In this case, the terminal device may perform cell reselection. For example, the terminal device may reselect to a third cell. The third cell may be referred to as the target cell 2.

[0171] In some embodiments, after the terminal device retransmits the random access preamble for the Nth time, when the TA value in the random access response message sent by the network device corresponding to the second cell received by the terminal device is greater than the second preset threshold, the terminal device sends an RRC connection reconfiguration complete message to the network device corresponding to the second cell to complete the random access process. Then, during the communication process between the terminal device and the second cell, the terminal device can adjust the transmission timing of the uplink frame according to the larger TA value (i.e., the TA value greater than the second preset threshold). During the communication process between the terminal device and the second cell, the terminal device may experience RLF. For example, if the terminal device has a high uplink error rate problem in the second cell, that is, the uplink bit error rate (the bit error rate of the uplink data sent in the second cell) exceeds the third preset threshold, the terminal device determines that RLF has occurred in the second cell.

[0172] Among them, the uplink bit error rate is an index to measure the accuracy of uplink data transmission within a specified time. Uplink bit error rate = number of error bits in uplink transmission / total number of bits transmitted in uplink transmission * 100%.

[0173] In other embodiments, the terminal device can determine whether RLF has occurred in the link between the terminal device and the second cell based on the RLC retransmission count, the sync (in sync or in synchronization, IS) / out-of-sync (Out of sync or Out of synchronization, OoS) indication, the number of failures of the terminal device to send service data, the random access result, the cell handover result, and the RRC reconfiguration result.

[0174] For example, if the number of RLC retransmissions on the link between the terminal device and the second cell reaches the maximum number of RLC retransmissions, it is considered that RLF occurs in the second cell. For another example, if on the link between the terminal device and the second cell, the terminal device receives consecutive preset numbers of OoS indications within a preset time period and has not recovered before the timer 310 (the timer T310 is started when consecutive preset numbers (e.g., N310 times) of OoS are detected) times out, it is considered that RLF occurs in the second cell. For another example, if the number of failures of the terminal device to send service data to the second cell within a preset time period is greater than or equal to a preset number of failures, the terminal device considers that RLF occurs in the second cell. For another example, if a random access failure occurs, the terminal device considers that RLF occurs in the second cell. For another example, if a handover failure occurs, that is, before the timer T304 (the timer T304 is started when the terminal device receives the RRC Connection Reconfiugration command and is ready for handover) times out, the terminal device cannot successfully access the second cell, the terminal device considers that RLF occurs in the second cell. For another example, if an RRC reconfiguration fails, the terminal device considers that RLF occurs in the second cell. Among them, the preset time, the preset number of failures, and the preset number can be set as needed, and can be agreed upon by the protocol or configured by the network device, which is not limited in this application.

[0175] Among them, the occurrence of RLF in the second cell may mean that normal data transmission cannot be carried out between the terminal device and the second cell or the network device corresponding to the second cell, such as the failure of uplink data transmission and / or downlink data transmission.

[0176] 511. The terminal device establishes an RRC connection with the network device corresponding to the third cell through the RRC reestablishment procedure.

[0177] After the terminal device determines that RLF occurs in the second cell, the terminal device can determine a new target cell (target cell 2, that is, the third cell), and establish an RRC connection with the network device corresponding to the third cell. Since the terminal device is in the connected state, it can establish an RRC connection with the network device corresponding to the third cell through the RRC reestablishment procedure.

[0178] In some embodiments, the terminal device may use the cell that meets the S criterion among at least one candidate cell (the cell searched by the UE) as the third cell. Among them, the S criterion can be used to select the RRC reestablishment cell. It should be noted that the S criterion can also be replaced by other criteria that can select the RRC reestablishment cell, etc., which is not limited in this application.

