CN-122027093-A - Low-delay retransmission method for high-speed rail communication

Abstract

The invention discloses a low-delay retransmission method for high-speed railway communication, which adopts MPTCP to carry out multi-stream redundancy transmission high-speed railway train control train adjustment service, selects at least two sub-streams to transmit the same data, selects a retransmission strategy through a retransmission judgment mode when one sub-stream is transmitted in error, namely whether to immediately retransmit the data packet transmitted in error sub-stream or wait for the other sub-streams to reach redundancy, if the subsequent other sub-streams are transmitted successfully, a sender simultaneously sends new data packets in the transmission error sub-stream and other sub-streams after the other sub-streams receive ACK (acknowledgement) containing a target data packet acknowledgement number, and if the other sub-streams are failed in transmission, the sender simultaneously retransmits the data packets in the transmission error sub-stream and other sub-streams under the condition that the other sub-streams receive three repeated ACK or overtime. The invention is applied to the scene of redundant data transmission by adopting a plurality of paths in the coexistence of multi-system networks, and ensures the low-delay requirement of the train control and train adjustment service of the high-speed rail by selecting a proper retransmission judgment mode.

Inventors

• MA LI
• LIU CHANG
• FU WENGANG
• JIANG HONGMIN
• Tang Maoshun
• YAN LI
• FANG XUMING
• LIN WEI
• GAO SHANGYONG
• SONG JUN
• WU TINGTING
• HE RONG
• HUANG GAOYONG

Assignees

• 西南交通大学
• 中国铁道科学研究院集团有限公司
• 中国国家铁路集团有限公司

Dates

Publication Date

20260512

Application Date

20260202

Claims (6)

1. 1. The low-delay retransmission method for the high-speed railway communication is characterized by reliably transmitting the train control and train adjustment service for the high-speed railway on the basis of adopting a multi-path transmission protocol MPTCP multi-stream redundancy transmission technology, and specifically comprises the following steps of: in the MPTCP subflow establishment stage, a sender and a receiver interact initialization information through SYN, SYN/ACK and ACK data packets; The method comprises the steps of selecting at least two sub-streams to transmit data packets by a sender and starting a delay retransmission timer, updating round trip time RTT value and periodically updating packet loss rate of each sub-stream by the sender in real time, calculating a new RTT value according to a transmission time difference and a receiving time difference after a certain sub-stream successfully transmits the data packets and receives ACK, smoothing by using a weighted average method to obtain a smooth RTT, and simultaneously adjusting the delay retransmission timer to ensure that the initial value of the RTT value is the maximum RTT value in each sub-stream; In the retransmission judgment stage, when the retransmission delay timer is not overtime and a certain sub-stream receives three repeated ACKs, namely, the sequence number in an ACK packet is not larger than the sequence number of a target data packet, two retransmission judgment modes are selected, namely, whether retransmission is immediately carried out is judged based on RTT and packet loss rate, and the mode II is judged whether retransmission is immediately carried out based on the path transmission quality factor.
2. 2. The low-latency retransmission method for high-speed railway communications according to claim 1, wherein the method one specifically comprises: If the RTT value of the error substream is smaller than or equal to the difference value with the RTT of the other substream, the data packet is immediately retransmitted on the transmission error substream; if the packet loss rate of the error sub-stream is smaller than or equal to the packet loss rate of the other sub-stream, the data packet is immediately retransmitted on the transmission error sub-stream, and if the packet loss rate of the error sub-stream is larger than or equal to the packet loss rate of the other sub-stream, the arrival of the redundant transmission data packet of the other sub-stream is waited.
3. 3. The low-latency retransmission method for high-speed railway communication according to claim 1, wherein the second mode is specifically: Firstly, calculating the transmission quality factor of each path, if the sub-stream quality factor of the error sub-stream is smaller than or equal to the sub-stream quality factor of another sub-stream, indicating that the link quality of the transmission error sub-stream is better, immediately retransmitting the data packet on the transmission error sub-stream, and if the sub-stream quality factor of the error sub-stream is larger than the sub-stream quality factor of the other sub-stream, indicating that the link quality of the transmission error sub-stream is worse, waiting for the arrival of the redundant transmission data packet of the other sub-stream.
4. 4. The method of claim 1, wherein the delay retransmission timer is set to a maximum value of each substream RTT, the sender sends a data packet and starts the delay retransmission timer, when one data packet fails to be transmitted on a substream, i.e., the sender receives multiple duplicate ACKs, if the delay retransmission timer is not 0, the retransmission judgment is triggered, when the sender does not receive an ACK containing the acknowledgement number of the target data packet and the delay retransmission timer times out, indicating that the sender waits for enough time without receiving expected data packet acknowledgements from other substreams, the sender immediately retransmits the data packet on multiple substreams simultaneously.
5. 5. The low-latency retransmission method for high-speed railway communications according to claim 1, wherein the sender and receiver perform information interaction when the MPTCP three-way handshake establishes a connection to a plurality of sub-streams; in the first handshake, the sender needs to send a SYN data packet with an improved MP_JOIN option field, informs the receiver that the currently transmitted service is a high-speed railway train control and rank adjustment service, and needs to execute multi-stream redundancy transmission, and a retransmission judgment mode for the high-speed railway train control and rank adjustment service selected by the sender; In the second handshake, the receiver needs to send a SYN/ACK data packet with an improved MP_JOIN option field to respond, and informs that the information informed by the sender is received; in the third handshake, the sender needs to send ACK packets with the modified mp_join option field to the receiver, informing the total number of sent packets of threshold information.
6. 6. The transmission system applicable to the low-delay retransmission method for high-speed railway communication according to any one of claims 1-5, which is characterized by comprising, but not limited to, a transmitting end device and a receiving end device, wherein the transmission system is used for realizing low-delay transmission of high-speed railway train control and adjustment services; The system comprises a receiving end, a transmitting end, a redundant data packet transmission initiating end, a transmitting end and a receiving end, wherein the transmitting end is used as the initializing initiating end and the redundant data packet transmission initiating end; The receiving end is used as an initialization receiving end and a redundant data packet receiving end, wherein the initialization receiving end needs to immediately feed back a confirmation frame after receiving initialization information to ensure the reliability of data transmission; the whole system is based on an MPTCP multipath transmission protocol, and redundant transmission of the high-speed railway train control train adjustment service data is carried out by utilizing a plurality of sub-streams, so that high reliability of transmission of the high-speed railway train control train adjustment service data is ensured.

