The University of British Columbia

In mobile cellular systems, handoff call blocking is less tolerable to the subscribers than new call blocking. To give handoff calls a lower blocking probability, the fixed guard channel scheme reserves a number of guard channels for handoff calls, which share the remaining channels with new calls. The number of guard channels is fixed and may be too high when handoff traffic is low, and vice versa. We propose a dynamic guard channel scheme which dynamically varies the number of guard channels in a cell with a current estimate of the handoff traffic, given by the current number of ongoing calls in neighbouring cells. We present a performance comparison of the fixed and the proposed dynamic guard channel schemes under the blocked-calls-dropped service discipline for both the new and handoff calls, and show that the adaptive control capability of the proposed dynamic guard channel scheme provides better performance when the system is subjected to non-stationary call arrival rates