Novel energy efficient relaying schemes for wireless sensor networks

This paper proposes novel relaying schemes based on recently proposed Modified Alamouti Code and Time Switch Space Time Coding for a homogeneous sensor network architecture. New relaying schemes based on the incorporation of aforementioned techniques in a Sensor Network framework are considered. An exhaustive analysis in terms of the total energy consumption and delay characteristics as performance metric is investigated and quantified both for stand alone and clustered sensor networking scenario. Variable Rate M-QAM modulation schemes are considered for varying gateway distances. It is observed that for the standalone case, the proposed schemes can provide significant savings in terms of energy consumption as compared to non cooperative mode and conventional Alamouti scheme. For clustered case, conventional Alamouti based scheme outperforms the proposed relaying scheme up to a certain critical threshold distance beyond which the M-Alamouti based relaying schemes becomes slightly more efficient by 16 % when we have a single antenna gateway and cluster distance is 100m and gateway distance is 500 meter. Similar trend is observed when the distance between the clusters is increased from 100 to 200 meters. For a system with gateway having single and dual antennas the energy efficiency with respect to a non cooperative single antenna gateway system falls typically within a window of 70 to 90% for long haul distances around 320 m onwards.