Channel assignment for wireless cellular system with multi-rate traffic

In cellular communication systems, an important problem is to allocate the communication resource (bandwidth) so as to maximize the service provided to a set of mobile callers whose demand for service changes stochastically. In this thesis, we will focus on the problem of channel assignment for cellular wireless system with multi-rate traffic. We will study the use of fixed, dynamic and hybrid channel assignment in multi-rate system. In Fixed Channel Assignment (FCA), a call in a particular cell can use only the group of channels preassigned to that cell. FCA algorithm is easy to implement and the blocking probability is easy to control. In the thesis, we make use of some knowledge in graph theory to derive the lower bound for the bandwidth units needed to satisfy certain call requirements. The lower bound is regarded as the Generalized Clique Bound. In Dynamic Channel Assignment (DCA), a channel can be used in any cell, provided that the interference constraint is satisfied. Among the several proposed algorithms, the one with rearrangement of calls performs the best. Some mathematics are done to analyze a simplified system. The state probability formula is derived. Simulation results are shown to verify the accuracy of the formula. Hybrid Channel Assignment (HCA) is the combination of FCA and DCA. Since FCA is good for heavy traffic and DCA is good for light traffic, we propose HCA to deal with the case of intermediate traffic. It is shown that in terms of the bandwidth usage efficiency, HCA performs better than pure FCA and DCA