Intra-cell multi-ru coverage mobile scenario uplink synchronization system

Abstract

The embodiment of the application discloses a cell multi-RU coverage mobile scene uplink synchronization system and method, the system comprises a terminal, a room split high-power base station and an RU, the room split high-power base station first calculates a cell coverage range, calculates a TA range according to the cell coverage range, then judges whether the TA range exceeds a CP, if yes, the physical layer receiving window of the base station is expanded, and a service channel TA value is measured, if the TA value exceeds a preset threshold X, it is considered that a coverage area switching is detected, the TA value is not smoothed in history, directly replaces the historical value and is issued to the terminal, and the terminal adjusts its uplink transmission timing according to the TA value received from the room split high-power base station. The application can effectively avoid the problem of service quality decline caused by the uplink TA dramatic change, and ensure that the user obtains seamless high-speed mobile experience in the large room split scene.

Description

Technical Field

[0001] This invention relates to the field of communication technology, and in particular to an uplink synchronization system and method for mobile scenarios with multiple RU coverage within a cell. Background Technology

[0002] As 3GPP standards gain increasing influence in the telecommunications industry, more and more successful commercial 4G and 5G products are emerging in the market. 4G and 5G base station technologies are becoming increasingly mature and diverse. From the traditional extensive coverage primarily using outdoor macro base stations, to the current indoor distributed antenna system (DAS) products supplementing insufficient indoor signal, and now to the refined and in-depth development of indoor DAS, which is gradually becoming on par with outdoor coverage. Outdoor macro base stations are characterized by high power and wide coverage, but lack penetration and suffer from significant signal attenuation through walls. Indoor small DAS base stations precisely address the pain points of indoor coverage, achieving significant improvements in service quality in indoor scenarios such as offices and homes with minimal effort, but they have lower power and a smaller coverage area.

[0003] High-power indoor distributed base station products can effectively combine the advantages of macro base stations and indoor distributed base stations while overcoming their disadvantages. They are widely used in indoor stadiums and multi-building coverage scenarios. As cell coverage is greatly expanded through EU and high-power RU, uplink TA maintenance becomes more complex.

[0004] When a user is located at the coverage boundary of two different high-power RUs in the same cell, the TA value may change abruptly, and traditional smoothing filtering is no longer applicable. Summary of the Invention

[0005] The technical problem to be solved by the embodiments of the present invention is to provide an uplink synchronization system and method for mobile scenarios with multiple RU coverage within a cell, so as to ensure service quality and continuity and avoid packet loss and call drops due to drastic changes in uplink TA.

[0006] To address the aforementioned technical issues, this invention proposes an uplink synchronization system for mobile scenarios with multiple RU coverage within a cell, comprising a terminal, an indoor high-power base station, and multiple RUs. The indoor high-power base station first calculates the cell coverage area, then calculates the TA range based on the cell coverage area, and then determines whether the TA range exceeds the CP. If it does, the physical layer receiving window of the base station is expanded, and the service channel TA value is measured. If the TA value exceeds a preset threshold X, it is considered that a coverage area handover has been detected. This TA value is not subject to historical smoothing and directly replaces the historical value and is sent to the terminal.

[0007] The terminal adjusts its uplink transmission timing based on the TA value received from the indoor high-power base station.

[0008] Accordingly, embodiments of the present invention also provide an uplink synchronization method for mobile scenarios with multiple RU coverage within a cell, including:

[0009] Step 1: Calculate the cell coverage area for indoor high-power base stations;

[0010] Step 2: Calculate the TA range for indoor high-power base stations based on the cell coverage area;

[0011] Step 3: The indoor high-power base station determines whether the TA range exceeds the CP. If it does, the base station physical layer receive window is expanded and the service channel TA value is measured.

[0012] Step 4: If the TA value exceeds the preset threshold X, the indoor high-power base station considers that a coverage area handover has been detected. The TA value will not be smoothed according to history, but will directly replace the historical value and be sent to the terminal.

[0013] Step 5: The terminal adjusts its uplink transmission timing based on the TA value received from the indoor high-power base station.

