Research Of Wireless Network Congestion Control Based On The Bandwidth Estimation

Nowadays, with the rapid development of Internet science and technology,computer network turns more and more common in people’s manufacture and living life,especially the widely use of the wireless network. The number of Internet users and thevarious of applications are growing in a rapid speed, which inevitably makes a sharpincrease in network traffic, and lead to the serious problem of network congestion. Withthe rapid development of network system at present, the control of network congestionis becoming an important issue, whether in wired or wireless network, the situation ofnetwork congestion is unable to avoid, if we don’t manage to control networkcongestion, eventually the entire network will in a state of paralysis. Therefore, theemployment of TCP congestion control mechanism plays a key role in network’sefficient and stable working. Although the existing congestion control mechanisms inTCP/IP protocol has played a role to some extent, but there are still some problems inthe wireless network.This paper makes a detailed analysis of the existing TCP protocol, the originalintention of designing TCP is for wired network, for the reason why TCP has played ahuge role in wired network. However there is only a single kind of packet loss type, thatis due to the amount of data in the network has reached the load capacity of the networkwhich causes packet loss, called congestion packet loss. The probability of link errorcan be negligible in wired network, but in a wireless network, due to the characteristicsof the link itself, the possibility of error is greatly improved, which can not be ignored,and with shielding of barrier, another type of packet loss caused by signal interferencecalled wireless packet loss. Therefore there are two kind of packet loss types in wirelessnetwork, while in the wireless network, TCP protocol does not distinguish the two typesof packet loss, and do all packet loss treatments as congestion packet loss, meanwhile,decrease SSTHRESH and the value of CWND blindly when throwing packets, in thisway, network bandwidth will be wasted greatly and the performance of wireless networks would reduce. To solve this problem, this paper presents a wireless TCPcongestion control method TCP-BD based on bandwidth estimation, by calculating thenetwork bandwidth value in real time figure out the utilization rate of current bandwidth,when packet loss occurs in networks, judge the type of the packet loss on the basis ofthe utilization rate of different bandwidth, at the same time, adjust the value ofSSTHRESH and CWND according to above algorithm, then conduct an experimentsimulation in NS2simulation software.Through simulation software, do comparison between TCP-BD algorithm and theclassical algorithm TCP-Reno and TCPWestwood algorithm, mainly do comparison inend to end delay, jitter, throughput, and so, the results show that TCP-BD algorithm candistinguish wireless packet loss and congestion loss to some extent, improve theperformance of wireless network to a large extent.