A channel borrowing protection scheme for handoffs in a cellular-based PCS system

For a cellular based PCS system that supports mobile as well as non-mobile users, the forced termination of mobile calls due to handoff failure is an important performance measure, in addition to the new call blockings. Generally speaking, the dropping of ongoing calls annoys users more than the blocking of new calls, thus for systems with small cell sizes some protection schemes should be adopted to reduce the handoff failure probability. However, these schemes do improve the handoff performance but increase the new call blockings on the other hand. This paper proposes a handoff protection scheme that combines the concepts of channel borrowing and cell overlaying. This scheme was originally used in previous work for reducing new call blockings of systems with only one class of non-mobile users and fixed channel assignment. The paper applies the scheme to protect handoffs for the systems that accommodate a mixture of non-mobile and mobile users. By examining system performance measures, it is concluded that the scheme substantially reduces the forced termination probability of mobile calls with almost no impact on new call blocking probability, thus improving the overall system performance.