Cell handover-based random access method, user equipment and storage medium

Abstract

This application proposes a random access method, user equipment, and storage medium based on cell handover. The method includes: responding to receiving a handover command from a source cell, parsing PRACH configuration information about the target cell from the handover command; detecting a synchronization signal and completing cell synchronization based on the synchronization signal; responding to completing cell synchronization, i.e., sending a preamble sequence, specifically sending the preamble sequence for the first time in the current system frame and for the second time in the next system frame; setting an enlarged first RAR listening window based on the PRACH configuration information; and receiving a RAR from the target cell based on the first RAR listening window, and performing corresponding operations according to the random access type upon receiving the RAR. Based on this, this application eliminates the need to wait for successful decoding of the MIB, thus improving the latency of random access during cell handover and increasing access efficiency.

Description

Technical Field

[0001] This application relates to the field of LTE (Long Time Evolution) technology, specifically to a random access method based on cell handover, user equipment, and storage medium. Background Technology

[0002] With the development of LTE technology, the handover needs of user equipment (UE) such as smartphones between different cells are becoming more and more frequent, especially in high-speed mobile, weak coverage, and dense deployment scenarios, this phenomenon is even more prominent. After entering the target cell, the UE must perform random access to complete uplink synchronization and uplink resource allocation, and finally establish an RRC (Radio Resource Control) connection.

[0003] In the standard LTE random access procedure, before initiating random access, the user equipment typically needs to receive and decode the target cell's Master Information Block (MIB) to obtain the parity of the SFN (System Frame Number). This SFN parity is used to determine the timing of the preamble sequence to meet the protocol requirements for the RA (Random Access) timing based on the SFN parity. Therefore, the existing LTE standard process requires the user equipment to successfully decode the MIB before entering the RACH process. The main steps include: the user equipment blindly scans the PBCH (Physical Broadcast Channel) of the target cell to obtain the MIB, and then decodes the MIB to obtain the bandwidth of the target cell, the PHICH (Physical Hybrid ARQ Indicator Channel) configuration, SFN parity identifier, etc. Then, the user equipment selects the corresponding PRACH (Physical Random Access Channel) to send the system frame number according to the SFN parity requirements, and sends the preamble sequence and enters the RAR (Random Access Response) listening process through the corresponding system frame number.

[0004] However, since the PBCH can only receive the MIB in specific system frames, if the user equipment fails to receive the MIB in time after cell handover, it needs to wait for the next corresponding odd / even system frame to send the MIB. Taking a time interval of 10ms between two adjacent system frames as an example, this results in a wait of at least 20ms. Furthermore, complete reception of the MIB requires waiting for at least a quarter cycle of the PBCH, which in turn requires a wait of at least 10ms. Therefore, when the MIB cannot be received and decoded from the PBCH in time, the random access latency is high, with a worst-case latency of at least 30ms. In addition, while waiting to receive the MIB, the user equipment cannot attempt random access, and the MIB reception and RACH initiation procedures are serial operations. This prevents the use of idle time to prepare for random access in advance, further increasing the random access latency and affecting overall access efficiency. Summary of the Invention

[0005] In view of this, this application provides a random access method, user equipment, and storage medium based on cell handover, which can at least improve the problem of high latency in random access during cell handover.

[0006] This application provides a random access method based on cell handover, comprising: In response to receiving a handover command from the source cell indicating a handover to the target cell, the user equipment parses the handover command to obtain the PRACH configuration information of the target cell; The user equipment detects the synchronization signal and completes cell synchronization based on the synchronization signal; In response to the completion of cell synchronization, the user equipment sends a preamble sequence according to the frame number in the PRACH configuration information; The user equipment sets a first RAR listening window based on the PRACH configuration information; The user equipment receives the RAR for the preamble sequence from the target cell based on the first RAR listening window, and performs the corresponding operation according to the random access type when it receives the RAR.

[0007] Optionally, the user equipment sends a preamble sequence according to the frame number in the PRACH configuration information, including: The user equipment sends a preamble sequence for the first time in the current system frame; The user equipment transmits the preamble sequence for the second time in the next system frame.

[0008] Optionally, the method further includes: In response to completing cell synchronization, the user equipment scans the physical broadcast channel of the target cell and performs a decoding process to obtain the master information block from the physical broadcast channel; and, Determine whether the main information block has been successfully decoded; If so, based on the PRACH configuration information and the parity identifier of the decoded system frame number, the corresponding physical random access channel is selected to send the preamble sequence only once; In addition, a second RAR listening window is set, the second RAR listening window has a first duration, and the start time is the time when the preamble sequence is sent; The user equipment receives the RAR for the preamble sequence from the target cell based on the second RAR listening window, and performs the corresponding operation according to the random access type when the RAR is received; If not, then the user equipment shall perform the step of sending the preamble sequence for the second time in the next system frame.

