Improving TCP Performance over WiMAX Networks Using Cross-Layer Design

With the rapid growth of wireless technologies, the task of providing efficient connectivity is still a challenge. Since almost wireless network poses many problems, including limited bandwidth, coping with bandwidth fluctuations, and lost or corrupted data, lots of studies have been done and many solutions proposed. The IEEE 802.16 WiMAX is a standard for the wireless broadband access networks and recognized as one of the strongest contenders. However, it also has some lossy wireless link problem.On the other hand, Transmission Control Protocol (TCP) is the most commonly used transport protocol on the Internet. But regular TCP is not suitable for wireless networks because packet losses will occur more often due to unreliable wireless links than due to congestion.In this paper, we study the performance when TCP is used on the wireless network and propose cross-layer design to improving TCP performance on wireless network, specifically, over the IEEE 802.16 WiMAX. The key feature in our proposal is that we use the feedback information about channel state to adaptively control packet size, packet amount, and retransmission decision between sender and receiver. And the Sender which send TCP packet adopts cross-layer architecture to improving TCP performance. The cross-layer design is a new paradigm to provide better performance gain. Preliminary simulations were provided and the result shows the performance enhancements of TCP connection over the WiMAX networks.