On the Coexistence of Overlapping BSSs in WLANs

In this paper, the authors investigate the issue of 20/40 MHz coexistence in next generation Wireless Local Area Networks (WLAN). To that end, they present simulation results of overlapping Basic Service Sets (BSSs) an 802.11n BSS operating in 20/40 MHz mode and a legacy BSS operating in 20 MHz channel. Their results show that if Clear Channel Assessment (CCA) is not used in the overlapping channel; i.e., the 20 MHz channel used by both BSSs, the throughput in legacy BSS falls to zero, while the throughput of 802.11n BSS decreases dramatically. If CCA is used in the overlapping channel, the throughput of both, legacy and 802.11n BSS increases compared to the earlier case.