Constrained Application Protocol (CoAP) is a communication protocol at application layer in the Internet of things (IoT). It employs NSTART parameter to maintain outstanding parallel connections toward individual destinations for data transfer. In the existing implementation of CoAP, the value for NSTART is defined statically. Where the higher values of this parameter up to a threshold give better throughput in moderate traffic, the lower values for the same control the congestion in overload situations. In overload situations, higher values of NSTART result in increased overhead and thereby perform poorly in terms of throughput. The static nature of the parameter and its relevant performance issues demand to manage NSTART dynamically in CoAP. In this work, we propose an algorithm to adjust the value of NSTART dynamically based on the congestion in the network. The proposed approach is an attempt to make the client free from managing NSTART dynamically. For the proof of concept, we implement and run simulations on Cooja mote at IoT/FIT-Lab testbed and Californium CoAP client. The results show 15% improvement in throughput, 15% reduction in average exchange duration, and 48% reduction in average number of retries (average taken of three scenarios) by proposed approach in comparison with the best case of CoCoA (NSTART = 4).

约束应用协议（CoAP）是物联网（IoT）中应用层的通信协议。它使用NSTART参数来维持与各个目的地的出色并行连接，以进行数据传输。在CoAP协议的现有实施，为值n开始定义是静态的。如果此参数的较高值（达到阈值）在中等流量中提供更好的吞吐量，则相同的较低值将控制过载情况下的拥塞。在过载情况下，较高的NSTART值会导致开销增加，从而在吞吐量方面表现不佳。参数的静态性质及其相关的性能问题要求管理NSTART在CoAP中动态地。在这项工作中，我们提出了一种基于网络拥塞动态调整NSTART值的算法。提出的方法是尝试使客户端摆脱动态管理NSTART的麻烦。为了进行概念验证，我们在IoT / FIT-Lab测试平台和Californium CoAP客户端上的Cooja mote上实现并运行了仿真。结果表明，与CoCoA的最佳情况（NSTART = 4）相比，所提出的方法将吞吐量提高了15％，平均交换持续时间减少了15％，平均重试次数减少了48％（三种情况的平均值）。