Channel Assignment in Multimedia Cellular Networks
This paper deals with multimedia channel assignment in a hexagonal cellular network with two-band buffering. After deriving a lower bound on the minimum bandwidth for real-life situations, we present an algorithm for assigning channels using Genetic Algor
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BSNL, Calcutta - 700 001, India [email protected] ACM Unit, Indian Statistical Institute, Kolkata - 700 108, India
Abstract. This paper deals with multimedia channel assignment in a hexagonal cellular network with two-band buffering. After deriving a lower bound on the minimum bandwidth for real-life situations, we present an algorithm for assigning channels using Genetic Algorithm (GA). We also propose an elegant technique for re-use of the channels, using only eighteen distinct frequency bands on a nine-node subgraph of the network, and then extend it for assignment of the complete network. The proposed algorithm converges very rapidly with required bandwidth close to the derived lower bound.
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Introduction
The Channel Assignment Problem (CAP) for a mobile cellular network is the task of assigning frequency channels to the calls satisfying some frequency separation constraints with a view to avoiding channel interference and using as small bandwidth as possible [5]. A lower bound on bandwidth requirement for assigning multimedia channels to a hexagonal cellular network has been derived in [6], considering only two types of multimedia signals, say type A and type B, with a single demand of each type at each node of the network. In this paper, we use the same system model as used in [6] and first estimate the lower bounds on the required bandwidth for assigning channels in some real-life situations. We next present an algorithm for solving the multimedia channel assignment problem, using genetic algorithm (GA), under the condition of 2-band buffering and with only two types of multimedia signals where each cell has a single demand for each type of signal. We then select a subset of only nine nodes of the network and propose a clever technique of re-using the frequency channels so that by repeatedly using only eighteen bands (two bands for each node for assigning both the types of multimedia signals), the required assignment for the whole network can be completed. For this purpose, we first find the required frequency separation constraints among the channels to be assigned to the different nodes of the network, and then use our proposed GA-based algorithm for assigning the multimedia channels for the complete network. Experiments show that the proposed assignment algorithm converges very rapidly and assigns channels with a bandwidth close to the derived lower bound. S. Rao et al. (Eds.): ICDCN 2008, LNCS 4904, pp. 540–545, 2008. c Springer-Verlag Berlin Heidelberg 2008
Channel Assignment in Multimedia Cellular Networks
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Notations
We denote the bandwidths required for type A and type B signals as BWA and BWB , respectively. W.l.o.g, we assume that BWA ≥ BWB . The required frequency separations for avoiding interference in a 2-band buffering system between two calls in the same cell, in two cells distance 1 apart and in two cells distance 2 apart are denoted by 1) s0 , s1 and s2 , respectively for the two type A calls, 2) s0 , s1 and s2 , respectively for the two calls, one of type A and the other of
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