The decorrelating detector is one of the detecting methods in a direct sequence code division multiple access systems. We investigate the blind adaptive decorrelating detector (BADD) using only the signature of the desired user (DU) according to the assumption that the algorithm is used in downlink. When the BADD is constructed with an antenna array, both the spatial and temporal signature must be taken into consideration for signal detection. We propose the BADD incorporated with the blind estimation of spatial signature (SS) of the DU only from the received signals. As the estimation procedure of SS, the orthogonal projection approximation and subspace tracking algorithm is adopted. The proposed BADD presented the BER improvement with using antenna array. The BER performance has a lower limit with increasing the number of antenna array elements.

Multiple access interference (MAI) due to many simultaneous users is the main factor that limits the performance of DS-CDMA system. Multiuser detection is a method to avoid performance degradation due to MAI. We propose a blind multiuser detection method based on the algorithm consisting of two-stage decoding process, i.e., linearly constrained constant modulus (LCCM) and iterative least squares (ILS). The computer simulations confirmed that the algorithm is near-far resistant and that the proposed method is effective in the application to the slow fading channels.

This paper shows the method of theoretical analysis for the bit error probability of the trellis-coded partial response continuous phase modulation (TCM-PR-CPM) over the correlated Rician fast frequency nonselective fading channel. In the analysis, the fading correlation of the channel and the effect due to finite interleaver are taken into account. By applying the method to the rate 1/2 (7, 2) trellis code with the raised cosine pulse of length 2 (2RC) partial response signaling, we show that the tighter upper bounds of the bit error rate are obtained than those in the preceding report.

Blind channel estimation algorithm which is applicable to the time-variant channel under frequency-selective fading is proposed. The condition on the blind channel identifiability using temporally and spatially oversampled data is shown. The proposed algorithm consists of two stages. At the first stage, the channel equalization matrix is estimated by taking account of the time-variant characteristics of the channel. At the second stage, the signals and the channel matrix are alternately estimated by using the finite alphabet property of the transmitted symbols. Periodical return from the second stage to the first makes the blind estimation algorithm feasible for the time-variant channel with fast fading. The simulation results confirm the fast convergence property and the effectiveness of the proposed algorithm in coping with the frequency-selective fading.