[0009] Optionally, the method further includes: In response to completing cell synchronization, the user equipment scans the physical broadcast channel of the target cell and performs a decoding process to obtain the master information block from the physical broadcast channel; and, After the user equipment transmits the preamble sequence for the second time in the next system frame, the method further includes: Determine whether the main information block has been successfully decoded; If so, based on the PRACH configuration information and the parity identifier of the decoded system frame number, the corresponding physical random access channel is selected to send the preamble sequence only once; In addition, a third RAR listening window is set, the third RAR listening window having a first duration, and the start time being the time when the preamble sequence is sent; The user equipment receives the RAR for the preamble sequence from the target cell based on the third RAR listening window, and performs the corresponding operation according to the random access type when the RAR is received; If not, then the user equipment shall perform the step of setting the first RAR listening window based on the PRACH configuration information.

[0010] Optionally, the method further includes: In response to completing cell synchronization, the user equipment scans the physical broadcast channel of the target cell and performs a decoding process to obtain the master information block from the physical broadcast channel; and, After the user equipment sends the preamble sequence for the first time in the current system frame, it determines whether the main information block has been successfully decoded. If the main information block is successfully decoded, then based on the PRACH configuration information and the parity identifier of the decoded system frame number, it is determined whether the current system frame for executing the first transmission preamble sequence meets the parity requirement. If the conditions are met, a fourth RAR listening window is set. The fourth RAR listening window has a first duration and is started at the moment when the preamble sequence is first sent. The user equipment receives the RAR for the preamble sequence from the target cell based on the fourth RAR listening window and performs the corresponding operation according to the random access type when the RAR is received. If not, based on the PRACH configuration information and the parity identifier of the decoded system frame number, the corresponding physical random access channel is selected to send the preamble sequence only once; and a fifth RAR listening window is set, the fifth RAR listening window having a first duration and starting at the time of sending the preamble sequence; the user equipment receives the RAR for the preamble sequence from the target cell based on the fifth RAR listening window, and performs the corresponding operation according to the random access type when the RAR is received; If the main information block is not successfully decoded, the user equipment shall execute the step of sending the preamble sequence for the second time in the next system frame.

[0011] Optionally, the user equipment sets a first RAR listening window based on the PRACH configuration information, including: The user equipment obtains a second duration of the interval between the current system frame and the next system frame based on the PRACH configuration information; The moment when the preamble sequence is first sent is taken as the start time of the first RAR listening window, and the first RAR listening window is set to have a third duration, wherein the difference between the third duration and the first duration is at least equal to the second duration.

[0012] Optionally, the first RAR monitoring window is a continuous and complete time period used for monitoring RARs.

[0013] Optionally, the first RAR monitoring window includes a first sub-window and a second sub-window, and one of the first sub-window and the second sub-window covers the time period corresponding to the second duration.

[0014] Optionally, the second duration is 10 milliseconds.

[0015] This application provides a user equipment including a processor and a memory, wherein the memory stores a random access program, and when the random access program is executed by the processor, it implements the steps of the random access method based on cell handover as described in any of the preceding claims.

[0016] This application provides a storage medium storing a computer program, which, when executed by a processor, implements the steps of the random access method based on cell handover as described in any of the preceding claims.

[0017] As described above, this application sends a preamble sequence immediately after cell synchronization is completed, based on the frame number in the PRACH configuration information, without waiting for successful decoding of the MIB. This reduces the delay caused by the complete reception and decoding of the MIB, improves the delay of random access during cell handover, and enhances access efficiency.

[0018] Furthermore, this application allows the same preamble sequence to be transmitted in two adjacent system frames. The user equipment transmits the preamble sequence immediately after cell synchronization, regardless of whether the current system frame is odd or even. The parity of the next system frame after the second transmission of the preamble sequence will always be the opposite of the current system frame. This ensures that at least one transmitted preamble sequence falls within a valid RO (RACH Occasion). The first RAR listening window, set accordingly, covers the reception times of both RARs. Even if one RAR is lost, random access can be confirmed based on the received other RAR. Therefore, this application enhances the robustness of random access in scenarios such as weak coverage and high-speed handover. Attached Figure Description

