Maximum likelihood detection with a linear array for synchronous DS/CDMA systems

Direct sequence code division multiple access (DS/CDMA) technology is attractive in cellular and personal communications systems because of potential capacity increases, anti-narrowband-interference capability, and soft handoff. We derive a maximum likelihood (ML) linear array receiver for a synchronous DS/CDMA Gaussian channel. We present an ML decision rule, utilizing the spatial information of users such as angles-of-arrivals, and corresponding receiver structure which consists of a bank of matched filters at each array element and a decision algorithm. We also derive an expression of the bit error rate (BER) of a user and show an example of BER for a two-element array with two users. For this particular example, an ML two-element linear array receiver achieves significant improvement in BER over a single antenna ML detection.