Random access method, communication device and system

Abstract

Provided are a random access method and device, the method comprising: receiving PRACH configuration information of a target cell sent by a source cell, the PRACH configuration information comprising the number of PRACH repetitions, and the absolute value of the relative time migration of system frames of the same frame index of the source cell and the target cell being less than half of the duration of the system frames; determining an associated pattern period according to the PRACH configuration information; a time period is determined according to the association pattern period, the time period comprises a set of ROs associated with the SSB index, the set of ROs comprises the ROs of the number of PRACH repetitions, the time period is m times of the duration of the system frame, and m is an integer greater than or equal to 2; and randomly accessing the target cell according to the time period. According to the method and the device provided by the invention, the terminal can carry out PRACH transmission meeting the repetition times configured by the base station, the random access efficiency is increased, and the time delay of the terminal in cell switching is reduced.

Description

Technical Field

[0001] Embodiments of the present application relate to the field of communications, and more specifically, to a random access method, a communication device, and a system. Background Art

[0002] With the development of communication technologies, in existing cellular mobile communication systems, terminal devices in various usage scenarios need to initiate random access in various scenarios. A network device may configure a set of physical random access channel (PRACH) resources for terminal devices in a cell in an uplink time slot. The set of PRACH resources includes multiple periodically configured PRACH resource subsets, and each PRACH resource subset includes multiple PRACH resources. The size of each PRACH resource in the set of PRACH resources is the same. During the random access process, a terminal device may send a preamble signal to the network device on a PRACH resource in the set of PRACH resources. Therefore, a PRACH resource is also referred to as a random access channel occasion (RO).

[0003] To increase the random access efficiency of a terminal during cell handover and reduce the handover delay, the terminal may perform repeated transmission of the preamble signal according to the repeated PRACH resources configured by the base station. Summary of the Invention

[0004] Embodiments of the present application provide a random access method, a communication device, and a system, which can increase the random access efficiency and reduce the delay of a terminal during cell handover.

[0005] In a first aspect, a random access method is provided, which is applied to a terminal. This method may be executed by the terminal device, or alternatively, may be executed by a component (such as a chip or a circuit) of the terminal device, and this is not limited. For ease of description, the following takes the execution by the terminal device as an example for illustration. However, it should be noted that the actions executed by the terminal device below may also be replaced by those executed by a component (such as a chip or a circuit) of the terminal device, that is, the terminal device in this method may be replaced by a component of the terminal device.

[0006] The method may include: receiving physical random access channel (PRACH) configuration information of a target cell sent by a source cell, where the PRACH configuration information includes the PRACH repetition count, and the absolute value of the relative time offset of system frames with the same frame index between the source cell and the target cell is less than half of the duration of a system frame; determining an associated pattern period according to the PRACH configuration information; determining a time period according to the associated pattern period, the time period includes a set of random access channel opportunities (ROs) associated with a synchronization signal block (SSB) index, the set of ROs includes ROs with the PRACH repetition count, and the time period is m times the duration of a system frame, where m is an integer greater than or equal to 2; and randomly accessing the target cell according to the time period.

[0007] In the solution provided by the embodiments of this application, the terminal receives the PRACH configuration information sent by the source cell indicating that the terminal randomly accesses the target cell, determines the associated pattern period for random access according to the PRACH configuration information, and can determine the time period according to the associated pattern period, so that the terminal can determine the set of ROs for random access when the time period is m times the duration of a system frame. On this set of ROs, the terminal can perform PRACH repeated transmissions that meet the PRACH repetition count configured by the base station, increasing the random access efficiency and reducing the delay of the terminal in cell handover. Among them, the source cell and the target cell are different serving cells, and the network devices supporting the source cell and the target cell may be the same network device or different network devices, which is not limited herein.

[0008] In combination with the first aspect, in some implementation manners of the first aspect, the associated pattern period is equal to the duration of a system frame.

[0009] In the solution provided by the embodiments of this application, the terminal can determine the associated pattern period for randomly accessing the target cell according to the PRACH configuration information of the target cell sent by the source cell, and determine the time period according to the associated pattern period. When the associated pattern period is equal to the duration of a system frame, the time period determined by the terminal includes two or more associated pattern periods. The terminal determines the set of ROs for random access according to the time period and the relative time offset of system frames with the same frame index between the source cell and the target cell. In this way, when the associated pattern period is equal to the duration of a system frame and the time period is m times the duration of a system frame, the terminal can perform PRACH repetition, increasing the random access efficiency and reducing the delay of the terminal in cell handover. Among them, the duration of the system frame of the target cell is equal to the duration of the system frame of the source cell.

[0010] In combination with the first aspect, in some implementation manners of the first aspect, the maximum number L of SSB indexes of the target cell max = 4.

[0011] In combination with the first aspect, in certain implementations of the first aspect, randomly accessing a target cell according to a time period includes: determining a system frame of the target cell; determining a set of random access channel opportunities ROs associated with SSB indexes included in the time period according to the system frame of the target cell; and randomly accessing according to the set of ROs.

[0012] In the solution provided by the embodiments of the present application, when the associated pattern period is equal to the duration of the system frame and the time period is m times the duration of the system frame, the terminal can determine the system frame of the target cell according to the time period, so that the terminal can determine the set of ROs associated with the indexes of the SSBs selected by the terminal for random access according to the system frame of the target cell, enabling the terminal to perform PRACH repetition on the determined set of ROs, increasing the random access efficiency, and reducing the latency of the terminal in cell handover.

[0013] In combination with the first aspect, in certain implementations of the first aspect, the method further includes: receiving a demodulation reference signal DMRS of a PBCH sent by the target cell; determining the system frame of the target cell, including: determining the boundary of the system frame of the target cell according to the DMRS; determining the index of the system frame of the target cell according to the boundary of the system frame of the target cell and the boundary of the system frame of the source cell; and determining the system frame of the target cell included in the time period according to the index of the system frame.

[0014] In the solution provided by the embodiments of the present application, the terminal can determine the system frame of the target cell according to the DMRS of the PBCH, and determine the index of the system frame of the target cell according to the relative time offset between the boundary of the system frame of the target cell and the boundary of the system frame of the source cell, so that the terminal can determine the system frame of the target cell according to the determined index of the system frame of the target cell, enabling the terminal to perform PRACH repetition on the determined set of ROs, increasing the random access efficiency, and reducing the latency of the terminal in cell handover.

[0015] In combination with the first aspect, in certain implementations of the first aspect, determining the boundary of the system frame of the target cell according to the DMRS includes: determining a half-frame indication according to the DMRS; and determining the boundary of the system frame of the target cell according to the half-frame indication.

[0016] In the solution provided by the embodiments of the present application, the number of SSB indexes of the target cell corresponds to the number of SSBs that the terminal can select for random access to the target cell. When the maximum number L max of the SSB indexes of the target cell is 4, the terminal can obtain the index of the SSB and the half-frame indication according to the decoding result of the DMRS of the PBCH, and obtain the boundary of the system frame of the target cell according to the half-frame indication, so that the terminal can determine the boundary of the system frame of the target cell by decoding only 3 bits of information carried by the DMRS, reducing the latency of the terminal for handover.

[0017] In a second aspect, a random access method is provided, which is applied to a network device of a source cell. The method includes: obtaining physical random access channel (PRACH) configuration information of a target cell, where the PRACH configuration information includes the PRACH repetition count; sending the PRACH configuration information to a terminal. The absolute value of the relative time offset of system frames with the same frame index between the source cell and the target cell is less than half of the duration of a system frame. The time period includes a set of random access channel opportunities (ROs) associated with a synchronization signal block (SSB) index. The set of ROs includes ROs with the PRACH repetition count. The time period is determined according to an associated pattern period, and the associated pattern period is determined according to the PRACH configuration information. The time period is m times the duration of a system frame, where m is an integer greater than or equal to 2.

[0018] In the solution provided by the embodiments of the present application, the source cell obtains and sends the PRACH configuration information indicating that the terminal randomly accesses the target cell, and the absolute value of the relative time offset of system frames with the same frame index between the source cell and the target cell is less than half of the duration of a system frame. This enables the terminal to determine the associated pattern period for random access based on the PRACH configuration information, and to determine the time period based on the associated pattern period. This allows the terminal to determine the set of ROs for random access when the time period is m times the duration of a system frame, and on this set of ROs, the terminal can perform PRACH repeated transmissions that meet the PRACH repetition count configured by the base station, increasing the random access efficiency and reducing the delay of the terminal during cell handover. Here, the source cell and the target cell are different serving cells, and the network devices supporting the source cell and the target cell may be the same network device or different network devices, which is not limited herein.

[0019] In combination with the second aspect, in some implementation manners of the second aspect, the associated pattern period is equal to the duration of a system frame.

[0020] In the solution provided by the embodiments of the present application, the source cell obtains and sends the PRACH configuration information indicating that the terminal randomly accesses the target cell, and the absolute value of the relative time offset of system frames with the same frame index between the source cell and the target cell is less than half of the duration of a system frame. This enables the terminal to determine the set of ROs for random access based on the time period and the relative time offset of system frames with the same frame index between the source cell and the target cell when the associated pattern period is equal to the duration of a system frame. This allows the terminal to perform PRACH repetition when the associated pattern period is equal to the duration of a system frame and the time period is m times the duration of a system frame, increasing the random access efficiency and reducing the delay of the terminal during cell handover. Here, the duration of the system frame of the target cell is equal to the duration of the system frame of the source cell.

[0021] In a third aspect, a random access method is provided, which is applied to a network device of a target cell. The method includes: sending physical random access channel (PRACH) configuration information to a source cell, where the PRACH configuration information includes the PRACH repetition count; receiving random access information of a terminal. The absolute value of the relative time offset of system frames with the same frame index between the source cell and the target cell is less than half of the duration of a system frame. A time period includes a set of random access channel opportunities (ROs) associated with a synchronization signal block (SSB) index. The set of ROs includes ROs with the PRACH repetition count. The time period is determined according to an associated pattern period, and the associated pattern period is determined according to the PRACH configuration information. The time period is m times the duration of a system frame, where m is an integer greater than or equal to 2.

[0022] In the solution provided by the embodiments of the present application, the target cell sends PRACH configuration information indicating that the terminal randomly accesses the target cell to the source cell, and the absolute value of the relative time offset of system frames with the same frame index between the source cell and the target cell is less than half of the duration of a system frame. In this way, the terminal can determine the associated pattern period for random access according to the PRACH configuration information, and can determine the time period according to the associated pattern period. In this way, the terminal can determine the set of ROs for random access according to the time period when the time period is m times the duration of a system frame, and the terminal can perform PRACH repeated transmissions that meet the PRACH repetition count configured by the base station on this set of ROs, increasing the random access efficiency and reducing the latency of the terminal during cell handover. Herein, the source cell and the target cell are different serving cells, and the network devices supporting the source cell and the target cell may be the same network device or different network devices, which is not limited herein.

[0023] In combination with the third aspect, in some implementation manners of the third aspect, the associated pattern period is equal to the duration of a system frame.

[0024] In the solution provided by the embodiments of the present application, the target cell sends PRACH configuration information indicating that the terminal randomly accesses the target cell to the source cell, and the absolute value of the relative time offset of system frames with the same frame index between the source cell and the target cell is less than half of the duration of a system frame. In this way, when the associated pattern period is equal to the duration of a system frame, the terminal can determine the set of ROs for random access according to the time period and the relative time offset of system frames with the same frame index between the source cell and the target cell. In this way, when the associated pattern period is equal to the duration of a system frame and the time period is m times the duration of a system frame, the terminal can perform PRACH repetition, increasing the random access efficiency and reducing the latency of the terminal during cell handover. Herein, the duration of the system frame of the target cell is equal to the duration of the system frame of the source cell.

[0025] Fourthly, a random access method is provided, which is applied to a terminal. The method includes: receiving physical random access channel (PRACH) configuration information and synchronization signal block (SSB) configuration information of a target cell sent by a source cell, where the PRACH configuration information includes the PRACH repetition times, and the SSB configuration information includes the SSB index; determining an association pattern period according to the PRACH configuration information; determining a time period according to the association pattern period, where the time period includes a set of random access channel opportunities (ROs) associated with the SSB index, the set of ROs includes ROs with the PRACH repetition times, and the time period is m times the duration of a system frame, and m is an integer greater than or equal to 2; receiving a physical broadcast channel (PBCH) sent by the target cell according to the SSB configuration information; determining the index of the system frame of the target cell according to the PBCH; and randomly accessing the target cell according to the index of the system frame of the target cell and the time period.

