Random access method and apparatus

Abstract

The embodiments of the present application relate to the technical field of communications. Provided are a random access method and apparatus, which can reduce the impact on an ongoing service of a terminal device, and can improve the quality of a service, so as to improve the user experience. The method comprises: a terminal device sending a random access preamble; the terminal device receiving a random access response message, the random access response message carrying a timing advance (TA) value; and when the TA value is greater than a first preset threshold, the terminal device retransmitting the random access preamble.

Description

A random access method and device

[0001] This application claims priority to the Chinese patent application filed with the State Intellectual Property Office on December 26, 2023, with application number 202311820749.6 and invention name “A method for improving the performance of electronic devices and electronic devices”, and the Chinese patent application filed with the State Intellectual Property Office on February 8, 2024, with application number 202410178294.0 and invention name “A random access method and device”, the entire contents of which are incorporated by reference into this application. Technical Field

[0002] The embodiments of the present 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 resides in a serving cell, it can receive a handover command from the network device corresponding to the serving cell (e.g., a base station) and initiate random access on the target cell based on the handover command. The random access process may include the following steps: S1. The terminal device sends a random access preamble to the network device corresponding to the target cell (e.g., a base station). 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 in the target cell, the network side may not be able to decode the uplink data sent by the terminal device normally, affecting the ongoing services of the terminal device (for example, it may cause the ongoing call of the terminal device to have no sound) and reduce the user experience.

[0005] Summary of the Invention

[0006] The embodiments of the present application provide a random access method and apparatus to reduce the impact on ongoing services of a terminal device, thereby improving service quality and thus enhancing user experience.

[0007] To achieve the above objectives, the embodiments of the present application adopt the following technical solutions:

[0008] In a first aspect, an embodiment of the present application provides a random access method, including: a terminal device sends a random access preamble code; the terminal device receives a random access response message, and the random access response message carries a time advance TA value; when the TA value is greater than a first preset threshold, the terminal device resends the random access preamble code.

[0009] Based on the method provided in the embodiments of the present application, the terminal device can resend the random access preamble (Msg1) to request a new TA value and ignore the received TA value that is too large. This can avoid the problem of the network side sending an excessively large TA value, which affects the terminal device's ongoing services (for example, voice services or data services), and can improve the user experience.

[0010] In one possible implementation, the method further includes: after the terminal device retransmits the random access preamble for the Nth time, if the TA value in the received random access response message is greater than a second preset threshold, the terminal device no longer retransmits the random access preamble; wherein N is an integer greater than or equal to 1. In this way, it is compatible with 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). The terminal device can adjust the timing of sending uplink frames according to the larger TA value during subsequent uplink transmission.

[0011] In one possible implementation, before the terminal device sends the random access preamble, the method further includes: when the terminal device is stationed in the first cell, receiving a radio resource control (RRC) connection reconfiguration message from a first network device, the first network device being the network device corresponding to the first cell, the RRC connection reconfiguration message carrying first information, the first information being used to instruct the terminal device to switch to the second cell; and the terminal device sending the random access preamble includes: the terminal device sending the random access preamble to the second network device according to the first information, the second network device being the network device corresponding to the second cell. That is, the terminal device may send 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, so as to switch to the second cell.

[0012] In one possible implementation, the method further includes: after the terminal device retransmits the random access preamble for the Nth time, if the TA value in the received random access response message is greater than a second preset threshold, the terminal device sending 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) has occurred in the second cell; and the terminal device sending an RRC connection reestablishment message to a third network device, where the third network device is a network device corresponding to a third cell, which is different from the second cell. After the terminal device sends the RRC connection reconfiguration complete message to the first network device, the terminal device and the second cell may adjust the timing of transmitting uplink frames according to the larger TA value (i.e., a TA value greater than the second preset threshold) during communication. However, during communication between the terminal device and the second cell, the terminal device may experience an RLF. In this case, the terminal device may send an RRC connection reestablishment 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 issues affecting ongoing services (e.g., voice services or data services) of the terminal device and improve the user experience.

[0013] In one possible implementation, the terminal device determining that a radio link failure (RLF) has occurred in the second cell includes: the terminal device determining that an uplink bit error rate (BER) of the terminal device in the second cell exceeds a third preset threshold. The uplink BER is an indicator measuring the accuracy of uplink data transmission within a specified time. The uplink BER = bit errors in uplink transmission / total number of codes transmitted in uplink transmission * 100%.

[0014] In one possible implementation, the method further includes: after the terminal device retransmits the random access preamble for the Nth time, if the TA value in the received random access response message is greater than the second preset threshold, 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 a network device corresponding to the third cell, and the third cell is different from the second cell. That is, after the terminal device retransmits the random access preamble for the Nth time, if the TA value in the received random access response message is greater than the second preset threshold, RLF can be triggered. 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 affecting the ongoing services of the terminal device (for example, voice services or data services) and can improve user experience.

[0015] In one possible implementation, when the terminal device sends the random access preamble, it is in a high-speed mobile state. The high-speed mobile 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 the preset time period is greater than a second preset threshold.

[0016] In one 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 mobile state when it resides in 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 mobile state, there will be a probability that a deviation will occur in the calculation of the TA value, resulting in the TA value carried in Msg2 being too large. Based on the method provided in the embodiment of the present application, the terminal device can resend the random access preamble (Msg1) to request a new TA value and ignore the received TA value that is too large. The problem of the network side sending down an excessively large TA value affecting the ongoing services of the terminal device (for example, voice services or data services) can be avoided, and the user experience can be improved.

[0017] In one possible implementation, the second cell is a high-speed rail cell or a subway cell. When the terminal device is about to switch to the high-speed rail cell or the subway cell, the terminal device may be in a high-speed mobile state. After the network side receives the random access preamble (Msg1) sent by the terminal device in a high-speed mobile state, there will be a probability that a deviation will occur in the calculation of the TA value, resulting in the TA value carried in Msg2 being too large. Based on the method provided in the embodiment of the present application, the terminal device can resend the random access preamble (Msg1) to request a new TA value and ignore the received TA value that is too large. The problem of the network side sending down an excessively large TA value affecting the ongoing services of the terminal device (for example, voice services or data services) can be avoided, and the user experience can be improved.

[0018] In one possible implementation, the terminal device retransmitting the random access preamble to the second network device includes: the terminal device discarding the random access response message and retransmitting the random access preamble to the second network device. This situation can be understood as the terminal device ignoring the excessively large TA value (i.e., a TA value greater than the first preset threshold) in Msg2 initially sent by the network device corresponding to the second cell, and re-requesting the TA value from the network device corresponding to the second cell.

[0019] In one possible implementation, the terminal device receives a radio resource control RRC connection reconfiguration message from the first network device when residing in the first cell, including: the terminal device receives an RRC connection reconfiguration message from the first network device when residing in the first cell to perform a first service, and the first service includes a voice service or a data service.

[0020] In one 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, handover of the terminal device from the first cell to the second cell / third cell may be a same-system cell handover or a different-system cell handover.

[0021] The present application provides some embodiments to improve the performance of a terminal and reduce the probability of service anomalies occurring on the terminal.

[0022] In a second aspect, an embodiment of the present application provides a method for improving the performance of a terminal device, including:

[0023] The terminal device sends a Msg1 message to the network side to initiate a random access process;

[0024] The terminal device receives a random access response message Msg2 sent by the network side, where the Msg2 message carries a timing advance TA value;

[0025] When the TA value is greater than the first preset threshold, the terminal device resends the Msg1 message.

