Channel-Aware Energy Efficient Transmission Strategies for Large Wireless Sensor Networks

Energy saving is the one of the most critical issues in wireless sensor networks (WSNs) due to limited battery power of sensor nodes. In this paper, we propose a channel-aware type-based multiple access (TBMA) scheme for longer lifetime of WSNs. In an effort to minimize data transmission which is the most energy consuming operation in a sensor device, the proposed scheme allows a subset of sensors to be opportunistically activated in TBMA when their channel gains are higher than a threshold broadcasted by the fusion center to satisfy a given detection error performance (DEP). With the assumption of the channel reciprocity in a narrowband time-division duplexing system, the activated sensors by the threshold exploit channel state information and control their transmit power in a way to maximize an error exponent of the DEP. Here, the broadcasted threshold plays a role in minimizing the number of activated sensors, and thereby it is expected to prolong the lifetime of WSNs. We analyze the DEPs of the proposed and a random selection schemes, and our results show that the proposed scheme provides significant energy saving as compared to the random selection scheme especially in the low signal-to-noise ratio regime.