SYNCHRONIZED CALL HANDOFF ALGORITHMS IN CELLULAR RADIO SYSTEMS

Abstract

This thesis is primarily concerned with the analysis of adaptive handoff algorithm in microcellular radio system for teletraffic load dissipation and equalisation. It reports the development of a novel hierarchical optimization handoff algorithm (HOHA) which not only reduces the probability of handoff failure but also attempts to equalize the teletraffic load distribution among the microcells. In general, our proposed hand off algorithm scans through layers of call handoff options and determines the best candidate based on a heuristic that synchronises reciprocal handoffs in adjacent cells and maximises the spare channel capacity in the destination cells. Our analysis and computer simulation studies show that the proposed HOHA technique improves the performance of the microcellular mobile radio network significantly, in terms of reduction in the probability of handoff failure and greater teletraffic load carried over the entire network. The proposed HOHA technique is also analysed together with the fixed channel assignment scheme [8,10], and dynamic channel assignment scheme [12,13]. It is found that our proposed handoff algorithm gives superior performance over the conventional handoff algorithms. Specifically, our proposed algorithm minimizes the probability of handoff failure with no penalty in total system load capacity. A complete analytical model using a 10-state Markov process to represent the characteristics of the HOHA technique is also introduced [9,11]. An approximate closed form expression is derived for the probability of handoff failure as a function of number of hops required to achieve a successful handoff process. The upper bound performance of the HOHA technique and its limitation is also derived and analysed.