[0026] In some embodiments, when the TA value is greater than a first preset threshold, the terminal device resending the Msg1 message includes:

[0027] When the TA value is greater than the first preset threshold, the terminal device discards the Msg2 message and resends the Msg1 message.

[0028] In some embodiments, before the terminal device sends the Msg1 message for initiating a random access process to the network side, the method further includes:

[0029] 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 RRCConnectionReconfiguration shown in Figure 7 or Figure 8 ) sent by a base station corresponding to the first cell, where the RRC connection reconfiguration message carries first information, and the first information (such as 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 a cell ID and / or frequency of the second cell);

[0030] The terminal device sends a Msg1 message to the network side for initiating a random access process, including:

[0031] The terminal device sends the Msg1 message to the base station corresponding to the second cell according to the first information.

[0032] In some embodiments, when the terminal device is camped in a first cell, receiving an RRC connection reconfiguration message sent by a base station corresponding to the first cell includes:

[0033] When the terminal device resides in a first cell and moves at high speed, it receives an RRC connection reconfiguration message sent by a base station corresponding to the first cell.

[0034] 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 located along a high-speed rail line.

[0035] In some embodiments, the network standards of the first cell and the second cell are the same or different, such as: 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.

[0036] In some embodiments, the method further comprises:

[0037] After the terminal device retransmits the Msg1 message for the Nth time, if the TA value in the received Msg2 message is greater than the second preset threshold, the terminal device completes the random access process according to the Msg2 message (it can be understood that the random access process may include more messages in addition to Msg1 and Msg2), and then successfully accesses the second cell (the target cell shown in Figure 8). The RRC Connection Reconfiguration Complete message shown in Figure 8 can indicate that the terminal device has completed the random access process.

[0038] 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.

[0039] In a third aspect, a terminal device is provided, comprising: 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 performs the method described in any possible implementation of the first aspect or the second aspect.

[0040] In a fourth aspect, a chip system is provided, comprising at least one processor and a communication interface, wherein the communication interface and the at least one processor are interconnected via a line, and the at least one processor is used to run a computer program or instruction to execute a method as described in any possible implementation of the first aspect or the second aspect.

[0041] In a fifth aspect, an embodiment of the present application provides a computer-readable storage medium storing a computer program, which, when executed by a processor, implements the method described in any possible implementation of the first aspect or the second aspect.

[0042] In a sixth aspect, an embodiment of the present application provides a computer program product, which includes a computer program. When the computer program is run, it enables the computer to execute the method described in any possible implementation of the first aspect or the second aspect.

[0043] It is understood that the terminal device provided in the 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 perform the method described in any one of the implementations of the first or second aspects. Therefore, the beneficial effects that can be achieved can be referenced to the beneficial effects of any possible implementation of the first or second aspects, and will not be repeated here. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] FIG1 is a schematic diagram of a signal interaction in related art;

[0045] FIG2 is a schematic diagram of a network architecture provided in an embodiment of the present application;

[0046] FIG3 is a schematic diagram of another network architecture provided in an embodiment of the present application;

[0047] FIG4 is a schematic diagram of a voice call scenario provided by an embodiment of the present application;

[0048] FIG5 is a schematic diagram of signal interaction applicable to a random access method provided in an embodiment of the present application;

[0049] FIG6 is a schematic diagram of a format of a RAR message provided in an embodiment of the present application;

[0050] FIG7 is another schematic diagram of signal interaction provided in an embodiment of the present application;

[0051] FIG8 is another schematic diagram of signal interaction provided in an embodiment of the present application;

[0052] FIG9 is a schematic diagram of the hardware structure of a terminal device provided in an embodiment of the present application;

[0053] FIG10 is a software structure block diagram of a terminal device provided in an embodiment of the present application;

[0054] FIG11 is a schematic structural diagram of a chip system provided in an embodiment of the present application. DETAILED DESCRIPTION

[0055] To make the description of the following embodiments clear and concise, a brief introduction to the relevant concepts or technologies is first given:

[0056] 1. Cell: A cell is an area within the wireless coverage of a network device (e.g., a base station). Within this area, terminal devices can reliably communicate with the network device via wireless signals. It can be understood that the coverage area 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 area of ​​one or more frequency points.

[0057] 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 co-located.

[0058] 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 may be different radio frequency processing units within the same base station.

[0059] 2. Neighboring Cell: Also known as a neighboring cell or adjacent cell, it refers to an area within the wireless coverage area of ​​network equipment that is physically adjacent to the current serving cell and transmits signals on the same or different frequencies. In other words, a neighboring cell is a cell that is adjacent to or adjacent to the current serving cell. In layman's terms, a neighboring cell can be understood as a "surrounding cell" of the current serving cell.

[0060] 3. Handover (HO): Handover is the process of migrating the communication link between a terminal device and its current network device to another network device in mobile communications. In wireless communication systems, when a terminal device moves from one cell to another or approaches another, a cell handover is necessary to maintain uninterrupted communication.

[0061] Cell handover can be intra-site handover or inter-site handover, which is not specifically limited in this application. Intra-site handover refers to the original cell (or source cell) and the target cell belonging to the same network device (e.g., base station). Inter-site handover refers to the source cell and the target cell belonging to different network devices (e.g., base stations).

[0062] In this application, the original cell refers to the cell that provides services to the terminal device before the cell switching, and the target cell refers to the cell that provides services to the terminal device after the cell switching.

[0063] In some scenarios, the terminal device can receive a handover command on the cell it is currently residing in (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 sending the preamble, and sends a random access preamble on the resource. S2. The base station sends a random access response to the terminal device. Thus, the terminal device can access the target cell.

[0064] However, after the terminal device accesses the target cell, the uplink data sent by the terminal device in the target cell may not be decoded normally on the network side, resulting in an excessively high uplink bit error rate of the terminal device, affecting the normal service of the terminal device (for example, it may cause no sound in the ongoing call of the terminal device), and reducing the user experience.

[0065] For example, when the terminal device resides in a high-speed rail cell or a subway cell (that is, the original cell is a high-speed rail cell or a subway cell), the terminal device can receive a switching message (for example, an RRC connection reconfiguration message) from the network device corresponding to the high-speed rail cell or the subway cell. The switching message is used to instruct the terminal device to switch to the target cell. As shown in Figure 1, after the terminal device receives the switching message from the original cell, it can initiate random access on the target cell according to the switching 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 the network device corresponding to the target cell receives the random access preamble sent by the terminal device, it can calculate the timing advance (TA) value based on the random access preamble, and can send a random access response message carrying the TA value to the terminal device (the random access response message can also be referred to as Msg2). After receiving the random access response message (Msg2), the terminal device can adjust the timing of sending uplink data according to the TA value carried in Msg2. However, since the terminal device is usually in a high-speed mobile state when it resides in a high-speed rail cell or a subway cell. After the network equipment corresponding to the target cell receives the random access preamble (Msg1) sent by the terminal device in a high-speed mobile state, there will be a probability that the calculation of the TA value will deviate, resulting in an excessively large TA value carried in Msg2. If the terminal device uses an excessively large TA value to adjust the transmission timing of uplink data in the target cell, it will cause a large offset in the time domain of the uplink data, affecting the decoding of the uplink data on the network side, thereby affecting the ongoing services of the terminal device (for example, a user's call on a high-speed train suddenly becomes silent and dropped), and reducing the user experience.

