Congestion Control in ATM Networks Using Fuzzy Logic

ATM is the paramount cell transmission technology supports a variety of applications and services with the appropriate Quality of Service. ATM networks requires flexible traffic control scheme to trim down the congestion, which helps to maintain the Quality of Service and utilize the resources in better way.
Call admission control is the mechanism employed in ATM networks to accept and reject the number of incoming connection based on the traffic analysis. CAC objective is maximizing number of connection and provide the Quality of service as mentioned in SLA.CAC based on complex queuing methods which using algorithms to make decision based on capacity of network resources. The algorithm must be simple it should minimize delay latency when attempting to accept or reject the connection and it attempt to achieve balance between cell loss and link utilization. Generally the problem of the CAC lies in the limitation to acquire complete and statistics if the input traffic.
Conventional CAC fails to gather complete statistics due to dynamics of the networks that randomly change its behavior of input traffic. Fuzzy based CAC implements the functionality that conventional CAC lacks to perform. The use of fuzzy based CAC implements fuzzifier which functionality is convert the crisp(non-fuzzy)input to fuzzy based inputs and the de-fuzzifier blocks converts the fuzzy output passing through the fuzzy inference model to a single valued crisp output. The fuzzy based CAC admit new connection after performing the following fuzzy operations.
Bandwidth Estimator, which takes, input parameters from the user such as PCR (Peak Cell Rate), SCR (Sustainable cell rate) and peak cell duration and then manipulates the value of required bandwidth. Congestion detector is the second fuzzy operations, which determines the state of congestion in ATM network based on three parameters.
They are buffer size, change in buffer and CLR (Cell Loss Ratio).if the buffer size is low and there is no decrease in the number of buffer elements over a period and CLR is high then the output of congestion indicator size is high. Fuzzy operation, which makes final decision based on bandwidth detector output, Congestion control detector output and CLR (Cell Loss Ratio) and generates output. The defuzzified output has to decide whether the call has to be accepted or rejected.

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