Experimental evaluation of channel state dependent scheduling in an in-building wireless LAN

Wireless links are often subject to burst errors leading to consecutive packet losses, which could be buffered and transmitted later, giving priority to packets on stronger links. This improves overall bandwidth utilization. A channel state dependent scheduling protocol based on the above idea is developed and implemented in a wireless LAN. A commercial wireless LAN, Lucent Technology´s Wavelan, is used with Pentium based laptops and PCs. The protocol is implemented as a part of the device driver in the Linux operating system. The protocol includes a channel sensing mechanism to help determine when a wireless link comes out of the error state. Experimental performance evaluation with UDP streams and FTP sessions demonstrates the significant performance benefits of channel state dependent scheduling. The performance evaluation includes a novel channel modulation technique based on previously collected traces for reproducibility of experiments