On the Influences of Enlarging or Shrinking the Soft Handoff Coverage for a Cellular CDMA System

This paper is concerned with the influences of enlarging or shrinking the soft handoff coverage on the new-call blocking and the handoff-call dropping probabilities in a cellular CDMA system. In the proposed analytic model, we assume a cell is in hexagonal shape with two parameters, a and b, representing the soft handoff region between the outer and the inner cell. In the traffic model, we assume mobile stations are uniformly distributed over the service area and the new-call generation rate per unit area is a Poisson process. Enlarging the soft handoff region may significantly increase the blocking and the dropping probabilities, while shrinking the soft handoff region can reduce the two probabilities slightly. The effect of activating a call admission control is also discussed. As new-call generation rate per unit area is small, reserving 40% of code channels for handoff calls can reduce the handoff-call dropping probability from 10 to 10, while the new-call blocking probability is increased form 10 to 10. Finally, the analytical model is compared with a previous work and a simulation is performed to validate the accuracy of our proposed model.