Downlink soft handover and power allocation for CDMA heterogeneous cellular networks

Abstmct Handover in heterogeneous cellular networks is one of the hottest topics for the wireless networks beyond the third generation. This paper presents a new downlink soft handover algorithm to solve the serious “power exhausting” problem during the traditional handover process in heterogeneous cellular systems. The power exhausting problem occurs when in the traditional handover process, the serving base stations usually adopt the equal power allocation (EPA) strategy for different sizes of cells. Thus we propose a constrained unequal power allocation (CUPA) technique to serve handover users by taking account of the effects of different cell sizes and shadowing. Compared to the EPA method, our simulation results show that the proposed soft handover algw rithm combining with the CUPA technique can improve total system capacity by 5% in a homogeneous cellular system, and 73% in a heterogeneous cellular system.