An adaptive traffic control scheme for hierarchically structured CDMA cellular systems

Hierarchical Cell Structure(HCS) describes a system when at least two types of cells (e.g, macrocell and microcell) operate one upon another. Due to increasing demand in the capacity of future cellular systems, HCS is expected to be increasingly popular trend in cellular system design. In this paper, we have proposed a traffic control mechanism for CDMA HCS, which dynamically adopts to varying traffic environment by redistributing traffic between macrocell and microcell. The proposed scheme dynamically adjusts coverage ana of microcell to maintain a required signal to interference ratio in both microcell and macrocell. Performances wen measured in terms of call blocking probability and call failure probability. Call blocking rate improves when the system is lightly loaded and the loads an unbalanced between macrocell and microcell. Performance improvements were significant in terms of call failure rate.