| With the development of wireless technologies, more and more users connect to Internet through Wireless Local Area Network (WLAN), which makes the quality of WLAN service to become one of the hot research topics. In recent years, Multi-hop WLAN has been confirmed as a new progress trend of WLAN. However, the performance of transport layer protocols in Multi-hop WLAN is still dissatisfactory. Therefore, investigating and improving the performance of this performance is necessary and significant.In order to improve the transport protocol performance in wireless networks, we proposed a new transport control protocol, named Mobile-host-centric Transport Protocol (MCP). When the mobile wireless nodes play as sender, MCP employs sender-centric control mechanism. Meanwhile, if the mobile nodes are receiver, MCP will employ receiver-centric control mechanism. The previous work of our group designed the architecture of MCP and implemented it in NS2 simulation platform and testbed environment. In this dissertation, we enhanced MCP by using cross-layer design, and introduced this protocol into Multi-hop WLAN.In Multi-hop WLAN, each implementation of MCP at each node will record the packet-drop information fed back from its MAC layer and interface queue. In order to collect this packet-drop information in intermediate nodes and feed them back to the mobile nodes, a MCP header is added between TCP header and IP header in each packet. When the intermediate nodes forward a data packet, the packet-drop information with the same flow ID will be extracted and recorded into the MCP header of that packet. As a result, all packet-drop feedback information will arrive at the mobile node, and the sending rate can be adjusted by this node according to the feedback information.We implemented MCP in NS2 and evaluated its performance in Multi-hop WLAN scenarios. The simulation results show that MCP can significantly improve the throughput; meanwhile fairness will not be impacted too much. |
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