[0026] In the solution provided by the embodiments of this application, the terminal receives the PRACH configuration information and the SSB configuration information sent by the source cell, which indicate that the terminal randomly accesses the target cell, and can determine the association pattern period for random access according to the PRACH configuration information, and can determine the time period according to the association pattern period. In this way, the terminal can determine the set of ROs for random access according to the time period when the time period is m times the duration of the system frame. On this set of ROs, the terminal can perform PRACH retransmission that meets the PRACH repetition times configured by the base station, improving the random access efficiency and reducing the delay of the terminal in cell handover. Herein, the source cell and the target cell are different serving cells, and the network devices supporting the source cell and the target cell can be the same network device or different network devices, which is not limited herein.

[0027] In combination with the fourth aspect, in some implementation manners of the fourth aspect, the association pattern period is equal to the duration of the system frame.

[0028] In the solution provided by the embodiments of this application, the terminal receives the PRACH configuration information and the SSB configuration information sent by the source cell, which indicate that the terminal randomly accesses the target cell, and can determine the association pattern period for random access according to the PRACH configuration information, and can determine the time period according to the association pattern period. When the association pattern period is equal to the duration of the system frame, the determined time period by the terminal contains two or more association pattern periods. The terminal determines the set of ROs for random access according to the time period and the decoding result of the PBCH. In this way, the terminal can perform PRACH repetition when the association pattern period is equal to the duration of the system frame and the time period is m times the duration of the system frame, improving the random access efficiency and reducing the delay of the terminal in cell handover. Herein, the duration of the system frame of the target cell is equal to that of the source cell.

[0029] In combination with the fourth aspect, in some implementation manners of the fourth aspect, the maximum number L of SSB indexes max = 4.

[0030] In the solution provided by the embodiments of the present application, the number of SSB indexes of the target cell corresponds to the number of SSBs that the terminal can select for random access to the target cell. When the maximum number L of SSB indexes of the target cell max = 4, the terminal can obtain the SSB index and the boundary of the system frame of the target cell by only decoding the 3-bit information carried by the DMRS.

[0031] Fifth aspect, a random access method is provided, which is applied to a terminal. The method includes:

[0032] Receiving the PRACH configuration information and the synchronization signal block SSB configuration information of the target cell sent by the source cell, where the PRACH configuration information includes the PRACH repetition times, the SSB configuration information includes the SSB index, the target cell is applied to a time division duplex TDD system, and the source cell and the target cell use the same frequency; determining an association pattern period according to the PRACH configuration information; determining a time period according to the association pattern period, the time period includes a set of random access channel opportunities RO associated with the SSB index of the synchronization signal block SSB, the set of RO includes RO with the PRACH repetition times, and the time period is m times the duration of the system frame, and m is an integer greater than or equal to 2; randomly accessing the target cell according to the time period.

[0033] In the solution provided by the embodiments of the present application, the terminal receives the PRACH configuration information and the SSB configuration information sent by the source cell indicating that the terminal randomly accesses the target cell, and can determine the association pattern period for random access according to the PRACH configuration information, and can determine the time period according to the association pattern period. The time period includes a set of random access channel opportunities RO associated with the SSB index in the SSB configuration information, so that the terminal can perform PRACH repeated transmission that meets the PRACH repetition times configured by the base station on the determined set of RO according to the time period when the time period is m times the duration of the system frame and when switching between the target cell and the source cell with the same frequency, improving the random access efficiency and reducing the delay of the terminal in cell handover. Among them, the source cell and the target cell are different serving cells, and the network devices supporting the source cell and the target cell can be the same network device or different network devices; the source cell and the target cell use the same frequency, and the source cell and the target cell are called co-frequency cells. Co-frequency cells can mean that the center frequencies of the carriers are the same, or the center frequencies and the sub-carrier spacings are the same. Or, co-frequency cells can also mean that the center frequencies for sending SSBs are the same, or the center frequencies and the sub-carrier spacings of the SSBs are the same, and this is not limited herein.

[0034] In combination with the fifth aspect, in some implementations of the fifth aspect, the associated pattern period is equal to the duration of a system frame.

[0035] In the solution provided by the embodiments of the present application, the terminal receives the PRACH configuration information and SSB configuration information sent by the source cell indicating that the terminal randomly accesses the target cell, and can determine the associated pattern period for random access according to the PRACH configuration information, and can determine the time period according to the associated pattern period. When the associated pattern period is equal to the duration of a system frame, the time period determined by the terminal contains two or more associated pattern periods. The time period includes a set of random access channel opportunities RO associated with the SSB index in the SSB configuration information. In this way, when the associated pattern period is equal to the duration of a system frame and the time period is m times the duration of a system frame, the terminal can perform PRACH repeated transmissions that meet the PRACH repetition times configured by the base station when switching between the target cell and the source cell on the same frequency, increasing the random access efficiency and reducing the delay of the terminal during cell handover. Among them, the duration of the system frame of the target cell is equal to the duration of the system frame of the source cell.

[0036] Sixth aspect, a communication device is provided. The device includes a processing module and a transceiver module. The transceiver module is used to receive the physical random access channel PRACH configuration information of the target cell sent by the source cell. The PRACH configuration information includes the PRACH repetition times, and the absolute value of the relative time offset of the system frames with the same frame index between the source cell and the target cell is less than half of the duration of the system frame. The processing module is used to determine the associated pattern period according to the PRACH configuration information. The processing module is further used to determine the time period according to the associated pattern period. The time period includes a set of random access channel opportunities RO associated with the synchronization signal block SSB index. The set of RO includes RO with the PRACH repetition times. The time period is m times the duration of the system frame, and m is an integer greater than or equal to 2. The transceiver module is further used to randomly access the target cell according to the time period.

[0037] In combination with the sixth aspect, in some implementations of the sixth aspect, the associated pattern period is equal to the duration of a system frame.

[0038] In combination with the sixth aspect, in some implementations of the sixth aspect, the maximum number L of SSB indexes of the target cell max = 4.

[0039] In combination with the sixth aspect, in some implementations of the sixth aspect, randomly accessing the target cell according to the time period includes: determining the system frame of the target cell; determining the set of random access channel opportunities RO associated with the SSB index included in the time period according to the system frame of the target cell; and randomly accessing according to the set of RO.

[0040] In combination with the sixth aspect, in some implementations of the sixth aspect, the transceiver module is further configured to: receive the demodulation reference signal DMRS of the PBCH sent by the target cell; determine the system frame of the target cell, including: determining the boundary of the system frame of the target cell according to the DMRS; determining the index of the system frame of the target cell according to the boundary of the system frame of the target cell and the boundary of the system frame of the source cell; and determining the system frame of the target cell included in the time period according to the index of the system frame.

[0041] In combination with the sixth aspect, in some implementations of the sixth aspect, determining the boundary of the system frame of the target cell according to the DMRS includes: determining the half-frame indication according to the DMRS; and determining the boundary of the system frame of the target cell according to the half-frame indication.

[0042] A seventh aspect provides a communication device, including a transceiver module, where the transceiver module is configured to obtain the physical random access channel PRACH configuration information of a target cell, where the PRACH configuration information includes the PRACH repetition times; the transceiver module is further configured to send the PRACH configuration information to a terminal, the absolute value of the relative time offset of the system frames with the same frame index of the source cell and the target cell is less than half of the duration of the system frame, the time period includes a set of random access channel opportunities RO associated with the synchronization signal block SSB index, the set of RO includes RO with the PRACH repetition times, the time period is determined according to an association pattern period, the association pattern period is determined according to the PRACH configuration information, and the time period is m times the duration of the system frame, where m is an integer greater than or equal to 2.

[0043] In combination with the seventh aspect, in some implementations of the seventh aspect, the association pattern period is equal to the duration of the system frame.

[0044] An eighth aspect provides a communication device, including a transceiver module, where the transceiver module is configured to send the physical random access channel PRACH configuration information to a source cell, where the PRACH configuration information includes the PRACH repetition times; the transceiver module is further configured to receive the random access information of the terminal, the absolute value of the relative time offset of the system frames with the same frame index of the source cell and the target cell is less than half of the duration of the system frame, the time period includes a set of random access channel opportunities RO associated with the synchronization signal block SSB index, the set of RO includes RO with the PRACH repetition times, the time period is determined according to an association pattern period, the association pattern period is determined according to the PRACH configuration information, and the time period is m times the duration of the system frame, where m is an integer greater than or equal to 2.

[0045] In combination with the eighth aspect, in some implementations of the eighth aspect, the association pattern period is equal to the duration of the system frame.

[0046] In a ninth aspect, a communication system is provided, including the communication device according to any one of the sixth aspect, the seventh aspect, or the eighth aspect.

[0047] In a tenth aspect, a communication device is provided, including a processor configured to execute the method according to any one of the first aspect, the second aspect, the third aspect, the fourth aspect, or the fifth aspect and its possible implementation manners. Optionally, the communication device further includes a memory. Optionally, the communication device further includes a communication interface, and the processor is coupled to the communication interface.

[0048] In combination with the tenth aspect, in some implementation manners of the tenth aspect, the communication device is a device. In this case, the communication interface may be a transceiver or an input / output interface. In another implementation manner, the communication device is a chip or a chip system. In this case, the communication interface may be an input / output interface, an interface circuit, an output circuit, an input circuit, a pin, or a related circuit on the chip or the chip system, etc. The processor may also be embodied as a processing circuit or a logic circuit.

[0049] In an eleventh aspect, a computer program product is provided, including: when the computer program is run, causing the computer to execute the method according to any one of the first aspect, the second aspect, the third aspect, the fourth aspect, or the fifth aspect and any one of its possible implementation manners.

[0050] In a twelfth aspect, a computer-readable medium is provided, storing a computer program (which may also be referred to as code or instruction), and when it runs on a computer, causing the computer to execute the method according to any one of the first aspect, the second aspect, the third aspect, the fourth aspect, or the fifth aspect and any one of its possible implementation manners. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] Figure 1 A communication system to which the embodiments of the present application are applicable is shown.

[0052] Figure 2 A schematic diagram of a contention-based random access procedure is shown.

[0053] Figure 3 A schematic diagram of a two-step random access procedure is shown.

[0054] Figure 4 A schematic diagram of the structure of an SSB is shown.

[0055] Figure 5 A schematic diagram of a time slot structure is shown.

[0056] Figure 6 A schematic diagram of the time domain position of a PRACH is shown.

[0057] Figure 7 A schematic diagram showing the association relationship between RO and SSB.

[0058] Figure 8 A schematic diagram showing the frequency-domain position of PRACH.

[0059] Figure 9 A schematic diagram showing the mapping period between RO and SSB.

[0060] Figures 10 - 12 A schematic diagram showing a possible mapping relationship between SSB and RO.

[0061] Figure 13 A schematic diagram showing a possible association pattern period.

[0062] Figure 14 A schematic diagram showing a possible time period.

[0063] Figure 15 A schematic diagram showing a random access method provided by an embodiment of the present application.

[0064] Figure 16 A schematic flowchart showing a random access method provided by an embodiment of the present application.

[0065] Figure 17 A schematic diagram showing the structure of a possible communication device provided by an embodiment of the present application.

[0066] Figure 18 A schematic diagram showing the structure of another possible communication device provided by an embodiment of the present application. Detailed implementation manners

[0067] Next, the technical solutions in the present application will be described with reference to the accompanying drawings.

[0068] Figure 1 It is a schematic diagram of the architecture of the communication system 1000 to which the embodiment of the present application is applied. As Figure 1 shown, the communication system includes a radio access network 100 and a core network 200. Optionally, the communication system 1000 may further include the Internet 300. Among them, the radio access network 100 may include at least one radio access network device (such as Figure 1 110a and 110b in Figure 1among 120a - 120j). The terminal is connected to the radio access network device wirelessly, and the radio access network device is connected to the core network wirelessly or wiredly. The core network device and the radio access network device can be independent different physical devices, or the functions of the core network device and the logical functions of the radio access network device can be integrated on the same physical device, or the functions of part of the core network device and part of the radio access network device can be integrated on one physical device. Terminals can be connected to each other and radio access network devices can be connected to each other in a wired or wireless manner. Figure 1 It is only a schematic diagram, and other network devices may also be included in this communication system, such as wireless relay devices and wireless backhaul devices, which are not drawn in Figure 1 it.

