Interference cancellation and 4-branch antenna diversity for WCDMA uplink packet access

This paper addresses the performance gain of interference cancellation (IC) and 4-branch antenna diversity for enhanced packet data access in WCDMA uplink. A theoretical analysis is derived showing that the cell throughput gain from IC mainly depends on three factors: 1) the efficiency of the multi-user detection (MUD) receiver, 2) the other-to-own cell interference ratio, and 3) the uplink load. The gain from 4-branch antenna diversity and IC is then estimated bv means of system level simulations for two different node B scheduling concepts. Given specific outage constraints for both network load and user performance, the capacity gain from 4-branch compared to 2-branch antenna diversity is approx. 100% The cell throughput gain from IC is approx. 20% for an IC efficiency of 30% and 50% for an IC efficiency of 70% The estimated gain numbers from IC are almost independent of the considered scheduling scenario and are in accordance with the theoretical results. In the most optimistic case, the total cell throughout gain from fast node B scheduling, IC and 4-branch antenna diversity is 364% compared to a system implementation with RNC scheduling, no interference cancellation and 2-branch antenna diversity.