Joint PHY/MAC based link adaptation for wireless LANs with multipath fading

Wireless local area networks offer a range of transmitted data rates that are to be selected according to estimated channel conditions. However, due to packet overheads and contention times introduced by the CSMA/CA multiple access protocol, effective throughput is much less than the nominal data rates. Most multimedia applications use small payload sizes in order to ensure reliable, low latency transmission. This results in a further loss in effective throughput thereby reducing network capacity drastically. Thus, a cross-layer based design approach along with link adaptation is required to improve the network performance under different channel conditions. We investigate the effect of payload size variations on single-user throughput for both non-fading and multipath fading environments. We explore the difference in link adaptation thresholds for different payload sizes with varying channel characteristics. A link adaptation scheme to maximize the throughput with a packet error constraint is presented