Neighbor cell measurement method for time asynchronous network

Abstract

The invention discloses a neighbor cell measurement method for a time asynchronous network, which comprises the following steps: determining a first batch of measurement interval configuration containing M groups of measurement interval parameters based on the period of a synchronization signal block SSB of a target neighbor cell, each group of parameters defining different measurement start offsets, the M groups of measurement start offsets being continuously distributed in time, the total time span at least covers one complete SSB period so as to ensure that the actual sending window of the target neighbor SSB is covered; issuing a first batch of measurement interval configuration to the terminal, and receiving a measurement report reported by the terminal based on the first batch of measurement interval configuration; according to the measurement report, screening out N groups of measurement interval parameters from the first batch of measurement interval configuration to form a second batch of measurement interval configuration; and performing subsequent neighbor cell measurement and mobility management by using the second batch of measurement interval configuration. According to the invention, the neighbor cell measurement and the neighbor cell discovery of the time-asynchronous network can be realized, so that the service quality of the time-asynchronous network is effectively guaranteed.

Description

Technical Field

[0001] This invention relates to the field of communication technology, and in particular to a method for measuring neighboring cells in a time-asynchronous network. Background Technology

[0002] In the mobile communication standards defined by the 3rd Generation Partnership Project (3GPP), both fifth-generation (5G) and fourth-generation (4G) rely on time synchronization networks for normal operation. Each base station receives signals from the Global Positioning System (GPS) or a high-precision time source (such as the BeiDou satellite system) to generate synchronized frame boundaries and system frame numbers (SFNs), thereby ensuring time alignment between nodes within the network and providing a timing basis for critical processes such as cell search, signal measurement, and mobility management.

[0003] In 4G networks, mobility management mechanisms are relatively mature, divided into intra-frequency and inter-frequency scenarios. When a terminal hands over between intra-frequency cells, it can directly use the received signal of the current operating frequency to perform neighbor cell measurements without introducing a measurement gap. However, in inter-frequency handover scenarios, the network needs to configure a dedicated measurement gap for the terminal, enabling it to suspend communication on the current frequency and instead detect the synchronization signal of the target inter-frequency cell. Since the primary synchronization signal (PSS) and secondary synchronization signal (SSS) of the 4G system are periodically transmitted within each radio frame, their detection windows are relatively dense. Therefore, even when the network time is not synchronized (i.e., there is a timing deviation between base stations), the terminal can almost always capture and detect the PSS / SSS of neighboring cells within a standard measurement gap (e.g., 6ms), thus completing cell identification and measurement and ensuring the reliability of mobility within the system.

[0004] However, to optimize system overhead and adapt to more flexible deployment scenarios, 5G New Radio (NR) has changed the transmission method of the Synchronization Signal Block (SSB), which carries basic cell information. Unlike the relatively fixed period and position in 4G, the SSB in 5G NR (carrying the primary synchronization signal, secondary synchronization signal, and physical broadcast channel) supports a series of configurable parameters and flexible periods (such as 5ms, 10ms, 20ms, 40ms, 80ms, 160ms) and concentrated bursts within a period. For example, when the SSB period is configured to 20ms, its actual transmission may be concentrated in the first 5ms of a period (i.e., the SSB burst window), with no transmission in the remaining 15ms. This design saves air interface resources but also imposes stricter timing requirements on neighbor cell measurements.

[0005] In time-asynchronous networks (i.e., where there is a time lag between base stations), the sparsity and uncertainty of SSB transmissions can cause serious mobility problems due to the unknown timing discrepancies between the serving base station and neighboring base stations. 1. Inter-frequency handover failure in 5G system: The measurement interval configured by the network for the terminal (e.g., the standard 6ms gap) is determined based on the timing of the serving cell. Due to the time difference between the target cell and the serving cell, its SSB transmission window (e.g., the first 5ms) may fall completely outside the active period of the terminal's measurement interval, causing the terminal to be unable to detect the target SSB throughout the entire gap, thus failing to complete the necessary measurements and reporting, resulting in the failure of the inter-frequency handover process.

