Investigation of uplink capacity based on the background noise floor in TDD-CDMA systems

The evaluations of system load are very important for CDMA systems. Due to the TDD-CDMA specialization in UL; i.e., multi user detection (MUD) technology and smart antenna technique is adopted and the transmission is discontinuous per frame, all these load evaluation schemes, which are based on the FDD mode, should be carefully investigated for TDD system. In this paper, the well-known formulation of UL background noise rise (BNR) for FDD-CDMA is modified and enhanced, and an advanced BNR formulation is presented. Pole capacity, load and capacity estimation of UL based on the proposed BNR formulation are all described. In order to demonstrate the efficiency of load strategy for TDD-CDMA, an admission control strategy based on the proposed BNR for omni-directional and switched beam antennas is proposed. All works demonstrate that the modified BNR gives a very good representation for capacity and load estimation in TDD-CDMA systems.