CN-121985405-A - Communication frequency offset compensation method suitable for high-speed magnetic levitation and high-speed railway

Abstract

The invention discloses a communication frequency offset compensation method suitable for high-speed magnetic levitation and high-speed railways, which belongs to the technical field of wireless communication and comprises the following steps of calculating a receiving power value and a Doppler frequency offset measurement value by BBU (base band unit) based on detection reference signals transmitted by each RRU to TAU (remote access unit), obtaining an effective RRU list, obtaining a wireless signal coverage condition of each RRU, using the receiving power value of each RRU in the effective RRU list to estimate and obtain an estimated value of the Doppler frequency offset of each RRU in the effective RRU list, carrying out fusion processing on the sum of each effective RRU to obtain a fusion frequency offset value, and carrying out Doppler frequency offset pre-compensation operation on downlink transmission signals by using the fusion frequency offset value. The communication frequency offset compensation method provided by the invention utilizes the known wireless coverage condition to estimate the Doppler frequency offset value, and is fused with the Doppler frequency offset measurement value based on the wireless signal, and the prior information is fully utilized to optimize the accuracy of the frequency offset value so as to reduce the influence of the Doppler frequency offset on the wireless communication.

Inventors

• TANG PEI
• XIONG ZHEN
• CAI BINGJIANG
• YANG ANYU
• AI PEIYUE
• FENG YAXIONG
• TANG LICHENG
• CHANG YONGHUA

Assignees

• 中铁第四勘察设计院集团有限公司

Dates

Publication Date

20260505

Application Date

20251231

Claims (10)

1. 1. The communication frequency offset compensation method suitable for the high-speed magnetic levitation and the high-speed railway is characterized in that the communication frequency offset compensation is realized by a base station, the base station comprises a plurality of RRUs and a BBU which are arranged on a target road section, and the method comprises the following steps: S1, BBU transmits a detection reference signal to TAU based on each RRU below the BBU, measures the detection reference signal, and calculates a receiving power value Measurement of Doppler frequency offset ; Wherein i is RRU index, n is current time slot index, n-1 is index of last time slot; S2, judging effective RRUs according to the received power values of the RRUs, and obtaining an effective RRU list; s3, acquiring the wireless signal coverage condition of each RRU, and using the receiving power value of each RRU in the effective RRU list Estimating to obtain the estimated value of Doppler frequency offset of each RRU in the effective RRU list ; The wireless signal coverage condition of each RRU comprises the vertical distance between the RRU and the target road section and the road mark position of the RRU; S4, for each effective RRU And Fusion processing is carried out to obtain a fused frequency offset value ; S5, using the fused frequency offset value And carrying out Doppler frequency offset pre-compensation operation on the downlink transmission signals.
2. 2. The communication frequency offset compensation method for high-speed magnetic levitation and high-speed railway according to claim 1, wherein the step S1 comprises the following steps: s11, BBU calculates SRS signal receiving power of TAU on all RRUs under the base station ; S12, according to Calculating Doppler frequency offset measurement value 。
3. 3. The communication frequency offset compensation method for high-speed magnetic levitation and high-speed railway according to claim 1, wherein the step S2 comprises the following steps: S21, filtering SRS receiving power of all RRUs; s22, for all RRUs Judging that the threshold is considered to be effective RRU, and recording each effective RRU to obtain an effective RRU list.
4. 4. The communication frequency offset compensation method suitable for high-speed magnetic levitation and high-speed railway according to claim 3, wherein the filtering process is as follows: ; In the formula, wherein Representing the SRS received power smoothed value, Representing a smoothed value for time slot n, Representing the smoothed value of time slot n-1, Is a preset filter coefficient.
5. 5. The communication frequency offset compensation method suitable for high-speed magnetic levitation and high-speed railway according to any one of claims 1-4, wherein the step S3 comprises the following steps: S31, according to SRS received power Calculating the path loss measurement value from TAU to each RRU ; ; In the formula, Is the TAU transmit power, which is determined by the TAU; s32, constructing a function or a mapping table of actual path loss values of each RRU relative to the position x of the circuit road sign so as to obtain the path loss priori value of each RRU; ; In the formula, The path loss value for the RRU on the line with index i, A function or mapping table of the index i RRU with respect to the landmark position x; s33, if the number of the effective RRUs is multiple, searching x with the minimum sum of the standard deviation of the path loss measured value and the path loss prior value of each RRU, and recognizing the x as the road sign position of the TAU in the current time slot n If the effective RRU is single, calculating the standard deviation, and entering S34; S34, corresponding to the effective RRU Is that And proceeds to step S5; S35, TAU position according to the previous time sequence Calculating the TAU running speed ; ; In the formula, A fixed time interval that is known to be two time slots; S36, calculating the included angle between the TAU moving direction and the transmitting signal under each RRU according to the TAU position of the current time slot, the RRU road sign position and the RRU and line vertical distance parameter ; S37 according to And Calculating an estimated value of RRU Doppler frequency offset with index of i 。
6. 6. The communication frequency offset compensation method for high-speed magnetic levitation and high-speed railway according to claim 5, wherein the sum tmp of standard deviation of the path loss measured value and the path loss priori value of each RRU is: ; Wherein M is the index of the effective RRU.
7. 7. The communication frequency offset compensation method for high-speed magnetic levitation and high-speed railway according to claim 5, wherein the method comprises the following steps of The calculation formula of (2) is as follows: ; In the formula, Is the landmark position of the RRU with index i.
8. 8. The communication frequency offset compensation method for high-speed magnetic levitation and high-speed railway according to claim 5, wherein the estimated value is The calculation formula of (2) is as follows: , where v is the running speed of TAU, c is the propagation speed of electric wave, Is the carrier frequency.
9. 9. The communication frequency offset compensation method for high-speed magnetic levitation and high-speed railway according to any one of claim 5, wherein S4 comprises the steps of: S41, for each effective RRU, according to the measured value of the current time slot And an estimated value Calculating standard deviation and fusion coefficient of current moment : ; S42, BBU uses the fusion coefficients to measure all effective RRUs Fusing to obtain Doppler frequency offset value after the current time slot fusion processing: ; In the formula, M is the number of effective RRUs.
10. 10. The communication frequency offset compensation method for high-speed magnetic levitation and high-speed railway according to claim 9, wherein the step S5 comprises the following steps: s51, calculating a Doppler frequency offset precompensation coefficient according to the fused frequency offset value; s52, performing precompensation processing on the time domain signal in a complex multiplication mode in downlink signal transmission.