[0179] Exemplarily, the terminal device taking the cell that meets the S criterion among at least one candidate cell (the cell searched by the UE) as the third cell may include: the terminal device determines whether at least one candidate cell meets the S criterion, and obtains one or more cells that meet the S criterion; if there is one cell that meets the S criterion, the cell that meets the S criterion is taken as the third cell. Alternatively, the cell with the best (or highest) signal quality (such as RSRP\RSRQ) among the multiple cells that meet the S criterion is taken as the third cell.

[0180] In some embodiments, the third cell may be one of at least one neighboring cell of the first cell or the second cell. Optionally, the third cell is the cell with the strongest signal among at least one neighboring cell of the first cell or the second cell.

[0181] In some embodiments, the third cell is a high-speed rail cell or a subway cell.

[0182] In some embodiments, the third cell may be an LTE cell or an NR cell.

[0183] The terminal device establishing an RRC connection with the network device corresponding to the third cell through the RRC reestablishment process includes: the terminal device sends an RRC reestablishment request message to the third cell, and this RRC reestablishment request message can be used to request to establish an RRC connection with the network device corresponding to the third cell. If the network device corresponding to the third cell accepts the RRC reestablishment request message sent by the terminal device, the network device corresponding to the third cell sends an RRC reestablishment message to the terminal device. The terminal device receives the RRC reestablishment message and establishes an RRC connection with the network device corresponding to the third cell. After the terminal device establishes an RRC connection with the network device corresponding to the third cell, the terminal device sends an RRC reestablishment complete message to the network device corresponding to the third cell.

[0184] Exemplarily, the RRC reestablishment request (RRC connection reestablishment request or RRC connection reestablishment request) may be generated by the RRC layer of the first terminal device, and the RRC layer of the first terminal device corresponds to the RRC layer of the radio access network device.

[0185] After the terminal device establishes an RRC connection with the network device corresponding to the third cell, the first service mentioned in step 501 may be continued through this RRC connection.

[0186] Based on the method provided in the embodiments of the present application, the terminal device can retransmit Msg1 to request a new TA value and ignore the received overly large TA value in order to obtain a normal TA value. This can avoid the problem that the network side issues an overly large TA value, which may affect the services being carried out by the terminal device (such as voice services or data services), and can improve the user experience.

[0187] In the prior art, in some scenarios, the terminal (terminal device) receives a handover command from the network side on an LTE cell, starts a random access on the target cell, sends Msg1, and then receives Msg2 from the network side and successfully accesses the target cell. However, the uplink data subsequently sent by the terminal cannot be normally decoded by the network side, affecting the normal services of the terminal (such as it may cause the ongoing call of the terminal to be silent).

[0188] The applicant found in the research that in the existing high-speed rail scenario of the network, during the random access of cell handover, if the network side issues an abnormally large TA value, it will cause the terminal device to have continuous high uplink error codes after accessing the cell, affecting the voice quality or data services. For example, the user suddenly experiences a silent call or call drop during high-speed rail travel.

[0189] In the high-speed rail scenario, the terminal device receives a handover command from the network side on an LTE high-speed rail cell, starts a random access on the target cell, sends Msg1, and then receives Msg2 from the network side and successfully accesses the target cell. However, the TA value carried in Msg2 is extremely large, resulting in the uplink data subsequently sent by the terminal device not being normally decoded by the network side, affecting the normal services of the terminal device.

[0190] The applicant found through research that the reasons for the above problems include the following two points:

[0191] 1. In a high-speed mobile scenario, after receiving Msg1, the network side may probabilistically have a deviation in the estimation of the TA value, resulting in an overly large TA value carried in Msg2.

[0192] 2. When the terminal device uses an overly large TA value in the target cell, it will cause a large offset in the time domain, affecting the network side's decoding of uplink data and resulting in continuous high uplink error codes of the terminal device.

[0193] The embodiments of the present application provide a method for improving the performance of the terminal device. Since the overly large estimation of the TA value by the network side is a probabilistic phenomenon, the terminal device can ignore the received overly large TA value and retransmit Msg1 to solve this problem or reduce the probability of this problem occurring.