[0006] 2. Failure of inter-system handover from 4G to 5G: When a terminal moves from a 4G network to a 5G network, the inter-system measurement interval sent by the 4G network side is also based on the timing of the 4G base station. Due to the possible timing deviation between the SSB transmission window of the 5G NR cell and the 4G measurement interval, the SSB burst sets of 5G neighboring cells are easily missed, causing the terminal to be unable to discover and measure 5G neighboring cells, thus hindering the normal handover from 4G to 5G.

[0007] In summary, existing methods cannot effectively adapt to the uncertainty of the target cell's SSB transmission window in asynchronous scenarios, leading to the risk of failure during inter-frequency handover within 5G systems and inter-system handover from 4G to 5G, severely impacting user experience and network performance continuity. Therefore, there is an urgent need for a method that can overcome the impact of time asynchrony and ensure reliable neighbor cell measurements in the aforementioned scenarios. Summary of the Invention

[0008] The present invention aims to at least solve one of the technical problems existing in the prior art. To this end, the present invention proposes a neighbor cell measurement method for time-asynchronous networks.

[0009] A neighbor cell measurement method for a time-disconnected network according to an embodiment of the present invention includes: S1. Based on the period of the synchronization signal block (SSB) of the target neighboring cell, determine the first batch of measurement interval configuration; wherein, the first batch of measurement interval configuration includes M sets of measurement interval parameters, each set of parameters defines a different measurement start offset, the M sets of measurement start offsets are continuously distributed in time, and their total time span covers at least one complete SSB period to ensure coverage of the actual transmission window of the target neighboring cell's SSB. S2. Send the first batch of measurement interval configuration to the terminal and receive the measurement report reported by the terminal based on it; S3. Based on the measurement report, select N sets of measurement interval parameters from the first batch of measurement interval configurations to form the second batch of measurement interval configurations, where N is a positive integer less than or equal to M; S4. Use the second batch of measurement interval configuration for subsequent neighbor cell measurements and mobility management.

[0010] According to the neighbor cell measurement method for time-asynchronous networks of the present invention, the time difference between base stations is roughly compensated by configuring the first batch of measurement intervals, and then the neighbor cell measurement and neighbor cell discovery are realized by configuring and traversing the second batch of measurement intervals. It can be applied to scenarios such as 5G inter-frequency mobility and 4G to 5G inter-system mobility, 5G ANR of 4G system, and 5G inter-frequency ANR of 5G system, and can effectively guarantee the quality of service of time-asynchronous networks.

[0011] In some embodiments of the present invention, the value of M in step S1 is obtained by dividing the period of the SSB by the maximum duration of the SSB burst set.

[0012] In some embodiments of the present invention, the maximum duration of the SSB burst set is 5 ms, and the M group measurement start offset is set at 5 ms intervals.

[0013] In some embodiments of the present invention, step S3, which involves selecting N groups based on the measurement report, includes: An evaluation value is calculated for each set of measurement interval parameters, the evaluation value being based on the neighbor cell signal quality and / or the number of neighbor cells discovered after the terminal uses the set of parameters for measurement; Based on the evaluation values, select the top N sets of measurement interval parameters from highest to lowest.

[0014] In some embodiments of the present invention, the evaluation value is preferentially based on the highest reported neighbor cell reference signal received power (RSRP); when different groups have the same highest RSRP, the selection is based on the number of physical cell identifiers (PCIs) reported by that group, with the group having the most PCIs taking precedence.

[0015] In some embodiments of the present invention, the method is applied to inter-frequency handover scenarios within a 5G system, or inter-system redirection / handover scenarios from a 4G system to a 5G system.

[0016] The present invention also discloses a network-side device for neighbor cell measurement in a time-asynchronous network. The device includes a processor and a memory, the memory storing a computer program that, when executed by the processor, implements the steps of the above method.

[0017] The present invention also discloses a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the steps of the above-described method. Attached Figure Description

[0018] Figure 1 This is a flowchart of the neighbor cell measurement method for time-asynchronous networks of the present invention; Figure 2 This is a schematic diagram of the measurement interval grouping of the present invention. Detailed Implementation

[0019] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0020] To facilitate understanding, before introducing the embodiments of this disclosure, several terms involved in the embodiments of this disclosure will be explained as follows: PSS: Primary Synchronization Signal, is a key signal used for physical layer synchronization in a communication system. It undertakes the initial cell search and time and frequency synchronization functions of terminal equipment and is mainly used to transmit the group ID, i.e., the N(2)_ID value. SSS: Secondary Synchronization Signal, is a secondary synchronization signal used for physical layer synchronization in a communication system. Its main function is to transmit the group ID information N(1)_ID of the physical cell ID (PCI).

