Communication frequency offset compensation method suitable for high-speed magnetic levitation and high-speed railway
By processing signals through RRUs and BBUs in the base station and optimizing Doppler frequency offset estimation in conjunction with wireless coverage, the signal problems caused by frequency offset in high-speed maglev and railway communication were solved, achieving accurate frequency offset compensation and stable communication.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- CHINA RAILWAY SIYUAN SURVEY & DESIGN GRP CO LTD
- Filing Date
- 2025-12-31
- Publication Date
- 2026-05-05
AI Technical Summary
In high-speed maglev and high-speed railway communications, Doppler frequency offset leads to a decrease in signal demodulation performance and an increase in bit error rate. In severe cases, it may cause communication link interruption, affecting train operation safety and passenger experience. Existing technologies have insufficient accuracy in frequency offset estimation under complex environments.
By utilizing the RRU and BBU in the base station, the received power and Doppler frequency offset are calculated by transmitting a detection reference signal. Combined with the wireless signal coverage, the accuracy of the frequency offset is optimized, and the downlink signal is pre-compensated.
It improves the accuracy and stability of communication frequency offset compensation, reduces the impact of Doppler frequency offset on wireless communication, and ensures the reliability and security of communication.
Smart Images
Figure CN121985405A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of wireless communication technology, specifically relating to a communication frequency offset compensation method applicable to high-speed maglev and high-speed railways. Background Technology
[0002] Doppler frequency shift in high-speed maglev and high-speed rail communications can have numerous negative impacts on communication signals between trackside base stations and trains. Due to their high-speed operation (600 km / h for maglev and 400 km / h for high-speed rail), their frequency shift characteristics are large-scale, leading to a decrease in signal demodulation performance. This makes it difficult for receiving equipment to accurately reconstruct the original signal, thus increasing the bit error rate. Severe frequency shifts can cause communication link interruptions, preventing normal communication between the train and the base station, affecting train operation safety and passenger communication experience.
[0003] In existing technologies for Doppler frequency offset compensation of downlink signals in high-speed maglev and high-speed railway wireless communication, the accuracy of frequency offset estimation is significantly insufficient in complex environments. For example, in mountainous areas and tunnels, signals are not only affected by multipath interference but also by obstruction and reflection from mountainsides and tunnel walls, leading to complex changes in signal characteristics. Traditional frequency offset estimation methods based on pilot signals suffer a significant drop in accuracy in such complex environments because pilot signals are easily interfered with. Summary of the Invention
[0004] In response to one or more of the above-mentioned defects or improvement needs of the existing technology, the present invention provides a communication frequency offset compensation method applicable to high-speed maglev and high-speed railway. It uses known wireless coverage to estimate the Doppler frequency offset value, and fuses it with the measured value of Doppler frequency offset based on wireless signal. It makes full use of prior information to optimize the accuracy of the frequency offset value and pre-compensates the downlink signal to reduce the impact of Doppler frequency offset on wireless communication.
[0005] To achieve the above objectives, this invention provides a communication frequency offset compensation method applicable to high-speed maglev and high-speed railways. This method utilizes a base station to achieve communication compensation. The base station includes several RRUs and a BBU deployed along the target line segment. The method comprises the following steps: S1 and BBU transmit detection reference signals to TAU based on their respective RRUs, and perform measurements to calculate the received power value and the measured value of Doppler frequency offset. ; Where i is the RRU index and n is the current time slot index. n-1 is the index of the previous time slot; S2. Based on the received power value of each RRU, determine the valid RRUs and obtain a list of valid RRUs; S3. Obtain the wireless signal coverage of each RRU, and use the received power value of each RRU in the valid RRU list. The estimated Doppler frequency offset of each RRU in the effective RRU list is obtained. ; The wireless signal coverage of each RRU includes the vertical distance between the RRU and the target line segment, and the location of the RRU's landmarks; S4. For each valid RRU and Perform fusion processing to obtain the fused frequency offset value. ; S5, Use fused frequency offset value Perform Doppler frequency offset pre-compensation on the downlink transmitted signal.
[0006] As a further preferred embodiment of the present invention, S1 includes the following steps: S11, BBU calculates the SRS signal received power of TAUs on all RRUs under this base station. ; S12, according to Calculate Doppler frequency offset measurement value .