[0019] Figure 1 This is a flowchart illustrating the random access method based on cell handover according to the first embodiment of this application; Figure 2 This is a schematic diagram illustrating the interaction of user equipment during cell handover in an embodiment of this application; Figure 3 This is a flowchart illustrating the random access method based on cell handover according to the second embodiment of this application; Figure 4 This is a flowchart illustrating the random access method based on cell handover according to the third embodiment of this application; Figure 5 This is a flowchart illustrating the random access method based on cell handover according to the fourth embodiment of this application; Figure 6 This is a schematic diagram of the structure of a user equipment according to an embodiment of this application. Detailed Implementation

[0020] In existing standard LTE procedures, a random access procedure can typically be initiated only after the MIB is successfully decoded from the PBCH. However, when the MIB cannot be received and successfully decoded in a timely manner, the random access latency is high. To address this technical problem, this application provides a random access method based on cell handover, as well as user equipment and a storage medium. These protection topics are based on the same concept, and the principles for solving the problem are basically the same or similar. The implementation methods of each protection topic can be referred to mutually, and repeated details will not be elaborated.

[0021] In the scheme of this application, the preamble sequence is sent immediately after cell synchronization is completed, without waiting for the MIB to be received and successfully decoded. This reduces the delay caused by the complete reception and decoding of the MIB, improves the delay of random access during cell handover, and enhances access efficiency.

[0022] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions of this application will be clearly described below in conjunction with specific embodiments and corresponding drawings. Obviously, the embodiments described below are only a part of the embodiments of this application, and not all of them. Unless otherwise specified, the following embodiments and their technical features can be combined with each other, and also belong to the technical solutions of this application.

[0023] Figure 1 This is a flowchart illustrating the random access method based on cell handover according to the first embodiment of this application. The random access method based on cell handover can also be called a "method" or "random access method," and the executing entity for each step can be a suitable user equipment (UE), or a storage medium, processor, controller, etc., with random access functionality. (In conjunction with...) Figure 2 As shown, cell handover can be understood as a user equipment switching from a source cell to a target cell. The source cell can be understood as the signal coverage area of ​​base station 1, and the target cell can be understood as the signal coverage area of ​​base station 2. Communication (including uplink and downlink transmission) between the source cell, the target cell and the user equipment is realized through the network side.

[0024] Combined Figure 1 and Figure 2 As shown, the method includes at least the following steps S11 to S15.

[0025] S11: In response to receiving a handover command from the source cell indicating a handover to the target cell, the user equipment parses the handover command to obtain the PRACH configuration information about the target cell.

[0026] When a user equipment (UE) is connected to the network, the network side will comprehensively determine whether the UE needs to perform a cell handover, i.e., switch from the current cell (also known as the "source cell") to the target cell, based on information such as the UE's network signal and uplink / downlink transmission status. Furthermore, when a handover is determined to be necessary, the network side will issue a handover command to the UE. This handover command will at least include a synchronization signal for synchronizing the UE with the target cell, and PRACH configuration information provided by the target cell.

[0027] The synchronization signals include a primary synchronization signal (PSS) and a secondary synchronization signal (SSS). User equipment (UE) can first detect the primary synchronization signal from, for example, six resource blocks (RBs) located at the center of the system bandwidth. Through the primary synchronization signal, UE can obtain information including, but not limited to, the physical cell identifier (value 0, 1, or 2) within the cell group, time slot boundary information, initial frequency synchronization, and the ability to distinguish between FDD and TDD duplex modes. Then, UE can immediately detect the secondary synchronization signal from, for example, a symbol located before the primary synchronization signal or a specific OFDM symbol. Through the secondary synchronization signal, UE can obtain information including, but not limited to, the frame header position of the radio frame, the group ID to which the target cell belongs, and the physical layer identifier (PCI) of the target cell obtained by combining the primary synchronization signal.

[0028] Based on the synchronization signal, the user equipment (UE) can at least estimate the frequency offset, timing, and cyclic prefix (CP), and complete a series of key operations such as frequency offset correction, timing synchronization, and CP identification, laying the foundation for subsequent demodulation of messages and access to the target cell's network. For example, the main synchronization signal is a known fixed sequence. The UE can detect the frequency offset by performing correlation operations with the received signal after locally copying this sequence. In one example, the coarse and fine frequency offsets can be estimated by searching for peaks in the frequency domain based on the periodic structure of the synchronization signal using the Schmidl algorithm or FFT frequency offset estimation algorithm. Once the frequency offset estimation is completed, the UE can perform frequency compensation on the received signal to restore subcarrier orthogonality. As another example, the synchronization signal has strong autocorrelation characteristics in the time domain. When the received signal slides correlated with the local sequence, a significant peak appears. The position of this peak is the symbol timing start point. The UE detects this peak to achieve frame synchronization and symbol timing synchronization, thereby determining the boundary of each OFDM symbol and completing timing synchronization. For example, the user equipment can blindly detect the auxiliary synchronization signal at two possible locations, and the location where it is successfully detected indicates the CP type currently used by the cell.

