  Paper derives and analyzes a novel block Fast Fourier Transform (FFT) based
joint detection algorithm. The paper compares the performance and complexity of
the novel block-FFT based joint detector to that of the Cholesky based joint
detector and single user detection algorithms. The novel algorithm can operate
at chip rate sampling, as well as higher sampling rates, unlike existing
algorithms. For the performance/complexity analysis, the time division duplex
(TDD) mode of a wideband code division multiplex access (WCDMA) is considered.
The results indicate that the performance of the fast FFT based joint detector
is comparable to that of the Cholesky based joint detector, and much superior
to that of single user detection algorithms. On the other hand, the complexity
of the fast FFT based joint detector is significantly lower than that of the
Cholesky based joint detector and less than that of the single user detection
algorithms. For the Cholesky based joint detector, the approximate Cholesky
decomposition is applied. Moreover, the novel method can also be applied to any
generic multiple-input-multiple-output (MIMO) system.
