Performance Analysis of a Fixedpoint Successive Interference Canceller for WCDMA.pdf

Performance Analysis of a Fixed-point Successive Interference Canceller for WCDMA Hongxia Zhao , Tony Ottosson , Erik G. Strom¨ and Anna Kidiyarova-Shevchenko Department of Signals and Systems, Chalmers University of Technology, 412 96 Gotebor¨ g, Sweden. Email: hz@s2.chalmers.se Department of Microtechnology and Nanoscience, Chalmers University of Technology, 412 96 Gotebor¨ g, Sweden. Abstract— In this paper we study the problem of implementing Based on a current traditional design using simulations, a Successive Interference Canceller (SIC) for a WCDMA system see [8], we construct a model of the fixed-point implemen- in fixed-point electronics. Typically, fixed-point implementation tation of SIC. Noise due to the fixed-point effects are studied is based on an iterative design of simulations and experience, resulting in a time-consuming and inefficient process. From and properly estimated. All the quantizers in the model are the experience of a conventional design with simulations, we replaced by noise sources. Results from simulations support- make a model of the fixed-point SIC. The advantage with this ing this model are presented. Under some assumptions and model is that it can be analyzed and hence be used to predict approximations, we further simplify this model so that it the performance of a fixed-point implementation with given is similar to a floating-point implementation but with extra precision. Simulations indicate that the analysis agrees well for additive noise ad