[0007] As a further preferred embodiment of the present invention, S2 includes the following steps: S21. Filter the SRS received power of all RRUs; S22, For all RRUs The system makes a judgment, and those that exceed the threshold are considered valid RRUs. Each valid RRU is recorded to obtain a list of valid RRUs.
[0008] As a further preferred embodiment of the present invention, the filtering process is as follows: ; In the formula, where This represents the smoothed value of the SRS received power. This represents the smoothing value of time slot n. This represents the smoothing value for time slot n-1. These are the preset filter coefficients.
[0009] As a further preferred embodiment of the present invention, S3 includes the following steps: S31. Based on SRS received power Calculate the road loss measurement from TAU to each RRU. ; ; In the formula, This is the TAU transmit power, which is determined by the TAU; S32. Construct a function or mapping table of the actual road loss value of each RRU with respect to the location x of the route marker, so as to obtain the prior road loss value of each RRU; ; In the formula, This represents the path loss value for the RRU with index i on this route. For the RRU with index i, this is a function or mapping table about the landmark position x; S33. If there are multiple valid RRUs, find the x that minimizes the sum of the standard deviations of the measured road loss value and the prior road loss value for each RRU, and determine this x as the landmark position of the TAU in the current time slot n. If the effective RRU is a single unit, calculate the standard deviation and proceed to S35; S34, the valid RRU corresponds to for Then proceed to step S5; S35, Based on the TAU position of the previous time sequence Calculate TAU running speed ; ; In the formula, Given a fixed time interval between two time slots; S36. Based on the current TAU location in the current time slot, the RRU landmark location, and the vertical distance between the RRU and the line, calculate the angle between the TAU's movement direction and the transmitted signal for each RRU. ; S37, according to and Calculate the estimated value of the RRU Doppler frequency offset at index i. .
[0010] As a further preferred embodiment of the present invention, the sum of the standard deviations tmp of the measured road loss value and the prior road loss value for each RRU is: ; In the formula, M is the index of the effective RRU.
[0011] As a further preferred embodiment of the present invention, the The calculation formula is: ; In the formula, The location of the RRU with index i.
[0012] As a further preferred embodiment of the present invention, the estimated value The calculation formula is: , In the formula, v is the operating speed of the TAU, and c is the propagation speed of radio waves. For carrier frequency.
[0013] As a further preferred embodiment of the present invention, S4 includes the following steps: S41. For each valid RRU, based on the measurement value of the current time slot... and estimated value Calculate the standard deviation and fusion coefficient at the current time. : ; S42, BBU uses these fusion coefficients for all valid RRU measurements. The fusion process yields the Doppler frequency offset value after the current time slot has been fused: ; In the formula, M is the number of effective RRUs.
[0014] As a further preferred embodiment of the present invention, S5 includes the following steps: S51. Calculate the Doppler frequency offset pre-compensation coefficient based on the fused frequency offset value; S52. In downlink signal transmission, the time-domain signal is pre-compensated using complex multiplication.
[0015] In summary, the beneficial effects of the above-described technical solutions conceived by this invention compared with the prior art include: (1) The communication frequency offset compensation method of the present invention applicable to high-speed maglev and high-speed railway includes the following steps: the BBU transmits a detection reference signal to the TAU based on each of its RRUs and performs measurements to calculate the received power value and the measured value of the Doppler frequency offset; based on the received power value of each RRU, the effective RRUs are determined and a list of effective RRUs is obtained; the wireless signal coverage of each RRU is obtained, and the estimated value of the Doppler frequency offset of each RRU in the effective RRU list is estimated using the received power value of each RRU in the effective RRU list; the sum of each effective RRU is fused to obtain a fused frequency offset value; and the fused frequency offset value is used to perform a Doppler frequency offset pre-compensation operation on the downlink transmitted signal. This communication frequency offset compensation method uses known wireless coverage to estimate the Doppler frequency offset value, fuses it with the measured value of the Doppler frequency offset based on the wireless signal, makes full use of prior information to optimize the accuracy of the frequency offset value, and performs pre-compensation on the downlink signal to reduce the impact of the Doppler frequency offset on wireless communication.