[0194] The embodiments of the present application provide a method for improving the performance of the terminal device, which may include the following content:

[0195] 1) In the high-speed rail community, for the random access process triggered by cell handover, the terminal device can increase the verification of the TA value in Msg2. For example, Figure 7 as shown, after the terminal (e.g., UE) receives the RRC connection reconfiguration message from the original cell, it can initiate random access on the target cell according to the RRC connection reconfiguration message, that is, it can send Msg1 to the network device corresponding to the target cell. After the network device corresponding to the target cell receives the random access preamble sent by the terminal device, it can calculate the TA value according to Msg1 and send Msg2 carrying this TA value to the terminal. If the TA value in Msg2 is greater than the preset threshold, the terminal can discard Msg2 (in this case, it can be understood as ignoring the too large TA value in Msg2) and immediately retransmit Msg1.

[0196] Furthermore, after the terminal retransmits Msg1, it can receive the Msg2 retransmitted by the network side. If the TA value in Msg2 is still greater than the preset threshold, the terminal device can continue to discard Msg2 and retransmit Msg1.

[0197] In an optional implementation manner, the terminal can keep retransmitting Msg1 until the TA value carried in the received Msg2 is less than or equal to the preset threshold. Then, the terminal can send the RRC connection reconfiguration complete message to the target cell.

[0198] Msg1 (message 1) and Msg2 (message 2) are both messages involved in the random access process. In the random access process, there is an important parameter in Msg2, that is, TA (timing advance). After the network side (such as the base station) receives Msg1, it calculates the uplink TA according to Msg1. After the terminal device receives the random access response message (Msg2), it can adjust the uplink transmission timing according to the TA value carried in Msg2.

[0199] 2) Further optionally, in order to be compatible with the scenario where the actual required TA value is very large itself, if the terminal device receives too large TA values multiple times, the terminal device can no longer ignore the too large TA value in the received Msg2. For example, Figure 8 as shown, if the terminal device retransmits Msg1 multiple times (taking Figure 8 as an example, assuming the terminal device retransmits Msg1 twice) and the TA value in the received Msg2 is still too large (such as greater than the preset threshold, and the preset thresholds of the TA values in the Msg2 received multiple times can be the same or different), then the terminal device can no longer ignore the too large TA value in the received Msg2, that is, the terminal device can no longer retransmit Msg1, but can successfully access the target cell according to Msg2 (such as the most recently received Msg2). The terminal can send the RRC connection reconfiguration complete message to the target cell.

[0200] Based on the method provided in the embodiments of this application, it is possible to solve the problem of high bit error rate caused by the network side sending an overly large TA value, resulting in silent voice / data unavailability, and improve the user experience.

[0201] A hardware structure of the terminal device is as Figure 9 shown and may include: a processor, an external memory interface, an internal memory, a Universal Serial Bus (USB) interface, a charging management module, a power management module, a battery, antenna 1, antenna 2, a mobile communication module, a wireless communication module, a sensor module, a key, a motor, an indicator, a camera, a display screen, and a SIM card slot, etc. Among them, the audio module may include a speaker, a receiver, a microphone, a headphone interface, etc., and the sensor module may include a pressure sensor, a gyroscope sensor, a barometric pressure sensor, a magnetic sensor, an acceleration sensor, a distance sensor, a proximity light sensor, a fingerprint sensor, a temperature sensor, a touch sensor, an ambient light sensor, a bone conduction sensor, etc.

[0202] It can be understood that the structure schematically shown in the embodiments of this application does not constitute a specific limitation on the terminal device. In other embodiments, the terminal device may include more or fewer components than shown, or combine certain components, or split certain components, or have different component arrangements. The illustrated components may be implemented in hardware, software, or a combination of software and hardware.