[0021] It's important to note that in most cases, both 4G and 5G networks use external GPS antennas, and the GPS signal is normal, making the network a time-synchronized network. However, in some special scenarios, such as private network environments where equipment lacks GPS antennas or GPS signals (e.g., indoors, basements, or remote areas), 4G and 5G devices cannot synchronize their time. In time-asynchronous networks, each base station operates in a non-synchronous freerun state, meaning each base station uses its own independent, deviated clock. This results in an unknown but fixed time difference between base stations. This time difference renders the effective, serving cell-based measurement interval mechanism in synchronous networks ineffective, failing to capture neighboring cell signals. Consequently, processes such as automatic neighbor cell discovery, inter-system handover, and inter-frequency handover behind the 5G or 4G protocol stack cannot proceed normally, severely impacting user experience and network performance continuity.

[0022] Based on this, the present invention provides a neighbor cell measurement method for time-asynchronous networks, referring to... Figures 1-2 The method includes...

[0023] S1. Based on the period of the synchronization signal block (SSB) of the target neighboring cell, determine the first batch of measurement interval configuration; wherein, the first batch of measurement interval configuration includes M sets of measurement interval parameters, each set of parameters defines a different measurement start offset, the M sets of measurement start offsets are continuously distributed in time, and their total time span covers at least one complete SSB period to ensure coverage of the actual transmission window of the target neighboring cell's SSB. S2. Send the first batch of measurement interval configurations to the terminal and receive the measurement reports reported by the terminal based on these configurations. S3. Based on the measurement report, select N sets of measurement interval parameters from the first batch of measurement interval configurations to form the second batch of measurement interval configurations, where N is a positive integer less than or equal to M. S4. Use the second batch of measurement interval configuration for subsequent neighbor cell measurements and mobility management.

[0024] Understandably, in time-asynchronous networks, the time difference between base stations is fixed. By using a batch-based method to distribute measurement intervals, the time difference between base stations is roughly compensated through the first batch of measurement interval configurations. Then, through the selection and traversal of the second batch of measurement interval configurations, neighbor cell measurement and discovery in time-asynchronous networks can be achieved. Specifically: First, the first batch of measurement interval configurations is determined based on the period of the Synchronization Signal Block (SSB) of the target neighboring cells. For example, the measurement interval period can be any of 1.5ms, 3ms, 3.5ms, 4ms, 5.5ms, or 6ms, and the number of packets M to be sent is determined according to the measurement interval period. The first batch of measurement interval configurations roughly compensates for the time difference by adjusting the starting position of the gap (i.e., the measurement interval, the same below), which requires multiple gaps to cover the complete SSB period. If the SSB period is long, more gaps are needed, and each time a gap is changed, the configuration signaling needs to be resent for it to take effect. Multiple gaps can easily cause the neighboring cell discovery and measurement time to be extended and the radio resource overhead to be large. In other words, the smaller the measurement interval period, the more packets are sent. Therefore, in order to reduce the number of packets sent in the measurement interval, the maximum measurement interval period of 6ms can be selected. Assuming the SSB period is 20ms, then M=4 measurement intervals are selected, namely: the first group gapoffset 0, the second group gapoffset 5, the third group gapoffset 10, and the fourth group gapoffset 15. The total span of these four measurement intervals is 21ms, which covers the 20ms of the complete SSB cycle.

[0025] Next, the first batch of measurement interval configurations is sent to the terminals, and measurement reports reported by the terminals based on these configurations are received. For example, as long as there are neighboring cells nearby, a measurement report can be reported through one of the four groups mentioned above. The measurement report can reveal information about the neighboring cells, thus determining that the measurement interval configuration of the corresponding group can compensate for the time difference, and this configuration can be used to discover neighboring cells.