[0069] A network device is a network-side device with wireless transceiver capabilities. The network device can be a device in a radio access network (RAN) that provides wireless communication capabilities for terminal devices, referred to as a RAN device. For example, the network device can be a base station, an evolved NodeB (eNodeB), a transmission reception point (TRP), a next generation NodeB (gNB) in a 5th generation (5G) mobile communication system, a next generation NodeB in a 6th generation (6G) mobile communication system, a base station in a future mobile communication system, or an access node in a WiFi system, etc.; it can also be a module or unit that completes some functions of the base station. For example, it can be a central unit (CU) or a distributed unit (DU). Here, the CU completes the functions of the radio resource control protocol and the packet data convergence protocol (PDCP) of the base station, and can also complete the function of the service data adaptation protocol (SDAP); the DU completes the functions of the radio link control (RLC) layer and the medium access control (MAC) layer of the base station, and can also complete some functions of the physical (PHY) layer or all functions of the physical layer. For specific descriptions of the above various protocol layers, reference can be made to the relevant technical specifications of the 3rd generation partnership project (3GPP). These network function entities can be network elements in hardware devices, software functions running on dedicated hardware, or virtualized functions instantiated on a platform (such as a cloud platform). The network device can also include an active antenna unit (AAU for short). The AAU implements some physical layer processing functions, radio frequency processing, and related functions of active antennas. Since the information in the RRC layer will ultimately become the information in the PHY layer, or is transformed from the information in the PHY layer, thus, in this architecture, high-layer signaling, such as RRC layer signaling, can also be considered to be sent by the DU, or sent by the DU + AAU. It can be understood that the network device can be a device including one or more of the CU node, DU node, and AAU node.In addition, the CU can be divided into network devices in the radio access network (RAN), or the CU can be divided into network devices in the core network (CN). This application does not make any limitations in this regard. For another example, in vehicle to everything (V2X) technology, the access network device can be a road side unit (RSU). The radio access network device can be a macro base station (such as Figure 1 110a) in, or it can be a micro base station or an indoor station (such as Figure 1 110b) in, or it can also be a relay node, a donor node, etc. The embodiments of this application do not make any limitations on the specific technologies and specific device forms adopted by the radio access network device. For the convenience of description, the base station is used as an example of the radio access network device in the following description.

[0070] The terminal can also be referred to as a terminal device, a user equipment (UE), a mobile station, an access station, a mobile terminal, etc. The terminal can be widely applied to various scenarios. For example, device-to-device (D2D), vehicle to everything (V2X) communication, machine-type communication (MTC), Internet of Things (IoT), virtual reality, augmented reality, industrial control, autonomous driving, remote medical treatment, smart grid, smart furniture, smart office, smart wearables, smart transportation, smart city, etc. The terminal can be a mobile phone, a tablet computer, a computer with wireless transceiver function, a wearable device, a vehicle, a drone, a helicopter, an airplane, a ship, a robot, a robotic arm, a smart home device, etc. In the embodiments of this application, the device for implementing the functions of the terminal device can be the terminal device, or it can be a device that can support the terminal device to implement this function, such as a chip system or a combined device or component that can implement the functions of the terminal device. This device can be installed in the terminal device. The embodiments of this application do not make any limitations on the specific technologies and specific device forms adopted by the terminal.

[0071] The base station and the terminal can be fixed in position or movable. The base station and the terminal can be deployed on land, including indoor or outdoor, handheld or vehicle-mounted; they can also be deployed on the water surface; they can also be deployed on airplanes, balloons, and artificial satellites. The embodiments of this application do not make any limitations on the application scenarios of the base station and the terminal.

[0072] The roles of the base station and the terminal can be relative. For example, Figure 1The helicopter or drone 120i therein can be configured as a mobile base station. For the terminals 120j accessing the radio access network 100 through 120i, 120i is the base station; but for the base station 110a, 120i is the terminal, that is, the communication between 110a and 120i is through the radio air interface protocol. Of course, the communication between 110a and 120i can also be through the interface protocol between base stations. At this time, relative to 110a, 120i is also the base station. Therefore, both the base station and the terminal can be uniformly referred to as communication devices. Figure 1 The 110a and 110b therein can be referred to as communication devices with base station functions. Figure 1 The 120a - 120j therein can be referred to as communication devices with terminal functions.

[0073] The communication between the base station and the terminal, between the base station and the base station, and between the terminal and the terminal can be carried out through the authorized spectrum, or through the unlicensed spectrum, or through both the authorized spectrum and the unlicensed spectrum at the same time; it can communicate through the spectrum below 6 gigahertz (GHz), or through the spectrum above 6 GHz, or use both the spectrum below 6 GHz and the spectrum above 6 GHz at the same time. The embodiments of the present application do not limit the spectrum resources used for wireless communication.

[0074] In the embodiments of the present application, the functions of the base station can also be executed by modules (such as chips) in the base station, or by a control subsystem including base station functions. The control subsystem including base station functions here can be the control center in the above application scenarios such as smart grid, industrial control, intelligent transportation, and smart city. The functions of the terminal can also be executed by modules (such as chips or modems) in the terminal, or by a device including terminal functions.

[0075] The technical solutions provided by the embodiments of the present application can be applied to the wireless communication between communication devices. The wireless communication between communication devices can include: the wireless communication between network devices and terminals, the wireless communication between network devices and network devices, and the wireless communication between terminal devices and terminal devices. Among them, in the embodiments of the present application, the term "wireless communication" can also be abbreviated as "communication", and the term "communication" can also be described as "data transmission", "information transmission", or "transmission".

[0076] The network device in the embodiment of the present invention may be a device for communicating with a terminal device. The network device may be an evolved Node B (eNB or eNodeB) in a Long Term Evolution (LTE) system, or a radio controller in a cloud radio access network (CRAN) scenario, or the network device may be a relay station, an access point, a vehicle-mounted device, a wearable device, and a network device in a 5G network or a network device in a future evolved PLMN network, etc.

[0077] The definition of a cell is an area that provides wireless communication services for users and is the basic unit of a wireless network. A cellular network cell corresponds to a physical cell identifier, a global cell identifier, and a set of system messages. System information broadcasting is implemented and operated by the network, and is sent periodically or on demand. After the terminal is powered on, it will receive the synchronization signal and system messages sent by the base station. The system messages include parameters related to random access, such as the physical random access channel configuration index, the initial value of the logical root sequence, the cyclic shift index, and the uplink and downlink configuration index of this cell. To access the base station network, the UE goes through processes such as cell search, determining a serving cell, then obtaining the system information of the cell, and initiating random access, so as to achieve frequency and symbol synchronization with a specific cell; obtaining the system frame clock, that is, the starting position of the downlink frame; determining the physical-layer cell identity (PCI) of the cell. The UE not only performs cell search when powered on, but also continuously searches for neighboring cells, achieves synchronization, and estimates the received quality of the signal of the cell to decide whether to perform a handover (when the UE is in the RRC_CONNECTED state) or cell selection and / or cell re-selection (when the UE is in the RRC_IDLE state) to support mobility. When performing cell search, the search order is for co-frequency cells, different-frequency cells, and then cells between different systems. After the previous cell search process, the terminal still needs to determine whether the signal quality of the cell meets certain requirements to further determine whether it can camp on this cell. When the UE performs a handover, it also selects a determined target cell for the handover.

[0078] In addition, in the embodiments of the present invention, a network device provides services for a cell, and a terminal device communicates with the network device through the transmission resources used by the cell (for example, frequency domain resources, or in other words, spectrum resources). The cell may be a cell corresponding to the network device (such as a base station). The cell may belong to a macro base station or a base station corresponding to a small cell. Here, the small cells may include: metro cells, micro cells, pico cells, femto cells, etc. These small cells have the characteristics of small coverage range and low transmission power, and are suitable for providing high-rate data transmission services. In addition, the cell may also be a hypercell.

[0079] It can be understood that in the embodiments of the present application, the physical downlink shared channel (PDSCH), the physical downlink control channel (PDCCH), the physical uplink shared channel (PUSCH), and the physical broadcast channel (PBCH) are only examples of the downlink data channel, the downlink control channel, the uplink data channel, and the data transmission channel respectively. In different systems and different scenarios, the data channel and the control channel may have different names, and the embodiments of the present application do not limit this.

[0080] To facilitate the understanding of the solutions of the embodiments of the present application, relevant concepts are explained as follows.

[0081] 1. Millimeter wave: It was initially defined as an electromagnetic wave with a wavelength in the range of 10 mm to 1 mm, corresponding to a frequency of 30 GHz - 300 GHz. The terahertz is defined as an electromagnetic wave with a frequency of 0.1 THz to 10 THz (wavelength between 3 mm and 30 μm). Thus, there is a certain overlap between the two. Therefore, the latest academic definition for the two is: the millimeter wave band is 30 GHz to 100 GHz, and the terahertz band is 100 GHz to 10 THz. In the field of mobile communication, 24 GHz - 100 GHz is usually referred to as 5G millimeter wave.

[0082] 2. Millimeter-wave communication: Millimeter waves have rich (76 GHz) spectrum bandwidth resources, with high frequencies, short wavelengths, and good reflection performance. However, they have high path loss, high diffraction loss, and high penetration loss, and phenomena such as absorption and scattering of rain, snow, and ice in the atmosphere have a greater impact on millimeter-wave signals. Generally speaking, the main challenge of millimeter waves is that the propagation loss in space is relatively large compared to sub 6 GHz (FR1: 410 MHz - 7125 MHz), especially because of fewer paths, insufficient diffraction ability, and insufficient penetration ability, resulting in its performance being more easily affected by the surrounding environment and decreasing.

[0083] To overcome the above challenges, the characteristics of the small wavelength of millimeter waves can be utilized to make the transmitting and receiving physical antennas very small, set a small antenna spacing, so as to integrate a large number of antennas within the same antenna array area. Compared with the sub 6 GHz frequency band, the order of magnitude of the physical antennas that can be integrated by millimeter waves will increase significantly, reaching hundreds or thousands of antennas. By using the characteristics that millimeter-wave base stations can integrate a large number of physical antennas, high-gain and adjustable beams can be obtained through beamforming, and the limited power can be concentrated and transmitted within a limited range, thereby improving the signal coverage. It should be noted that although beamforming improves the coverage ability of millimeter waves to a certain extent, the propagation loss of the wireless signals within each beam still retains the characteristics of millimeter waves.

[0084] 3. Symbol: The abbreviation of the time-domain symbol, which can also be called the OFDM symbol. It should be noted that the time-domain symbol can also be named in combination with other multiple access methods, and the embodiments of this application do not make limitations. For different subcarrier spacings, the length of the time-domain symbol can be different. For example, from the time domain perspective, the OFDM symbol is a time length. Using the serial-to-parallel conversion technology in the OFDMA principle, the originally high-speed serial data is converted into low-speed parallel data for transmission. The time that originally transmitted X symbols (symbols after digital mapping, for example, each quadrature phase shift keying (QPSK) symbol contains 2 bits) now only transmits one symbol (but due to parallel transmission, each of the X subcarriers transmits one, which is equivalent to transmitting X at the same time. However, these X subcarriers are independent of each other, and the data they represent is only a small part of the original data). The time used is called the OFDM symbol length, or the OFDM symbol period. In practice, in order to eliminate inter-symbol interference, a cyclic prefix (CP) also needs to be inserted between symbols, that is, after the transmitted data after the inverse fast fourier transform (IFFT) undergoes parallel-to-serial conversion, the symbols with the length of the CP at the end are copied to the start of the OFDM symbol to eliminate inter-symbol interference. At this time, the actual length of each OFDM symbol becomes T symbol+T cp , the IFFT length + CP length seen usually is represented in units of the OFDM symbol period. In OFDM technology, a subcarrier with a symbol length (also known as the time length in the time domain) of T is a Sinc function in the frequency domain and crosses zero at 1 / T. To satisfy orthogonality, the peaks of each subcarrier should correspond to the zero-crossing points of other subcarriers. Therefore, the subcarrier spacing should be 1 / T. For example, in 5G NR, the subcarrier spacing is 15 kHz, so the OFDM symbol length is 1 / 15 kHz = 66.7 us. This length is the modulation symbol time of the subcarrier and also the time for physical processing of the device.

[0085] 4. Time unit: The time unit can be a slot, or a symbol, or a subframe, or a frame, or a mini-subframe, or a mini-slot, and this application does not make any limitation on this.

[0086] 5. Preamble: The access sequence sent by the terminal device during random access. Up to 64 preamble sequences can be configured on a random access occasion, and the terminal device selects one preamble sequence from the 64 preamble sequences.

[0087] 6. Random access process: In a millimeter-wave communication system, the terminal device obtains uplink synchronization through the random access process to access the network for communication. Random access includes contention-based random access and non-contention-based random access. Non-contention-based access is usually used when the terminal has been able to successfully receive radio resource control (RRC) signaling.

[0088] 7. Random Access Opportunity (RACH occasion, RO): The random access channel opportunity RO is configured by the base station, specifically through the PRACH configuration index. RO can be understood as the time-frequency resources used by the terminal device for random access, and the network device pre-configures the association relationship between RO and the SSB index. To improve performance, the network device broadcasts SSBs using different analog beams. The terminal measures the received signal strength of the SSBs under different analog beams and selects the best analog beam. To facilitate the terminal device to feedback the selected analog beam, the network device binds the SSB with RO to form an RO-SSB association. In this way, based on the RO position of the preamble sequence selected by the terminal device, the analog beam selected by the terminal can be determined. In the time domain, the PRACH configuration period can be 10 ms, 20 ms, 40 ms, 80 ms, or 160 ms. Within a configuration period, which time slots or subframes can have RO, how many PRACH slots are included in a time slot or subframe, and how many ROs are included in a PRACH slot are all obtained according to the PRACH configuration index. In the frequency domain, the base station can also configure the number of ROs in the frequency domain through msg1-FDM (RRC layer parameter), which can be {1, 2, 4, 8}. ROs can be divided into valid ROs and invalid ROs. Whether an RO is valid is determined according to certain rules. For example, an RO with a time domain gap from the SSB is called a valid RO. The following examples are all based on valid ROs, unless otherwise specified.

