Capacity of a band-limited CDMA MMSE receiver-based system when combined with trellis or convolutional coding

This paper examines the achievable capacity of a direct-sequence spread-spectrum multiple-access system based on an adaptive minimum mean-square-error (MMSE), single-user receiver over a Gaussian channel. The effect of using both trellis and convolutional codes of varying rates and complexity is investigated in relation to the effect on the maximum number of users and the achievable bit-error rate for a given number of users. A system based on a matched filter receiver is presented for the purposes of comparison. It has been found that, over the band-limited channel considered, the use of convolutional coding reduces the total system capacity for the high efficiency MMSE receiver while still providing coding gain at small numbers of users. The use of trellis codes however leads to increased system capacity.