Cooperative Hybrid ARQ in Solar Powered Wireless Sensor Networks

Energy harvesters are used in today’s Wireless Sensor Networks (WSNs) to harvest energy from the environment. Although an energy harvester can provide a supply source with a much greater lifetime than a battery, the amount of available energy for an energy harvesting system is a random variable. Furthermore, the proper management of energy harvesters has a considerable impact on reliability. It has been observed that cooperative error control mechanisms like Cooperative Automatic Repeat Request (C-ARQ) and Cooperative Hybrid ARQ (C-HARQ) can be used for improving the energy management and reliability in Energy Harvesting WSNs (EH-WSNs). Recently, the impact of C-ARC mechanism has been considered in an energy harvesting system (GAP4S), however, GAP4S is an EH-WSN powered by microwave with linear recharge rate and unbounded storage capacity. This work evaluates the effect of C-HARC using a new method of relay node selection in EH-WSNs which are powered by the solar energy and have variable recharge rates. Furthermore, a comparative study of C-ARQ and C-HARQ mechanisms, considering the impact of variations in transmission rate and packet error probability on the energy consumption, is provided. The results show that C-HARQ outperforms C-ARQ under the same conditions and the energy consumption of a relay node in C-HARQ is 50% less than the one in C-ARQ.