Rate Adaptation with FEC-Recombining in IEEE 802.11 Wireless Networks

Abstract

Rate adaptation is the mechanism in which nodes adapt the data rate to an optimal value that can be sustained by the channel conditions in a wireless network. Several attempts have been made to design such an algorithm. Packet loss occurs due to corruption in bits caused by bad channel conditions or collisions. Rate adaptation algorithm uses physical layer or Medium Access Control(MAC) layer metrics to determine optimal rate. An increase in the packet loss at MAC layer leads to rate decrease. In this thesis, we attempt to use forward error correction approach to eliminate small channel losses from packet transmission and, recombining approach to reduce the number of retransmissions, thereby, sustaining higher transmission rates with increased overall throughput. Such an approach will also be helpful in transmitting multimedia traffic via a wireless network, as it is sensitive to retransmissions and delay. We have applied the approach on Robust Rate Adaptation Algorithm(RRAA) and have carried out simulations in QualNet. We have compared the approach against the static rate and RRAA algorithm. We have also studied the performance of the algorithm for multimedia traffic by emulating the network in EXata and compared it against RRAA. The results show superior performance of our approach over others.