Bandwidth Estimation Algorithm Based On ACK Packet Pair

With the development of Internet, the management and performance of networks face new challenges. To improve network performance, network measurement is important for protocol design and quality of service. As a key performance indicator, Bandwidth is widely used in various network mechanisms, such as network congestion control, routing and streaming media applications. And bandwidth estimation has been a hot topic in the research field of networks.This thesis focuses on the estimation method of available bandwidth. The algorithms of available bandwidth estimation can be classified into two categories.(1) Packet pair technique analyzes the intervals of packet pairs which are due to the queueing delay of the bottleneck link to estimate available bandwidth. However, it is very sensitive to cross traffic.(2) Another technique uses the one-way delay of probe packets to estimate the available bandwidth. The basic idea is that the one-way delay has a rising trend when the transmission rate of probe packets is higher than the available bandwidth. But this technique costs high and is unsuitable for the network with limited resource, such as wireless networks.In order to overcome the above shortcomings, this thesis proposes a new bandwidth estimation algorithm in which ACK packet pairs are taken as probes (APROBE). APROBE improves the packet pair technique and revises the acknowledgement (ACK) schemes of Transmission Control Protocol (TCP). APROBE can reduce the influence of cross traffic by improving the selection of delay samples, and reduce the overhead of bandwidth estimation because the probe packets are ACK packets whose sizes are much small. We have implemented and verified the APROBE algorithm in NS-3. The simulation results have shown that the accuracy of APROBE is similar with the one of Pathload and is10%higher than the one of Pathchirp. Compared with these two tools, the measurement overhead of APROBE reduces one order of magnitude. In order to reflect the availability of APROBE, we applies it to the congest control mechanism TCP Westwood, and implemented a new mechanism TCPWA. After using of APROBE, TCPWA improves the network performance obviously, for example the network throughput is increased37.5%at most.