Lower bound of weighted fairness guaranteed congestion control protocol for WSNs

In wireless sensor networks, congestion not only leads to packet loss, but also increases delays and lowers network throughput with a lot of energy wastage due to retransmissions. Therefore an effective solution should be proposed to mitigate congestion to increase energy efficiency and prolong the lifetime of network. Traditional solutions work in an open-loop fashion. In this paper, we propose a novel decentralized and weighted fairness guaranteed congestion control protocol (WFCC). WFCC introduces node weight to reflect the importance of each node, and uses the ratio of packet inter-arrival time to packet service time as congestion metric. Based on node weight and congestion metric, WFCC divides time axis into period sequences, and uses closed-loop control method to mitigate congestion by adjusting the incoming data rate of each node periodically. Importantly, WFCC introduces a weighted fairness metric and gives its lower bound for the first time, i.e., 1 - (10c/9)² where 0 <; c <; 0.2 is a constant. The results of simulation show that the weighted fairness of WFCC achieves 95% on the average, which is much better than the existing rate-based congestion control protocol. Moreover, WFCC achieves 50% and 19% gains in network throughput and weighted fairness on the average, compared with PCCP that is the state-of-art rate control based congestion control protocol.