In this paper, an enhanced soft handoff algorithm is proposed to improve system capacity for multi-rate DS-CDMA cellular systems. In the algorithm, we first propose a load-based power allocation scheme for serving soft handoff users in the forward link; we next develop two kinds of active set determination mechanism: a quality-based active set control (QBASC) scheme and fuzzy active set control (FASC) scheme, to re-select active set members so as to not only save system resource but also maintain required signal quality. Simulation results show that the proposed enhanced soft handoff algorithms can successfully achieve load balancing between cells. Compared to the conventional soft handoff algorithm, QBASC and FASC schemes can enhance 71.43% and 85.71% system capacity in the multirate DS-CDMA cellular system with hotspot, respectively.
['Chao Chi Chen', 'Ching Yu Liao', 'Chung Ju Chang']
The enhanced soft handoff algorithm for multirate DS-CDMA cellular systems