[0026] Based on the reported measurement reports, measurement interval groups are selected from the above 4 groups. Assuming the target interval measurement is N groups, if M is less than N, then no selection is needed. Therefore, N should be a positive integer less than or equal to M. The N groups of measurement intervals constitute the second batch of measurement interval configuration.

[0027] Finally, the second batch of measurement interval configurations is used for subsequent neighbor cell measurements and mobility management.

[0028] In some embodiments of the present invention, the value of M in step S1 is obtained by dividing the period of the SSB by the maximum duration of the SSB burst set.

[0029] In some embodiments of the present invention, the maximum duration of the SSB burst set is 5 ms, and the start offset of the M group measurements is set at 5 ms intervals.

[0030] In some embodiments of the present invention, step S3, which involves selecting N groups based on the measurement report, includes: Calculate an evaluation value for each set of measurement interval parameters. The evaluation value is based on the neighbor cell signal quality and / or the number of neighbor cells discovered after the terminal uses the set of parameters to measure. Based on the evaluation values, select the top N sets of measurement interval parameters from highest to lowest.

[0031] Specifically, an evaluation value based on the neighbor cell signal quality and / or the number of neighbor cells discovered can be set for each group of measurement interval parameters. The top N groups with the highest to lowest evaluation values ​​are selected from the M measurement interval parameters, and the selected N groups are used as the second batch of measurement interval configurations.

[0032] In some embodiments of the present invention, the evaluation value is preferentially based on the highest reported neighbor cell reference signal received power (RSRP); when different groups have the same highest RSRP, the selection is based on the number of physical cell identifiers (PCIs) reported by that group, with the group having the most PCIs taking precedence.

[0033] Specifically, selection can be made according to the following principles: a. Select the neighboring cell signal quality with the highest quality from the reported measurement reports in the gap group and use it as the RSRP of that gap group; b. Gap groups are sorted by RSRP, and the top N groups are selected as the target gap. If the RSRP is the same, the gap group with more PCIs in the measurement report is selected.

[0034] In some embodiments of the present invention, the method can be applied to inter-frequency handover scenarios within a 5G system, or inter-system redirection / handover scenarios from a 4G system to a 5G system.

[0035] Example 1 Scenario: 5G inter-frequency switching The normal procedure for inter-frequency handover within a 5G system is as follows: 1) The terminal accesses the cell from frequency point A; 2) The base station sends the A2 measurement configuration to the terminal; 3) When the terminal moves to the edge of the cell, if the signal quality is lower than the A2 threshold, report an A2 measurement report; 4) After receiving the A2 measurement report, the base station sends out the frequency point B measurement configuration and gap; 5) During the gap period, the terminal measures neighboring cells on frequency point B. Cells that meet the measurement conditions are reported to the base station through a measurement report. 6) The base station makes a handover decision based on the measurement report and switches the terminal to the cell on frequency point B.

[0036] It should be noted that if the time of this cell is not synchronized with that of other frequency cells in the above handover process, the measurement gap issued by this cell cannot be aligned with the SSB of the neighboring cell according to the existing method, and therefore the neighboring cell cannot be measured, and the terminal cannot perform inter-frequency handover normally.

[0037] Using the method of this invention, when configuring the first batch of measurement intervals to cover the SSB cycle, in step 4), assuming that the frequency point B measurement configuration and gap are sent out during an SSB cycle of 20ms, the gapoffset parameter of the gap in the 5G reconfiguration signaling is divided into 4 groups, namely (0, 5, 10, 15), and the measurement interval mgl parameter of the gap is set to ms6, corresponding to 6ms. Initially, gapoffset0 is selected for sending, and the terminal uses this gap to measure neighboring cells and report the measurement report to the base station; after 5s, gapoffset 5 is selected for sending, and the terminal uses this gap to measure neighboring cells and report the measurement report to the base station; after 10s, gapoffset 10 is selected for sending, and the terminal uses this gap to measure neighboring cells and report the measurement report to the base station; after 15s, gapoffset 15 is selected for sending, and the terminal uses this gap to measure neighboring cells and report the measurement report to the base station.

