Analysis of an approximate decorrelating detector

In this paper, an approximate decorrelating detector is proposed on the basis of a second order approximation to the inverse correlation matrix of signature waveforms. One advantage of the decorrelating detector is that it does not require knowledge of the amplitude of users in the system. In this paper, we find that the approximate detector will retain the advantages of decorrelating detector, while reducing the implementation complexity greatly. In order to reduce the implementation complexity, we truncate the decompose series to just terms of second order, and each term is multiplied by a weight factor. By simulation, we find a region of the weight pair set where the bit error rate is very low, and we call the region a "passage". Numerical results are provided that show that this detector offers significant performance gains relative to the matched filter receiver, and degrades a little with respect to decorrelating detector and MMSE detector. We conclude that the approximate detector can alleviate the need for stringent power control in CDMA systems, and may be, a practical alternative to the matched filter receiver.