[0016] (2) The communication frequency offset compensation method of the present invention, applicable to high-speed maglev and high-speed railway, is accurate, stable in operation, and has good applicability. The base station is configured with SRS period parameters, and the TAU transmits SRS signals according to these period parameters. The base station then performs SRS measurements in the corresponding time slots according to these period parameters. At the same time, it uses prior information on known road loss conditions to estimate the frequency offset. The measured and estimated values are used to calculate the fused Doppler frequency offset value, and finally, the Doppler frequency offset of the downlink signal is pre-compensated. In addition, by using known wireless coverage conditions to estimate the Doppler frequency offset value and fusing it with the measured value of the Doppler frequency offset based on the wireless signal, the prior information is fully utilized to optimize the accuracy of the frequency offset value and pre-compensate the downlink signal to reduce the impact of Doppler frequency offset on wireless communication. This method has good prospects for promotion and application value. Attached Figure Description
[0017] Figure 1 This is a flowchart of a communication frequency offset compensation method applicable to high-speed maglev and high-speed railways in an embodiment of the present invention; Figure 2 This is a schematic diagram of the base station structure for a communication frequency offset compensation method applicable to high-speed maglev and high-speed railways in an embodiment of the present invention; Figure 3 This is a schematic diagram of the coverage of multiple effective RRUs in the communication frequency offset compensation method applicable to high-speed maglev and high-speed railway in an embodiment of the present invention; Detailed Implementation To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.
[0018] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.
[0019] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.
[0020] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.
[0021] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "over," and "on top" of the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.
[0022] Example: Please see Figures 1-3 The communication frequency offset compensation method applicable to high-speed maglev and high-speed railways in the preferred embodiment of the present invention uses known wireless coverage to estimate the Doppler frequency offset value, and fuses it with the measured value of Doppler frequency offset based on wireless signal. It makes full use of prior information to optimize the accuracy of the frequency offset value and pre-compensates the downlink signal to reduce the impact of Doppler frequency offset on wireless communication.
[0023] Specifically, such as Figure 1 As shown in the preferred embodiment of this application, the communication frequency offset compensation method applicable to high-speed maglev and high-speed railways utilizes a base station to achieve communication compensation. The base station includes several RRUs and one BBU deployed on the target line segment, and the compensation method includes the following steps: S1 and BBU transmit detection reference signals to TAU based on their respective RRUs, and perform measurements to calculate the received power value. Doppler frequency deviation measurement value ; Where i is the RRU index, n is the current time slot index, n-1 is the previous time slot index, and TAU is the Train Access Unit for high-speed maglev and high-speed railway trains.
[0024] S2. Based on the received power value of each RRU, determine the valid RRUs and obtain a list of valid RRUs; S3. Obtain the wireless signal coverage of each RRU, and use the received power value of each RRU in the valid RRU list. The estimated Doppler frequency offset of each RRU in the effective RRU list is obtained. ; The wireless signal coverage of each RRU includes the vertical distance between the RRU and the target line segment, and the location of the RRU's landmarks; S4. For each valid RRU and Perform fusion processing to obtain the fused frequency offset value. ; S5, Use fused frequency offset value Perform Doppler frequency offset pre-compensation on the downlink transmitted signal.
[0025] Furthermore, such as Figure 2 As shown in the preferred embodiment of this application, the base station is a 5G base station. The Remote Radio Unit (RRU) of the base station is responsible for transmitting and receiving wireless signals, and the Baseband Unit (BBU) of the base station is responsible for acquiring the fused Doppler frequency offset and performing frequency offset pre-compensation processing for the downlink signal. A base station system includes one BBU and multiple RRUs to achieve wireless signal coverage for a section of high-speed maglev and high-speed railway line. Preferably, Further, in a preferred embodiment of this application, S1 includes the following steps: S11, BBU calculates the SRS signal received power of TAUs on all RRUs under this base station. ; S12, according to Calculate Doppler frequency offset measurement value .
[0026] More preferably, in a preferred embodiment of this application, step S2 includes the following steps: S21. Filter the SRS received power of all RRUs; S22, For all RRUs The system makes a judgment, and those that exceed the threshold are considered valid RRUs. Each valid RRU is recorded to obtain a list of valid RRUs.