[0089] The following uses the contention-based random access procedure as an example to describe the four-step random access procedure, taking the base station as an example of the network device for illustration.

[0090] As Figure 2 shown, the detailed procedure of contention-based random access is described as follows:

[0091] - Transmission of Message 1 (Msg1): Before the terminal sends Msg1, according to the received system message or configuration message and the index of the selected synchronization signal and PBCH block (SSB) (each SSB corresponds to a millimeter wave beam, and the terminal selects the beam with the maximum received power from the terminal beams, which is called the terminal selection SSB index), a certain RO in the RO associated with the SSB index is randomly selected to send a preamble (that is, Msg1). After determining the time-frequency resources, the UE selects a preamble sequence in the selected RO (up to 64 preambles can be configured on one RO, and the UE selects one preamble sequence from the 64 preamble sequences) to send. Then the terminal sends the preamble sequence to the network device, and this sequence is carried by the physical random access channel (PRACH). It can be understood that this preamble sequence is Msg1.

[0092] - Transmission of Message 2 (Msg2): After receiving the preamble, the network device allocates the time-frequency domain resources of Msg2 and the scheduling information of Msg3, etc. Msg2 is also called the random access response (RAR) information. The RAR includes the scheduling information of Msg3, that is, the RAR UL grant information.

[0093] - Transmission of Message 3 (Msg3): Msg3 is sent on the time-frequency resources specified by Msg2 and is carried by the PUSCH channel.

[0094] - Transmission of Message 4 (Msg4): Msg4 is mainly used for conflict resolution. When multiple terminals access simultaneously, it is necessary to determine which terminal to access for this random access.

[0095] The following describes the two-step random access process, taking the base station as an example of the network device for illustration.

[0096] As Figure 3 shown, the detailed process of two-step random access is described as follows:

[0097] - The terminal device sends message A (message A, MsgA) to the network device. Correspondingly, the network device receives message A from the terminal device. Among them, MsgA includes a preamble part and a PUSCH part. The preamble part is sent on the PRACH resource (such as the RO described above), and L2 or L3 information can be carried on the PUSCH resource. For example, BFR MAC CE or an RRC connection establishment request message.

[0098] - Message 2 (Msg2) transmission: The network device sends message B (message B, MsgB) to the terminal device. Correspondingly, the terminal device receives message B from the network device. Among them, the MsgB message can include a successful RAR (success RAR) or a fallback RAR (fallback RAR).

[0099] Exemplarily, in the case where the terminal device receives a fallback RAR, the terminal device needs to fallback to a four-step random access procedure and send Msg3 to the network device, that is, perform the Msg3 transmission described above. Figure 2 of the Msg3 transmission.

[0100] Optionally, in addition to the above fallback process from two-step random access to four-step random access, if the network device selects to perform a two-step random access procedure when triggering random access, after the preamble of the two-step random access procedure reaches the maximum number of transmissions, the terminal device can also fallback to the four-step random access procedure to attempt access, thereby increasing the access success rate of the terminal device and ensuring the access performance of the terminal device.

[0101] 8. Physical random access channel (PRACH): It can be used to carry preamble sequences. PRACH resources can include time-frequency resources in the PRACH and / or code resources carried on the PRACH, such as preamble sequences.

[0102] 9. Synchronization Signal and PBCH Block (SSB): The SSB is one of the most important pilot channels used in 5G and can be used for UE to access the cell, such as cell search, beam measurement, beam selection, and beam recovery. It can also be called a synchronization signal block, synchronization signal, or PBCH block. In 5G, the SSB includes synchronization signals and broadcast signals. Specifically, the synchronization signals include the Primary Synchronization Signal (PSS) and the Secondary Synchronization Signal (SSS); the broadcast signals include PBCH Data and PBCH DMRS signals. Specifically, the time-frequency domain structure of the SSB is as Figure 4 shown. The SSB occupies 4 OFDM symbols in the time domain and 20 RBs in the frequency domain, that is, 240 subcarriers (SCs). The SSB of NR mainly has two functions: 1) Cell synchronization and acquisition of the Master Information Block (MIB); 2) Beam training on the base station side. The SSB is configured through a bitmap. For example, the first bit in the bitmap corresponds to SS / PBCH block index 0, the second bit corresponds to SS / PBCH block index 1, and so on. L max = 4 indicates that there are 4 SSB indexes, which can be understood as candidate SSB indexes, that is, SS / PBCH block indexes 0, 1, 2, 3. The corresponding bitmap size is 4 bits. When a certain bit in the bitmap is equal to 0, it means that the corresponding SS / PBCH block index is not sent by the base station. When it is equal to 1, it means that the corresponding SS / PBCH block index is sent. The number of SSBs actually sent by the base station is determined by this bitmap. It can also be configured through other bitmaps such as inOneGroup or groupPresence. The SSB associated with the RO is the SSB index actually sent by the base station. For example, L max = 4, and the base station actually only sends SSB indexes 0, 1, 2 Then only these 3 SSB indexes need to be associated with the RO.

[0103] In the random access process of millimeter-wave communication, if the terminal only uses one RO to send the preamble, due to the large millimeter-wave propagation loss and susceptibility to the environment, when the terminal is far from the network device and / or the surrounding environment is not conducive to millimeter-wave transmission, the probability that the preamble power received by the network device is less than the expected value is very high, which will cause the terminal to be unable to access the network reliably. Currently, the RO resources for retransmitting the preamble can be configured, and all terminals are allowed to retransmit the preamble on the RO resources corresponding to the selected SSB that can retransmit the preamble, so as to increase the received power of the preamble and improve the coverage ability. In the scenario of cell handover, the terminal needs to determine the index of the radio frame of the target cell for handover to determine the RO resource configuration for retransmitting the preamble.

[0104] Exemplarily, a method for configuring PRACH resources is given below.

[0105] The PRACH is configured in the UL time slot through the RACH-ConfigGeneric cell, and the terminal can use the PRACH in the UL time slot for random access. As Figure 5 shown, where the horizontal direction represents the time domain and the vertical direction represents the frequency domain. The left side of the figure is the downlink time slot (DL slot), and the right side of the figure is the uplink time slot (UL slot). The dashed box in the UL time slot represents a block of PRACH resources specified by RACH-ConfigGeneric. Specifically, the terminal device can obtain the time domain position information such as the period, frame number, subframe number, time slot number, and the number of ROs in the time slot of the PRACH in the time domain by looking up Tables 6.3.3.2-2 to 6.3.3.2-4 (this table is in the 3GPP TS 38.211 V18.0.0 protocol) according to the parameter physical random access channel - configuration index prach-ConfigurationIndex in the high-layer cell RACH-ConfigGeneric sent by the network device.

[0106] A brief introduction to the structure of PRACH resources is as follows. As Figure 6As shown in the figure, the three slanted-bar filled squares at the top layer of the figure are the radio frames where the PRACH is located. The time-domain distance between two adjacent slanted-bar filled squares is the PRACH period. The middle layer is composed of subframes of the radio frame where the PRACH is located. Each slanted-bar filled square is the subframe where the PRACH is located. The bottom layer shows the time-slot structure of the subframe where the PRACH is located. The previous slanted-bar filled long square is the time slot where the PRACH is located, which is called the PRACH slot. It contains 6 slanted-bar filled small squares, and each small square is 1 RO, that is, the PRACH slot contains 6 ROs. In addition, according to the parameters msg1-FrequencyStart and msg1-FDM in the high-layer cell RACH-ConfigGeneric, the starting position of the PRACH in the frequency domain and the frequency-division multiplexing times can be obtained respectively, thereby determining the frequency-domain position of the PRACH.

[0107] As described above, during the transmission of Msg1, the UE will select a RO according to the index of the SSB to transmit the preamble sequence. In the current NR standard, in addition to specifying the PRACH position, it is also necessary to specify the mapping relationship (also called the association relationship, for example, one SSB index can be associated with multiple ROs, or multiple SSB indexes are associated with one RO) between the RO and the SSB.

[0108] Specifically, the network device can configure the mapping relationship of N SSBs to 1 RO through the high-layer parameter ssb-perRACH-Occasion. When N is less than 1, 1 SSB is associated with 1 / N ROs; when N is greater than 1, N SSBs are associated with 1 RO (1 SSB is associated with 1 / N ROs), and N can be {1 / 8, 1 / 4, 1 / 2, 1, 2, 4, 8, 16}. Exemplarily, as shown in (a) of Figure 7 , when N = 1 / 2, one SSB is associated with 2 ROs. As shown in (b) of Figure 7 , when N = 2, 1 RO is associated with 2 SSBs. Therefore, in the case where one SSB index is associated with multiple ROs, the UE can select one of the multiple ROs and transmit the preamble sequence on that RO. The distribution method of the PRACH resources in the frequency domain can refer to Figure 8 , where the vertical direction represents the frequency domain, each square represents 1 RO, and the ROs are arranged starting from the frequency-domain position specified by msg1-FrequencyStart. In this example, 4 ROs are distributed in the frequency domain.

[0109] After the terminal determines the mapping relationship between the RO and the SSB, it can start the mapping between the RO and the SSB. The mapping order can be first in the frequency domain and then in the time domain, first in the same time slot, then in the same frame, and finally in different frames. For example, in one RO: ① Map in ascending order of preambleindex, ② Map in ascending order of frequency domain, ③ Map in ascending order of time domain within a PRACH slot, ④ Map in ascending order of PRACH slot index; that is, first map in the RO according to the preamble, and then in the frequency domain first and then in the time domain.

[0110] Exemplarily, as Figure 9 shown, where the horizontal direction represents the time domain and the vertical direction represents the frequency domain. The set of SSBs used by the base station is {SSB i, SSB i+1, SSB i+2, SSB i+3}. When msg1-FDM = 4 and N = 1 / 4, 1 SSB is associated with 4 ROs, denoted as {RO 0, RO 1, RO 2, RO 3}, and 16 ROs complete a complete RO-SSB mapping cycle. Specifically, the mapping of RO-SSB starts from radio frame 0 in the time domain and starts from low frequency to high frequency in the frequency domain, that is, RO 0-RO 3 corresponding to SSB i occupy 4 ROs in the frequency domain corresponding to the time domain position of the first RO in the first PRACH time slot, RO 0-RO3 corresponding to SSB i+1 occupy 4 ROs in the frequency domain corresponding to the time domain position of the second RO in the first PRACH time slot, RO 0-RO 3 corresponding to SSB i+2 occupy 4 ROs in the frequency domain corresponding to the time domain position of the first RO in the second PRACH time slot, and RO 0-RO 3 corresponding to SSBi+3 occupy 4 ROs in the frequency domain corresponding to the time domain position of the second RO in the second PRACH time slot.

[0111] The above Figures 6 to 9 introduced the relevant parameters of PRACH resource configuration. Next, each parameter in the mapping between the SSB and the RO will be described.

[0112] Exemplarily, as Figures 10 to 12 shown, where the horizontal direction represents the time domain and the vertical direction represents the frequency domain. Figure 10 In Therefore, the set of SSBs used by the base station is {SSB 0, SSB 1, SSB 2, SSB 3} (where the index of the SSB is 0 to 3, and it can also be other values, such as 5, 7, 8, 10, specifically depending on the configuration of the bitmap mentioned above and L max(value of), msg1-FDM = 1 and N = 2, 1 SSB is associated with 1 / 2 RO, and 2 ROs complete a full RO-SSB mapping cycle (the mapping cycle is the cycle required to map all actually transmitted SSBs completely). When the repetition number is 2, the RO set includes 2 ROs, {RO 0, RO 2}; another RO set includes {RO 1, RO 3}. The RO set is used for PRACH repeated transmission, that is, SSB 0 and SSB 1 correspond to using RO 0 and RO 2 for PRACH repeated transmission. SSB 2 and SSB 3 correspond to using RO 1 and RO 3 for PRACH repeated transmission. Figure 11 in Therefore, the SSB set used by the base station is {SSB 0, SSB 1, SSB 2, SSB 3}, msg1-FDM = 2 and N = 1, 1 SSB is associated with 1 RO, and 4 ROs complete a full RO-SSB mapping cycle. When the repetition number is 2, {RO 0, RO 0}, {RO 1, RO 1}, {RO 2, RO 2}, {RO 3, RO 3} are each an RO set. Figure 12 in Therefore, the SSB set used by the base station is {SSB 0, SSB 1, SSB 2, SSB 3, SSB 4}, msg1-FDM = 2 and N = 2, 1 SSB is associated with 1 / 2 RO, and 3 ROs complete a full RO-SSB mapping cycle.

