A Power-Efficient Scheme for Wireless Sensor Networks Based on Transmission of Good Bits and Threshold Optimization

We propose a power-efficient transmission scheme for wireless sensor networks. In this scheme, the sensor nodes compress their corresponding source-relay channel state information (CSI) and transmit this compressed CSI sequence along with a selected subset of their received bits from the source, which we refer to as the good bits. We assume slowly varying fading channels between source and relays and analytically derive the compression rate of the CSI sequence. We then study the relay-fusion centre link and find an optimal threshold for our proposed scheme, based on the target bit error rate and the packet delivery ratio of the network. Combining the threshold optimization and the reliable bit transmission schemes, we study the total number of transmitted bits for our proposed system. We show that for slowly varying fading channels, our proposed scheme considerably reduces the number of transmitted bits, and consequently the transmission power of the relay nodes compared with a conventional scheme where all bits are transmitted to the fusion center. We also compare the performance of our proposed scheme with a special decode and forward (SDF) scheme previously introduced in the literature. In order to have a fair comparison, we modify the SDF scheme, such that the modified scheme includes the originally proposed SDF scheme as a special case. We provide detailed comparisons and discussions on the achieved bit error rate, energy efficiency, and feasibility of the proposed and the modified SDF schemes.