A CAC scheme with code and interference limits on the forward link in CDMA cellular network

Future CDMA cellular networks are expected to carry a wide variety of data traffic. Traffic characteristics of data users can be characterized by burstiness and asymmetricity. Data traffic such as in Internet web browsing applications show asymmetric characteristics that cause a relatively heavy load on the forward link. Bursty data can drive the system into a situation wherein available CDMA codes are depleted even when there is enough margin of signal-to-interference ratio (SIR) to accept a new call. Thus, we propose a new call admission control (CAC) scheme on the CDMA forward link that reserves both some codes and interference margin for handoff calls. With the proposed CAC scheme, we construct a Markovian model for voice and data calls (two classes) in progress. The proposed scheme is compared with the conventional scheme that reserves interference margin only. Numerical results show that the proposed scheme is more efficient in accommodating calls under a given set of constraints.