Document Type : Original Article
Egyptian Armed Forces.
Recently, the code division multiple access (CDMA) technique has become the most widely communication technique, because of its varity of applications. The well-known matched filter (MF) is considered as the optimum filter that recovers the CDMA signals. However; its performance recently becomes unsatisfying. This is due to increasing the multiple access interference (MAI), in addition to the other channel impairments such as the fading or the multi path interference (MPI). In this paper, an adaptive minimum mean square error-maximum likelihood (MMSE-ML) receiver is presented as an alternative solution to overcome the drawbacks of the MF receiver. This adaptive MMSE-ML receiver uses adaptive aided tentative coefficients in addition to the basic adaptive coefficients to increase the tracking ability of the channel impulse response variations. The performance of the adaptive MMSE-ML receiver is compared with the traditional adaptive MMSE receiver over a frequency selective fading channel. Moreover, the performances of both the presented and traditional adaptive receivers are compared with the performance of the MF under the same condition. It is found that the performance of the adaptive MMSE-ML receiver is much improved using the proposed technique.