Fuzzy Power Allocation for Opportunistic Relay in Energy Harvesting Wireless Sensor Networks

Abstract

Compared with line powered wireless sensor nodes, power allocation, and rate adaption in energy harvesting (EH) nodes are challenging problems, due to the intermittent nature of the energy arrival process and data causality constraints. To address this problem, in this paper we propose an online fuzzy logic-based power allocation (FPA) scheme for a cooperative and delay constraint EH wireless sensor network (EHWSN) using opportunistic relaying. An EHWSN model is developed with finite energy and data buffer constraints at the relay node. The performance of FPA scheme is evaluated in terms of throughput, fairness, delay, transmission time, and energy consumption. The performance of FPA is also compared with one offline policy and two online policies. It is observed that the delay and the energy consumption of FPA scheme for a given throughput are very close to the offline power allocation policy. The results show that for a given EH profile tradeoff exists between data buffer capacity and throughput for a given payload in all the schemes. In addition, the opportunistic behavior of relay can be controlled by increasing buffer size, however, that may compromise the throughput beyond a certain buffer size. Furthermore, the performance of FPA scheme is also evaluated under Uniform, Rayleigh and Beta distributed energy arrivals.