Cooperative partner nodes selection criteria for cooperative routing in underwater WSNs

Underwater environment suffers from a number of impairments which effect reliability and integrity of data being transmitted. Cooperative transmission is well known for reliable data transfer. Hence, cooperative routing can be implemented in Underwater Wireless Sensor Networks (UWSNs) in order to reduce the impact of existing link impairments on transmitted data. Cooperative routing involves data transmission via partner node (relay/destination node) towards sink. Selection of partner node for cooperative routing is to be performed on basis of a certain criterion so that effective results can be achieved. In this paper, two different partner node selection criteria are implemented and compared. We consider source node´s depth threshold (d_th), potential relay/destination nodes´s depth, residual energy and Signal to Noise Ratio (SNR) of the link connecting source node with potential relay/destination node as selection parameters. One criterion considers depth and residual energy while the other also takes link´s SNR into account along with depth and residual energy. SNR based criterion is proved to outperform the one involving only depth and residual energy information. Simulation results show that the SNR based criterion achieves better results with respect to stability period and Packet Acceptance Ratio (PAR) along with reduced delay and packet drop.