Description

Communication frequency offset compensation method suitable for high-speed magnetic levitation and high-speed railway Technical Field The invention belongs to the technical field of wireless communication, and particularly relates to a communication frequency offset compensation method suitable for high-speed magnetic levitation and high-speed railways. Background Doppler frequency shift in high-speed magnetic levitation and high-speed railway communication can have a plurality of negative effects on communication signals between a trackside base station and a train. Because of the characteristic of high running speed (high-speed magnetic levitation 600km/h and high-speed railway 400 km/h), the frequency offset characteristic of the device presents large-scale characteristics, and the device can lead to the reduction of the demodulation performance of signals, so that the receiving device is difficult to accurately restore the original signals, thereby increasing the error rate. The serious frequency offset may cause interruption of a communication link, so that normal communication between a train and a base station is not possible, and operation safety of the train and communication experience of passengers are affected. In the existing high-speed magnetic levitation and high-speed railway wireless communication downlink signal Doppler frequency offset compensation processing technology, the frequency offset estimation precision has obvious defects in a complex environment. In the scenes such as mountainous areas, tunnels and the like, the signals are not only interfered by multipath effects, but also can be blocked and reflected by mountains, tunnel walls and the like, so that the characteristics of the signals are changed in a complex manner. In the traditional frequency offset estimation method based on the pilot signal, under the complex environment, the estimation accuracy of the pilot signal is greatly reduced because the pilot signal is easy to be interfered. Disclosure of Invention Aiming at one or more of the defects or improvement demands of the prior art, the invention provides a communication frequency offset compensation method suitable for high-speed magnetic levitation and high-speed railways, which utilizes the known wireless coverage condition to estimate Doppler frequency offset value, fuses the Doppler frequency offset value with the measured value of Doppler frequency offset based on wireless signals, fully utilizes prior information to optimize the accuracy of the frequency offset value, and pre-compensates downlink signals so as to reduce the influence of the Doppler frequency offset on wireless communication. In order to achieve the above object, the present invention provides a communication frequency offset compensation method suitable for high-speed magnetic levitation and high-speed railway, which implements communication compensation by means of a base station, the base station comprising a plurality of RRUs and a BBU arranged on a target road section, comprising the steps of: S1, BBU transmits detection reference signals to TAU based on each RRU below the BBU, measures the detection reference signals, and calculates measured values of a receiving power value and Doppler frequency offset ; Wherein i is RRU index, n is current time slot indexN-1 is the index of the last slot; S2, judging effective RRUs according to the received power values of the RRUs, and obtaining an effective RRU list; s3, acquiring the wireless signal coverage condition of each RRU, and using the receiving power value of each RRU in the effective RRU list Estimating to obtain the estimated value of Doppler frequency offset of each RRU in the effective RRU list; The wireless signal coverage condition of each RRU comprises the vertical distance between the RRU and the target road section and the road mark position of the RRU; S4, for each effective RRU AndFusion processing is carried out to obtain a fused frequency offset value; S5, using the fused frequency offset valueAnd carrying out Doppler frequency offset pre-compensation operation on the downlink transmission signals. As a further preferred aspect of the present invention, the step S1 includes the steps of: s11, BBU calculates SRS signal receiving power of TAU on all RRUs under the base station ; S12, according toCalculating Doppler frequency offset measurement value。 As a further preferred aspect of the present invention, the step S2 includes the steps of: S21, filtering SRS receiving power of all RRUs; s22, for all RRUs Judging that the threshold is considered to be effective RRU, and recording each effective RRU to obtain an effective RRU list. As a further preferred aspect of the present invention, the filtering process is: ; In the formula, wherein Representing the SRS received power smoothed value,Representing a smoothed value for time slot n,Representing the smoothed value of time slot n-1,Is a preset filter coefficient. As a further preferred a