[0203] Among them, the processor may include one or more processing units. For example, the processor may include an Application Processor (AP), a Modem (which may also be referred to as a baseband processor), a Graphics Processing Unit (GPU), an Image Signal Processor (ISP), a controller, a video codec, a Digital Signal Processor (DSP), and / or a Neural-network Processing Unit (NPU), etc. Among them, different processing units may be independent devices or integrated in one or more processors. The processor is the nerve center and command center of the terminal device. The controller can generate operation control signals according to the instruction operation code and timing signal to complete the control of fetching instructions and executing instructions.

[0204] The wireless communication function of the terminal device can be implemented through Antenna 1, Antenna 2, the mobile communication module, the wireless communication module, and the Modem, etc. In some embodiments, Antenna 1 of the terminal device is coupled with the mobile communication module, and Antenna 2 is coupled with the wireless communication module, enabling the terminal device to communicate with network-side devices and other terminal devices through wireless communication technologies.

[0205] In addition, an operating system runs on top of the above components. For example, iOS operating system, Android open-source operating system, Windows operating system, etc.

[0206] The operating system of the terminal device can adopt a layered architecture, an event-driven architecture, a microkernel architecture, a microservices architecture, or a cloud architecture. In the embodiments of the present application, the Android system with a layered architecture is taken as an example to exemplarily illustrate the software and hardware structure of the terminal device. It should be noted that although the embodiments of the present application are described by taking the Android system as an example, its basic principles are equally applicable to terminal devices based on operating systems such as iOS or Windows.

[0207] Figure 10 It is a schematic diagram of the software structure of the terminal device. The software structure adopts a layered architecture. The layered architecture divides the software into several layers, and each layer has a clear role and division of labor. The layers communicate with each other through software interfaces. Taking the Android system running on the AP as an example, in some embodiments, the Android system is divided into five layers, from top to bottom, namely the application layer, the application framework layer (Framework), the Android runtime and system libraries, the hardware abstraction layer (HAL), and the system kernel layer (Kernel).

[0208] Among them, the application layer may include a series of application packages. The application packages may include apps such as camera, gallery, calendar, call, map, WLAN, Bluetooth, music, video, short message, etc. The application layer may also include systemUI (system user interface), which is used to display the interface of the terminal device, such as displaying the signal icon corresponding to the SIM card, displaying the call interface, etc. The application framework layer provides application programming interfaces (APIs) and programming frameworks for the applications in the application layer. The application framework layer includes some predefined functions. For example, the application framework layer may include window manager, content provider, view system, telephony manager, resource manager, notification manager, etc. The telephony manager is used to provide the call function of the terminal device, such as the management of call status (including connection, disconnection, etc.). The application framework layer may also include a radio interface layer (RIL). The modem can interact with the telephony through the RIL.

[0209] The modem may include a non-access stratum (NAS) layer, a radio resource control (RRC) layer, a packet data convergence protocol (PDCP) layer, a radio link control (RLC) layer, a medium access control (MAC) layer, and a physical (PHY) layer. The foregoing layers may be software modules. The modem can interact with the base station through an antenna.

[0210] In addition, some embodiments of the present application provide a terminal device, which includes: one or more processors and a memory; the memory is used to store computer program code, and the computer program code includes computer instructions. When the one or more processors execute the computer instructions, the terminal device executes the following random access method.

[0211] Some embodiments of the present application provide a chip system, which is applied to a terminal device. The chip system includes at least one processor and an interface. The interface is used to receive instructions and transmit them to the at least one processor; the at least one processor runs the instructions to make the terminal device execute the following random access method. Among them, the chip system may be a modem, or a system on chip (SoC) including a modem. The above method may be implemented by a single modem.

[0212] The methods of some embodiments of the present application may be implemented by the Modem of the terminal device.

[0213] For example, the Modem may send Msg1 through the antenna and receive Msg2. The Modem may determine whether the TA value carried in Msg2 is greater than the first preset threshold. If the TA value carried in Msg2 is greater than the first preset threshold, the Modem may retransmit Msg1 through the antenna.

