Method and device for realizing TCP (Transmission Control Protocol) transmission

Abstract

The invention discloses a method and a device for realizing TCP (Transmission Control Protocol) transmission, aiming to improve the transmission performance of TCP connection crossing a 3G (The 3rd Generation Telecommunication) wireless network and increase the bandwidth utilization rate of an air interface. The method for realizing the TCP transmission comprises the following steps that: data transmitted by a server is received by a TCP agent and is cached locally, an acknowledgment character ACK is sent back to the server end, and the data is data to be transmitted to a terminal through the TCP agent after the TCP connection is built between the server end and the terminal; data transmission is carried out through a wire between the TCP agent and the server end, and data transmission is carried out through the air interface between the TCP agent and the terminal; and the local cached data is transmitted to the terminal through the TCP agent in a full-bandwidth way, and the full bandwidth means the maximum quantities of data capable of being born by a transmission channel between the TCP agent and the terminal.

Description

technical field [0001] The present invention relates to the communication field, in particular to a method and device for realizing TCP (Transmission Control Protocol, Transmission Control Protocol) transmission. Background technique [0002] At present, the PS (Packet Switch, packet switching) data service capability of ME (Mobile Equipment, mobile terminal equipment) has been significantly improved due to the substantial increase in air interface bandwidth of the third-generation mobile communication network (such as 3G network). Typical services such as FTP (File Transfer Protocol, file transfer protocol) and WEB (web browsing) are inseparable from the support of TCP. Therefore, the quality of TCP transmission will affect FTP, WEB and other services to a certain extent. performance. [0003] The TCP protocol is mainly a reliable transmission protocol proposed for the wired network. Since the transmission characteristics of the wired network are low bit error rate and eas...

AI Technical Summary

Problems solved by technology

In this way, when the ACK feedback from ME is not received, the data will be cached, and when the FTP / WEB server has out-of-order packets, local sorting will be performed, and when it is detected that the air interface may lose packets, it needs to Local retransmission of data packets is performed when the timeout timer expires, or local retransmission is performed when 1 to 2 Dup ACKs reported by ME are received; for TPE, after receiving less Dup ACKs (less than 3) Local retransmission is relatively easy to implement, but it is difficult to implement retransmission when the timeout timer of the FTP / WEB server expires

Therefore, for the continuous loss of packets sent by the FTP / WEB server or the loss of ACK reported by the ME, the TPE will not perform local retransmission, and will only perform local retransmission when the timeout timer on the FTP / WEB server side expires , at this time, the FTP / WEB server needs to perform the slow start process, and the slow start process will cause a waste of air interface bandwidth resources

[0022] 3. RNC sends Dup ACK to the FTP / WEB server; when the local downlink buffer is empty, RNC sends 3 Dup ACKs to the FTP / WEB server, and uses the fast retransmission algorithm of TCP to quickly send data to ME; this method uses Although the fast retransmission algorithm can speed up the speed of sending data from the FTP / WEB server to the ME, it is at the cost of reducing ssthresh. Therefore, relatively speaking, the sending window of the FTP / WEB server is relatively low as a whole, and there is still a waste of air interface bandwidth.

This method makes the FTP / WEB server increase the sending window by dynamically increasing the receiving window of ME, but the sending window needs to be determined by both cwnd and rwnd and cannot be increased arbitrarily, so this method is only applicable to the case where cwnd is greater than rwnd , does not work for other cases

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