Overlay Handoff Algorithms

An overlay system is a hierarchical architecture that uses large macrocells to overlay clusters of small microcells. The overlay system attempts to balance maximizing system capacity and minimizing cost and when done correctly provides much flexibility to handle changing demands for a region or distinctly different traffic patterns in a region. For example, fast moving traffic would require many handoffs if handled by the microcells. Furthermore, additional channels for a region are needed during certain times (e.g., rush hour), while at another time of the day, these channels are needed for a different region. This chapter proposes an adaptive overlay handoff algorithm that improves overall system performance.