Abstract:
The linear decorrelator provides a good solution for multiuser detection in code division
multiple access (CDMA) systems. However, the computations needed to invert the
correlation matrix have rendered its implementation difficult in practice. Considerable
interest has been shown on realization of multiuser asynchronous CDMA reception by a
finite length decorrelator of small window size. One-shot and extended window based
decorrelators reported in literature are near-far resistant, however, they have considerable
enhancement of noise power with increase in the number of users that limits their user
capacity. Truncated window based algorithms, on the other hand, suffer from edge effects
that introduce multiple access interference (MAI) which degrades the performance with
increased number of users and also results in near–far dependence. Thus the existing
finite length decorrelator algorithms show variable tradeoffs between the performance,
complexity and user capacity. In this thesis some aspects of design improvements for
improved tradeoff between the performance and the user capacity of finite length
decorrelators in asynchronous system, while keeping the computational overheads low, is
considered.