[0113] The association period is an integer multiple of the PRACH configuration period. As shown in Table 1, for example, when the PRACH configuration period is equal to 10 ms, the association period can include {1, 2, 4, 8, 16} configuration periods, that is, 10 ms, 20 ms, 40 ms, 80 ms, 160 ms. During the association period, all actually transmitted SSB indexes can be associated with ROs, and all SSBs can be completely associated at least once, that is, including 1 or more mapping cycles. The number of PRACH configuration periods included in the association period is to find a minimum value from these values in Table 1 and ensure that all transmitted SSBs are mapped at least once. As Figure 12As shown, the first PRACH configuration period only contains RO 0 and RO 1, which cannot satisfy mapping all SSBs once. Therefore, a second PRACH configuration period is required. The second PRACH configuration period contains RO 2, RO 3, RO 4, RO 5, RO 6, and RO 7. Then, these two PRACH configuration periods can satisfy mapping all SSBs at least once. These two PRACH configuration periods form an association period (i.e., 2 configuration periods, and at this time the association period is equal to 20 ms). Within this association period, after all SSBs are mapped once, there are still some ROs left unmapped (RO 3 to 7, and in addition, there is still a position for one SSB left in RO 2). Among these remaining ROs, the SSBs can be mapped 2 more times, that is, mapped a total of 3 times, which can also be understood as mapping 3 rounds, with a total of 3 mapping periods. At this time, if there are still ROs left and these remaining ROs cannot map all SSBs once, then no SSBs are mapped. If there are still some preamble indices in the remaining ROs that have not mapped SSBs, then no SSBs are mapped either. For example, in RO 7, only SSB 4 is mapped, and there is still a position for one SSB left, and no more SSBs are mapped. At this time, the number of SSBs mapped in this RO 7 is less than N (N = 2). The determination of the association period starts from radio frame 0.

[0114] Table 1 Relationship between PRACH Configuration Period and Association Period

[0115]

[0116] (Continued from Table 1)

[0117] 20 {1，2，4，8} 40 {1，2，4} 80 {1，2} 160 {1}

[0118] The time lengths of different association periods can be different. Therefore, the mapping relationships between SSBs and ROs in different association periods may also be different. Based on this, the association pattern period is introduced. The association pattern period consists of one or more association periods, with a maximum of 160 ms. The mapping between SSBs and ROs is exactly the same between different association pattern periods, that is, the mapping relationships between SSBs and ROs in different association pattern periods are repeated. For example, the mapping relationship between SSB 1 and ROs in the first association pattern period is exactly the same as the mapping relationship between SSB 1 and ROs in the third association pattern period. Once the mapping relationship between ROs and SSBs in a certain association pattern period is determined, the mapping relationships between ROs and SSBs in all other association pattern periods can be determined. As Figure 13 shown, a possible mapping relationship is shown. In Figure 13In it, a square represents an RO, and the number in the square corresponds to the index of the SSB mapped by this RO (SSB index: 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16). Among them, msg1-FDM = 1 and N = 1, the period of the SSB is 80 ms, there is only one radio frame in the configuration period of the PRACH that has an RO, and there are 10 ROs in one radio frame. The associated pattern period is 80 ms, and this associated pattern period contains an associated period of 40 ms and two associated periods of 20 ms. Each associated period contains multiple 10-ms radio system frames. The RO corresponding to the square with a diagonal line inside is an invalid RO, and the RO corresponding to the square with two intersecting diagonal lines inside is an RO that has not been mapped to an SSB.

[0119] To determine the positions of the n ROs (RO set) for which PRACH repetition is performed, that is, in the time domain, the positions of the n ROs associated with the same SSB index for which preamble repeated transmission is performed, the concept of time period is introduced. Among them, n is the number of repetitions configured by the base station and can be {2, 4, 8}. The time period is composed of M associated pattern periods. M is the smallest integer greater than or equal to 1, and the value of M should be such that in the time period, all actually sent SSBs can be mapped to the RO set at least once for each configured number of repetitions. It can be understood that M is the smallest integer greater than or equal to 1 such that in the time period, for each configured number of repetitions, all actually sent SSBs can be mapped to the RO set at least once. Therefore, within the determined time period, each actually sent SSB index can determine the corresponding RO set. Between time periods, the association relationship between the SSB corresponding to each number of repetitions and the RO set is exactly the same, that is, the association relationship between the SSB corresponding to each number of repetitions and the RO set in different time periods is the same. The terminal can determine the RO set corresponding to each SSB within one time period. In Figure 13In the case where n = {2}, the time period consists of M = 1 associated pattern period. Because within this associated pattern period, for each SSB index, the corresponding RO set can be determined. For example, for SSB 1, the 2 ROs in the first associated period form one RO set; the ROs in the second associated period and the ROs in the third associated period form one RO set. When n = {4}, the time period consists of M = 1 associated pattern period. For example, for SSB 1, the 2 ROs in the first associated period, the ROs in the second associated period, and the ROs in the third associated period form one RO set. Similarly, when n = {2, 4}, the time period consists of M = 1 associated pattern period. When n = {8}, the time period consists of M = 2 associated pattern periods, and these two associated pattern periods are exactly the same. The determination of the time period starts from radio frame 0.

[0120] In the current resource configuration, when the terminal performs handover between cells, the terminal can obtain the SSB index and the frame boundary of the system frame of the target cell by only receiving the DMRS of the PBCH (when L max = 4, it can not receive the PBCH, that is, it does not need to obtain the MIB, which can reduce the latency). If the associated pattern period on the target cell is not 10 ms (i.e., the associated pattern period is 20 ms, 30 ms,..., 160 ms), at this time, the terminal can assume that the absolute value of the relative time offset between the radio frame i (i is an integer greater than or equal to 0, for example, the value range of i can be 0 to 1023) of the source cell and the radio frame i of the target cell is less than 5 ms, that is, the relative offset is less than 5 ms and greater than -5 ms. Then the terminal can obtain the frame index of the system frame of the target cell according to the SSB index and the relative time offset between the frame boundaries of the system frames of the target cell and the source cell, so as to determine the positions of the ROs for PRACH repetition. However, when the associated pattern period on the target cell is 10 ms and the time period ≠ 10 ms (such as 20 ms), at this time, the time period contains multiple associated pattern periods, and there is no limit on the relative time offset between the radio frame i of the source cell and the radio frame i of the target cell. Therefore, as Figure 14 shown, the terminal UE cannot determine which 2 radio frames the time period consists of, that is, the UE cannot determine the positions of the n ROs for PRACH repetition, and thus cannot perform PRACH repetition.

[0121] In view of the above problems, an embodiment of the present application proposes a communication method. When the correlation pattern period on the target cell is 10 ms, this method enables the UE to determine the positions of n ROs for PRACH repetition according to the time period, so as to perform PRACH repetition and improve the random access efficiency of the terminal. It should be understood that in the following, the network device and the terminal device are used as the two communication parties for description, but the present application is not limited to these two communication parties.

[0122] Figure 15 FIG. shows a schematic diagram of a random access method provided by an embodiment of the present application. Figure 16 FIG. shows a schematic flowchart of a random access method provided by an embodiment of the present application. As Figure 15 and Figure 16 shown, this method is applied to cell handover and may include the following steps:

[0123] Step 1001: Receive the physical random access channel (PRACH) configuration information of the target cell sent by the source cell. The PRACH configuration information includes the PRACH repetition times, and the absolute value of the relative time offset of the system frames with the same frame index between the source cell and the target cell is less than half of the duration of the system frame.

[0124] Exemplarily, the absolute value of the relative time offset between the radio frame i (i is an integer greater than or equal to 0, for example, the value range of i can be 0 to 1023) of the source cell and the radio frame i of the target cell is less than half of the duration of the system frame. When the duration of the system frame is 10 ms, that is, the absolute value of the relative time offset is less than 5 ms, which can also be understood as less than 153600 Ts, where Ts = 1 / (15000×2048) seconds.

[0125] Step 1002: Determine the correlation pattern period according to the PRACH configuration information.

[0126] The determination of the correlation pattern period can refer to the relevant description in the above text.

[0127] Step 1003: Determine the time period according to the correlation pattern period. The time period includes a set of random access channel opportunities (ROs) associated with the synchronization signal block (SSB) index. The set of ROs includes ROs with the PRACH repetition times, and the time period is m times the duration of the system frame, where m is an integer greater than or equal to 2.

[0128] Exemplarily, the set of ROs includes ROs with the PRACH repetition times, which can be understood as the number of ROs in the set of ROs is equal to the PRACH repetition times.

[0129] The determination of the time period can refer to the relevant description in the above text.

[0130] Step 1004: Randomly access the target cell according to the time period.

[0131] In some embodiments, when a terminal in cell A (source cell) hopes to switch to cell B (target cell) to obtain better network services, cell A obtains the random access related information of cell B and sends it to the terminal. The random access related information may include the PRACH configuration information of the target cell (the PRACH configuration information includes the preamble repetition count n). After the terminal obtains the random access related information of cell B sent by cell A, it needs to select an SSB on cell B and send a preamble sequence on the RO associated with the index of the selected SSB for random access. Repeating the preamble sequence on the RO set can increase the probability of random access. Therefore, after the terminal obtains the random access related information of cell B sent by cell A, based on the mapping rule between RO and SSB, it determines the associated pattern period for random access, determines the time period according to the associated pattern period. The time period includes a set of random access channel opportunities RO associated with the synchronization signal block SSB index, and the set of RO includes the RO with the PRACH repetition count. When the time period is m times the duration of the system frame and m is an integer greater than or equal to 2 (for example, time period = 20ms, duration of the system frame = 10ms, time period = 2 × duration of the system frame, m = 2), the terminal can determine the system frames included in the time period by the absolute value of the relative time offset of the system frames with the same frame index between the source cell and the target cell being less than half of the duration of the system frame, that is, which system frames the time period consists of, and randomly access the target cell according to the time period. Herein, the source cell and the target cell are different serving cells, and the network devices supporting the source cell and the target cell may be the same network device (for example, the base station serving the source cell and the base station serving the target cell are both base station A), or different network devices (for example, the base station serving the source cell is base station A, and the base station serving the target cell is base station B), which is not limited. The target cell may be on paired spectrum or unpaired spectrum, which is not limited.

[0132] In the solution provided by the embodiment of the present application, the terminal receives the PRACH configuration information sent by the source cell indicating the terminal to randomly access the target cell, determines the associated pattern period for random access according to the PRACH configuration information, and can determine the time period according to the associated pattern period. In this way, when the time period is m times the duration of the system frame, the terminal can determine the RO set for random access according to the time period, and on this RO set, the terminal can perform PRACH retransmission that meets the PRACH repetition times configured by the base station, increasing the random access efficiency and reducing the delay of the terminal in cell handover. Among them, the source cell and the target cell are different serving cells, and the network devices supporting the source cell and the target cell can be the same network device or different network devices, which is not limited herein.

[0133] In some embodiments, when the terminal determines that the time period ≠ 10 ms, random access can be performed. When the terminal determines that the time period is m times the duration of the system frame and m is an integer greater than or equal to 2, the terminal needs to compare the system frames of the source cell and the target cell by the absolute value of the relative time offset of the system frames with the same frame index between the source cell and the target cell being less than half of the duration of the system frame, obtain the index of the system frame of the target cell, and perform random access.

[0134] Exemplarily, the terminal determines the duration of the time period. If the time period ≠ 10 ms, the terminal assumes that the absolute value of the relative time offset between the radio frame i of the source cell and the radio frame i of the target cell is less than half of the duration of the system frame (i.e., 5 ms), thereby obtaining the index of the system frame of the target cell, and then determining the system frames of the target cell included in the time period, that is, which system frames of the target cell the time period consists of, and then performing random access. If the time period = 10 ms, each system frame of the target cell is a time period, and random access can be directly performed without obtaining the index of the system frame of the target cell.

