A Multiple Relay-Based Medium Access Control Protocol in Multirate Wireless Ad Hoc Networks with Multiple Beam Antennas

• Main Authors: Ta-Po Chen, 陳柏達
• Other Authors: Yuh-Shyan Chen
• Format: Others
• Language: en_US
• Published: 2007
• Online Access: http://ndltd.ncl.edu.tw/handle/88468115281447542519

碩士 === 國立中正大學 === 資訊工程所 === 95 === Multiple beam antennas can be used to enhance the throughput of wireless networks by increasing spatial reuse, avoiding co-channel interference, and reducing collisions. The application of multiple beam antennas is similar to the concept of Space Division Multiple Access (SDMA), hence each beam can treat as a data channel. Moreover, wireless networks can increase the total throughput and decrease transmission latency if the physical layer supports multirate capability. However, multirate wireless networks may bring the anomaly problem. The anomaly problem is incurred because lower data rate hosts may influence the original performance of higher data rate nodes. This thesis supposes that each node fits out multiple beam antennas with multirate capability, and a node can either transmit or receive multiple data on multiple beams at the same time but not both. We propose a multiple relay-based medium access control (MAC) protocol to improve throughput of lower data rate hosts. Our MAC protocol exploits multiple relay nodes and helps the source and the destination to create more than one data channel to shorten the transmission latency. Especially for low data rate links, the long-winded transmission latencies are distributed by multiple relay nodes. and the anomaly problem can be alleviated. In addition, this thesis solves the ACK synchronization problem to avoid that source nodes can not receive ACK from destination nodes, and adjusts unnecessary relay nodes during fragment burst period. Finally, simulations show that multiple relay-based MAC protocol can achieve higher throughput and lower transmission latency.