[0027] More specifically, in a preferred embodiment of this application, the filtering process is as follows: ; In the formula, where This represents the smoothed value of the SRS received power. This represents the smoothing value of time slot n. This represents the smoothing value for time slot n-1. These are the preset filter coefficients.
[0028] Furthermore, in a preferred embodiment of this application, S3 includes the following steps: S31. Based on SRS received power Calculate the road loss measurement from TAU to each RRU. ; ; In the formula, This is the TAU transmit power, which is determined by the TAU; S32. Construct a function or mapping table of the actual road loss value of each RRU with respect to the location x of the route marker, so as to obtain the prior road loss value of each RRU; ; In the formula, This represents the path loss value for the RRU with index i on this route. For the RRU with index i, this is a function or mapping table about the landmark position x; S33. If there are multiple valid RRUs, find the x that minimizes the sum of the standard deviations of the measured road loss value and the prior road loss value for each RRU, and determine this x as the landmark position of the TAU in the current time slot n. If the effective RRU is a single unit, calculate the standard deviation and proceed to S35; S34, the valid RRU corresponds to for Then proceed to step S5; S35, Based on the TAU position of the previous time sequence Calculate TAU running speed ; ; In the formula, Given a fixed time interval between two time slots; S36. Based on the current TAU location in the current time slot, the RRU landmark location, and the vertical distance between the RRU and the line, calculate the angle between the TAU's movement direction and the transmitted signal for each RRU. ; S37, according to and Calculate the estimated value of the RRU Doppler frequency offset at index i. .
[0029] Further preferably, in the preferred embodiment of this application, the sum of the standard deviations tmp of the measured road loss value and the prior road loss value for each RRU is: ; In the formula, M is the index of the effective RRU.
[0030] More specifically, in the preferred embodiment of this application, the... The calculation formula is: ; In the formula, The location of the RRU with index i.
[0031] Furthermore, in a preferred embodiment of this application, the estimated value The calculation formula is: , In the formula, v is the operating speed of the TAU, and c is the propagation speed of radio waves. For carrier frequency.
[0032] More preferably, such as Figure 3 As shown in the preferred embodiment of this application, S4 includes the following steps: S41. For each valid RRU, based on the measurement value of the current time slot... and estimated value Calculate the standard deviation and fusion coefficient at the current time. : ; S42, BBU uses these fusion coefficients for all valid RRU measurements. The fusion process yields the Doppler frequency offset value after the current time slot has been fused: ; In the formula, M is the number of effective RRUs.
[0033] Furthermore, in a preferred embodiment of this application, S5 includes the following steps: S51. Calculate the Doppler frequency offset pre-compensation coefficient based on the fused frequency offset value; S52. In downlink signal transmission, the time-domain signal is pre-compensated using complex multiplication.
[0034] The communication frequency offset compensation method for high-speed maglev and high-speed railways presented in this invention is accurate, stable in operation, and highly applicable. The base station is configured with SRS period parameters, and the TAU transmits SRS signals according to these parameters. The base station then performs SRS measurements in the corresponding time slots based on these parameters. Simultaneously, it uses prior information about known road loss conditions to estimate the frequency offset. The measured and estimated values are used to calculate a fused Doppler frequency offset value, and finally, Doppler frequency offset pre-compensation is performed on the downlink signal. Furthermore, by using known wireless coverage conditions to estimate the Doppler frequency offset value and fusing it with the measured value based on the Doppler frequency offset of the wireless signal, the method fully utilizes prior information to optimize the accuracy of the frequency offset value and pre-compensates the downlink signal, thus reducing the impact of Doppler frequency offset on wireless communication. This method has good prospects for promotion and application value.
[0035] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.
Claims
1. A communication frequency offset compensation method applicable to high-speed maglev and high-speed railways, characterized in that, It achieves communication compensation by means of a base station, which includes several RRUs and a BBU deployed on the target line segment, and includes the following steps: S1 and BBU transmit detection reference signals to TAU based on their respective RRUs, and perform measurements to calculate the received power value. Doppler frequency deviation measurement value ; Where i is the RRU index, n is the current time slot index, and n-1 is the index of the previous time slot; S2. Based on the received power value of each RRU, determine the valid RRUs and obtain a list of valid RRUs; S3. Obtain the wireless signal coverage of each RRU, and use the received power value of each RRU in the valid RRU list. The estimated Doppler frequency offset of each RRU in the effective RRU list is obtained. ; The wireless signal coverage of each RRU includes the vertical distance between the RRU and the target line segment, and the location of the RRU's landmarks; S4. For each valid RRU and Perform fusion processing to obtain the fused frequency offset value. ; S5, Use fused frequency offset value Perform Doppler frequency offset pre-compensation on the downlink transmitted signal.