[0135] Exemplarily, when a terminal in cell A switches cells, cell A obtains random access related information of cell B and sends it to the terminal. The random access related information may include information such as the PRACH configuration information of the target cell and the SSB configuration information of cell B. Cell B has configured RO resources for all SSBs it sends that can repeatedly send preambles. After the terminal obtains the random access related information of cell B sent by cell A, it receives the SSB sent by cell B according to the SSB configuration information, and selects the SSB used for random access to cell B from the SSBs sent by cell B, and sends a preamble sequence on the RO associated with the index of the selected SSB for random access. After the terminal obtains the random access related information of cell B sent by cell A, based on the mapping rule between the RO and the SSB, it determines the associated pattern period for random access, and determines the time period according to the associated pattern period. The time period includes a set of random access channel opportunities ROs associated with the SSB index, and the set of ROs includes ROs with the number of PRACH repetitions. When the time period is m times the duration of the system frame and m is an integer greater than or equal to 2 (for example, the time period = 20 ms, the duration of the system frame = 10 ms, the time period = 2 × the duration of the system frame, m = 2), the terminal can determine the frame number of the system frame of cell B by comparing the boundaries of the system frames of cell A and cell B. For example, if the absolute value of the relative time offset between the boundary of radio frame 2 of cell A and the boundary of radio frame i of cell B is less than 5 ms, the terminal can determine that radio frame i of cell B is radio frame 2. The terminal can determine the set of ROs for repetition according to information such as the index of the system frame of the target cell and the PRACH configuration index in the PRACH configuration information, and send Msg1 (preamble sequence, also known as pilot sequence) to cell B on this set of ROs for random access.

[0136] In some embodiments, before cell A sends the random access related information of cell B to the terminal, methods such as periodically synchronizing the clocks of cell A and cell B with cell C can be used to ensure that the absolute value of the relative time offset between the boundaries of radio frame x of cell A and radio frame x of cell B is less than 5 ms. Therefore, based on the fact that the absolute value of the relative time offset between the boundaries of radio frame x of cell A and radio frame x of cell B is less than 5 ms, the terminal can determine the frame index of the radio frame of cell B, where x is the index value of the radio frame. Alternatively, cell A and cell B use methods such as periodically synchronizing the clocks to ensure that the absolute value of the relative time offset between the boundaries of radio frames with the same frame index is less than 5 ms.

[0137] In some embodiments, the associated pattern period is equal to the duration of the system frame.

[0138] Exemplarily, the terminal determines a time period according to the associated pattern period. When the associated pattern period is equal to the duration of a system frame and the length of the time period is greater than the duration of the system frame, for example, the length of the time period determined by the terminal is 20 ms, which is twice the duration of the system frame (the duration of the system frame is equal to 10 ms), and the associated pattern period = 10 ms. The terminal cannot determine the frame numbers of the two system frames within this time period, and thus cannot determine the RO set associated with the selected SSB, and cannot perform repeated transmission of the preamble sequence on this RO set; or, the length of the time period that satisfies the repetition number n determined by the terminal is 40 ms, which is four times the duration of the system frame. The terminal cannot determine the indexes of the four system frames within this time period, and thus cannot determine the RO set associated with the selected SSB index, and cannot perform repeated transmission of the preamble sequence on this RO set. At this time, the terminal can obtain the index of the system frame of the target cell by the absolute value of the relative time offset of the system frames with the same frame index between the source cell and the target cell being less than half of the duration of the system frame, so that the terminal can also perform PRACH repetition when the associated pattern period is equal to the duration of the system frame.

[0139] In some embodiments, the terminal determines the duration of the associated pattern period and the duration of the time period. If the duration of the associated pattern period = 10 ms and the time period ≠ 10 ms, the terminal assumes that the absolute value of the relative time offset of the radio frame i of the source cell and the radio frame i of the target cell is less than half of the duration of the system frame (i.e., 5 ms), and then obtains the index of the system frame of the target cell. Then, the terminal determines the system frames of the target cell included in the time period, that is, which system frames of the target cell the time period consists of, and then performs random access. If the duration of the associated pattern period = 10 ms and the time period = 10 ms, each system frame of the target cell is a time period and also an associated pattern period, and random access can be directly performed without obtaining the index of the system frame of the target cell.

[0140] In the solution provided by the embodiments of the present application, the terminal can determine the associated pattern period for random access to the target cell according to the PRACH configuration information of the target cell sent by the source cell, and determine the time period according to the associated pattern period. When the associated pattern period is equal to the duration of the system frame (i.e., each system frame is an associated pattern period), the time period determined by the terminal contains two or more associated pattern periods. The terminal determines the RO set for random access according to the time period and the relative time offset of the system frames with the same frame index between the source cell and the target cell. This can enable the terminal to perform PRACH repetition when the associated pattern period is equal to the duration of the system frame and the time period is m times the duration of the system frame, improve the random access efficiency, and reduce the latency of the terminal during cell handover. Wherein, the duration of the system frame of the target cell is equal to the duration of the system frame of the source cell.

[0141] In some embodiments, the maximum number L of SSB indexes of the target cell max = 4.

[0142] Specifically, the terminal obtains the actually transmitted SSB indexes included in the SSB configuration information of the target cell. For example, the SSB configuration information obtained by the terminal indicates that the target cell transmits SSB 1 and SSB 2, and the terminal can receive SSB 1 and SSB 2 according to the SSB configuration information (the SSB configuration information may also include other information, such as the period of the SSB, etc.). After the terminal obtains the relevant information of SSB 1 and SSB 2, it can select an SSB with the best signal quality from them for random access. When the maximum number L of SSB indexes of the target cell max = 4, there can be at most 4 SSBs for the terminal to select.

[0143] In some embodiments, random access to the target cell according to a time period includes: determining the system frame of the target cell; determining a set of random access channel opportunities ROs associated with SSB indexes included in the time period according to the system frame of the target cell; and performing random access according to the set of ROs.

[0144] Exemplarily, the terminal can obtain time domain position information such as the period, frame number, sub-frame number, time slot number, and the number of ROs in the time slot of the PRACH in the time domain by looking up a table according to the PRACH configuration index in the PRACH configuration information. The terminal can determine the frame number of the system frame of cell B by comparing the boundaries of the system frames of cell A and cell B. According to the frame number of the system frame of cell B and the time domain position information such as the period, frame number, sub-frame number, time slot number, and the number of ROs in the time slot of the PRACH obtained by looking up a table according to the PRACH configuration index and the mapping rule between RO and SSB, the terminal determines the set of ROs for random access, and sends Msg1 to cell B in the set of ROs for random access. There may be multiple sets of ROs associated with a certain SSB index within the time period. For example, in Figure 13In [the above case], when n = {2}, the time period consists of M = 1 associated pattern period. Within this associated pattern period, for each SSB index, the corresponding RO set can be determined. For example, for SSB 1, the 2 ROs in the first associated period (the 2 ROs both associated with SSB 1) form an RO set, and the ROs in the second associated period and the ROs in the third associated period form an RO set. At this time, the set of ROs associated with SSB 1 within the time period is two; when n = {4}, the time period consists of M = 1 associated pattern period. For example, for SSB 1, the 2 ROs in the first associated period, the ROs in the second associated period, and the ROs in the third associated period form an RO set; similarly, when n = {2, 4}, the time period consists of M = 1 associated pattern period; when n = {8}, the time period consists of M = 2 associated pattern periods, and these two associated pattern periods are exactly the same. Each RO in the RO set is associated with the same one or more SSB indices.

[0145] In the solution provided by the embodiments of this application, when the associated pattern period is equal to the duration of a system frame and the time period is m times the duration of a system frame, the terminal can determine the system frame of the target cell according to the time period. In this way, the terminal can determine the set of ROs associated with the index of the SSB selected by the terminal for random access according to the system frame of the target cell, enabling the terminal to perform PRACH repetition on the determined set of ROs, increasing the random access efficiency, and reducing the delay of the terminal during cell handover.

[0146] In some embodiments, the method further includes: receiving the demodulation reference signal DMRS of the PBCH sent by the target cell; determining the system frame of the target cell, including: determining the boundary of the system frame of the target cell according to the DMRS; determining the index of the system frame of the target cell according to the boundary of the system frame of the target cell and the boundary of the system frame of the source cell; determining the system frame of the target cell included in the time period according to the index of the system frame.

[0147] In the solution provided by the embodiments of this application, the terminal can determine the system frame of the target cell according to the DMRS of the PBCH, and determine the index of the system frame of the target cell according to the relative time offset between the boundary of the system frame of the target cell and the boundary of the system frame of the source cell. In this way, the terminal can determine the time period according to the determined index of the system frame of the target cell, enabling the terminal to perform PRACH repetition on the determined set of ROs, increasing the random access efficiency, and reducing the delay of the terminal during cell handover.

[0148] In some embodiments, determining the boundary of the system frame of the target cell according to DMRS includes: determining a half-frame indication according to DMRS; and determining the boundary of the system frame of the target cell according to the half-frame indication.

[0149] Exemplarily, the terminal may receive the SSB of cell B according to the SSB index in the relevant information sent by cell A, and the terminal receives the DMRS on the SSB of cell B. When the maximum number L max of the SSBs of cell B is 4, the terminal can obtain the index of the SSB and the half-frame indication indicating the position of the SSB in the system frame by receiving the DMRS, and the terminal can obtain the boundary of the system frame where the SSB sent by cell B is located according to the half-frame indication.

[0150] In the solution provided by the embodiments of the present application, the number of actually sent SSB indexes of the target cell corresponds to the number of SSBs that the terminal can select for random access to the target cell. When the maximum number L max of the SSB indexes of the target cell is 4, the terminal can obtain the index of the SSB and the half-frame indication according to the DMRS of the PBCH, and obtain the boundary of the system frame of the target cell according to the half-frame indication, so that the terminal can determine the boundary of the system frame of the target cell by only receiving the 3-bit information carried by the DMRS, reducing the latency of the terminal for handover.

[0151] Correspondingly, the embodiments of the present application provide a random access method applied to a network device of a source cell. The method includes: obtaining the physical random access channel PRACH configuration information of the target cell, where the PRACH configuration information includes the PRACH repetition times; sending the PRACH configuration information to the terminal, the absolute value of the relative time offset of the system frames with the same frame index of the source cell and the target cell is less than half of the duration of the system frame, the time period includes a set of random access channel opportunities RO associated with the synchronization signal block SSB index, the set of RO includes RO with the PRACH repetition times, the time period is determined according to the associated pattern period, the associated pattern period is determined according to the PRACH configuration information, and the time period is m times the duration of the system frame, where m is an integer greater than or equal to 2.

[0152] In some embodiments, the associated pattern period is equal to the duration of the system frame.

[0153] Correspondingly, an embodiment of the present application provides a random access method, which is applied to a network device of a target cell. The method includes: sending physical random access channel (PRACH) configuration information to a source cell, where the PRACH configuration information includes the PRACH repetition count; receiving random access information of a terminal. The absolute value of the relative time offset of system frames with the same frame index between the source cell and the target cell is less than half of the duration of a system frame. A time period includes a set of random access channel opportunities (ROs) associated with a synchronization signal block (SSB) index. The set of ROs includes ROs with the PRACH repetition count. The time period is determined according to an associated pattern period, and the associated pattern period is determined according to the PRACH configuration information. The time period is m times the duration of a system frame, where m is an integer greater than or equal to 2.

[0154] In some embodiments, the associated pattern period is equal to the duration of a system frame.

[0155] For the process of the above terminal obtaining the frame number of the system frame of cell B, there is another possible implementation method. The method includes: receiving the physical random access channel (PRACH) configuration information and synchronization signal block (SSB) configuration information of the target cell sent by the source cell, where the PRACH configuration information includes the PRACH repetition count, and the SSB configuration information includes the actually sent SSB index; determining the associated pattern period according to the PRACH configuration information; determining the time period according to the associated pattern period. The time period includes a set of random access channel opportunities (ROs) associated with the SSB index. The set of ROs includes ROs with the PRACH repetition count. The time period is m times the duration of a system frame, where m is an integer greater than or equal to 2; receiving the physical broadcast channel (PBCH) sent by the target cell according to the SSB configuration information to obtain the master information block (MIB); determining the index of the system frame of the target cell according to the PBCH; randomly accessing the target cell according to the index of the system frame of the target cell and the time period.

[0156] Exemplarily, the terminal can receive the PBCH of the SSB to obtain the frame number of the system frame of cell B, so as to determine the RO for repetition according to the configuration index, and send a preamble sequence on the RO to perform random access to cell B.

[0157] In the solution provided by the embodiments of this application, the terminal receives the PRACH configuration information and SSB configuration information sent by the source cell, indicating that the terminal randomly accesses the target cell. The terminal can determine the associated pattern period for random access according to the PRACH configuration information, and can determine the time period according to the associated pattern period. In this way, when the time period is m times the duration of a system frame, the terminal can determine the RO set for random access according to the time period. On this RO set, the terminal can perform PRACH retransmission that meets the PRACH repetition times configured by the base station, increasing the random access efficiency and reducing the delay of the terminal during cell handover. Herein, the source cell and the target cell are different serving cells. The network devices supporting the source cell and the target cell may be the same network device or different network devices, which is not limited herein.

[0158] In some embodiments, the associated pattern period is equal to the duration of a system frame.

