| Summary: | 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.
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