[0066] The embodiment of the present application provides a random access method to reduce the impact on the ongoing services of the terminal device, thereby improving the service quality and thus improving the user experience.

[0067] In order to better understand a communication method and related equipment provided by an embodiment of the present application, the network architecture of an embodiment of the present application is described below.

[0068] The network architecture of an embodiment of the present application may include at least two cells (for example, a first cell and a second cell) and at least one terminal device.

[0069] For example, please refer to Figure 2, which is a schematic diagram of a network architecture provided in an embodiment of the present application. As shown in Figure 2, 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 shown in Figure 2, the cell in which the terminal device is currently residing may be the first cell. The movement trajectory of the terminal device may be moving 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 (e.g., a high-speed rail or subway). The first cell, the second cell, and the third cell may be high-speed rail cells or subway cells.

[0070] It is understandable that the network architecture provided in the embodiments of the present application may further include more cells, and this application does not impose any restrictions on 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, 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 non-identical network devices. That is, network device a, network device b, and network device c may be non-identical network devices. The first cell, the second cell, and the third cell may belong to non-identical network devices, which 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 devices to which the third cell belongs are identical.

[0071] Please refer to Figure 3, which is another schematic diagram of a network architecture provided by an embodiment of the present application. As shown in Figure 3, the network architecture may include terminal devices, LTE, NR, core network, and IMS or the Internet. The following is a detailed description of it:

[0072] (1) Terminal device: This refers to a device that includes wireless transceiver functionality and can work with network equipment (e.g., base stations) to provide communication services to users. Terminal devices can be mobile phones or wearable devices (e.g., smart watches).

[0073] (2) LTE: can be understood as the fourth generation (4 thThe wireless access network of the long-term evolution (4G) mobile communication system is a radio access network. In the LTE network (commonly known as the 4G network), due to the evolution relationship, the access network part is called the evolved UMTS Terrestrial Radio Access Network (Evolved UMTS Terrestrial Radio Access Network, E-UTRAN). In this application, the meaning of LTE is the same as that of E-UTRAN, both referring to the access network part of the 4G network. The terminal device can access the 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).

[0074] (3)NR: can be understood as the fifth generation (5 th The wireless access network of the new radio (5G) mobile communication system is a wireless access network. In the 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 the 5G network. The terminal device can access the NR through a 5G base station. Among them, the 5G base station can be the next generation base station (gNodeB, gNB) in the new radio (NR). The base station in NR can also be called a transmission reception point (TRP).

[0075] As you can understand, both LTE and NR are access networks. The access network uses wired or wireless connections and communication technologies to connect end users to the core network (also known as the backbone) layer by layer, establishing connectivity. The access network is the edge of the network, the part closest to users and often referred to as the "last mile."

[0076] (4) Core Network: Its main functions are to provide user connections, user management, and service delivery. It serves as a bearer network and provides an interface to external networks. Establishing user connections includes functions such as mobility management (MM), call management (CM), switching / routing, and recording notifications (combined with intelligent network services to complete connections to intelligent network peripheral devices).

[0077] The core network of a 4G network is the evolved packet core (EPC). The EPC is the core network of a 4G mobile communications network. It encompasses traditional mobile network capabilities, such as user subscription data storage, mobility management, and data exchange, and provides users with an ultra-high-speed internet experience. The core network of a 5G network is the 5G Core (abbreviated as 5GC). 5GC uses general-purpose network function virtualization equipment to replace the dedicated communication equipment of 4G networks.

[0078] It should be noted that the core network in the network architecture shown in Figure 3 can be obtained by integrating EPC and 5GC. That is to say, the core network in the network architecture can include both network elements in EPC and network elements in 5GC. For example, the core network in the network architecture can include access and mobility management function (AMF) network elements, mobility management entity (MME) network elements, serving gateway (SGW) network elements, packet data network gateway (PGW) network elements, session management function (SMF) network elements, user plane function (UPF) network elements, unified data management function (UDM) network elements and home subscriber server (HSS) network elements, etc.

[0079] In some embodiments of the present application, the core network in the network architecture may include converged network elements obtained from network elements in the EPC and 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.

[0080] In some embodiments of the present application, the core network in the network architecture shown in FIG3 may include a proxy session border control (PSBC) network element, which is a combined network element that integrates a session border control (SBC), a proxy call session control function (P-CSCF), an access transfer control function (ATCF), and an access transfer gateway (ATGW). As an SBC network element, it connects the IMS core network / softswitch network with the external user access area, provides service access for IMS / softswitch users, enables interoperability of user services in different network environments, ensures IMS / softswitch network security, and supports QoS management, CAC traffic control, media management, CDR media call detail records, and other functions.

[0081] Each network element in the core network can also be called a functional entity, which can be a network element implemented on dedicated hardware, a software instance running on dedicated hardware, or an instance of a virtualized function on an appropriate platform.

[0082] It should be understood that the names of all network elements in this application are only examples. In future communications, such as 6G, they may also be called other names, or, in future communications, such as 6G, the network elements involved in this application may also be replaced by other entities or devices with the same functions, etc., and this application does not limit this. A unified explanation is given here and will not be repeated later. Optionally, the various network elements in the embodiments of the present application may be communication devices, or chips or chip systems that can be used in the communication devices, etc., and this embodiment of the present application does not limit this.

[0083] It is understood that the core network in the network architecture shown in Figure 3 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 limit this. It should be noted that this application does not limit the distribution method of each network element in the core network. The specific distribution method can be referred to in relevant technical documents, and this application does not elaborate on it here.

[0084] (5) IMS is a network architecture that provides voice and multimedia communication services (e.g., voice, video, and text messaging) based on the Internet Protocol (IP) network. IMS enables secure and reliable multimedia communication between different devices on different networks. The architectural model provides a unified infrastructure and common mechanisms for controlling, operating, routing, and managing sessions, as well as implementing authentication, authorization, and accounting controls. The IMS specifications include widely used Internet Engineering Task Force (IETF) recommendations. For example, the Session Initialization Protocol (SIP) is used for session control signaling.

[0085] The Internet, also known as the international network, generally refers to a vast network of interconnected networks, connected by a common set of protocols to form a single, logically vast international network. From a network communications perspective, the Internet is a data communications network that uses the Transmission Control Protocol (TCP) / Internet Protocol to connect computer networks in countries, regions, and institutions around the world.

[0086] It should be noted that the network architecture shown in FIG3 is not limited to including only the devices and networks shown in the figure, but may also include other devices not shown in the figure, and this application will not illustrate them one by one.

[0087] Network devices a, b, and c in FIG2 belong to LTE or NR in FIG3 . For example, network devices a, b, and c may be 4G base stations (e.g., eNBs) or 5G base stations (e.g., gNBs). The first cell, the second cell, and the third cell in FIG2 may be LTE cells or NR cells.

[0088] Please refer to Figure 4, which is a schematic diagram of a voice call scenario provided in an embodiment of the present application. As shown in Figure 4, the terminal device 100 can transmit voice data with the terminal device 200 through the network device 1, the IMS, and the network device 2. Among them, the network device 1 is the network device corresponding to the cell where the terminal device 100 is currently located, and the network device 2 is the network device corresponding to the cell where the terminal device 200 is currently located. In some embodiments of the present application, the network device 1 and the network device 2 can be the same network device. In some embodiments of the present application, the terminal device 100 can be the party that initiates the voice call to request a voice call with the terminal device 200. In some other embodiments of the present application, the terminal device 200 can be the party that initiates the voice call to request a voice call with the terminal device 100.