[0159] Exemplarily, after the terminal receives the relevant configuration information of the random access cell B, it maps the RO and the SSB index according to the configuration information. The terminal can determine the associated pattern period and the time period of the mapping between the RO and the SSB index. When the associated pattern period determined by the terminal is equal to the duration of a system frame and the time period is not equal to the duration of a system frame (for example, the duration of a system frame = 10 ms, the associated pattern period determined by the terminal = 10 ms, and the time period = 40 ms), the terminal can directly receive the PBCH (or the DMRS of the PBCH) of cell B to obtain the index of the SFN carried in the PBCH; the terminal can also receive the PBCH (or the DMRS of the PBCH) of cell B to obtain the index of the SFN carried in the PBCH when the associated pattern period determined is equal to the duration of a system frame and the time period is not equal to the duration of a system frame (for example, the duration of a system frame = 10 ms, the associated pattern period determined by the terminal = 10 ms, and the time period = 20 ms) and it is determined that preamble retransmission is to be performed. If the associated pattern period determined by the terminal is equal to the duration of a system frame and the time period is not equal to the duration of a system frame (for example, the duration of a system frame = 10 ms, the associated pattern period determined by the terminal = 10 ms, and the time period = 30 ms) and there is no need to retransmit the preamble, the terminal does not perform PRACH retransmission.

[0160] In the solution provided by the embodiment of the present application, the terminal receives the PRACH configuration information and the SSB configuration information sent by the source cell to indicate the terminal to randomly access the target cell, and can determine the associated pattern period for random access according to the PRACH configuration information, and can determine the time period according to the associated pattern period. When the associated pattern period is equal to the duration of the system frame, the time period determined by the terminal includes two or more associated pattern periods. The terminal determines the RO set for random access according to the time period and the PBCH, so that the terminal can perform PRACH repetition when the associated pattern period is equal to the duration of the system frame and the time period is m times the duration of the system frame, increasing the random access efficiency and reducing the latency of the terminal in cell handover. Among them, the duration of the system frame of the target cell is equal to the duration of the system frame of the source cell.

[0161] In some embodiments, the maximum number L of SSB indexes max = 4.

[0162] In the solution provided by the embodiment of the present application, the number of actually sent SSB indexes of the target cell corresponds to the number of SSBs that the terminal can select for randomly accessing the target cell. When the maximum number L of SSB indexes of the target cell max = 4, the terminal can obtain the index of the SSB and the boundary of the system frame of the target cell by only receiving the 3-bit information carried by the DMRS.

[0163] For the above process of the terminal performing random access during cell handover, there is another possible implementation method. The method includes: receiving the PRACH configuration information and the synchronization signal block SSB configuration information of the target cell sent by the source cell, where the PRACH configuration information includes the PRACH repetition times, and the SSB configuration information includes the actually sent SSB index. The target cell is applied to the time division duplex TDD system, and the source cell and the target cell use the same frequency; determining the associated pattern period according to the PRACH configuration information; determining the time period according to the associated pattern period. The time period includes a set of random access channel opportunities RO associated with the synchronization signal block SSB index. The set of RO includes ROs with the number of PRACH repetitions, and the time period is m times the duration of the system frame, where m is an integer greater than or equal to 2; randomly accessing the target cell according to the time period.

[0164] Exemplarily, when the target cell, cell B, is applied to a time division duplex (TDD) system and uses the same frequency as the source cell, cell A (cell A is also applied to the TDD system), the cell handover involved in this random access method is an intra-frequency cell handover. The system frames of cell A and cell B can be approximately considered synchronized, that is, the absolute value of the relative time offset of the system frames with the same frame index of cell A and cell B is less than or equal to 3 μs, which is much less than 5 ms. The terminal can determine the frame index of the radio frame of cell B by comparing the boundaries of the system frames based on the relative time offset between the radio frame x of cell A and the radio frame x of cell B. The coverage areas of cell A and cell B may overlap, and this is not limited.

[0165] In the solution provided by the embodiments of the present application, the terminal receives the PRACH configuration information and the SSB configuration information sent by the source cell indicating that the terminal randomly accesses the target cell, and can determine the associated pattern period for random access according to the PRACH configuration information, and can determine the time period according to the associated pattern period. The time period includes a set of random access channel opportunities (ROs) associated with the SSB index in the SSB configuration information. This enables the terminal to perform PRACH repeated transmissions that meet the PRACH repetition times configured by the base station on the determined RO set according to the time period when the time period is m times the duration of the system frame and when switching between the intra-frequency target cell and the source cell, increasing the random access efficiency and reducing the latency of the terminal during cell handover. Here, the source cell and the target cell are different serving cells, and the network devices supporting the source cell and the target cell may be the same network device or different network devices; the source cell and the target cell use the same frequency, and the source cell and the target cell are called intra-frequency cells. The intra-frequency cells may refer to the same center frequency of the carrier, or the same center frequency and subcarrier spacing. Or, the intra-frequency cells may also refer to the same center frequency for transmitting the SSB, or the same center frequency and the subcarrier spacing of the SSB, and this is not limited.

[0166] In some embodiments, the associated pattern period is equal to the duration of the system frame.

[0167] In the solution provided by the embodiment of the present application, the terminal receives the PRACH configuration information and SSB configuration information sent by the source cell to indicate the terminal to randomly access the target cell, and can determine the associated pattern period for random access according to the PRACH configuration information, and can determine the time period according to the associated pattern period. When the associated pattern period is equal to the duration of the system frame, the time period determined by the terminal includes two or more associated pattern periods. The time period includes a set of random access channel opportunities RO associated with the SSB index in the SSB configuration information. In this way, when the associated pattern period is equal to the duration of the system frame and the time period is m times the duration of the system frame, the terminal can perform PRACH retransmission that meets the PRACH repetition times configured by the base station when switching between the target cell and the source cell with the same frequency, increasing the random access efficiency and reducing the delay of the terminal during cell handover. Wherein, the duration of the system frame of the target cell is equal to the duration of the system frame of the source cell.

[0168] Figure 17 and Figure 18 FIG. is a schematic structural diagram of a possible communication device provided by an embodiment of the present application. These communication devices can be used to implement the functions of the terminal device or the network device in the above method embodiment, and thus can also achieve the beneficial effects possessed by the above method embodiment. In the embodiment of the present application, the communication device may be one of the terminals 120a-120j shown in Figure 1 or may be the base station 110a or 110b shown in Figure 1 , or may also be a module (such as a chip) applied to the terminal device or the network device cell.

[0169] As Figure 17 shown, the communication device 1700 includes a processing module 1710 and a transceiver module 1720. The communication device 1700 is used to implement the functions of the terminal device or the cell in the method embodiment shown in the above possible embodiment.

[0170] Exemplarily, when the communication device 1700 is used to implement as Figure 15When implementing the functions of the terminal device in the method embodiments shown: The transceiver module 1720 is used to receive the physical random access channel PRACH configuration information of the target cell sent by the source cell, where the PRACH configuration information includes the PRACH repetition times, and the absolute value of the relative time offset of the system frames with the same frame index between the source cell and the target cell is less than half of the system frame duration; The processing module 1710 is used to determine the associated pattern period according to the PRACH configuration information; The processing module 1710 is further used to determine the time period according to the associated pattern period, and the time period includes a set of random access channel opportunities RO associated with the synchronization signal block SSB index, and the set of RO includes RO with the PRACH repetition times, and the time period is m times the duration of the system frame, and m is an integer greater than or equal to 2; The transceiver module 1720 is further used to randomly access the target cell according to the time period.

[0171] In some embodiments, the associated pattern period is equal to the duration of the system frame.

[0172] In some embodiments, the maximum number L of the SSB indexes of the target cell max = 4.

[0173] In some embodiments, randomly accessing the target cell according to the time period includes: determining the system frame of the target cell; determining the set of random access channel opportunities RO associated with the SSB index included in the time period according to the system frame of the target cell; randomly accessing according to the set of RO.

[0174] In some embodiments, the transceiver module 1720 is further used to receive the demodulation reference signal DMRS of the PBCH sent by the target cell; determining the system frame of the target cell includes: determining the boundary of the system frame of the target cell according to the DMRS; determining the index of the system frame of the target cell according to the boundary of the system frame of the target cell and the boundary of the system frame of the source cell; determining the system frame of the target cell included in the time period according to the index of the system frame.

[0175] In some embodiments, determining the boundary of the system frame of the target cell according to the DMRS includes: determining the half-frame indication according to the DMRS; determining the boundary of the system frame of the target cell according to the half-frame indication.

[0176] Exemplarily, when the communication device 1700 is used to implement as Figure 15When implementing the functions of the network device of the source cell in the method embodiments shown: The transceiver module 1720 is used to obtain the physical random access channel (PRACH) configuration information of the target cell, where the PRACH configuration information includes the PRACH repetition count; the transceiver module 1720 is further used to send the PRACH configuration information to the terminal. The absolute value of the relative time offset of the system frames with the same frame index between the source cell and the target cell is less than half of the duration of the system frame. The time period includes a set of random access opportunities (ROs) associated with the synchronization signal block (SSB) index. The set of ROs includes ROs with the PRACH repetition count. The time period is determined according to the associated pattern period, the associated pattern period is determined according to the PRACH configuration information, and the time period is m times the duration of the system frame, where m is an integer greater than or equal to 2.

[0177] In some embodiments, the associated pattern period is equal to the duration of the system frame.

[0178] Exemplarily, when the communication device 1700 is used to implement the functions of the network device of the target cell in the method embodiments shown as Figure 15 When implementing the functions of the network device of the target cell in the method embodiments shown: The transceiver module 1720 is used to send the physical random access channel (PRACH) configuration information to the source cell, where the PRACH configuration information includes the PRACH repetition count; the transceiver module 1720 is further used to receive the random access information of the terminal. The absolute value of the relative time offset of the system frames with the same frame index between the source cell and the target cell is less than half of the duration of the system frame. The time period includes a set of random access opportunities (ROs) associated with the synchronization signal block (SSB) index. The set of ROs includes ROs with the PRACH repetition count. The time period is determined according to the associated pattern period, the associated pattern period is determined according to the PRACH configuration information, and the time period is m times the duration of the system frame, where m is an integer greater than or equal to 2.

[0179] In some embodiments, the associated pattern period is equal to the duration of the system frame.

[0180] For a more detailed description of the above processing module 1710 and transceiver module 1720, reference can be directly made to the relevant descriptions in the method embodiments shown above, and details are not repeated here.

[0181] In some embodiments, a communication system is provided, including a terminal device or a network device for implementing the method embodiments shown in the above possible embodiments.

[0182] As Figure 18As shown, the communication device 1800 includes a processor 1810 and an interface circuit 1820. The processor 1810 and the interface circuit 1820 are coupled to each other. It can be understood that the interface circuit 1820 can be a transceiver or an input / output interface. Optionally, the communication device 1800 may further include a memory 1830 for storing instructions executed by the processor 1810, or input data required for the processor 1810 to run instructions, or data generated after the processor 1810 runs instructions.

[0183] Exemplarily, when the communication device 1800 is used to implement the method in the method embodiment shown above, the processor 1810 is used to implement the functions of the above-mentioned processing module 1710, and the interface circuit 1820 is used to implement the functions of the above-mentioned transceiver module 1720.

[0184] In some embodiments, a communication device is provided, including a processor that can be used to implement the method in the method embodiment shown in the above possible embodiments. Optionally, the communication device further includes a memory. Optionally, the communication device further includes a communication interface, and the processor is coupled to the communication interface.

[0185] In some embodiments, the communication device is a device. In this case, the communication interface can be a transceiver or an input / output interface. In another implementation, the communication device is a chip or a chip system. In this case, the communication interface can be an input / output interface, an interface circuit, an output circuit, an input circuit, a pin, or a related circuit, etc. on the chip or the chip system. The processor can also be embodied as a processing circuit or a logic circuit.

[0186] In some embodiments, a computer program product is provided, and the computer program product includes: when the computer program is run, it causes the computer to execute the method in the method embodiment shown in the above possible embodiments.

[0187] In some embodiments, a computer-readable medium is provided, and the computer-readable medium stores a computer program (which can also be referred to as code or instructions). When it runs on a computer, it causes the computer to execute the method in the method embodiment shown in the above possible embodiments.

[0188] Those of ordinary skill in the art can realize that the units and algorithm steps of the examples described in combination with the embodiments disclosed herein can be implemented by electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are executed in a hardware or software manner depends on the specific application and design constraints of the technical solution. Professional technicians can use different methods to implement the described functions for each specific application, but such implementation should not be considered to exceed the scope of this application.

[0189] When the above communication device is a chip applied to a terminal, the terminal chip implements the functions of the terminal in the above method embodiments. The terminal chip receives information from other modules in the terminal (such as a radio frequency module or an antenna), and this information is sent by the base station to the terminal; or, the terminal chip sends information to other modules in the terminal (such as a radio frequency module or an antenna), and this information is sent by the terminal to the base station.

