Discrete-time analysis of soft handoff in CDMA cellular networks

Proper design of soft handoff mechanisms for CDMA cellular networks is critical to overcoming propagation impairments and providing a transparent radio access service for multiple data user profiles. The connectivity of the mobile user to the core network via an active set of access points is determined dynamically by the handoff algorithm via measurements of received pilot signal strengths. Using a discrete-time framework, we derive analytical expressions and develop associated numerical procedures for evaluating the soft handoff performance of a mobile unit travelling along an arbitrary straight-line trajectory in a CDMA cellular network. In particular, we obtain expressions for the cell assignment probabilities, which can be used to compute performance measures such as outage probability, macrodiversity gain, and signaling load. Our methodology provides an accurate and efficient means of designing and dimensioning high performance soft handoff algorithms for CDMA networks, while avoiding the need for approximations or time-consuming computer simulation.