[0089] The network device in the embodiment of the present application may be a device for communicating with a terminal device, for example, the network device may be a base station.

[0090] The terminal device in Figure 2 may be terminal device 100 or terminal device 200 in Figure 4. Network device a, network device b, and network device c in Figure 2 may be network device 1 or network device 2 in Figure 4. The first cell, second cell, and third cell in Figure 2 may be cells covered by network device 1 or network device 2.

[0091] The technical solutions of the embodiments of the present 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, and world-wide interoperability for microwave access (WiMAX) system. The technical solutions of the embodiments of the present application can also be applied to other communication systems, such as public land mobile network (PLMN) system, etc., which are not limited by the embodiments of the present application.

[0092] The terminal device in the embodiments of the present application may 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, a laptop computer, a subscriber unit, a cellular phone, a smart phone, a wireless data card, a personal digital assistant (PDA) computer, a tablet computer, a wireless modem, a handheld device, a laptop computer, a cordless phone or a wireless local loop (WLL) station, a machine type communication (MTC) terminal, a wearable device (such as a smart watch, a smart bracelet, a pedometer, etc.), an in-vehicle device (such as a car, a bicycle, an electric car, an airplane, a ship, a train, a high-speed rail, etc.), a virtual reality (VR) device, an augmented reality (AR) device, a wireless terminal in industrial control, a smart home device (such as a refrigerator, a television, an air conditioner, an electric meter, etc.), an intelligent robot, a workshop device, a wireless terminal in self-driving, a wireless terminal in remote medical surgery, a smart grid, etc. The present invention does not specifically limit the wireless terminals in the embodiments of the present invention, such as wireless terminals in a 5G network, wireless terminals in a transportation safety network, wireless terminals in a smart city, wireless terminals in a smart home, flying equipment (for example, smart robots, drones), or wireless terminals in a 5G network or a future communication network.

[0093] The network device in the embodiment of the present application can be a device for communicating with a terminal device. For example, the network device can be a base station (base transceiver station, BTS) in a GSM system or CDMA, or a base station (NodeB, NB) in a WCDMA system, or an eNB or eNodeB in an LTE system, or a wireless controller in a cloud radio access network (cloud radio access network, CRAN) scenario, or the network device can 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 of antenna panels (including multiple antenna panels) of a base station in a 5G system, etc., and the embodiment of the present application is not limited to this.

[0094] Optionally, the base station in the embodiment of the present application may include various forms of base stations, such as: macro base stations, micro base stations (also called small stations), relay stations, access points, gNBs, transmission points (transmitting and receiving points, TRP), transmitting points (transmitting points, TP), mobile switching centers, and devices that perform base station functions in device-to-device (D2D), vehicle-to-everything (V2X), and machine-to-machine (M2M) communications, etc. The embodiment of the present application does not specifically limit this.

[0095] The embodiments of the present application do not specifically limit the specific structure of the execution subject of the method provided in the embodiments of the present application; as long as it is capable of communicating according to the method provided in the embodiments of the present application by running a program that records the code of the method provided in the embodiments of the present application, it is sufficient. For example, the execution subject of the method provided in the embodiments of the present application can be a terminal device or a network device, or a functional module in the terminal device or the network device that can call and execute the program.

[0096] The following will be combined with the accompanying drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. In the description of the embodiments of the present application, unless otherwise specified, " / " means or, for example, A / B can mean A or B; "and / or" in the text is only a description of the association relationship of associated objects, indicating that there can be three relationships, for example, A and / or B can mean: A exists alone, A and B exist at the same time, and B exists alone. In addition, in the description of the embodiments of the present application, "multiple" means two or more than two.

[0097] It should be understood that the terms "first," "second," and the like in the specification, claims, and drawings of this application are used to distinguish between different objects, rather than to describe a particular order. Furthermore, the terms "including," "having," and any variations thereof, are intended to cover non-exclusive inclusions. For example, a process, method, system, product, or apparatus comprising a series of steps or elements is not limited to the listed steps or elements, but may optionally include steps or elements not listed, or may optionally include other steps or elements inherent to the process, method, product, or apparatus.

[0098] References to "embodiments" in this application mean that a particular feature, structure, or characteristic described in connection with the embodiment may be included in at least one embodiment of the application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor does it constitute an independent or alternative embodiment that is mutually exclusive of other embodiments. It is understood, both explicitly and implicitly, by those skilled in the art that the embodiments described in this application may be combined with other embodiments.

[0099] For ease of understanding, the random access method provided in the embodiments of the present application is described in detail below with reference to the accompanying drawings.

[0100] As shown in FIG5 , an embodiment of the present application provides a random access method, including:

[0101] 501. The terminal device resides in the first cell and performs a first service.

[0102] 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.

[0103] The terminal device may reside in the first cell and perform a first service. The first service may include a voice service or a data service. The voice service includes a telephone service (e.g., making a phone call). The data service may include services such as web browsing, online gaming, or video / short video playback, which are not specifically limited in this application.

[0104] 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 a network device corresponding to the first cell so that the network device configures an event for handover for the user.

[0105] The events used for switching may include the following events:

[0106] A3 event: indicates that the signal quality of the neighboring cell is better than that of the first cell, and is used to decide whether the terminal device switches to the neighboring cell.

[0107] A4 event: indicates that the signal quality of the neighboring cell is better than the absolute threshold, which is used to decide whether the terminal device switches to the neighboring cell.

[0108] A5 event: indicates that the signal quality of the first cell is worse than absolute threshold 1 and the signal quality of the neighboring cell is better than absolute threshold 2, which is used to decide whether the terminal device switches to the neighboring cell.

[0109] Among them, events A3-A5 are three events used by the LTE system or NR system to perform intra-system measurements.

[0110] B1 event: indicates that the signal quality of the neighboring cell is better than the absolute threshold and is used to measure high-priority RAT cells.

[0111] B2 event: indicates that the signal quality of the first cell is worse than absolute threshold 1, and the signal quality of the neighboring cell is better than absolute threshold 2. It is used for measurement of RAT cells of the same or lower priority.

[0112] Among them, event B1 and event B2 are two events used by the LTE system or the NR system to perform inter-system measurements.

[0113] When the terminal device is in a connected state, the network device corresponding to the first cell (e.g., a base station) can configure an event for switching (e.g., an A3 event, an A4 event, an A5 event, a B1 event, a B2 event, etc.) to the terminal device. The terminal device reports the measurement result to the network device corresponding to the first cell according to the configured event. The network device corresponding to the first cell can send an RRC connection reconfiguration message to the terminal device based on the measurement result to instruct the terminal device to switch to the second cell.

[0114] 502. The terminal device receives an RRC connection reconfiguration message sent by the network device corresponding to the first cell.

[0115] When the terminal device resides in the first cell, it can receive an RRC connection reconfiguration message (RRC Connection Reconfiguration) sent by network device a. Network device a is a network device corresponding to the first cell (first network device), for example, a base station.

[0116] The RRC connection reconfiguration message carries first information, and the first information is used to instruct the terminal device to switch to the second cell. The second cell can be referred to as the target cell of the terminal device. In order to distinguish it from the third cell described below (the third cell involved in step 511), the second cell can be referred to as the target cell 1 of the terminal device, and the third cell described below can be referred to as the target cell 2 of the terminal device.

