Abstract: In this article, we suggest a new call admission control (CAC) scheme based on guard channel scheme. Guard channels are set dynamically. Each cellular calculates the current call arrival rate. The call counter feeds the ratio back to the CAC system. Then the CAC system sets the guard channel number by the ratio. This scheme helps to balance the new call blocking probability and handover call blocking probability as different call arrival rate sets different guard channels. A performance comparison using simulation results between the new dynamically set guard channel scheme and the traditional guard channel scheme suggests considerable improvement from the new scheme.