2. The communication frequency offset compensation method applicable to high-speed maglev and high-speed railways according to claim 1, characterized in that, S1 includes the following steps: S11, BBU calculates the SRS signal received power of TAUs on all RRUs under this base station. ; S12, according to Calculate Doppler frequency offset measurement value .
3. The communication frequency offset compensation method applicable to high-speed maglev and high-speed railways according to claim 1, characterized in that, S2 includes the following steps: S21. Filter the SRS received power of all RRUs; S22, For all RRUs The system makes a judgment, and those that exceed the threshold are considered valid RRUs. Each valid RRU is recorded to obtain a list of valid RRUs.
4. The communication frequency offset compensation method applicable to high-speed maglev and high-speed railways according to claim 3, characterized in that, The filtering process is as follows: ； In the formula, where This represents the smoothed value of the SRS received power. This represents the smoothing value of time slot n. This represents the smoothed value for time slot n-1. These are the preset filter coefficients.
5. The communication frequency offset compensation method applicable to high-speed maglev and high-speed railways according to any one of claims 1 to 4, characterized in that, S3 includes the following steps: S31. Based on SRS received power Calculate the road loss measurement from TAU to each RRU. ; ； In the formula, This is the TAU transmit power, which is determined by the TAU; S32. Construct a function or mapping table of the actual road loss value of each RRU with respect to the location x of the route marker, so as to obtain the prior road loss value of each RRU; ； In the formula, This represents the path loss value for the RRU with index i on this route. For the RRU with index i, this is a function or mapping table about the landmark position x; S33. If there are multiple valid RRUs, find the x that minimizes the sum of the standard deviations of the road loss measurement and the prior road loss value for each RRU, and determine this x as the landmark position of the TAU in the current time slot n. If the effective RRU is a single unit, calculate the standard deviation and proceed to S35; S34, the valid RRU corresponds to for Then proceed to step S5; S35, Based on the TAU position of the previous time sequence Calculate TAU running speed ; ； In the formula, Given a fixed time interval between two time slots; S36. Based on the current TAU location in the current time slot, the RRU landmark location, and the vertical distance between the RRU and the line, calculate the angle between the TAU's movement direction and the transmitted signal for each RRU. ; S37, according to and Calculate the estimated value of the RRU Doppler frequency offset at index i. .
6. The communication frequency offset compensation method applicable to high-speed maglev and high-speed railways according to claim 5, characterized in that, The sum of the standard deviations of the measured road loss and the prior road loss for each RRU, tmp, is: ； In the formula, M is the index of the effective RRU.
7. The communication frequency offset compensation method applicable to high-speed maglev and high-speed railways according to claim 5, characterized in that, The The calculation formula is: ； In the formula, The location of the RRU with index i.
8. The communication frequency offset compensation method applicable to high-speed maglev and high-speed railways according to claim 5, characterized in that, The estimated value The calculation formula is: ， In the formula, v is the operating speed of the TAU, and c is the propagation speed of radio waves. For carrier frequency.
9. The communication frequency offset compensation method applicable to high-speed maglev and high-speed railways according to any one of claims 5, characterized in that, S4 includes the following steps: S41. For each valid RRU, based on the measurement value of the current time slot... and estimated value Calculate the standard deviation and fusion coefficient at the current time. : ； S42, BBU uses these fusion coefficients for all valid RRU measurements. The fusion process yields the Doppler frequency offset value after the current time slot has been fused: ； In the formula, M is the number of effective RRUs.
10. The communication frequency offset compensation method applicable to high-speed maglev and high-speed railways according to claim 9, characterized in that, S5 includes the following steps: S51. Calculate the Doppler frequency offset pre-compensation coefficient based on the fused frequency offset value; S52. In downlink signal transmission, the time-domain signal is pre-compensated using complex multiplication.