[0038] Assuming N=1, and among the above 4 groups, gapoffset 10 reports the highest neighboring cell RSRP, then gapoffset10 is selected as the gap configuration for inter-frequency handover of this base station.

[0039] Assuming N=2, among the above 4 groups, gapoffset 5 and gapoffset 15 report the same and highest neighboring cell RSRP, while configuration group 5 reports more Physical Cell Identifiers (PCIs). Therefore, gapoffset 5 is selected as the gap configuration for inter-frequency handover of this base station.

[0040] Therefore, the method of this invention can be used to complete the handover of 5G inter-frequency neighbor cells in time-asynchronous networks, and a set of gap configurations with optimal performance has been selected.

[0041] Example 2 Scenario: 4G to 5G inter-system mobility, including inter-system redirection and inter-system handover. In a 4G to 5G cross-system mobility scenario, the normal process is as follows: 1) The terminal accesses a 4G cell; 2) The base station sends the A2 measurement configuration to the terminal; 3) When the terminal moves to the edge of the cell, if the signal quality is lower than the A2 threshold, report an A2 measurement report; 4) After receiving the A2 measurement report, the base station issues the 5G inter-system measurement configuration and gap; 5) During the gap period, the terminal measures neighboring cells on different 5G systems. Cells that meet the measurement conditions are reported to the base station through a measurement report. 6) Based on the measurement report, the base station makes a handover decision or a redirection decision, and switches or redirects the terminal to the 5G cell.

[0042] It should be noted that if the time of this cell is not synchronized with other frequency cells in the above process, the measurement gap issued by the 4G cell in the current way cannot be aligned with the SSB of the neighboring cell, and therefore the neighboring cell cannot be measured, and the terminal cannot perform inter-system movement normally.

[0043] When the timing is out of sync, using the method of this invention, when configuring the first batch of measurement intervals to cover the SSB cycle, in step 4), assuming that the 5G measurement configuration and gap are sent out every 20ms of the 5G SSB cycle, the gapgp0 or gp1 parameters in the 4G reconfiguration signaling are divided into 4 groups, configured as (0, 5, 10, 15), and the measurement interval of the 4G gap is fixed at 6ms. Initially, configuration 0 is selected for sending, and the terminal uses this gap to measure neighboring cells and report the measurement to the base station; after 5s, configuration 5 is selected for sending, after 10s, configuration 10 is selected for sending, and so on.

[0044] Assuming N=1, among the above 4 groups, configuration 15 reports the highest neighbor cell RSRP, so configuration 15 is selected as the gap configuration for inter-frequency handover of this base station.

[0045] Assuming N=2, among the above 4 groups, configuration 10 and configuration 15 report the same and highest neighbor cell RSRP, while configuration 10 reports more physical cell identifiers (PCIs). Therefore, configuration 10 is selected as the gap configuration for inter-frequency handover of this base station.

[0046] Therefore, by using the method of the present invention, 4G to 5G inter-system handover or inter-system redirection can be completed in time-asynchronous networks, and a set of gap configurations with optimal performance is selected.

[0047] Example 3 Scenario: 5G ANR process, including automatic addition of 5G neighbor cells in 4G and automatic addition of inter-frequency neighbor cells in 5G.

[0048] It should be noted that ANR, as a key technology of SON functionality, enables self-configuration and self-optimization of neighbor cell relationships, reducing the workload of neighbor cell optimization and lowering network construction and operating costs. Neighbor cell relationship configuration is a key focus of daily optimization work, impacting the overall network performance metrics. Its main advantages include: reducing unnecessary handovers, minimizing dropped calls caused by missing or incorrectly defined neighbor cells, improving throughput, balancing service load, and enhancing measurement quality.

[0049] Enabling the ANR (Automatic No-Network Registry) function can automatically detect missing neighbor cells, enabling the terminal to smoothly switch to the target neighbor cell of the missing neighbor cell in the original system, and automatically add the missing neighbor cell to the neighbor cell list. The principle is as follows: 1) Issue event measurement configuration; 2) Submit a measurement report, including the neighboring cell PCI and signal strength; 3) CGI measurement configuration, instructing the terminal to read the CGI information of the neighboring cell corresponding to this PCI; 4) Report information such as the CGI and Tracking Area Code (TAC) of neighboring cells, and the serving cell can add them to the neighboring cell relationship table.