[0029] For other methods of obtaining information, please refer to existing technologies.

[0030] Based on the above, the user equipment can obtain the synchronization signal without decoding any other channels, and complete the initial synchronization with the target cell accordingly, also known as coarse synchronization, which includes at least time and frequency synchronization.

[0031] The PRACH configuration information for the target cell is provided by the target base station to the source base station. The source and target base stations exchange handover preparation information via the X2 interface. The target base station sends the PRACH configuration information, carrier frequency, PCI, and other parameters of the target cell to the source base station. The PRACH configuration information is primarily used to guide user equipment to transmit the preamble sequence on the correct time-frequency resources to initiate the random access procedure. The PRACH configuration information includes, but is not limited to, the following: PRACH configuration index, root sequence index, zero-correlation field configuration, PRACH frequency domain offset, high-speed mode flag, and PRACH time-domain transmission position configuration, used to determine the preamble sequence generation method and transmission time-frequency resources. The specific meanings and functions of these configuration information can be found in existing technologies and will not be elaborated upon here.

[0032] S12: User equipment detects the synchronization signal and completes cell synchronization based on the synchronization signal.

[0033] S13: In response to the completion of cell synchronization, the user equipment sends a preamble sequence according to the frame number in the PRACH configuration information.

[0034] S14: The user equipment sets the first RAR listening window based on the PRACH configuration information.

[0035] Since the key parameters required for random access can be obtained from the handover command, random access is essentially independent of the information obtained from decoding the master information block. Therefore, this application can achieve random transmission of the preamble sequence immediately after the user equipment and the target cell complete cell synchronization. Compared with the existing LTE random access procedure, this application does not need to wait for the complete reception of the MIB, nor does it need to wait for the successful decoding of the MIB. This reduces the delay caused by the complete reception and successful decoding of the MIB, improves the delay of random access during cell handover, and enhances the overall efficiency of random access.

[0036] In one example, the user equipment performs two transmissions of the same preamble sequence using two consecutive system frames, such as... Figure 3 As shown, step S13 may include S131 and S132.

[0037] S131: The user equipment sends a preamble sequence for the first time in the current system frame; S132: The user equipment transmits the preamble sequence for the second time in the next system frame.

[0038] The time interval between the current system frame and the next system frame can be determined according to the LTE frame structure limitations in the PRACH configuration information, for example, 10 milliseconds, to fully adapt to the LTE frame structure.

[0039] In this example, the user equipment immediately performs the first transmission of the preamble sequence after cell synchronization is completed. Regardless of whether the current system frame is an odd or even frame, the parity of the next system frame after the second transmission of the preamble sequence will definitely be opposite to that of the current system frame. This ensures that there will always be a preamble sequence that falls within a valid RO, which can completely cover two consecutive ROs.

[0040] Based on the two transmissions of the preamble sequence, this application also needs to reset the RAR listening window, referred to as the first RAR listening window. For ease of description and to distinguish it from existing RAR listening windows, the duration of the existing RAR listening window is referred to as the first duration, the interval between the current system frame and the next system frame is referred to as the second duration, and the duration of the first RAR listening window is referred to as the third duration. Specifically, step S14 can be implemented as follows: First, the user equipment obtains the second duration of the interval between the current system frame and the next system frame based on the PRACH configuration information; then, the moment of the first transmission of the preamble sequence is taken as the start time of the first RAR listening window, and the first RAR listening window is set to have a third duration, the difference between the third duration and the first duration being at least equal to the second duration. That is to say, compared to the existing RAR listening window, the reset RAR listening window in this application adds an adjacent frame interval to its duration. Taking an interval between the current system frame and the next system frame (i.e., the second duration) of 10ms as an example, the reset first RAR listening window is extended by 10ms or more.

[0041] In this example, the reset first RAR listening window can cover the arrival times of the two potential RARs fed back by the two preamble sequences. That is, the first RAR listening window can cover the reception times of the two RARs. Even if the first RAR is lost, for example in a weak signal environment, the second RAR can be waited for, and the corresponding operation can be performed according to the random access type based on the received second RAR. Thus, this application can enhance the robustness of random access in scenarios such as weak coverage and high-speed handover.

[0042] S15: The user equipment receives the RAR for the preamble sequence from the target cell based on the first RAR listening window, and performs the corresponding operation according to the random access type when the RAR is received.