[0117] The first information may include a mobilityControlInfo information element. The mobilityControlInfo information element is used to instruct the terminal device to switch to the second cell.

[0118] Exemplarily, the mobilityControlInfo information element may include fields such as the ID of the second cell, carrier frequency, bandwidth, identifier of the terminal device, and parameters of each physical channel.

[0119] In some embodiments, when the terminal device resides in the first cell and performs a first service (eg, a voice service or a data service), the terminal device may receive an RRC connection reconfiguration message from a network device corresponding to the first cell.

[0120] In some embodiments, when the terminal device is stationed in the first cell, the terminal device may be in a high-speed mobile state. The terminal device being in a high-speed mobile state includes the terminal device's displacement in a preset time period being greater than a first preset threshold, and / or the terminal device's average speed / acceleration in the preset time period being greater than a second preset threshold.

[0121] For example, the terminal device can detect the horizontal acceleration / speed of the terminal device through an accelerometer. The terminal device can obtain the terminal device's geographic location through a positioning system (GPS or BeiDou system) and determine the terminal device's displacement based on the geographic location at different times.

[0122] In one possible scenario, a terminal device's determination of its state based on data collected by an accelerometer may result in a misjudgment. For example, if the terminal device is moving in a uniform linear motion and the accelerometer detects that the horizontal acceleration of the terminal device is zero, the terminal device's state cannot be accurately determined. In this case, the terminal device can use both the accelerometer and the positioning system to determine whether the terminal device is in a high-speed movement state. For example, if the positioning system output data is detected to have changed significantly over a recent period of time and the acceleration value is zero or less than a threshold, the terminal device is determined to be in a high-speed movement state.

[0123] In some embodiments, the first cell is a high-speed rail cell or a subway cell.

[0124] Among them, high-speed rail communities can also be called high-speed rail communication communities, which refer to communities covering high-speed rail tracks. Subway communities can also be called subway communication communities, which refer to communities covering subway tunnels.

[0125] In some embodiments, the terminal device may determine whether the 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 may determine whether the cell is an NR high-speed rail cell through the highSpeedMeasFlag field in the SIB message (e.g., SIB1).

[0126] In other embodiments, the terminal device may obtain the geographic 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 based on the geographic location information of the first cell. For example, the terminal device may compare the geographic location information of the first cell with the geographic location information corresponding to the high-speed rail line or the subway line. If the geographic location information of the first cell matches the geographic location information corresponding to the high-speed rail line or the subway line (i.e., the geographic location information corresponding to the high-speed rail line or the subway line contains the geographic location information of the first cell), the first cell is determined to be a high-speed rail cell or a subway cell. The geographic location information corresponding to the high-speed rail line or the subway line may be obtained by the terminal device from a network device, or may be stored in the terminal device in advance, and the embodiments of the present application do not make specific limitations.

[0127] In some embodiments, before / after the terminal device switches to the second cell, the terminal device may be in a high-speed moving state.

[0128] 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 is not repeated here.

[0129] 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, handover of a terminal device from the first cell to the second cell may be an intra-system cell handover. In 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, handover of a terminal device from the first cell to the second cell may be an inter-system cell handover.

[0130] 503. The terminal device sends a random access preamble code to the network device corresponding to the second cell.

[0131] The terminal device can send a random access preamble code to network device b (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.

[0132] The random access preamble may be referred to as Msg1 (message 1), or simply referred to as the preamble, which is not specifically limited in this application.

[0133] The terminal device may send a random access preamble based on preamble-associated parameters. These parameters include the target received power (PREAMBLE RECEIVED TARGET POWER), the preamble transmission counter (PREAMBLE TRANSMISSION COUNTER), and the preamble power ramping counter (PREAMBLE POWER RAMPING COUNTER). These parameters may be configured via higher-layer signaling.

[0134] The terminal device determines whether to send a random access preamble based on 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 so, the terminal device may send a random access preamble.

[0135] If the terminal device determines to send a random access preamble, the terminal device may determine the transmit power of the random access preamble based on the preamble target receive power and the value of the preamble power increment counter.

[0136] Exemplarily, the transmission power of the random access preamble can be determined by formula (1):

[0137] P PRACH，b，f，c (i) = min{P CMAX，f，c (i), P PRACH，target，f，c +PL b，f，c Formula (1)

[0138] Among them, P PRAC，Hb，f，c (i) is the maximum transmission power of the terminal device in the transmission time unit i, P PRACH，target，f，c is the first pilot target received power, PL b，f，c is the path loss estimated based on the downlink reference signal, b represents the BWP number, f represents the carrier number, and c represents the serving cell number.

[0139] Among them, P PRACH，target，f，c=preambleReceivedTargetPower+DELTA PREAMBLE+(PREAMBLE POWER RAMPING COUNTER–1)×PREAMBLE POWER RAMPING STEP

[0140] Where 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 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 represent the number of power increments for random access preamble retransmissions. This value is determined by whether the number of random access preamble retransmissions changes based on the transmit-side filter 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.

[0141] 504. The network device corresponding to the second cell sends a random access response message to the terminal device.

[0142] The network device corresponding to the second cell can receive the random access preamble code sent by the terminal device on the corresponding PRACH resource.

[0143] After the network device corresponding to the second cell receives the random access preamble code sent by the terminal device, it can calculate the timing advance (TA) value corresponding to the terminal device based on the random access preamble code.

[0144] The TA value is used to indicate to the terminal device the timing advance that needs to be adjusted when sending the physical uplink shared channel (PUSCH), the physical uplink control channel (PUCCH) and the sounding reference signal (SRS).

[0145] It is understood that in a wireless communication system, uplink frames are sent by the UE to a network device (e.g., a base station), and downlink frames are transmitted by the network device to the UE. To ensure that uplink and downlink frames are synchronized in the time domain, the transmission time of the uplink frames of the terminal device needs to be adjusted. The transmission time of the uplink frames of the terminal device can be adjusted by the TA value to ensure that the uplink and downlink frames are synchronized in the time domain.

[0146] The network device may send a random access response (RAR) message to the 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.

[0147] As shown in Figure 6, the TA value may be carried in the timing advance command (TAC) field of the RAR message, which includes 12 bits. The TA value may range from 0 to 3846.

[0148] Optionally, the RAR message may also include information such as a temporary cell radio network temporary identity (TC-RNTI) and an uplink grant (UL (uplink) grant), which is not limited in this application.

[0149] 505. The terminal device determines whether the TA value carried in the random access response message is greater than a first preset threshold.

[0150] After the terminal device receives the random access response message (Msg2) sent by the network device corresponding to the second cell, it can parse Msg2 to obtain the TA value and determine whether the TA value carried in Msg2 is greater than the first preset threshold.

[0151] Since the terminal device resides in a high-speed rail cell or a subway cell (that is, 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 mobile state, and the distance between the terminal device and the network device of the target cell (target cell 1, that is, the second cell) will change significantly in a short period of time. As a result, the network device of the second cell may generate a large error (that is, an abnormality) when calculating the TA value of the terminal device. For example, the TA value of the terminal device calculated by the network device of the second cell is too large (for example, the TA value is greater than the first preset threshold). If the terminal device uses the excessively large TA value in the second cell to send uplink data, the uplink data sent by the terminal device in the target cell may not be decoded normally on the network side, resulting in an excessively high uplink bit error rate of the terminal device, affecting the normal service of the terminal device (for example, it may cause the ongoing call of the terminal device to have no sound), and reducing the user experience. Therefore, when the terminal device resides in a high-speed rail cell or a subway cell, that is, when the first cell is a high-speed rail cell or a subway cell, for the random access process triggered by cell switching, the terminal device can add a check for the TA value in Msg2. That is, it is determined 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 may be performed. If the TA value is less than or equal to the first preset threshold, step 507 may be performed.

