Mobility Aided Cooperative MIMO Transmission in Wireless Sensor Networks

Energy efficiency in data collection and transmission is always a crucial factor in wireless sensor network (WSN). Unreliability in data transmission is very common for long range communications in WSNs. Factors like fading of channel, interference and radio irregularity further pose a big challenge on the design of energy efficient data transmission protocols in WSNs. Cooperative MIMO (Multiple Input Multiple Output) communication may help to solve these problems in long range transmission. In this paper we propose a mobility aided cooperative MIMO based communication model where a few mobile sensors using Alamouti diversity schemes take part in cooperative communication. A mobile sensor can move to a specific location of the field, gather the sensed data from the nearby sensors and finally transmit cooperatively to the sink or other cooperative sensor node. We take two different types of sensors, namely Listeners and Supervisors, which are deployed together in the field, each having different kinds of responsibilities. Listeners only sense the environment and communicate the sensed data to the Supervisors. Supervisors (usually do not sense) are capable of moving and they have higher capacity in terms of battery power (also rechargeable) and communication range than the Listeners. This model of communication helps in achieving both uniform energy expenditures by the nodes and a good average lifetime for the network. By choosing some costly re-chargeable supervisors, we can avoid the problem of energy expenditure in cluster head selection as well as dynamic cooperative node selection of any Cooperative MIMO based LEACH (Low-Energy Adaptive Clustering Hierarchy) protocol. Simulation results demonstrate the working strategy of the proposed model and show much better result in terms of network lifetime than an existing energy efficient LEACH based cooperative MIMO model.