Power-efficient estimation in IEEE 802.11ah wireless sensor networks with a cooperative relay

We consider a wireless sensor network (WSN) where each sensor node samples a random signal and transmits the result to an access point (AP)/fusion center (FC). The WSN operates under the sub-1GHz IEEE 802.11ah MAC/PHY standard and it also includes a relay node that may be used for forwarding the data to the FC. The FC collects the data from the sensors and the relay and estimates the random signal of each sensor with the linear weighted least squares (WLS) algorithm. The objective of the FC is to minimize the power consumption of the sensors subject to an MSE distortion constraint by selecting the use of the relay for the sensors that need it. We cast the power minimization problem as a mixed integer linear program (MILP). Our detailed simulation results indicate the efficacy of our scheme under a path loss channel model and randomly deployed sensor populations, while the performance gains are increased even more for denser sensor population. Since the IEEE 802.11ah standard leaves open aspects related to the relay selection process for IEEE 802.11ah-based WSNs, our system can be readily implemented in this emerging class of WSNs.