A power efficient medium access control protocol for heterogeneous wireless networks

Power efficiency is an important issue in wireless networks, since the operating time of mobile terminals is restricted by battery capacity. We propose a power efficient MAC protocol for a heterogeneous wireless network environment in which mobile terminals are able to transmit at various power levels according to the distance separating the transmitter and the receiver. Compared to a fixed-power MAC protocol, in which uniform transmission power is employed, our protocol can reduce the power consumption thanks to the dynamically adjusted transmission power. At the same time, system throughput is improved by better spatial reuse. In addition, the mechanism proposed successfully solves hidden/exposed terminal problems and heterogeneous terminal problems defined in the paper, and deals with node mobility without employing the power-consuming busy tone mechanism. We call our novel protocol RAPO (request-to-send/agree-to-send/plan-to-send/object-to-send).