[0190] When the above communication device is a module applied to a base station, the base station module implements the functions of the base station in the above method embodiments. The base station module receives information from other modules in the base station (such as a radio frequency module or an antenna), and this information is sent by the terminal to the base station; or, the base station module sends information to other modules in the base station (such as a radio frequency module or an antenna), and this information is sent by the base station to the terminal. Here, the base station module can be the baseband chip of the base station, or it can be a DU or other modules. Here, the DU can be a DU under the open radio access network (O-RAN) architecture.

[0191] It can be understood that the processor in the embodiments of the present application can be a central processing unit (CPU), or it can be other general-purpose processors, digital signal processors (DSPs), application specific integrated circuits (ASICs), field programmable gate arrays (FPGAs), or other programmable logic devices, transistor logic devices, hardware components, or any combination thereof. The general-purpose processor can be a microprocessor or any conventional processor.

[0192] Those skilled in the art can clearly understand that for the convenience and brevity of description, the specific working processes of the above-described systems, devices, and units can refer to the corresponding processes in the foregoing method embodiments, and will not be elaborated herein.

[0193] It should be understood that in this application, "at least one" means one or more, and "a plurality" means two or more. "And / or" describes the association relationship of associated objects and indicates that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist simultaneously, and B exists alone, where A and B can be singular or plural. In the textual description of this application, the character " / " generally represents an "or" relationship between the associated objects before and after; in the formulas of this application, the character " / " represents a "division" relationship between the associated objects before and after. "Including at least one of A, B, and C" can represent: including A; including B; including C; including A and B; including A and C; including B and C; including A, B, and C.

[0194] In the embodiments of this application, the various numerical numbers involved are only for the convenience of description and are not used to limit the scope of the embodiments of this application. The magnitudes of the serial numbers of the above processes do not mean the sequence of execution, and the execution sequence of each process should be determined by its function and internal logic.

[0195] In several embodiments provided in this application, it should be understood that the disclosed systems, devices, and methods can be implemented in other ways. The method steps in the embodiments of this application can be implemented in hardware or in software instructions executable by a processor. The software instructions can be composed of corresponding software modules, and the software modules can be stored in a random access memory, a flash memory, a read-only memory, a programmable read-only memory, an erasable programmable read-only memory, an electrically erasable programmable read-only memory, a register, a hard disk, a removable hard disk, a CD-ROM, or any other form of storage medium well-known in the art. An exemplary storage medium is coupled to the processor so that the processor can read information from the storage medium and write information to the storage medium. The storage medium can also be a component of the processor. The processor and the storage medium can be located in an ASIC. Additionally, the ASIC can be located in a base station or a terminal. The processor and the storage medium can also exist as discrete components in a base station or a terminal. For example, the device embodiments described above are merely illustrative. For example, the division of the units is only a logical function division, and there can be other division methods in actual implementation. For example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the displayed or discussed coupling or direct coupling or communication connection to each other can be through some interfaces, and the indirect coupling or communication connection of the devices or units can be in an electrical, mechanical, or other form.

[0196] In the above embodiments, it can be implemented in whole or in part by software, hardware, firmware, or any combination thereof. When implemented using software, it can be implemented in the form of a computer program product in whole or in part. The computer program product includes one or more computer programs or instructions. When the computer program or instructions are loaded and executed on a computer, the processes or functions described in the embodiments of the present application are executed in whole or in part. The computer can be a general-purpose computer, a special-purpose computer, a computer network, a network device, a user device, or other programmable devices. The computer program or instructions can be stored in a computer-readable storage medium, or transmitted from one computer-readable storage medium to another computer-readable storage medium. For example, the computer program or instructions can be transmitted from one website, computer, server, or data center to another website, computer, server, or data center in a wired or wireless manner. The computer-readable storage medium can be any available medium that can be accessed by a computer, or a data storage device such as a server or data center that integrates one or more available media. The available medium can be a magnetic medium, such as a floppy disk, a hard disk, or a magnetic tape; it can also be an optical medium, such as a digital video disc; it can also be a semiconductor medium, such as a solid-state drive. The computer-readable storage medium can be a volatile or non-volatile storage medium, or can include both volatile and non-volatile types of storage media. The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they can be located in one place, or distributed to multiple network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0197] In addition, in each embodiment of the present application, the functional units can be integrated into one processing unit, or each unit can exist physically alone, or two or more units can be integrated into one unit.

[0198] When the above-mentioned functions are implemented in the form of software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, or a part of this technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions for causing a computer device (which may be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the methods described in various embodiments of this application. The foregoing storage medium includes: various media such as USB flash drives, mobile hard disks, read-only memories (ROMs), random access memories (RAMs), magnetic disks, or optical discs that can store program codes.

[0199] As described above, the above are only specific implementation manners of this application, but the protection scope of this application is not limited thereto. Any person skilled in the art within the technical scope disclosed by this application can easily think of changes or substitutions, which should all be covered by the protection scope of this application. Therefore, the protection scope of this application should be subject to the protection scope of the claims.

Claims

1. A random access method, characterized in that, Applied to a terminal, the method includes: Receiving physical random access channel (PRACH) configuration information of a target cell sent by a source cell, where the PRACH configuration information includes the PRACH repetition count, and the absolute value of the relative time offset of system frames with the same frame index between the source cell and the target cell is less than half of the duration of the system frame; Determining an association pattern period according to the PRACH configuration information; Determining a time period according to the association pattern period, where the time period includes a set of random access channel opportunities (ROs) associated with a synchronization signal block (SSB) index, the set of ROs includes ROs with the PRACH repetition count, and the time period is m times the duration of the system frame, where m is an integer greater than or equal to 2; Randomly accessing the target cell according to the time period.

2. The method according to claim 1, wherein: The association pattern period is equal to the duration of the system frame.

3. The method according to claim 1 or 2, wherein: The maximum number L of SSB indexes of the target cell max = 4.

4. The method according to any one of claims 1 to 3, characterized in that, Randomly accessing the target cell according to the time period includes: Determining the system frame of the target cell; Determining the set of random access channel opportunities (ROs) associated with the SSB index included in the time period according to the system frame of the target cell; Randomly accessing according to the set of ROs.

5. The method according to any one of claims 1 to 4, characterized in that, The method further includes: Receiving the demodulation reference signal (DMRS) of the physical broadcast channel (PBCH) sent by the target cell; Determining the system frame of the target cell includes: Determining the boundary of the system frame of the target cell according to the DMRS; Determining the index of the system frame of the target cell according to the boundary of the system frame of the target cell and the boundary of the system frame of the source cell; Determining the system frame of the target cell included in the time period according to the index of the system frame.

6. The method according to claim 5, wherein Determining the boundary of the system frame of the target cell according to the DMRS includes: Determining a half-frame indication according to the DMRS; Determining the boundary of the system frame of the target cell according to the half-frame indication.

7. A random access method, characterized in that, Applied to a network device of a source cell, the method includes: Obtaining physical random access channel (PRACH) configuration information of a target cell, where the PRACH configuration information includes the PRACH repetition count; Sending the PRACH configuration information to a terminal, The absolute value of the relative time offset of system frames with the same frame index between the source cell and the target cell is less than half of the duration of the system frame, the time period includes a set of random access channel opportunities (ROs) associated with a synchronization signal block (SSB) index, the set of ROs includes ROs with the PRACH repetition count, the time period is determined according to an association pattern period, the association pattern period is determined according to the PRACH configuration information, and the time period is m times the duration of the system frame, where m is an integer greater than or equal to 2.

8. The method according to claim 7, wherein: The association pattern period is equal to the duration of the system frame.

9. A random access method, characterized in that, Applied to a network device of a target cell, the method includes: Send the physical random access channel (PRACH) configuration information to the source cell, where the PRACH configuration information includes the PRACH repetition count; Receive the random access information of the terminal, The absolute value of the relative time offset of the system frames with the same frame index between the source cell and the target cell is less than half of the duration of the system frame. The time period includes a set of random access channel opportunities (ROs) associated with the synchronization signal block (SSB) index. The set of ROs includes the ROs with the PRACH repetition count. The time period is determined according to the associated pattern period, and the associated pattern period is determined according to the PRACH configuration information. The time period is m times the duration of the system frame, where m is an integer greater than or equal to 2.

10. The method according to claim 9, wherein, The associated pattern period is equal to the duration of the system frame.

11. A communication device, characterized in that, Comprising a transceiver module and a processing module, The transceiver module is configured to receive the PRACH configuration information of the target cell sent by the source cell, where the PRACH configuration information includes the PRACH repetition count, and the absolute value of the relative time offset of the system frames with the same frame index between the source cell and the target cell is less than half of the duration of the system frame; The processing module is configured to determine the associated pattern period according to the PRACH configuration information; The processing module is further configured to determine the time period according to the associated pattern period. The time period includes a set of ROs associated with the SSB index. The set of ROs includes the ROs with the PRACH repetition count. The time period is m times the duration of the system frame, where m is an integer greater than or equal to 2; The transceiver module is further configured to randomly access the target cell according to the time period.

12. The communication device according to claim 11, wherein, The associated pattern period is equal to the duration of the system frame.

13. The communication device according to claim 11 or 12, wherein, The maximum number L of SSB indexes of the target cell max = 4.

14. The communication device according to any one of claims 11 to 13, characterized in that, Randomly accessing the target cell according to the time period includes: Determine the system frame of the target cell; Determine the set of ROs associated with the SSB index included in the time period according to the system frame of the target cell; Randomly access according to the set of ROs.

15. The communication device according to any one of claims 11 to 14, characterized in that, The transceiver module is further configured to: Receive the demodulation reference signal (DMRS) of the physical broadcast channel (PBCH) sent by the target cell; Determine the system frame of the target cell, including: Determine the boundary of the system frame of the target cell according to the DMRS; Determine the index of the system frame of the target cell according to the boundary of the system frame of the target cell and the boundary of the system frame of the source cell; Determine the system frame of the target cell included in the time period according to the index of the system frame.

16. The communication device according to claim 15, characterized in that, Determine the boundary of the system frame of the target cell according to the DMRS, including: Determine the half-frame indication according to the DMRS; Determine the boundary of the system frame of the target cell according to the half-frame indication.

17. A communication device, characterized in that, Comprising a transceiver module, The transceiver module is used to obtain the physical random access channel (PRACH) configuration information of the target cell, where the PRACH configuration information includes the PRACH repetition times; The transceiver module is further used to send the PRACH configuration information to the terminal. The absolute value of the relative time offset of the system frames with the same frame index between the source cell and the target cell is less than half of the duration of the system frame. The time period includes a set of random access channel opportunities (ROs) associated with the synchronization signal block (SSB) index. The set of ROs includes the ROs with the PRACH repetition times. The time period is determined according to the associated pattern period, and the associated pattern period is determined according to the PRACH configuration information. The time period is m times the duration of the system frame, where m is an integer greater than or equal to 2.

18. The communication device according to claim 17, wherein The associated pattern period is equal to the duration of the system frame.

19. A communication device, characterized in that, It includes a transceiver module. The transceiver module is used to send the physical random access channel (PRACH) configuration information to the source cell, where the PRACH configuration information includes the PRACH repetition times; The transceiver module is further used to receive the random access information of the terminal. The absolute value of the relative time offset of the system frames with the same frame index between the source cell and the target cell is less than half of the duration of the system frame. The time period includes a set of random access channel opportunities (ROs) associated with the synchronization signal block (SSB) index. The set of ROs includes the ROs with the PRACH repetition times. The time period is determined according to the associated pattern period, and the associated pattern period is determined according to the PRACH configuration information. The time period is m times the duration of the system frame, where m is an integer greater than or equal to 2.

20. The communication device according to claim 19, wherein The associated pattern period is equal to the duration of the system frame.

21. A communication system, characterized in that, It includes the communication device according to any one of claims 11 to 16, and / or the communication device according to claim 17 or 18, and / or the communication device according to claim 19 or 20.

22. A communication device, characterized in that, It includes: A processor, which is used to execute the computer instructions stored in the memory, so that the device executes: the method according to any one of claims 1 to 6, or the method according to claim 7 or 8, or the method according to claim 9 or 10.

23. The device according to claim 22, characterized in that, The device further includes the memory.

24. The device according to claim 22 or 23, characterized in that, The device further includes a communication interface, and the communication interface is coupled to the processor. The communication interface is used to input and / or output information.

25. The device according to any one of claims 22 to 24, characterized in that, The device is a chip.

26. A computer program product, characterized in that, When the computer program in the computer program product is executed by the communication device, the method according to any one of claims 1 to 6, or the method according to claim 7 or 8, or the method according to claim 9 or 10 is implemented.

27. A computer-readable storage medium, characterized in that, The storage medium stores a computer program or instructions, and when the computer program or instructions are executed by a communication device, the method described in any one of claims 1 to 6, or the method described in claim 7 or 8, or the method described in claim 9 or 10 is implemented.

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