[0050] However, for the 5G neighbor cell addition function of 4G base stations, the problem of not being able to detect neighbor cells also exists in time-asynchronous networks. Based on the method of this invention, the first batch of measurement interval configurations for 4G base stations can be configured to cover the 5GSSB cycle, as described in Embodiment 2. Then, the second batch of measurement interval configurations can be selected, choosing the gap combination with the best neighbor cell measurement quality.

[0051] Similarly, 5G base stations in time-asynchronous networks also face the problem of not being able to detect neighboring cells. As per the example, the first batch of measurement interval configurations for 5G base stations can be configured to cover the 5G inter-frequency SSB cycle, and then the second batch of measurement interval configurations can be selected, choosing the gap combination with the best neighboring cell measurement quality.

[0052] In summary, the neighbor cell measurement method for time-asynchronous networks according to embodiments of the present invention roughly compensates for the time difference between base stations by configuring the first batch of measurement intervals, and then selects and traverses the second batch of measurement intervals, thereby realizing neighbor cell measurement and neighbor cell discovery for time-asynchronous networks. It can be applied to scenarios such as 5G inter-frequency mobility and 4G to 5G inter-system mobility, 5G ANR for 4G systems, and 5G inter-frequency ANR for 5G systems, and can effectively guarantee the quality of service for time-asynchronous networks.

[0053] The present invention also discloses a network-side device for neighbor cell measurement in a time-asynchronous network. The device includes a processor and a memory, the memory storing a computer program that, when executed by the processor, implements the steps of the above method.

[0054] The present invention also discloses a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the steps of the above-described method.

[0055] Although embodiments of the invention have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.

Claims

1. A method of measuring a neighbor cell of a time-asynchronous network, the method comprising: The method comprises: S1. determining a first batch of measurement interval configurations based on a periodicity of synchronization signal blocks (SSBs) of a target neighbor cell; wherein the first batch of measurement interval configurations comprises M groups of measurement interval parameters, each group of parameters defining a different measurement starting offset, and the M groups of measurement starting offsets are distributed continuously in time with a total time span covering at least one complete SSB period to ensure covering an actual transmission window of SSBs of the target neighbor cell; S2. issuing the first batch of measurement interval configurations to a terminal and receiving a measurement report reported by the terminal based on the first batch of measurement interval configurations; S3. selecting N groups of measurement interval parameters from the first batch of measurement interval configurations based on the measurement report to form a second batch of measurement interval configurations, wherein N is a positive integer less than or equal to M; S4. using the second batch of measurement interval configurations for subsequent neighbor cell measurement and mobility management.

2. The method of claim 1, wherein, The value of M in step S1 is obtained by dividing the periodicity of the SSBs by the maximum duration of an SSB burst set.

3. The method of claim 2, wherein, The maximum duration of the SSB burst set is 5 ms, and the M groups of measurement starting offsets are set at intervals of 5 ms.

4. The method of claim 1, wherein, In step S3, the N groups are selected based on the measurement report as follows: an evaluation value is calculated for each group of measurement interval parameters, and the evaluation value is based on a neighbor cell signal quality reported by the terminal after using the group of parameters for measurement and / or a number of neighbor cells discovered; the first N groups of measurement interval parameters are selected in descending order of the evaluation values.

5. The method of claim 4, wherein, The evaluation value is preferentially based on a highest value of a reported reference signal received power (RSRP) of a neighbor cell; when the highest RSRP of different groups is the same, the number of physical cell identifiers (PCIs) reported by the group is used for selection, and the group with a larger number of PCIs is preferred.

6. The method of claim 1, wherein, The method is applied to an inter-frequency handover scenario in a 5G system or an inter-system redirection / handover scenario from a 4G system to a 5G system.

7. A network-side device for neighbor cell measurement in a time-asynchronous network, the device comprising: The device comprises a processor and a memory, and the memory stores a computer program which, when executed by the processor, implements the steps of the method of any one of claims 1 to 6.

8. A computer-readable storage medium, characterized in that, The computer program stored on the memory, when executed by the processor, implements the steps of the method of any one of claims 1 to 6.

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