Implementing a low power TDMA protocol over 802.11

A wireless network of remotely located, self-powered video sensors must make efficient use of limited network capacity and power. An ideal media-access protocol for such a network would fully utilize available throughput while using no more power than necessary and maintaining a reasonable level of fairness. To accomplish these goals, the paper proposes and evaluates a time-division multiple-access protocol that may run on top of unmodified IEEE 802.11 hardware. Our protocol uses an 802.11 access point as a controller for a set of 802.11 clients. The controller allocates timeslots to its clients; during its timeslot, a client may send to and receive from the controller. Each client may turn its radio off during other clients' timeslots to save power that would otherwise be wasted contending for a busy channel. We compare and contrast our protocol to other wireless power-saving mechanisms, then discuss the design and implementation of our protocol and its performance compared to standard 802.11 in terms of throughput, power, and fairness. We conclude that our protocol offers a significant reduction in power consumption and improved fairness. Finally, we show that our protocol's throughput is similar to that of standard 802.11.