Optimum soft handoff considering non-uniform traffic in CDMA cellular systems

Soft handoff techniques are generally used in the downlink of CDMA cellular systems. When there is traffic deviation, the communications quality differs between cells. Some methods of equalizing the quality, such as signal-to-interference ratio (SIR)-based power control methods and flexible cell control methods have been developed. The method described in this paper controls the transmission power ratio allocated to the mobile stations in a soft handoff region according to the traffic load. The SIR difference between cells can be reduced by controlling the power transmitted to the soft handoff mobile stations. We calculate an optimum power allocation ratio for minimizing the SIR difference for a given traffic deviation range and the downlink orthogonality factor.