Saturation Throughput Analysis of 802.11 DCF in Presence of Different Receiver Combining Techniques

The Performance of IEEE 802.11 distributed coordination function (DCF), under ideal channel conditions degrades mainly due to packet collisions at MAC layer. However, studies reveal that MAC layer performance significantly reduces when wireless networks encounter channel fading at physical layer. Since fading results in burst errors, in addition to errors caused by collisions at MAC layer. In this paper, cross layer analysis is performed between MAC layer and physical layer. An analytical expression for throughput computation is used to investigate the effect of fading on the MAC layer performance which is verified through simulation. Further to enhance the network throughput in fading, receiver diversities are used. Selection Combining (SC), Equal Gain Combining (EGC) and Maximal Ratio Combining (MRC) diversity techniques are used at physical layer to calculate the enhancement of the system throughput of MAC layer. Outcomes for different diversities are compared and proposed that the same analysis can be useful for upcoming standards of WLAN using MIMO techniques.