[0043] In step S5, for contention-based random access, upon receiving the RAR, the user equipment will also send a message containing its own CRNTI (Cell Radio Network Temporary Identifier) ​​or RRC connection request, commonly known as Msg3. The random access will only be confirmed as complete upon receiving the contention resolution message (Msg4) from the target cell. For non-contention-based random access, the user equipment can confirm the completion of random access upon receiving the RAR, and then perform uplink and downlink operations.

[0044] In traditional LTE random access procedures, the master information block (MIB) is located on the first four OFDM symbols of the second slot in subframe 0 of each system frame. This results in a minimum wait of 10ms for complete reception of the MIB. Furthermore, if the user equipment fails to receive the MIB in time after cell handover, it must wait for the next corresponding odd / even system frame to send the MIB, which adds another minimum wait of 20ms for complete reception. However, based on the method described in steps S1 to S5, this application eliminates the need to wait for complete reception and successful decoding of the MIB, thereby reducing the worst-case latency of over 30ms and improving random access efficiency.

[0045] Furthermore, in the example of sending the preamble sequence twice and resetting the RAR listening window, the repeated transmission of the preamble sequence is essentially an internal attempt by the user equipment and does not violate LTE-related specifications, such as 3GPP specifications. Moreover, the reset first RAR listening window only executes within the user equipment; for example, it only requires resetting the user equipment's own timer. The network side still sends RAR according to LTE-related specifications, and there are no modifications to these specifications. Therefore, this application has extremely high deployment feasibility and is easy to commercialize.

[0046] In one example, the first RAR listening window can be a continuous and complete time period for listening to RARs, so that the user device only needs one timer to perform the listening, or the timer inside the user device only needs to be started once, which facilitates internal management of the user device.

[0047] In other examples, the first RAR monitoring window may include a first sub-window and a second sub-window, one of which covers the time period corresponding to the second duration. Therefore, this application can perform monitoring using two timers within the user equipment. One timer executes RAR monitoring within the first sub-window for monitoring the RAR of the first transmitted preamble sequence, and the other timer executes RAR monitoring within the second sub-window for monitoring the RAR of the second transmitted preamble sequence. These two timers can execute their respective monitoring in parallel.

[0048] Figure 4 This is a flowchart illustrating the random access method based on cell handover according to the third embodiment of this application. Figure 4 As shown, the specific steps of the random access method in this embodiment are as follows: S21: In response to receiving a handover command from the source cell indicating a handover to the target cell, the user equipment parses the handover command to obtain the PRACH configuration information about the target cell.

[0049] S22: User equipment detects the synchronization signal and completes cell synchronization based on the synchronization signal.

[0050] S231: In response to the completion of cell synchronization, the user equipment sends a preamble sequence for the first time in the current system frame.

[0051] And, after completing cell synchronization, perform the following steps S2311 and S2312. It should be noted that, although... Figure 4 The steps S2311 and S2312 are shown to be executed after step S231, but this is not a limitation on the order of execution. In actual scenarios, steps S2311 and S2312 can be performed synchronously with step S231, that is, receiving the main information block and sending the preamble sequence can be performed synchronously.

[0052] S2311: The user equipment scans the physical broadcast channel of the target cell and performs the decoding process of obtaining the master information block from the physical broadcast channel.

[0053] S2312: Determine whether the main information block has been successfully decoded.

[0054] If the main information block is successfully decoded, proceed with steps S2313 to S2315.

[0055] S2313: Based on the PRACH configuration information and the parity identifier of the decoded system frame number, select the corresponding physical random access channel and transmit the preamble sequence only once. And, S2314: Set a second RAR listening window, the second RAR listening window has a first duration, and the start time is the time when the preamble sequence is sent.

[0056] S2315: The user equipment receives the RAR for the preamble sequence from the target cell based on the second RAR listening window, and performs the corresponding operation according to the random access type when the RAR is received.

[0057] If the main information block is not successfully decoded, proceed with steps S232 to S25 below.

[0058] S232: The user equipment transmits the preamble sequence for the second time in the next system frame. And, S24: The user equipment sets the first RAR listening window based on the PRACH configuration information.

[0059] S25: The user equipment receives the RAR for the preamble sequence from the target cell based on the first RAR listening window, and performs the corresponding operation according to the random access type when the RAR is received.

[0060] The steps in this embodiment that are the same as those in the previous embodiments can be implemented using the same methods, and will not be repeated here. Figure 3 Based on the aforementioned embodiments, the difference lies in the combination of Figure 4 As shown, this embodiment will still perform the reception and decoding of the main information block. After successfully decoding the main information block, the second transmission of the preamble sequence will be stopped, as well as the related steps based on the two previous transmissions of the preamble sequence will be stopped. Then, the preamble sequence will be transmitted only according to the parity requirement of the system frame required by the PRACH configuration information, and the RAR will be monitored according to the RAR monitoring window set therethere (i.e., the second RAR monitoring window) to perform the corresponding operation according to the random access type.

