Energy optimal transmission scheduling in wireless sensor networks

Abstract

One of the main issues in the design of sensor networks is energy efficient\ncommunication of time-critical data. Energy wastage can be caused by failed\npacket transmission attempts at each node due to channel dynamics and\ninterference. Therefore transmission control techniques that are unaware of the\nchannel dynamics can lead to suboptimal channel use patterns. In this paper we\npropose a transmission controller that utilizes different "grades" of channel\nside information to schedule packet transmissions in an optimal way, while\nmeeting a deadline constraint for all packets waiting in the transmission\nqueue. The wireless channel is modeled as a finite-state Markov channel. We are\nspecifically interested in the case where the transmitter has low-grade channel\nside information that can be obtained based solely on the ACK/NAK sequence for\nthe previous transmissions. Our scheduler is readily implementable and it is\nbased on the dynamic programming solution to the finite-horizon transmission\ncontrol problem. We also calculate the information theoretic capacity of the\nfinite state Markov channel with feedback containing different grades of\nchannel side information including that, obtained through the ACK/NAK sequence.\nWe illustrate that our scheduler achieves a given throughput at a power level\nthat is fairly close to the fundamental limit achievable over the channel.\n