SRCP: Sensor Reliability and Congestion Control Protocol

In this paper, a new transport protocol called Sensor Reliability and Congestion Control Protocol (SRCP) is proposed for Wireless Sensor Networks (WSNs) which has both the functionalities of providing end-to-end reliability as well as delay-based congestion detection and control. It uses packet sequence numbering and Selective Negative Acknowledgements (SNACKs) for providing reliability in the form of retransmissions. The sink continuously records trip times and receives the rate of incoming packets and observes the delay trend. Congestion is avoided and actively controlled by sending control packets containing packet receiving rate value to the sending sensors if there is an increase trend in the trip times. Exact rate adjustment is performed by the sender according to the receiving rate and then slow additive increase is done after small fixed intervals of time resulting in fairness among sensors. The simulation results show that SRCP saves a lot of energy by scheduling packets according to the channel capacity, resulting in small number of packet losses while maintaining the data fidelity.