A lower bound on SINR threshold for call admission control in multiple-class CDMA systems with imperfect power-control

Call admission control (CAC) is essential to guarantee the signal quality in CDMA systems. Signal-to-interference-and-noise ratio (SINR) is used as the criterion for user admission by comparing the SINR with a predefined threshold value (SINR_th). Lowering this threshold level is desirable to reduce the blocking rate. However, a lower bound of SINR_th is vital to keep the outage probability (P_out) below a maximum value. In this paper, we derive this lower bound of SINRth (SINR_th-lb) for multi-class CDMA systems with imperfect power control. SINR_th-lb of class i (SINR_th-lb(i), i=1, 2,...., L) is determined by finding the relationship between P_out(i) (i=1, 2,...., L) and SINR_th(i) (i=1, 2,...., L) where L is the number of classes. Then, SINR_th-lb(i) is determined as the lowest value of SINR_th(i) that keeps the outage probability of all classes below the corresponding maximum values.