Iterative Detection in Code-Division Multiple-Access with Error Control Coding

A code-division multiple-access system with channel coding may be viewed as a serially-concatenated coded system. In this paper we propose a low complexity method for decoding the resulting inner code (due to the spreading sequence), which allows iterative (turbo) decoding of the serially-concatenated code pair. The per-bit complexity of the proposed decoder increases only linearly with the number of users. Performance within a fraction of a dB of the single user bound for heavily loaded asynchronous CDMA is shown both by simulation and analytically. This work was performed, in part, while P.D. Alexander was at the Institute for Telecommunications Research, South Australia y This work was performed while A.J. Grant was at the Laboratory for Signal and Information Processing, Swiss Federal Institute of Technology, Zurich. 1 Introduction It is well known that channel coding can be used to combat mobile radio channel effects such as noise and fading. For multiple-access channels, in..