[0152] 506. When the TA value is greater than the first preset threshold, the terminal device retransmits the random access preamble code to the network device corresponding to the second cell.

[0153] When the TA value is greater than the first preset threshold, the terminal device may discard the random access response message (Msg2) sent by the network device corresponding to the second cell and resend the random access preamble to the network device corresponding to the second cell. This situation can be understood as the terminal device ignoring the excessively large TA value (i.e., the TA value greater than the first preset threshold) in the Msg2 first sent by the network device corresponding to the second cell, and re-requesting the TA value from the network device corresponding to the second cell.

[0154] Since the TA value carried in Msg2 is probabilistically large, to reduce the probability of the TA value carried in Msg2 being too large, the terminal device can ignore the received TA value that is too large and resend Msg1 to request a new TA value in order to obtain a normal TA value. This allows the terminal device to send uplink frames based on the normal TA value, thereby avoiding the problem of a persistent high uplink bit error rate on the terminal device, avoiding impacts on voice or data services, and improving user experience. A normal TA value is a TA value within a reasonable value range, for example, a normal TA value is less than or equal to a first preset threshold.

[0155] 507. When the TA value is less than or equal to the first preset threshold, the terminal device sends an RRC connection reconfiguration completion message to the network device corresponding to the second cell.

[0156] If the TA value carried in the random access response message (Mg2) is less than or equal to the first preset threshold, the terminal device does not need to discard the random access response message (Mg2). 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.

[0157] When the TA value is less than or equal to the first preset threshold, the TA value is considered to be within 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 a continuous high uplink bit error rate of the terminal device, avoiding the impact on voice services or data services, and improving the user experience.

[0158] In the embodiment of the present application, step 508 may be further included after step 506 .

[0159] 508. The network device corresponding to the second cell sends a random access response message to the terminal device.

[0160] After the network device corresponding to the second cell receives the random access preamble code retransmitted by the terminal device for the first time (ie, the random preamble code sent by the terminal device in step 506), it may retransmit the random access response message to the terminal device.

[0161] After the network device corresponding to the second cell retransmits the random access response message to the terminal device, the terminal device receives the retransmitted random access response message and, if it is determined that the TA value carried in the retransmitted random access response message is greater than the first preset threshold, step 506 may be performed again. Steps 506 and 508 may be performed in a loop N times, where N is an integer greater than or equal to 1.

[0162] In this way, the terminal device ignores the received excessively large TA value multiple times (for example, N times) and resends Msg1 to request a new TA value in order to obtain a normal TA value. This allows the terminal device to send uplink frames based on the normal TA value, thereby avoiding the problem of continuous high uplink bit errors on the terminal device, preventing the impact on voice or data services, and improving user experience.

[0163] 509. After the terminal device retransmits the random access preamble code for the Nth time, if 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 code to the network device corresponding to the second cell.

[0164] Exemplarily, assuming that 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 resend 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) resent by the terminal device for the first time, it may resend the random access response message (e.g., random access response message 1) to the terminal device. After the terminal device receives the 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 resend 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 resent by the terminal device for the second time, it may resend the random access response message (e.g., random access response message 2) to the terminal device. After the terminal device receives the random access response message (for example, 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 will no longer resend the random access preamble code to the network device corresponding to the second cell for the third time.

[0165] In this way, it is 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). That is, after the terminal device retransmits the random access preamble code for the Nth time, if 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 larger TA value can no longer be ignored. And in the subsequent uplink transmission process, the timing of sending the uplink frame is adjusted according to the larger TA value.

[0166] In some embodiments, after the terminal device retransmits the random access preamble code for the Nth time, when 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 can record the correspondence between the excessively large TA value received by the terminal device in the second cell (the TA value is greater than the first preset threshold or the second preset threshold) and the second cell. In this way, when the terminal device switches to the second cell next time, it can directly use the excessively large TA value indicated by the network device corresponding to the second cell without frequently retransmitting the random access preamble code. 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 information interaction time, and avoid the problem that the uplink data sent by the subsequent terminal device cannot be decoded normally on the network side, thereby avoiding affecting the normal service of the terminal device.

[0167] 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.

[0168] After the terminal device retransmits the random access preamble code 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.

[0169] Optionally, the method provided in the embodiment of the present application may further include the following steps:

[0170] 510. The terminal device determines that RLF occurs in the second cell.

[0171] 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 received from the network device corresponding to the second cell is greater than a second preset threshold, the terminal device determines that a radio link failure (RLF) has occurred in the second cell. In this case, the terminal device can reselect the cell. For example, the terminal device can reselect to a third cell. The third cell can be referred to as target cell 2.

[0172] 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 received from the network device corresponding to the second cell is greater than the second preset threshold, the terminal device sends an RRC connection reconfiguration completion message to the network device corresponding to the second cell to complete the random access process. Thereafter, during the communication process between the terminal device and the second cell, the timing of sending the uplink frame can be adjusted 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, RLF may occur in the terminal device. For example, if the terminal device has an uplink high bit error problem in the second cell, that is, the uplink bit error rate of the terminal device (the bit error ratio (BER) of the uplink data sent in the second cell) exceeds the third preset threshold, the terminal device determines that RLF occurs in the second cell.

[0173] The uplink bit error rate (BER) is an indicator that measures the accuracy of uplink data transmission within a specified timeframe. BER = bit errors in uplink transmission / total number of bits transmitted in uplink transmission * 100%.

[0174] In other embodiments, the terminal device can determine whether RLF occurs in the link between the terminal device and the second cell based on the number of RLC retransmissions, in sync (or in synchronization, IS) / out of sync (or Out of synchronization, OoS) indication, the number of failures of the terminal device to send service data, random access (Random Access) results, cell switching results and RRC reconfiguration results.

[0175] For example, if the number of RLC retransmissions by the terminal device on the link between the terminal device and the second cell reaches the maximum number of RLC retransmissions, then RLF is considered to have occurred in the second cell. For another example, if on the link between the terminal device and the second cell, the terminal device receives a preset number of consecutive Out-of-Service (OoS) indications within a preset time period, and does not recover before timer 310 (timer T310 is activated when a preset number (e.g., N310 times) of OoS is detected) expires, then RLF is considered to have occurred in the second cell. For another example, if the number of failures by the terminal device to send service data to the second cell within a preset time period is greater than or equal to the preset number of failures, then RLF is considered to have occurred in the second cell. For another example, if a random access failure occurs, then RLF is considered to have occurred in the second cell. For another example, if a handover failure occurs, that is, the terminal device cannot successfully access the second cell before timer T304 (timer T304 is activated when the terminal device receives an RRC Connection Reconfiugration command and prepares for handover) expires, then RLF is considered to have occurred in the second cell. For another example, if the RRC reconfiguration fails, the terminal device considers that RLF occurs in the second cell. The preset time, preset number of failures, and preset number can be set as needed, and can be agreed upon in the protocol or configured by the network device, and this application does not limit them.

