An optimizable guard-channel-based handover procedure for mobile microcellular systems

In mobile macrocellular systems the effectiveness of queueing and/or channel reservation for handover requests has been widely proved. The authors have previously proposed a priority-based handover algorithm for a mixed macro-microcellular environment. The effectiveness of a combined use of handover request queueing at the microcell level and handover channel reservation at the macrocell level has been shown. However, the use of reserved (guard) channels for handover requests needs for a proper compromise between system performance and frequency reuse efficiency. In fact, any channel which is reserved for handovers contributes to reducing the effectiveness of the system frequency reuse plan. The effects of handover reserved channels on the system performance are explored, in particular by varying the frequency reuse plan of a mixed macro-microcellular system. An optimization potentiality of guard channel allocation is identified. The latter represents an important step toward the design of handover procedures aimed at a proper compromise between frequency reuse efficiency and handover protection in critical urban environments