[0014] The beneficial effects of this invention are: it has low cost and strong feasibility, and can effectively avoid the problem of service quality degradation caused by drastic changes in uplink TA, ensuring that users have a seamless high-speed mobile experience in large indoor distribution scenarios. Attached Figure Description

[0015] Figure 1 This is a flowchart illustrating the uplink synchronization method for mobile scenarios with multiple RU coverage within a cell, according to an embodiment of the present invention. Detailed Implementation

[0016] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0017] In this embodiment of the invention, directional indicators (such as up, down, left, right, front, back, etc.) are only used to explain the relative positional relationship and movement of each component in a specific posture (as shown in the figure). If the specific posture changes, the directional indicator will also change accordingly.

[0018] Furthermore, in this invention, descriptions involving "first," "second," etc., are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features.

[0019] The uplink synchronization system for mobile scenarios with multiple RU coverage within a cell, as described in this embodiment of the invention, includes a terminal, an indoor high-power base station, and multiple RUs. The indoor high-power base station may have multiple high-power RUs, each of which needs to independently calculate its coverage area. The coverage area of ​​the base station is the sum of the coverage areas of all its subordinate RUs.

[0020] The indoor high-power base station first calculates the cell coverage area, then calculates the TA range based on the cell coverage area, and then determines whether the TA range exceeds the CP. If it does, the physical layer receiving window of the base station is expanded, and the TA value of the service channel is measured. If the TA value exceeds a preset threshold X, it is considered that a coverage area handover has been detected. This TA value is not smoothed according to history, but directly replaces the historical value and is sent to the terminal. This invention adjusts the TA to ensure that the terminal is always within the original receiving window. CP (Cyclic Prefix) is a guard interval used in Orthogonal Frequency Division Multiplexing (OFDM) technology to eliminate inter-symbol interference and inter-carrier interference. It forms a cyclic structure by copying the tail data of each OFDM symbol to the symbol header, ensuring that the signal maintains orthogonality in a multipath propagation environment, thereby reducing interference and maintaining transmission reliability.

[0021] The terminal adjusts its uplink transmission timing based on the TA value received from the high-power indoor base station. The terminal's TA is adjusted via TA commands issued by the base station. Although the base station can estimate the TA by detecting the uplink signal, this estimation and command issuance process takes time. In high-speed mobile scenarios, the network may not be able to update the TA in time, and the terminal may still send data using the old TA value, causing the uplink signal to misalign with the base station's receiving window. When the TA measurement value changes beyond a threshold N, the current measurement value is no longer smoothed and filtered, but directly replaces the historical value. When the terminal moves from one RU coverage area to another, the TA change may exceed the CP, leading to uplink demodulation errors, loss of synchronization, and the UE service terminal re-accessing randomly. To avoid this situation, the present invention extends the uplink receiving window based on the coverage range of the high-power RU. The method of extending the receiving window in the present invention is to obtain the RU coverage range, calculate the possible range X of the timing advance, and then extend the original receiving window forward and backward by X. When the physical layer detects that the signal is received from the extended window, the physical layer reports the type of the extended window and the TA measurement value and instructs the MAC through the FAPI interface. The current measurement value is no longer subject to smoothing filtering, but directly replaces the historical value.

[0022] As one implementation method, the indoor high-power base station calculates the cell coverage area according to the following steps:

[0023] Suppose there are n RUs. Iterate through each RU from 1 to RUn in sequence to obtain the maximum and minimum coverage range of each RU. Calculate the maximum and minimum air interface transmission times of each RU. Use the minimum minimum air interface transmission time and the maximum maximum air interface transmission time among all RUs as the minimum and maximum values ​​of the cell coverage range.

[0024] The coverage area of ​​each RU needs to be converted into air interface transmission time. When a UE moves from one RU to another, the air interface transmission time will jump due to the different distances to the two RUs. This step only calculates the maximum and minimum air interface transmission times for each RU for subsequent steps. The calculation method for the maximum and minimum air interface transmission times of RU n is as follows:

[0025] The maximum and minimum coverage ranges of RU n are MaxCover m and MinCover m, respectively, and the maximum and minimum air interface transmission times are MaxCover*1 / c and MminCover*1 / c, respectively, where c is the speed of light.

