基于CoAP协议的泛在电力物联网拥塞控制算法

泛在电力物联网具有接入节点数多、设备资源受限的特点，易发生网络拥塞而导致电力信息流丢失、时延过大等问题。基于受限应用协议（CoAP）的泛在电力物联网应用层通信架构，提出一种链路稳定性的CoAP拥塞控制（L-CoCC）算法。通过强、弱和失败消息往返时间来确定网络环境状态并平滑估计超时重传时间（RTO），根据超时重传次数和消息往返时间抖动值，引入下界RTO限制方法和更新老化概念，避免出现不必要的重传。仿真结果表明，相比CoCoA++和CoAP算法，L-CoCC算法能够提升吞吐量和请求成功率，降低平均端到端时延，有效缓解网络拥塞。

Congestion Control Algorithm for Ubiquitous Electric IoT Based on CoAP Protocol

Ubiquitous electric IoT is characterized by massive access nodes and limited device resources.When providing reliable transmission service, ubiquitous electric IoT tend to suffer from congestion, resulting in loss of power information flow and excessive delay.To solve this problem, a link-stability-based congestion control algorithm, L-CoCC, is proposed based on the Constrained Application Protocol(CoAP) for the application layer in ubiquitous electric IoT.By using the Round-Trip Time(RTT) of strong, weak and failed messages, the algorithm determines the state of the network environment and smoothly estimates the Retransmission Timeout(RTO).Based on the number of retransmission times and the fluctuation value of message RTT, a method for limiting the lower bound RTO is introduced, and the aging concept is updated to avoid unnecessary retransmissions.The experimental results show that compared with the CoCoA++ algorithm and the CoAP algorithm, the proposed algorithm improves the throughput and the success rate, and reduces the average delay.It can effectively alleviate network congestion.