This paper addresses the energy consumption of forward error correction (FEC) protocols as used to improve quality-of-service (QoS) for wireless computing devices. The paper also characterizes the effect on energy consumption and QoS of the power saving mode in 802.11 wireless local area networks (WLANs). Experiments are described in which FEC-encoded audio streams are multicast to mobile computers across a WLAN. Results of these experiments quantify the trade-offs between improved QoS, due to FEC, and additional energy consumption caused by receiving and decoding redundant packets. Two different approaches to FEC are compared relative to these metrics. The results of this study enable the development of adaptive software mechanisms that attempt to manage these tradeoffs in the presence of highly dynamic wireless environments.