[0176] Among them, the occurrence of RLF in the second cell may mean that data transmission between the terminal device and the second cell or the network device corresponding to the second cell cannot be carried out normally, such as failure of uplink data transmission and / or downlink data transmission.

[0177] 511. The terminal device establishes an RRC connection with the network device corresponding to the third cell through the RRC re-establishment process.

[0178] After the terminal device determines that an RLF has occurred in the second cell, the terminal device can determine a new target cell (target cell 2, i.e., the third cell) and establish an RRC connection with the network device corresponding to the third cell. Since the terminal device is in a connected state, an RRC connection can be established with the network device corresponding to the third cell through the RRC re-establishment process.

[0179] In some embodiments, the terminal device may select a cell that satisfies the S criterion from at least one candidate cell (cell searched by the UE) as the third cell. The S criterion may be used to select an RRC re-establishment cell. It should be noted that the S criterion may be replaced with other criteria capable of selecting an RRC re-establishment cell, and this application is not limited thereto.

[0180] Exemplarily, the terminal device selecting a cell that satisfies the S criterion among at least one candidate cell (cell searched by the UE) as the third cell may include: the terminal device determining whether the at least one candidate cell satisfies the S criterion, obtaining one or more cells that satisfy the S criterion; if there is only one cell that satisfies the S criterion, selecting the cell that satisfies the S criterion as the third cell. Alternatively, the terminal device selects the cell with the best (or highest) signal quality (e.g., RSRP\RSRQ) among the multiple cells that satisfy the S criterion as the third cell.

[0181] 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.

[0182] In some embodiments, the third cell is a high-speed rail cell or a subway cell.

[0183] In some embodiments, the third cell may be an LTE cell or a NR cell.

[0184] The terminal device establishes an RRC connection with the network device corresponding to the third cell through the RRC re-establishment process, including: the terminal device sends an RRC re-establishment request (RRC restablishment request) message to the third cell, and the RRC re-establishment request message can be used to request the establishment of an RRC connection with the network device corresponding to the third cell. If the network device corresponding to the third cell accepts the RRC re-establishment request message sent by the terminal device, the network device corresponding to the third cell sends an RRC re-establishment message (RRC re-establishment) to the terminal device. The terminal device receives the RRC re-establishment 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, it sends an RRC re-establishment completion message to the network device corresponding to the third cell.

[0185] Exemplarily, an RRC re-establishment request (RRC connection reestablishment request or RRC connection reestablishment request) may be generated by the RRC layer of the first terminal device, where the RRC layer of the first terminal device corresponds to the RRC layer of the wireless access network device.

[0186] After the terminal device establishes an RRC connection with the network device corresponding to the third cell, the first service mentioned in step 501 can be continued through the RRC connection.

[0187] Based on the method provided in the embodiments of the present application, the terminal device can resend Msg1 to request a new TA value, ignoring the received overly large TA value in order to obtain a normal TA value. This can avoid the problem of the network side sending an overly large TA value, which affects the terminal device's ongoing services (e.g., voice services or data services), and can improve the user experience.

[0188] Existing technology allows a terminal (terminal device) to receive a handover command from the network side in some scenarios on an LTE cell, initiate random access on the target cell, send Msg1, and then receive Msg2 from the network side, successfully accessing the target cell. However, the network side cannot properly decode the uplink data subsequently sent by the terminal, affecting normal terminal services (for example, it may cause the terminal to silence an ongoing call).

[0189] During their research, the applicant discovered that, in existing high-speed rail scenarios, if an abnormally large TA value is issued by the network side during random access during cell handover, the terminal device will experience persistent high uplink bit errors after accessing the cell, impacting voice quality or data services. For example, a user on a high-speed train might experience a sudden loss of voice or dropped calls.

[0190] In a high-speed rail scenario, a terminal device receives a handover command from the network side in an LTE high-speed rail cell and initiates random access to the target cell. After sending Msg1, it receives Msg2 from the network side, successfully accessing the target cell. However, the TA value carried in Msg2 is extremely large, causing the network side to be unable to properly decode the uplink data subsequently sent by the terminal device, affecting normal service of the terminal device.

[0191] After research, the applicant found that the above-mentioned problems were caused by the following two reasons:

[0192] 1. In high-speed mobility scenarios, the network side may misjudge the TA value after receiving Msg1, causing the TA value carried in Msg2 to be too large.

[0193] 2. If the terminal device uses an excessively large TA value in the target cell, it will cause a large offset in the time domain, affecting the network-side decoding of uplink data and causing the terminal device to experience continuous high uplink bit errors.

[0194] An embodiment of the present application provides a method for improving the performance of a terminal device. Since an overestimated TA value on the network side is a probabilistic phenomenon, the terminal device can ignore the received overly large TA value and resend Msg1 to solve this problem or reduce the probability of this problem occurring.

[0195] This embodiment of the present application provides a method for improving the performance of a terminal device, which may include the following:

[0196] 1) In the high-speed rail cell, for the random access process triggered by cell switching, the terminal device can add a check for the TA value in Msg2. As shown in Figure 7, after the terminal (for example, 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 based on Msg1 and can send Msg2 carrying the 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 excessively large TA value in Msg2) and immediately resend Msg1.

[0197] Furthermore, after the terminal retransmits Msg1, it can receive Msg2 retransmitted by the network. If the TA value in Msg2 is still greater than the preset threshold, the terminal device can continue to discard Msg2 and retransmit Msg1.

[0198] In an optional implementation, the terminal may keep resending Msg1 until the TA value carried in the received Msg2 is less than or equal to a preset threshold. Then, the terminal may send an RRC connection reconfiguration complete message to the target cell.

[0199] Msg1 (message 1) and Msg2 (message 2) are both messages involved in the random access process. Msg2 contains a crucial parameter: the timing advance (TA). After receiving Msg1, the network (e.g., the base station) calculates the uplink TA based on it. Upon receiving the random access response message (Msg2), the terminal device can adjust its uplink transmission timing based on the TA value carried in Msg2.

[0200] 2) Further optionally, in order to be compatible with the scenario where the actual required TA value itself is very large, if the TA value received by the terminal device multiple times is still too large, the terminal device may no longer ignore the excessively large TA value in the received Msg2. As shown in Figure 8, if the terminal device retransmits Msg1 multiple times (taking Figure 8 as an example, assuming that the terminal device retransmits Msg1 twice), and the TA value in the received Msg2 is still too large (such as greater than a preset threshold, the preset threshold of the TA value in the multiple received Msg2 may be the same or different), the terminal device may no longer ignore the excessively large TA value in the received Msg2, that is, the terminal device may no longer retransmit Msg1, but successfully access the target cell according to Msg2 (such as the most recently received Msg2). The terminal may send an RRC connection reconfiguration completion message to the target cell.

[0201] Based on the method provided in the embodiment of the present application, the problem of high bit error caused by excessively large TA value sent down by the network side, resulting in silent voice / unavailable data, can be solved, thereby improving user experience.

[0202] A hardware structure of a terminal device is shown in FIG9 , 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, buttons, a motor, an indicator, a camera, a display, and a SIM card slot. The audio module may include a speaker, a receiver, a microphone, and a headphone jack, and the sensor module may include a pressure sensor, a gyroscope sensor, an air 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, and a bone conduction sensor.

