Voice over wireless LAN via IIEE 802.16 wireless MAN and IEEE 802.11 wireless distribution system

Today, IEEE 802.11 wireless LANs (WLAN) have been widely deployed to provide wireless broadband access in local areas such as campuses or offices. Most of the WLANs are connected to the backbone via a wired distribution system (DS). IEEE 802.16 wireless MANs (WMAN) aim to extend the wireless broadband access up to kilometers to facilitate the long-range "last-mile" solution. For short-range extension, IEEE 802.11 wireless distribution system (WDS) can be set up easily by connecting access points (AP) together to form multi-hop networks. This provides a quick, easy and low-cost solution up to hundreds meters. In this paper, we exam the capacity challenges in delivering voice traffic over WLANs which are connected to 1) IEEE 802.16 WMAN and 2) IEEE 802.11 WDS. For 1), we show that the capacity is limited by the WLAN bottleneck and we propose a multiplex-multicast (M-M) scheme to double the capacity. For 2), we show that the M-M scheme should also be adopted in WDS. This scheme can sufficiently improve the voice capacity up to 7 times (from 3 to 22 voice sessions) in a 4-hop WDS. To verify our simulation results in Ng, P.C. et al, (2005), we set up a real multi-hop WDS. Experimental measurements confirm that our proposed scheme can increase both the voice capacity and service coverage of WDS.