[0061] Figure 5 This is a flowchart illustrating the random access method based on cell handover according to the fourth embodiment of this application. Figure 5 As shown, the specific steps of the random access method in this embodiment are as follows: S31: In response to receiving a handover command from the source cell indicating a handover to the target cell, the user equipment parses the handover command to obtain the PRACH configuration information about the target cell.

[0062] S32: User equipment detects the synchronization signal and completes cell synchronization based on the synchronization signal.

[0063] S331: In response to the completion of cell synchronization, the user equipment sends a preamble sequence for the first time in the current system frame.

[0064] S332: The user equipment transmits the preamble sequence for the second time in the next system frame.

[0065] After cell synchronization is completed, the method also performs the following steps S3311 and S3312.

[0066] S3311: The user equipment scans the physical broadcast channel of the target cell and performs the decoding process of obtaining the master information block from the physical broadcast channel.

[0067] Step S3312 is executed only after the preamble sequence is sent for the second time in step S332: determine whether the main information block has been successfully decoded.

[0068] If the main information block is successfully decoded, proceed with steps S3313 to S3315.

[0069] S3313: Based on the PRACH configuration information and the parity identifier of the decoded system frame number, select the corresponding physical random access channel and transmit the preamble sequence only once. And, S3314: Set a third RAR listening window, the third RAR listening window having a first duration and starting at the time of sending the preamble sequence.

[0070] S3315: The user equipment receives the RAR for the preamble sequence from the target cell based on the third RAR listening window, and performs the corresponding operation according to the random access type when the RAR is received.

[0071] If the main information block is not successfully decoded, proceed with steps S34 to S35 below.

[0072] S34: The user equipment sets the first RAR listening window based on the PRACH configuration information.

[0073] S35: The user equipment receives the RAR for the preamble sequence from the target cell based on the first RAR listening window, and performs the corresponding operation according to the random access type when the RAR is received.

[0074] The steps in this embodiment that are the same as those in the previous embodiments can be implemented using the same methods, and will not be repeated here. Figure 3 Based on the aforementioned embodiments, the difference lies in the combination of Figure 5As shown, in this embodiment, after the second transmission of the preamble sequence, the reception and decoding of the main information block are still performed. After successfully decoding the main information block, the steps related to the previous two transmissions of the preamble sequence are stopped. Instead, the preamble sequence is transmitted only according to the parity requirement of the system frame required by the PRACH configuration information, and the RAR is monitored according to the RAR monitoring window set accordingly (i.e., the third RAR monitoring window) to perform the corresponding operation according to the random access type. This embodiment can avoid the situation where the RAR is not received after the previous two transmissions of the preamble sequence, but the corresponding operation can still be monitored and performed according to the random access type.

[0075] and Figure 4 The difference in the embodiments is that, in combination with Figure 5 As shown, in this embodiment, the determination of whether the main information block has been successfully decoded is made after the preamble sequence is sent for the second time. The third RAR listening window and the second RAR listening window can be exactly the same, for example, the start time and end time are exactly the same.

[0076] This application also provides another example of a random access method. Combined with Figure 4 In the example described, step S2311 is executed after the user equipment completes cell synchronization, but step S2312 is executed after the preamble sequence is sent for the first time in the current system frame.

[0077] S2311: The user equipment scans the physical broadcast channel of the target cell and performs the decoding process of obtaining the master information block from the physical broadcast channel.

[0078] S2312: Determine whether the main information block has been successfully decoded.

[0079] If the main information block is successfully decoded, proceed with the following steps: Based on the PRACH configuration information and the parity indicator of the decoded system frame number, it is determined whether the current system frame for executing the first transmission preamble sequence meets the parity requirements.

[0080] For example, if the PRACH configuration information specifies that the system frame for executing the transmission preamble sequence is an odd frame, then the parity requirement is met when the current system frame is an odd frame; conversely, if the current system frame is an even frame, then the parity requirement is determined not to be met.

[0081] If the conditions are met, a fourth RAR listening window is set. The fourth RAR listening window has a first duration and is started at the moment when the preamble sequence is first sent. The user equipment receives the RAR for the preamble sequence from the target cell based on the fourth RAR listening window and performs the corresponding operation according to the random access type when the RAR is received. If not, based on the PRACH configuration information and the parity identifier of the decoded system frame number, the corresponding physical random access channel is selected to send the preamble sequence only once; and a fifth RAR listening window is set, the fifth RAR listening window having a first duration and starting at the time of sending the preamble sequence; the user equipment receives the RAR for the preamble sequence from the target cell based on the fifth RAR listening window, and performs the corresponding operation according to the random access type when the RAR is received; If the main information block is not successfully decoded, then proceed with steps S232 to S25.