[0203] It is understood that the structures illustrated in the embodiments of this application do not constitute specific limitations on the terminal device. In other embodiments, the terminal device may include more or fewer components than shown, or may combine or separate certain components, or arrange the components differently. The illustrated components may be implemented in hardware, software, or a combination of software and hardware.

[0204] The processor may include one or more processing units, for example, the processor may include an application processor (AP), a modem processor (also known as a baseband processor), a graphics processor (GPU), an image signal processor (ISP), a controller, a video codec, a digital signal processor (DSP), and / or a neural-network processing unit (NPU). Different processing units may be independent devices or integrated into one or more processors. The processor is the nerve center and command center of the terminal device. The controller can generate operation control signals based on instruction opcodes and timing signals to complete the control of instruction fetching and execution.

[0205] The wireless communication function of the terminal device can be implemented through antenna 1, antenna 2, a mobile communication module, a wireless communication module, and a modem. In some embodiments, antenna 1 of the terminal device is coupled to the mobile communication module, and antenna 2 is coupled to the wireless communication module, so that the terminal device can communicate with network-side devices and other terminal devices through wireless communication technology.

[0206] In addition, operating systems run on the above components, such as the iOS operating system, the Android open source operating system, and the Windows operating system.

[0207] The operating system of the terminal device can adopt a layered architecture, event-driven architecture, microkernel architecture, microservice architecture, or cloud architecture. The embodiments of this application use the Android system with a layered architecture as an example to illustrate the hardware and software structure of the terminal device. It should be noted that although the embodiments of this application use the Android system as an example, the basic principles are also applicable to terminal devices based on operating systems such as iOS or Windows.

[0208] Figure 10 is a schematic diagram of the software structure of a terminal device. The software structure adopts a layered architecture, which divides the software into several layers, each with clear roles and division of labor. The layers communicate with each other through software interfaces. Taking the Android system running on an AP as an example, in some embodiments, the Android system is divided into five layers: from top to bottom, the application layer, the application framework layer (Framework), the Android runtime (Android runtime) and system library, the hardware abstraction layer (HAL), and the system kernel layer (Kernel).

[0209] The application layer can include a series of application packages. Application packages may include apps such as camera, gallery, calendar, call, map, WLAN, Bluetooth, music, video, and short messaging. The application layer may also include the system UI, which is used to display the terminal device interface, such as the signal icon corresponding to the SIM card and the call interface. The application framework layer provides the application programming interface (API) and programming framework for the applications in the application layer. The application framework layer includes some predefined functions. For example, the application framework layer may include a window manager, content provider, view system, telephony manager, resource manager, notification manager, etc. The telephony manager is used to provide call functions for the terminal device, such as call status management (including connecting and hanging up). The application framework layer may also include the radio interface layer (RIL), through which the modem processor (modem) can exchange information with the telephony.

[0210] The modem can include the Non-Access Stratum (NAS) layer, the Radio Resource Control (RRC) layer, the Packet Data Convergence Protocol (PDCP) layer, the Radio Link Control (RLC) layer, the Medium Access Control (MAC) layer, and the Physical (PHY) layer. Each of these layers can be a software module. The modem can interact with the base station through an antenna.

[0211] 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.

[0212] Some embodiments of the present application provide a chip system for use in a terminal device. The chip system includes at least one processor and an interface, wherein the interface is configured to receive instructions and transmit them to the at least one processor. The at least one processor executes the instructions, causing the terminal device to perform the following random access method. The chip system may be a modem, or a system on a chip (SoC) including a modem, and the above method may be implemented by a modem.

[0213] The methods of some embodiments of the present application may be implemented by a modem of a terminal device.

[0214] For example, the modem may send Msg1 and receive Msg2 via the antenna, and the modem may determine whether the TA value carried in Msg2 is greater than a first preset threshold. If the TA value carried in Msg2 is greater than the first preset threshold, the modem may resend Msg1 via the antenna.

[0215] After the modem retransmits Msg1 for the Nth time, if the TA value in the received Msg2 is greater than the second preset threshold, the modem may not retransmit Msg1.

[0216] The present application also provides a chip system, as shown in FIG11 , which includes at least one processor 1101 and at least one interface circuit 1102. The processor 1101 and the interface circuit 1102 can be interconnected via a line. For example, the interface circuit 1102 can be used to receive signals from other devices (e.g., a memory of a terminal device). For another example, the interface circuit 1102 can be used to send signals to other devices (e.g., the processor 1101).

[0217] For example, the interface circuit 1102 may read instructions stored in a memory in 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 the terminal device shown in FIG9 ) may execute the steps in the above embodiment.

[0218] Of course, the chip system may also include other discrete devices, which is not specifically limited in the embodiments of the present application.

[0219] An embodiment of the present application also provides a computer-readable storage medium, which includes computer instructions. When the computer instructions are executed on a terminal device (the terminal device shown in Figure 9), the terminal device executes the various functions or steps performed by the terminal device (for example, UE) in the above method embodiment.

[0220] An embodiment of the present application further provides a computer program product, which, when executed on a computer, enables the computer to execute the functions or steps executed by the terminal device in the above method embodiment.

[0221] An embodiment of the present application also provides a processing device, which can be divided into different logical units or modules according to function, and each unit or module performs a different function, so that the processing device performs each function or step performed by the terminal device in the above method embodiment.

[0222] Through the description of the above implementation methods, technical personnel in the relevant field can clearly understand that the above functions can be distributed and completed by different functional modules as needed, that is, the internal structure of the device can be divided into different functional modules to complete all or part of the functions described above.

[0223] In the several embodiments provided herein, it should be understood that the disclosed devices and methods can be implemented in other ways. For example, the device embodiments described above are merely illustrative. For example, the division of modules or units is merely a logical functional division. In actual implementation, other division methods may be used, such as multiple units or components being combined or integrated into another device, or some features being ignored or not implemented. Furthermore, the coupling or direct coupling or communication connection shown or discussed between each other may be through some interface, indirect coupling or communication connection between devices or units, and may be electrical, mechanical, or other forms. The units described as separate components may or may not be physically separate. The components shown as units may be one physical unit or multiple physical units, i.e., they may be located in one place or distributed across multiple locations. Some or all of the units may be selected to achieve the purpose of the present embodiment according to actual needs. In addition, the functional units in the various embodiments of the present application may be integrated into a single processing unit, each unit may exist physically separately, or two or more units may be integrated into a single unit. The above-mentioned integrated units may be implemented in either hardware or software functional units. If 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 embodiment of the present application is essentially 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, which is stored in a storage medium and includes several instructions for making a device (which can be a single-chip microcomputer, chip, etc.) or a processor (processor) perform all or part of the steps of the method described in each embodiment of the present application. The aforementioned storage medium includes various media that can store program code, such as a USB flash drive, a mobile hard disk, a read-only memory (ROM), a random access memory (RAM), a magnetic disk or an optical disk. The above content is only a specific embodiment of the present application, but the scope of protection of the present application is not limited thereto. Any change or replacement within the technical scope disclosed in the present application should be included within the scope of protection of the present application. Therefore, the scope of protection of the present application should be based on the scope of protection 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, wherein 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 camps 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 a first piece of information is carried in the RRC connection reconfiguration message, and the first piece of 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 piece of information, and 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, wherein 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, wherein 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, wherein The first cell is a high-speed rail cell or a subway cell.

9. The method according to any one of claims 3-7, wherein 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 3-10, 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 processors; 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 processors, 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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