Channel assignment and layer selection in hierarchical cellular system with fuzzy control

We consider a hierarchical cellular system, which consists of a macrolayer and a microlayer. The macrocells accommodate fast mobile users. However, if we direct too many mobile users to the macrocells, the system capacity is low On the other hand, the microcells are designed to increase capacity, bu t they cause a large number of handoffs, The aim is to maximize the system capacity while keeping the amount of handoff small. We minimize the handoff rate by a fuzzy layer selection algorithm, which makes use of the past cel l dwell times of a user and the channel occupancy of the target cell. To ma ximize the capacity, we propose a distributed channel assignment algorithm to dynamically allocate the channels among the two layers. Exchange of info rmation is allowed between neighboring macrocells. The state of channel ass ignment in a macrocell and its interfering cells are tabulated in a channel allocation table, which provides all information required in the integrate d resource allocation scheme, The performance is evaluated by simulation an d compared with the popular layer selection scheme known as the threshold m ethod.