Gallager codes for CDMA applications - Part II: Implementations, complexity, and system capacity

We focus our attention on Gallager codes with parameters compatible with th e IS-95 cellular radio standard. We discuss low complexity software and har dware implementations of an iterative decoder for {N, -, 3} Gallager codes. We estimate that by using Gallager codes, a factor of five improvement in the code-division multiple-access system capacity relative to an uncoded sy stem can be achieved, equivalent to a factor of two improvement relative to state-of-the art orthogonal convolutional codes. Simulation results demons trate the good performance of short-frame Gallager codes in the additive wh ite Gaussian noise and certain fading channels.