[0082] S232: The user equipment transmits the preamble sequence for the second time in the next system frame. And, S24: The user equipment sets the first RAR listening window based on the PRACH configuration information.

[0083] S25: The user equipment receives the RAR for the preamble sequence from the target cell based on the first RAR listening window, and performs the corresponding operation according to the random access type when the RAR is received.

[0084] In other words, this embodiment will still receive and decode the master information block, but will further determine whether the current system frame that first sends the preamble sequence meets the parity requirements of the PRACH configuration information. If it does, there is no need to send the preamble sequence again, thereby saving transmission resources. The fifth and fourth RAR listening windows can be completely identical to the aforementioned third and second RAR listening windows; for example, their start and end times can be exactly the same.

[0085] This application embodiment also provides a storage medium storing a random access program, which is essentially a computer program, and when executed by a processor, the random access program implements the steps of the random access method based on cell handover in any of the foregoing examples.

[0086] The storage medium includes, but is not limited to, any one of read-only memory (ROM), random access memory (RAM), magnetic disk, and optical disk.

[0087] Since the program stored in the storage medium can execute the steps in the random access method based on cell handover provided in any embodiment of this application, it can achieve the beneficial effects that the method of any of the foregoing embodiments can achieve, as detailed in the foregoing embodiments, which will not be repeated here.

[0088] This application also provides a user equipment or chip, including a memory and a processor. The memory stores a random access program, which, when executed by the processor, implements the steps of the random access method based on cell handover in any of the foregoing embodiments; and / or, the user equipment or chip is provided with a storage medium as shown in the above example, and the processor loads the storage medium to execute the steps of the method, thereby achieving the beneficial effects that the random access method based on cell handover in the corresponding embodiment can achieve.

[0089] Figure 6 This is a schematic diagram of the structure of a user equipment provided in an embodiment of this application. For example... Figure 6 As shown, the user equipment 60 includes: The parsing module 61 is used to parse the PRACH configuration information of the target cell from the handover command received from the source cell indicating a handover to the target cell. Synchronization module 62 is used to detect synchronization signals and complete cell synchronization based on the synchronization signals; Transmitting module 63 is configured to transmit a preamble sequence in response to the completion of cell synchronization and immediately according to the frame number in the PRACH configuration information; Setting module 64 is used to set the first RAR listening window based on the PRACH configuration information; The receiving module 65 is configured to receive RAR for the preamble sequence from the target cell based on the first RAR listening window; The random access module 66 is used to perform corresponding operations according to the random access type when the RAR is received.

[0090] Through the cooperation of the above modules, random access based on cell handover can be completed.

[0091] It should be understood that the various modules of the user equipment 60 described above can be represented as physical devices or virtual modules (i.e., commonly referred to as logical modules) in actual scenarios. A single module can be implemented by a single physical device or by two or more physical devices working together. Similarly, the function performed by a single module can be implemented by a single physical device or by two or more physical devices working together. Furthermore, the functions corresponding to each module can be implemented by the corresponding steps of the random access method based on cell handover in any of the foregoing embodiments.

[0092] The above are only some embodiments of this application and do not limit the patent scope of this application. For those skilled in the art, any equivalent structural transformations made using the content of this specification and drawings are similarly included within the patent protection scope of this application.

[0093] The use of step designations such as S11 and S12 in this document is intended to more clearly and concisely describe the corresponding content and does not constitute a substantial restriction on the order. In specific implementation, those skilled in the art may execute S12 first and then S11, etc., but these should all be within the protection scope of this application.

[0094] Although this document uses terms such as "first," "second," etc., to describe various types of information, this information should not be limited to these terms. These terms are only used to distinguish information of the same type from one another. Furthermore, the singular forms "a," "an," and "the" are intended to also include the plural forms. The terms "or" and "and / or" are interpreted as inclusive, or meaning either one or any combination thereof. Exceptions to this definition only arise when combinations of elements, functions, steps, or operations are inherently mutually exclusive in some way.

Claims

1. A cell change based random access method, characterized by, include: In response to receiving a handover command from the source cell indicating a handover to the target cell, the user equipment parses the handover command to obtain PRACH configuration information about the target cell; The user equipment detects the synchronization signal and completes cell synchronization based on the synchronization signal; In response to the completion of cell synchronization, the user equipment sends a preamble sequence according to the frame number in the PRACH configuration information; The user equipment sets a first RAR listening window based on the PRACH configuration information; The user equipment receives the RAR for the preamble sequence from the target cell based on the first RAR listening window, and performs the corresponding operation according to the random access type when it receives the RAR.

