Adaptive soft handoff method using mobile location information

This paper presents an adaptive soft handoff algorithm that dynamically calculates the threshold values for soft handoff based on mobile location, signal strength and RF propagation statistics. An analytical model has been previously developed to study the performance of an adaptive hard handoff method using mobile location information. We extend the adaptive hard handoff algorithm to study the performance of an adaptive soft handoff algorithm and also analyze the soft handoff considerations. Unlike conventional soft handoff algorithms, the threshold values for the adaptive soft handoff algorithm are chosen dynamically based on a set of quantitative descriptors for various propagation environments. Simulation results show that the adaptive soft handoff method reduces the unnecessary handoff probability and the number of base stations in the active set while still maintaining the call quality. This improvement is significant if the propagation signal varies rapidly in the cell or in the dense urban area.