[0026] The cell coverage area is min (minimum air interface transmission time for all RUs) and max (maximum air interface transmission time for all RUs).

[0027] As one implementation method, the TA range of an indoor high-power base station is calculated according to the following formula:

[0028] TA range = cell coverage area / TA duration.

[0029] Duration calculation for a single TA. According to the protocol, TA = Where u is the subcarrier spacing index, and the length of Tc is ,in Hz, .

[0030] As one implementation method, after detecting that the TA range exceeds the CP, the indoor high-power base station adds XX receiving windows sequentially before and after the original receiving window, where XX = ceiling (maximum cell coverage range - minimum cell coverage range) / CP duration; according to the protocol, the CP duration is calculated using the following formula:

[0031] ;

[0032] in, For CP duration, For the duration of a subframe, , , Hz, ; , , N f It is the 5G system FFT points, Δf max N is the maximum subcarrier spacing in a 5G system. f，ref It is the 4G system FFT points, Δf ref It is the subcarrier spacing of the 4G system, Tc It is the smallest unit of time in the 5G system, T s It is the smallest unit of time in the 4G system.

[0033] The calculation is based on the CP duration / TA duration, with the CP duration in units of TA. If the cell coverage area exceeds the CP, the terminal will experience TA hopping when moving between different RUs, degrading the PUSCH / PUCCH demodulation performance and potentially causing the channel to fail to demodulate. Upon detecting that the CP is exceeded, physical layer receive window expansion is performed. The number of receive windows is 2*XX = 2*ceiling((maximum cell coverage area - minimum cell coverage area) / CP duration) + 1. The receive windows are arranged with the original receive window as the base station, and XX receive windows added sequentially before and after it.

[0034] The present invention performs traffic channel TA measurement and receive window measurement according to the following steps:

[0035] 1) If the change value of TA in the original receiving window exceeds the threshold X, it is considered that a coverage area handover has been detected. In this case, the TA will not be smoothed according to history, but will directly replace the historical value and adjust the TA to ensure that the terminal is always within the original receiving window.

[0036] 2) If the signal strength is higher than the historical value within the original receiving window, but a CRC error occurs, it is considered that a coverage area handover has been detected and the uplink signal exceeds the original receiving window. The physical layer then performs channel demodulation within all extended receiving windows. If there is correctly demodulated data, the demodulation result, receiving window index, and TA measurement value within the receiving window are reported to the indoor high-power base station (i.e., MAC). Multiple Access Channel (MAC) is a communication channel type with multiple input signals and only one output signal, primarily used in cellular network uplink scenarios.

[0037] 3) The indoor high-power base station calculates the TA difference between the new coverage area and the original receiving window. The TA difference = TA value from the target receiving window to the original window + TA measurement value within the receiving window. The indoor high-power base station sends the TA difference to the terminal.

[0038] 4) The terminal performs TA adjustment so that the uplink signal of the terminal is located within the original receiving window under the new coverage RU.

[0039] In high-power indoor distributed base station scenarios, when a user moves between two RU coverage areas, the solution of this invention can ensure service quality and continuity, and avoid packet loss and dropped calls due to drastic changes in uplink TA.

[0040] Please refer to Figure 1 The uplink synchronization method for mobile scenarios with multiple RU coverage within a cell according to this embodiment of the invention includes steps 1 to 5.

[0041] Step 1: Calculate the cell coverage area for indoor high-power base stations.

[0042] Step 2: Calculate the TA range for indoor high-power base stations based on the cell coverage area.

[0043] Step 3: The indoor high-power base station determines whether the TA range exceeds the CP. If it does, the base station physical layer receive window is expanded, and the service channel TA value is measured.

[0044] Step 4: If the TA value exceeds the preset threshold X, the indoor high-power base station considers that a coverage area handover has been detected. The TA value will not be smoothed according to history, but will directly replace the historical value and be sent to the terminal.

