In Wireless Sensor Networks (WSN's), congestion plays an important role in degrading the performance of the network. Under idle condition, the network load is very low whereas when an event is detected the network load becomes high which leads to congestion. Due to congestion the overall performance of the network degrades. Hence it is necessary to detect and control congestion. In this paper an efficient technique to detect and control congestion has been proposed. The congestion is detected by calculating a metric called Congestion Degree (Cd). It is the ratio between packet inter arrival time and packet inter service time. Once the congestion is detected, it is notified using Implicit Congestion Notification (ICN) signaling. On receiving the congestion notification signal, the transmission rate is controlled in order to reduce congestion. Further congestion control is implemented using Fuzzy Logic Controller. The performance of the network is measured for delivery ratio with different transmission rate and the PDR is compared with CODA.

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Mobile ad hoc network is an autonomous system of mobile nodes characterized by wireless links. The major challenge in ad hoc networks lies in adapting multicast communication to environments, where mobility is unlimited and failures are frequent. Such problems increase the delays and decrease the throughput. To meet these challenges, to provide QoS, and hence to improve the performance, a scheduler can be used. In this paper we design a fuzzy-based priority scheduler to determine the priority of the packets. The performance of the scheduler is studied with the multicast routing protocols. The scheduler is evaluated in terms of the quantitative metrics such as packet delivery ratio and average end-to-end delay and the results are found to be encouraging.

Mobile Ad-hoc network is an autonomous system of mobile wireless nodes connected dynamically without any preexisting infrastructure. Here, since the nodes are mobile, the network topology changes rapidly and unpredictably over time. The QoS routing has challenging problems due to the network's dynamic topology. The multi hop wireless forwarding of packets, broadcasting of control traffic and the fact that, all nodes may act as routers in addition to being sources and sinks of data in ad-hoc networks produce different Queuing behaviour. Hence, a scheduling algorithm to schedule the packets based on their respective priorities will improve the performance of the network. Here, we present an efficient fuzzy based priority scheduler for mobile ad-hoc networks, to determine the priority of the packets. The performance of this scheduler is studied using GloMoSim and evaluated in terms of quantitative metrics such as packet delivery ratio, average end to end delay and throughput. It is found that the scheduler provides overall improvement in the performance of the system with various mobility models, when tested with different routing protocols.

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