Performance of space-time MMSE adaptive receivers in DS-CDMA systems using FEC coding in flat fast-fading channels

This paper investigates the use of soft-decision convolutional coding (SD-CC) in a space-time MMSE adaptive receiver over single-path flat fast-fading channels. Both the normalized least-mean square (NLMS) and the recursive-least square (RLS) algorithms are used. The significant performance improvement of the RLS algorithm over the NLMS is evident in our analysis. We also employ error bounds developed earlier for the coded multiuser-type receiver and show their validity when a suitable channel interleaver is used for the space-time adaptive case. Then, we use these bounds to estimate the improvement in system user capacity that accrues due to error-control coding. It is found that the coded system offers as much as 225% gain in user capacity for the fading channel.