[0214] In the case where the TA value in the received Msg2 is greater than the second preset threshold after the Modem retransmits Msg1 for the Nth time, the Modem may no longer retransmit Msg1.

[0215] The embodiments of the present application further provide a chip system, as Figure 11 shown, the chip system includes at least one processor 1101 and at least one interface circuit 1102. The processor 1101 and the interface circuit 1102 may be interconnected by a line. For example, the interface circuit 1102 may be used to receive signals from other devices (for example, the memory of the terminal device). Again, for example, the interface circuit 1102 may be used to send signals to other devices (for example, the processor 1101).

[0216] For example, the interface circuit 1102 may read the instructions stored in the memory of the terminal device and send the instructions to the processor 1101. When the instructions are executed by the processor 1101, the terminal device (such as Figure 9 the terminal device shown) may execute each step in the above embodiments.

[0217] Of course, the chip system may further include other discrete devices, and the embodiments of the present application do not make specific limitations thereto.

[0218] The embodiments of the present application further provide a computer-readable storage medium, the computer-readable storage medium includes computer instructions, when the computer instructions run on the terminal device (such as Figure 9 the terminal device shown), enabling the terminal device to execute each function or step executed by the terminal device (for example, UE) in the above method embodiments.

[0219] The embodiments of the present application further provide a computer program product, when the computer program product runs on a computer, enabling the computer to execute each function or step executed by the terminal device in the above method embodiments.

[0220] The embodiments of the present application also provide a processing device, which can be divided into different logical units or modules according to functions, and each unit or module performs different functions, so that the processing device can perform each function or step executed by the terminal device in the above method embodiments.

[0221] Through the description of the above embodiments, those skilled in the art can clearly understand that the above functions can be allocated to different functional modules according to needs, that is, the internal structure of the device is divided into different functional modules to complete all or part of the functions described above.

[0222] In several embodiments provided by the present application, it should be understood that the disclosed device and method can be implemented in other ways. For example, the device embodiments described above are merely illustrative. For example, the division of the modules or units is only a logical function division. In actual implementation, there may be other division methods. For example, multiple units or components can be combined or integrated into another device, or some features can be ignored or not executed. Another point is that the displayed or discussed coupling or direct coupling or communication connection between each other can be through some interfaces. The indirect coupling or communication connection of the device or unit can be in electrical, mechanical or other forms.

[0223] The unit described as a separated component may or may not be physically separated. The component displayed as a unit may be a physical unit or multiple physical units, that is, it may be located in one place, or may be distributed to multiple different places. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0224] In addition, each functional unit in the various embodiments of the present application can be integrated in a processing unit, or each unit can exist physically alone, or two or more units can be integrated in one unit. The above integrated unit can be implemented in the form of hardware or in the form of a software functional unit.

[0225] When the integrated unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a readable storage medium. Based on this understanding, the technical solution of the embodiments of the present application, in essence, or the part that contributes to the prior art, or all or part of the technical solution, can be embodied in the form of a software product. The software product is stored in a storage medium and includes several instructions for causing a device (which can be a single-chip microcomputer, a chip, etc.) or a processor to execute all or part of the steps of the methods described in the embodiments of the present application. The foregoing storage medium includes: various media that can store program codes, such as USB flash drives, mobile hard disks, read only memory (ROM), random access memory (RAM), magnetic disks, or optical discs.

[0226] The above content is only the specific implementation manner of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions within the technical scope disclosed in the present application should be covered by 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 random access method, characterized in that, Including: The terminal device sends a random access preamble. The terminal device receives a random access response message, and a timing advance (TA) value is carried in the random access response message. When the TA value is greater than a first preset threshold, the terminal device retransmits the random access preamble.

2. The method according to claim 1, characterized in that, The method further includes: After the terminal device retransmits the random access preamble for the Nth time, when the TA value in the received random access response message is greater than a second preset threshold, the terminal device stops retransmitting the random access preamble; where N is an integer greater than or equal to 1.

