Capacity Improvement with Interference Cancellation in the WCDMA Enhanced Uplink

Own-cell interference limits capacity and coverage in the WCDMA enhanced uplink, and the use of interference cancellation (IC) techniques is required to provide high-data-rate availability. For a typical uplink WCDMA system with mixed traffic generated by few high-data-rate users and many low-rate users (e.g., voice users), this paper considers an IC receiver that cancels the high-data-rate signals prior to low-rate traffic reception. The IC receiver provides substantial capacity gains and the benefits of cancellation can be seen as increased achievable data rate for a fixed voice load and/or increased voice load for a target data load. For example, with a data rate of 1.5 Mbps, voice capacity gains are between 60% and 80%. In low voice load, the achievable data rate exceeds 3.5 Mbps. Due to the nature of traffic in WCDMA networks and the option of a short transmission time interval (TTI) for high-data-rate transmission in WCDMA Release 6, this IC scheme is an attractive solution for implementation in base station receivers. In addition, this paper considers also an uplink receiver that cancels the control channels of all users in the cell. Capacity gains are substantial in cells highly loaded with low-rate users