Win CoAP: A Window-Based Congestion Control Approach for Burst Traffic in IoT Networks
Archana K. Rajan, Masaki Bandai · IEEE Access · 2025
Constrained Application Protocol (CoAP) is a widely used communication protocol in Internet of Things (IoT) networks. Congestion is a major concern in IoT networks as it affects the performance of applications as well as network reliability. Congestion control (CC) needs to be employed by the application since CoAP is based on User Datagram Protocol (UDP). IoT devices transfer burst of data upon detecting an event. There are suitable features in Non-confirmable (NON) message type of CoAP for burst data transfer. Absence of CC method for NON message type in CoAP hinders its applicability. OBSERVE defines a static rate control for NON messages which is inappropriate for dynamic needs. The Block-wise Transfer also employs static rate control for NON message blocks, resulting in the same limitation. CoAP simple congestion control/advanced (COCOA) provides a dynamic CC method for NON message type. COCOA employs reliable packets inside NON message burst at regular intervals to capture network dynamics. Infringement of reliable packets adds up overhead and periodic monitoring caters to insufficient vigilance. In this paper, we propose a window-based dynamic congestion control method calledWin CoAP to regulate the burst traffic based on the window of packets.Window size is additively increased on successful delivery and adaptively decreased otherwise. Win CoAP is implemented and validated against COCOA using the Cooja simulator in Contiki OS. We carried out extensive simulations using different topologies and burst rates. Win CoAP outperforms COCOA in all analyzed scenarios and can improve the efficiency of event-based applications.