Optimization models for call control in cellular radio networks

Abstract

The growing demand and diversity of mobile communication services present an array of technical challenges which must be met in order to provide high quality service to users. Among them, call control and frequency assignment have been standard and critical procedures in the design and operation of the mobile communication system. This thesis is concerned with some optimization models for the call control and frequency assignment in cellular radio networks. Call control, for the systems which have a variety of call types with the different characteristics, is the problem of, when a certain call is generated, determining whether to accept that call or not. Many priority-oriented strategies have been reported in the literature, which can be assorted into several categories according to the way how limit entrance of non-prioritized calls and how handle the rejected calls at their first attempts. Representative mobile communication systems on whose performances the call control strategies play a great role are the dual-mode TDMA system and the system with handoff calls. The dual-mode TDMA system has to support both analog and digital calls. According to the current establishments every one analog call consume radio resources upto six times than digital calls. Therefore, some priority should be given to the digital calls over the analog calls for optimizing the system performances such as average blocking probability. The threshold type strategy without queueing is adopted in this study, which limits the number of active analog calls in a cell within a given value and allows neither of calls to be queued. After analyzing mathematically relationships between blocking probabilities, we formulate two non-linear integer problems for single and multi-cell systems. One of them is to determine the number of required channels, and the other is to find out the threshold value for each cell which optimizes the performance criterion, while satisfying the prespecified GOS f...