Description

Low-delay retransmission method for high-speed rail communication Technical Field The invention belongs to the technical field of wireless communication, and particularly relates to a low-delay retransmission method for high-speed rail communication. Background Along with the reply of the industrial and communication department of the new generation of Railway mobile communication system (5G for Railway, 5G-R) test frequency based on the 5G (the Fifth Generation of Mobile Communication) technology, the Railway mobile communication system enters a transition period of coexistence of multiple communication modes of a GSM-R (Global System for Mobile Communication-Railway), a 5G-R and a 400MHz digital wireless train dispatching system, and the 5G-R, GSM-R and the 400MHz digital wireless train dispatching system are deeply fused to form a multi-mode and multi-frequency band cooperative vehicle-mounted comprehensive wireless access architecture, so that the transmission reliability of Railway train control train dispatching service can be further improved, and the safety of Railway transportation is ensured. The train control and regulation service of the high-speed rail has important roles in maintaining the safe and efficient operation of the train and the like. The service needs high-reliability low-delay data transmission capability to support reliable real-time data interaction between the train and the ground control system. In order to improve the reliable transmission of the train control train adjustment service data, the invention provides a low-delay retransmission method for high-speed railway communication based on a railway multimode cooperative mobile communication network architecture of a multipath transmission protocol (Multipath Transmission Control Protocol, MPTCP) so as to realize the high-reliability and low-delay transmission of the train control service data. Disclosure of Invention The invention provides a low-delay retransmission method for high-speed railway communication under a 5G-R, GSM-R and railway 400MHz digital wireless train dispatching system multimode fusion cooperative vehicle-mounted comprehensive wireless access architecture based on MPTCP mechanism fusion. The invention discloses a low-delay retransmission method for high-speed railway communication, which is based on reliable transmission of high-speed railway train control and adjustment service by adopting a multi-path transmission protocol (Multipath Transmission Control Protocol, MPTCP) multi-stream redundancy transmission technology, and specifically comprises the following steps: in the MPTCP subflow establishment stage, the sender and the receiver interact initialization information through SYN, SYN/ACK and ACK data packets. The method comprises the steps of selecting at least two sub-streams to transmit data packets and starting a delay retransmission timer by a sender, updating Round-Trip Time (RTT) value and periodically updating packet loss rate of each sub-stream in real Time by the sender, calculating a new RTT value according to a transmission Time difference and a reception Time difference after a certain sub-stream successfully transmits the data packets and receives the ACK, smoothing the data packets by using a weighted average method to obtain a smoothed RTT, adjusting the delay retransmission timer to ensure that the initial value is the maximum RTT value in each sub-stream, recording the number of the transmitted and lost data packets by the sender for the packet loss rate, calculating the current packet loss rate when the total number of the transmitted data packets reaches a total number threshold value of the transmitted data packets, and obtaining the smoothed packet loss rate by using the weighted average method to improve the stability of performance evaluation. In the retransmission judgment stage, when the retransmission delay timer is not overtime and a certain sub-stream receives three repeated ACKs, namely, the sequence number in an ACK packet is not larger than the sequence number of a target data packet, two retransmission judgment modes are selected, namely, whether retransmission is immediately carried out is judged based on RTT and packet loss rate, and the mode II is judged whether retransmission is immediately carried out based on the path transmission quality factor. The first mode is as follows: And if the transmission error substream packet loss rate is larger than the other substream packet loss rate, further judging whether the transmission error substream packet loss rate is larger than the other substream packet loss rate. If the packet loss rate of the error sub-stream is smaller than or equal to the packet loss rate of the other sub-stream, the data packet is immediately retransmitted on the transmission error sub-stream, and if the packet loss rate of the error sub-stream is larger than or equal to the packet loss rate of the other sub-stream, the arrival of the redundant t