3. The method according to claim 1 or 2, characterized in that Before the terminal device sends the random access preamble, the method further includes: When the terminal device is camped on a first cell, the terminal device receives a radio resource control (RRC) connection reconfiguration message from a first network device. The first network device is the network device corresponding to the first cell, and first information is carried in the RRC connection reconfiguration message. The first information is used to instruct the terminal device to switch to a second cell. The terminal device sending the random access preamble includes: The terminal device sends the random access preamble to a second network device according to the first information. The second network device is the network device corresponding to the second cell.

4. The method according to claim 3, characterized in that, The method further includes: After the terminal device retransmits the random access preamble for the Nth time, when the TA value in the received random access response message is greater than a second preset threshold, the terminal device sends an RRC connection reconfiguration complete message to the first network device. After the terminal device sends the RRC connection reconfiguration complete message to the first network device, the terminal device determines that a radio link failure (RLF) occurs in the second cell. The terminal device sends an RRC connection re-establishment message to a third network device. The third network device is the network device corresponding to a third cell, and the third cell is different from the second cell.

5. The method according to claim 4, characterized in that The terminal device determining that an RLF occurs in the second cell includes: The terminal device determines that the uplink bit error rate of the terminal device in the second cell exceeds a third preset threshold.

6. The method according to claim 2 or 3, characterized in that, The method further includes: After the terminal device retransmits the random access preamble for the Nth time, when the TA value in the received random access response message is greater than a second preset threshold, the terminal device determines that an RLF occurs in the second cell. The terminal device sends an RRC connection re-establishment message to a third network device. The third network device is the network device corresponding to a third cell, and the third cell is different from the second cell.

7. The method according to any one of claims 1-6, characterized in that: When the terminal device sends the random access preamble, it is in a high-speed moving state.

8. The method according to any one of claims 3-7, characterized in that: The first cell is a high-speed rail cell or a subway cell.

9. The method according to any one of claims 3-7, characterized in that: The second cell is a high-speed rail cell or a subway cell.

10. The method according to any one of claims 1-9, characterized in that, The terminal device retransmitting the random access preamble to the second network device includes: The terminal device discards the random access response message and retransmits the random access preamble to the second network device.

11. The method according to any one of claims 3 to 10, characterized in that, When the terminal device is camped on the first cell, it receives a radio resource control (RRC) connection reconfiguration message from the first network device, including: When the terminal device is camped on the first cell to perform a first service, it receives the RRC connection reconfiguration message from the first network device, where the first service includes a voice service or a data service.

12. The method according to any one of claims 4 to 11, characterized in that The method further includes one or more of the following: The third cell is a high-speed rail cell or a subway cell; or, The first cell is a Long Term Evolution (LTE) cell, and the second cell is an LTE cell; or, The first cell is a New Radio (NR) cell, and the second cell is an NR cell; or, The first cell is an LTE cell, and the second cell is an NR cell; or, The first cell is an NR cell, and the second cell is an LTE cell; or, The third cell is an LTE cell or an NR cell.

13. A terminal device, characterized in that, The terminal device includes: a memory and one or more processors; the memory is coupled to the processor; Wherein, the memory is used to store computer program code, and the computer program code includes computer instructions; when the computer instructions are executed by the processor, the terminal device executes the method according to any one of claims 1-12.

14. A computer-readable storage medium, characterized in that, Including computer instructions; When the computer instructions run on the terminal device, the terminal device executes the method according to any one of claims 1-12.

15. A chip system, characterized in that, The chip system includes one or more interface circuits and one or more processors; the interface circuits and the processors are interconnected by lines; The chip system is applied to a terminal device including a communication module and a memory; the interface circuit is used to receive a signal from the memory and send the signal to the processor, and the signal includes computer instructions stored in the memory; when the processor executes the computer instructions, the terminal device executes the method according to any one of claims 1-12.

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