Performance of Inter-base Station Soft Handoff for 3g Cdma Networks

Soft handoff function is a critical feature for Code Division Multiple Access (CDMA) based networks and contributes significantly to their capacity in terms of carried load. Numerous algorithms and analyses have focused on intra-base station system handoff techniques. However, due to the explosive growth of wireless mobile services, the exploitation of inter-base station soft handoff (inter-BS SHO) is unavoidable. With this mode of handoff, the mobile station communicates simultaneously with two or more base station transceivers belonging to two or more base station systems. Service areas with extreme subscriber density and elongated coverage zones exhibit significant occurrence of this type of handoff. This paper examines inter-BS SHO procedure and characterizes its performance as a function of the protocol stack at the BS system, and the underlying physical layer. A queuing model is developed and key performance figures such as SHO delays and failure rates are given relative to that of inter-BS SHO.