[0045] Step 5: After receiving the TA value sent by the indoor high-power base station, the terminal adjusts its uplink transmission timing according to the instruction.

[0046] In one implementation method, in step 1, the indoor high-power base station calculates the cell coverage area according to the following steps:

[0047] Iterate through each RU in turn to obtain the maximum and minimum coverage range of each RU, calculate the maximum and minimum air interface transmission times of each RU, and take the minimum minimum air interface transmission time and the maximum maximum air interface transmission time of all RUs as the minimum and maximum values ​​of the cell coverage range.

[0048] As one implementation method, in step 2, the indoor high-power base station calculates the TA range according to the following formula:

[0049] TA range = cell coverage area / TA duration.

[0050] As one implementation method, in step 3, after the indoor high-power base station detects that the TA range exceeds the CP, it sequentially adds XX receiving windows before and after the original receiving window, where XX = ceiling (maximum cell coverage range - minimum cell coverage range) / CP duration; the CP duration is calculated according to the following formula:

[0051] ;

[0052] in, For CP duration, For the duration of a subframe, , , Hz, ; , , N f It is the 5G system FFT points, Δf max N is the maximum subcarrier spacing in a 5G system.f，ref It is the 4G system FFT points, Δf ref It is the subcarrier spacing of the 4G system, T c It is the smallest unit of time in the 5G system, T s It is the smallest unit of time in the 4G system.

[0053] In one implementation, in step 4, if the signal strength is higher than the historical value within the original receiving window, but there is a CRC error, it is considered that a coverage area handover has been detected and the uplink signal exceeds the original receiving window. Then, the base station physical layer performs channel demodulation in all extended receiving windows. If there is data that has been demodulated, the demodulation result, the receiving window index, and the TA measurement value within the receiving window are reported. The indoor high-power base station calculates the TA difference between the new coverage area and the original receiving window and sends the TA difference to the terminal. The TA difference is calculated as: TA value from the target receiving window to the original window + TA measurement value within the receiving window.

[0054] Example: Assume that the BBU supports one cell, and the BBU is cascaded with 4 EUs, each EU is cascaded with 8 high-power RUs, each high-power RU has a power of 5W, and the coverage range is 0-5km. Then the physical layer receiving window is extended by 34us on the original basis, and the TA change exceeds 5. It is considered to be in the coverage area of ​​another RU, and historical filtering is no longer performed. Instead, the historical value is directly replaced.

[0055] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art 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 appended claims and their equivalents.

Claims

1. A mobile scenario uplink synchronization system with multiple RUs covering a cell, comprising a terminal, an indoor high-power base station, and multiple RUs, characterized in that, The indoor high-power base station first calculates the cell coverage area, then calculates the TA range based on the cell coverage area, and then determines whether the TA range exceeds the cyclic prefix CP. If it exceeds the CP, the physical layer receiving window of the base station is expanded and the service channel TA value is measured. If the TA value exceeds the preset threshold X, it is considered that a coverage area handover has been detected. This TA value is not smoothed by history, but directly replaces the historical value and is sent to the terminal. The terminal adjusts its uplink transmission timing based on the TA value received from the indoor high-power base station.

2. The uplink synchronization system for mobile scenarios with multiple RU coverage within a cell as described in claim 1, characterized in that, Indoor high-power base stations calculate cell coverage area using the following steps: Iterate through each RU in turn to obtain the maximum and minimum coverage range of each RU, calculate the maximum and minimum air interface transmission times of each RU, and take the minimum minimum air interface transmission time and the maximum maximum air interface transmission time of all RUs as the minimum and maximum values ​​of the cell coverage range.

3. The uplink synchronization system for mobile scenarios with multiple RU coverage within a cell as described in claim 1, characterized in that, The TA range for indoor high-power base stations is calculated using the following formula: TA range = cell coverage area / TA duration.

