An Energy-Efficient Cooperative Algorithm for Data Estimation in Wireless Sensor Networks

In wireless sensor networks (WSN), nodes operate on batteries and network's lifetime depends on energy consumption of the nodes. Consider the class of sensor networks where all nodes sense a single phenomenon at different locations and send messages to a fusion center (FC) in order to estimate the actual information. In classical systems all data processing tasks are done in the FC and there is no processing or compression before transmission. In the proposed algorithm, network is divided into clusters and data processing is done in two parts. The first part is performed in each cluster at the sensor nodes after local data sharing and the second part will be done at the fusion center after receiving all messages from clusters. Local data sharing results in more efficient data transmission in terms of number of bits. We also take advantage of having the same copy of data at all nodes of each cluster and suggest a virtual multiple-input multiple-output (V-MIMO) architecture for data transmission from clusters to the FC. A Virtual-MIMO network is a set of distributed nodes each having one antenna. By sharing their data among themselves, these nodes turn into a classical MIMO system. In the previously proposed cooperative/virtual MIMO architectures there has not been any data processing or compression in the conference phase. We modify the existing V-MIMO algorithms to suit the specific class of sensor networks that is of our concern. We use orthogonal space-time block codes (STBC) for MIMO part and by simulation show that this algorithm saves considerable energy compared to classical systems.