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Congestion control in Wireless Sensor Networks (WSNs) is one of the key areas of research and different algorithms have been proposed using either of the notions of fair rate allocation, traffic class priority, and queue management. Use of the any one of the above is not adequate to address the challenges. Hence, in this paper, we have proposed a novel congestion control algorithm using the combined notions of fair allocation of bandwidth, prioritizing traffic classes, and Adaptive Queue Management (ADQM). The proposed Weighted Priority based Fair Queue Gradient Rate Control (WPFQGRC) scheme achieves the fair distribution of spare bandwidth by considering the traffic class priority, average queue size, and the connected loads of a node. Average queue size at every node is adapted based on the proposed notion of the gradient of the differential of Global Priority (GP) with respect to the differential of queue size. The output rate of a given node is computed based on the GP of the node and the average queue size. The spare bandwidth of a node is fairly distributed by taking into account the connected load of the given node. The proposed algorithm is developed to suit to a general topology of WSN, however for the sake of illustration, we have considered a tree topology network that deals with both Real-Time (RT) and Non-Real Time (NRT) traffic classes. The proposed algorithm is implemented in NS3 platform in Linux environment and the performance of the algorithm is evaluated in terms of throughput, packet loss, and packet delay. Besides the effect of traffic class patterns, effects of node mobility and the average queue size on throughput have also been studied. The performance of the proposed algorithm is found to be superior to that of Yaghmaee et al.

Wireless Sensor Networks (WSN), when deployed in a real world scenario have to deal with a wide variety of data. Because of the constrained bandwidth, different types of data need to be handled with different priorities in order to prevent congestion in a network. Traffic class priority based rate control algorithms have been proposed by Yaghmaee et al. for congestion avoidance and these are based on the rate difference at a given node. In this research work, we have proposed a Difference of Differential Rate Control (DDRC) algorithm at a given node, which is based on the difference of differential rate between sink node and the given node. The next proposed one is Weighted Priority Difference of Differential Rate Control (WPDDRC) algorithm which is based on the combination of the weighted priority of the traffic class and the difference of differential rate of a given node. This is intended to handle Real Time (RT) data, which may be bursty in nature, and also a combination of the RT and Non-Real Time (NRT) data. Though the proposed algorithms are validated on a fixed topology, they are also valid for the general topology of WSN. The proposed algorithms have been implemented in NS3 platform and the performances of the algorithms have been found to be superior to those of counterpart techniques. INDEX TERMS Rate control, traffic class priority, wireless sensor networks.

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