Uplink admission control and soft capacity with MUD in CDMA

This paper presents an analysis of the WCDMA uplink capacity with admission control and multiuser detection (MUD). An uplink admission control strategy based on the received wideband interference is introduced in this paper. The CDMA uplink capacity formula is used, and the uplink capacity is calculated in terms of the average number of channels per cell assuming the presented admission control strategy. The amount of supported traffic with a given blocking probability is calculated with Erlang B formula. In this paper the Erlang B formula is extended to cover the soft blocking case in WCDMA uplink when an interference based admission control is used. The difference in the capacity between soft and hard blocking is shown with a few examples, and it is referred here as soft capacity. Also, the effect of the base station multiuser detection to the soft capacity is evaluated. It is shown that with an interference based admission control algorithm up to 50% more users with 144 kbps real time data can be supported than with a non-interference based admission control approach