A study on the effects of soft interference cancellation for uplink WCDMA system

Abstract

WCDMA system is an interference limited system. Interference cancellation (IC) is a technique that has been widely studied and implemented for WCDMA uplink system to achieve performance close to potential capacity. Most studies until now have been focused on hard interference cancellation. Hard IC occurs after each user has its cyclic redundancy check (CRC) passed, meaning it would not perform cancellation until the end of a transmission time interval (TTI), therefore causing potential delays in cancellation. Recently engineers have proposed a soft IC scheme where one would perform cancellation without passing CRC, therefore one would not have as much delay on cancellation but at the cost of lower cancellation efficiency because of bad estimation on signals. In my thesis I will attempt to build a framework that gives some insight to the tradeoff between hard and soft IC to serve as a reference for engineers when implementing IC into our WCDMA systems.