Aggressive fuzzy distributed dynamic channel assignment for PCS

In this paper, two variants of the aggressive fuzzy distributed dynamic channel assignment (AFDDCA) schemes, namely, the aggressive simple fuzzy distributed dynamic channel assignment (AFS-DDCA) scheme and the aggressive maxavail fuzzy distributed dynamic channel assignment (AFMA-DDCA) scheme, are introduced. The respective crisp counterparts of the two schemes are the simple and the maxavail schemes formulated by McEliece and Siverajan of Caltech (1989, 1990). The crisp and the fuzzy versions of both schemes are identical in formulation and complexity, except: (1) fuzzified constraints are used in the fuzzy schemes while crisp constraints are used in the crisp schemes; (2) the fuzzy schemes automatically enter aggressive mode when all perfectly feasible channels are not available. Under this scenario, slightly less feasible channels are activated for assignment. The aggressive feature can be interpreted as a soft constraint violation. Fuzzifying constraints effectively enlarge the feasible solution space and hence can increase throughput performance with simple search schemes. We will show through simulations that both AFDDCA variants surpass their crisp counterparts in throughput performance. Quality degradation due to constraint violation is mild. Hence, the grade of service (GOS) is better than that of many DCA algorithms based on complex search schemes