2. The method of claim 1, wherein, The user equipment sends a preamble sequence according to the frame number in the PRACH configuration information, including: The user equipment sends a preamble sequence for the first time in the current system frame; The user equipment transmits the preamble sequence for the second time in the next system frame.

3. The method of claim 2, wherein, The method further includes: In response to completing cell synchronization, the user equipment scans the physical broadcast channel of the target cell and performs a decoding process to obtain the master information block from the physical broadcast channel; and, Determine whether the main information block has been successfully decoded; If so, based on the PRACH configuration information and the parity identifier of the decoded system frame number, the corresponding physical random access channel is selected to send the preamble sequence only once; In addition, a second RAR listening window is set, the second RAR listening window has a first duration, and the start time is the time when the preamble sequence is sent; The user equipment receives the RAR for the preamble sequence from the target cell based on the second RAR listening window, and performs the corresponding operation according to the random access type when the RAR is received; If not, then the user equipment shall perform the step of sending the preamble sequence for the second time in the next system frame.

4. The method according to claim 2, characterized in that, The method further includes: In response to completing cell synchronization, the user equipment scans the physical broadcast channel of the target cell and performs a decoding process to obtain the master information block from the physical broadcast channel; and, After the user equipment transmits the preamble sequence for the second time in the next system frame, the method further includes: Determine whether the main information block has been successfully decoded; If so, based on the PRACH configuration information and the parity identifier of the decoded system frame number, the corresponding physical random access channel is selected to send the preamble sequence only once; In addition, a third RAR listening window is set, the third RAR listening window having a first duration, and the start time being the time when the preamble sequence is sent; The user equipment receives the RAR for the preamble sequence from the target cell based on the third RAR listening window, and performs the corresponding operation according to the random access type when the RAR is received; If not, then the user equipment shall perform the step of setting the first RAR listening window based on the PRACH configuration information.

5. The method according to claim 2, characterized in that, The method further includes: In response to completing cell synchronization, the user equipment scans the physical broadcast channel of the target cell and performs a decoding process to obtain the master information block from the physical broadcast channel; and, After the user equipment sends the preamble sequence for the first time in the current system frame, it determines whether the main information block has been successfully decoded. If the main information block is successfully decoded, then based on the PRACH configuration information and the parity identifier of the decoded system frame number, it is determined whether the current system frame for executing the first transmission preamble sequence meets the parity requirement. If the conditions are met, a fourth RAR listening window is set. The fourth RAR listening window has a first duration and is started at the moment when the preamble sequence is first sent. The user equipment receives the RAR for the preamble sequence from the target cell based on the fourth RAR listening window and performs the corresponding operation according to the random access type when the RAR is received. If not, based on the PRACH configuration information and the parity identifier of the decoded system frame number, the corresponding physical random access channel is selected to send the preamble sequence only once; and a fifth RAR listening window is set, the fifth RAR listening window having a first duration and starting at the time of sending the preamble sequence; the user equipment receives the RAR for the preamble sequence from the target cell based on the fifth RAR listening window, and performs the corresponding operation according to the random access type when the RAR is received; If the main information block is not successfully decoded, the user equipment shall execute the step of sending the preamble sequence for the second time in the next system frame.

6. The method according to any one of claims 2 to 5, characterized in that, The user equipment sets a first RAR listening window based on the PRACH configuration information, including: The user equipment obtains a second duration of the interval between the current system frame and the next system frame based on the PRACH configuration information; The moment when the preamble sequence is first sent is taken as the start time of the first RAR listening window, and the first RAR listening window is set to have a third duration, wherein the difference between the third duration and the first duration is at least equal to the second duration.

7. The method according to claim 6, characterized in that, The first RAR monitoring window is a continuous and complete time period used for monitoring RARs; Alternatively, the first RAR monitoring window may include a first sub-window and a second sub-window, with one of the first sub-window and the second sub-window covering the time period corresponding to the second duration.

8. The method according to claim 6, characterized in that, The second duration is 10 milliseconds.

9. A user equipment, characterized in that, The user equipment includes a processor and a memory, the memory storing a random access program, which, when executed by the processor, implements the steps of the random access method based on cell handover as described in any one of claims 1 to 8.

10. A storage medium, characterized in that, The device contains a computer program that, when executed by a processor, implements the steps of the method as described in any one of claims 1 to 8.

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