SNR-WPA: an adaptive protocol for mobile 802.11 wireless LANs

This paper presents a method for dynamically setting 802.11 wireless LAN waveforms and transmission power levels based on the wireless channel´s signal to noise ratio. Our method, known as the signal-to-noise ratio-waveform power adaptation (SNR-WPA), changes the power in discrete steps matched to each of the 802.11 data rate-waveform steps. By matching the power to the spreading symbol rate, our technique maximizes the network throughput while minimizing the MAC layer contention. Unlike the other power adaptation methods, this method does not increase the wireless LAN (WLAN) station´s overall effective operational range and does not change the minimum-spanning tree used to calculate routing. We found through experimentation that the power adaptation in SNR-WPA yields up to a 30% increase in throughput in a mobile wireless LAN network.