4. The uplink synchronization system for mobile scenarios with multiple RU coverage within a cell as described in claim 1, characterized in that, When a high-power indoor distributed base station detects that the TA range exceeds the CP range, it sequentially adds XX receiving windows before and after the original receiving window, where XX = ceiling (maximum coverage area of ​​the cell - minimum coverage area of ​​the cell) / CP duration; the CP duration is calculated according to the following formula: ； in, For CP duration, , , , ; , , μ is the subcarrier spacing index, T s It is the smallest unit of time in the 4G system, T c It is the smallest time unit in the 5G system, Δf max N is the maximum subcarrier spacing in a 5G system. f For the 5G system FFT points, Δf ref It is the subcarrier spacing of the 4G system, N f，ref It refers to the FFT points of the 4G system.

5. The uplink synchronization system for mobile scenarios with multiple RU coverage within a cell as described in claim 1, characterized in that, If the signal strength is higher than the historical value within the original receiving window, but there is a CRC error, it is considered that a coverage area handover has been detected and the uplink signal exceeds the original receiving window. The base station physical layer then performs channel demodulation in all extended receiving windows. If there is data that has been demodulated, the demodulation result, the receiving window index, and the TA measurement value within the receiving window are reported. The indoor high-power base station calculates the TA difference between the new coverage area and the original receiving window and sends the TA difference to the terminal. The TA difference is calculated as: TA value from the target receiving window to the original window + TA measurement value within the receiving window.

6. A method for uplink synchronization in a mobile scenario with multiple RUs covering a cell, characterized in that, include: Step 1: Calculate the cell coverage area for indoor high-power base stations; Step 2: Calculate the TA range for indoor high-power base stations based on the cell coverage area; Step 3: The indoor high-power base station determines whether the TA range exceeds the CP. If it does, the base station physical layer receive window is expanded, and the service channel TA value is measured. Step 4: If the TA value exceeds the preset threshold X, the indoor high-power base station considers that a coverage area handover has been detected. The TA value will not be smoothed according to history, but will directly replace the historical value and be sent to the terminal. Step 5: The terminal adjusts its uplink transmission timing based on the TA value received from the indoor high-power base station.

7. The uplink synchronization method for mobile scenarios with multiple RU coverage within a cell as described in claim 6, characterized in that, In step 1, the indoor high-power base station calculates the cell coverage area according to the following steps: Iterate through each RU in turn to obtain the maximum and minimum coverage range of each RU, calculate the maximum and minimum air interface transmission times of each RU, and take the minimum minimum air interface transmission time and the maximum maximum air interface transmission time of all RUs as the minimum and maximum values ​​of the cell coverage range.

8. The uplink synchronization method for mobile scenarios with multiple RU coverage within a cell as described in claim 6, characterized in that, In step 2, the TA range of the indoor high-power base station is calculated according to the following formula: TA range = cell coverage area / TA duration.

9. The uplink synchronization method for mobile scenarios with multiple RU coverage within a cell as described in claim 6, characterized in that, In step 3, after the indoor high-power base station detects that the TA range exceeds the CP, it sequentially adds XX receiving windows before and after the original receiving window, where XX = ceiling (maximum cell coverage range - minimum cell coverage range) / CP duration; the CP duration is calculated according to the following formula: ； in, For CP duration, , , , ; , , μ is the subcarrier spacing index, T s It is the smallest unit of time in the 4G system, T c It is the smallest time unit in the 5G system, Δf max N is the maximum subcarrier spacing in a 5G system. f For the 5G system FFT points, Δf ref It is the subcarrier spacing of the 4G system, N f，ref It refers to the FFT points of the 4G system.

10. The uplink synchronization method for mobile scenarios with multiple RU coverage within a cell as described in claim 6, characterized in that, In step 4, if the signal strength is higher than the historical value within the original receiving window, but there is a CRC error, it is considered that a coverage area handover has been detected and the uplink signal exceeds the original receiving window. The base station physical layer then performs channel demodulation in all extended receiving windows. If there is data that has been demodulated, the demodulation result, the receiving window index, and the TA measurement value within the receiving window are reported. The indoor high-power base station calculates the TA difference between the new coverage area and the original receiving window and sends the TA difference to the terminal. The TA difference is calculated as: TA value from the target receiving window to the original window + TA measurement value within the receiving window.

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