Wireless multicast transmission and rate adaptation method during train-ground communication and system thereof

Abstract

The invention relates to a wireless multicast transmission and rate adaptation method during train-ground communication and a system thereof. The communication method comprises the following steps that: a. an access point and a mobile node work in a multicast mechanism state and the multicast mechanism is correspondingly arranged corresponding to a frame control domain; b. the access point initially sends a multicast data flow to the mobile node as a fixed rate and receives an ACK data frame of the mobile node in a multicast group; c. after receiving the ACK data frame corresponding to the mobile node, the access point analyzes and compares link communication quality between the mobile node corresponding to the ACK data frame and the access point and selects a link with the poor communication quality between the access point and the mobile node as a reference link, and a signal to noise ratio of the reference link is selected as the reference signal to noise ratio; d. the access point selects to send the multicast data flow as the optimum transmission rate corresponding to the reference link according to a range of the reference signal to noise ratio. In the invention, the multicast rate adaptation can be realized; fluency and reliability of data transmission in a train-ground communication system can be increased.

Description

technical field [0001] The invention relates to a wireless communication method and system, in particular to a method and system for wireless multicast transmission and rate self-adaptation during vehicle-to-ground communication, belonging to the technical field of wireless communication. Background technique [0002] PIS (Passenger Information System) system is becoming more and more popular along with WLAN mobile communication and other related technologies. As the most intuitive information interaction platform between subway companies and passengers, it not only ensures the safety of train operation but also increases the comfort of passengers; In addition to text information such as travel instructions and train timetables displayed in the compartment, real-time dynamic information such as stock information, news, live events, advertisements, etc. can also be played in case of abnormal situations such as fire, congestion, and terrorist attacks. [0003] In order to meet...

AI Technical Summary

Problems solved by technology

IEEE 802.11a, 802.11b, and 802.11g all provide multi-rate transmission capabilities at the physical layer. All control frames, broadcast, and multicast frames are sent at the basic rate, and RTS / CTS and ACK must be sent at this rate, generally 1Mbps. , this rate cannot guarantee the normal transmission of multicast video streams, which will inevitably cause serious packet loss, resulting in unclear and unsmooth images

With the development of technology, due to the use of rate control algorithms in unicast transmission, unicast data frames can choose different rates according to channel conditions: when the channel has a high signal-to-noise ratio, you can choose to send data at a high rate, but this method only Relies on the estimation of a single channel state and cannot be directly applied to multicast services

There is no practical rate control algorithm that does this for multicast transmissions

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