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Round Trip Time Based Adaptive Congestion Control with CoAP for Sensor Network

Constrained Application Protocol (CoAP) was developed to support the communication between resource constrained nodes via low-power links. As an Internet protocol, CoAP needs congestion control primarily to stabilize the networking operation. In this paper we propose a new round trip time based adaptive congestion control scheme, which improves CoAP by utilizing the retransmission count information in estimating the retransmission timeout. An experiment is conducted based on Californium CoAP framework and real devices. It shows that the proposed scheme significantly improves CoAP in terms of throughput and rate of successful transaction.