Joint rate and cooperative MIMO scheme optimization for uniform energy distribution in Wireless Sensor Networks

An energy efficient adaptive rate cooperative MIMO selection scheme is proposed for uniform load distribution in the cluster based wireless sensor networks. The intrinsic data flow direction in multi-hop cluster based sensor networks causes uneven load distribution in the network. The transit clusters and the clusters near the base station carry more network traffic than the other clusters. Cooperative MIMO can artistically reduce the per bit energy consumption, Space–Time Block Codes are designed to achieve maximum diversity for a given number of transmit and receive antennas with very simple decoding algorithm. In radio fading channel, STBC require less transmission energy than SISO technique for the same Bit Error Rate and can be employed practically in Wireless Sensor Networks by using the cooperative MIMO scheme. Considering Alamouti and Tarokh Space–Time Block Codes, the number of antennas at both the transmission and the reception sides are selected with respect to the cluster load. The crude energy consumption per cluster then refined through adaptive rate transmission. It has been shown that the load based joint adaptive selection of rate and cooperative nodes in clusters renders uniform energy consumption in the network.