Multiple-access interference (MAI) and multipath fading are two of the most significant factors limiting the capacity and performance of direct-sequence code-division multiple-access (DS-CDMA) systems. In this paper, synchronous multiuser receivers that combine antenna diversity, RAKE reception, and a multipath decorrelator for MAI cancellation are analyzed in a Nakagami faded environment using a maximal ratio combiner or a selection combiner. A coherent binary phase-shift keying employing DS-CDMA is considered. Arbitrary branch correlation is also considered for any diversity order in the case of identical severity fading on the branches.

Abstract In this paper, we propose and analyse parallel CCI multistage cancellation by combining RAKE and selection diversity. In order to account for channel variations, adaptive implementation of decision thresholds at the RAKE output is suggested. It is shown to provide significant improvement over either hard or soft decision techniques especially in the near‐far situation. Investigation of the system robustness to imperfect channel parameter estimation is also presented. The communication channel is modelled as slowly varying Rayleigh fading discrete multipath channel. Copyright © 2002 John Wiley & Sons, Ltd.

A parallel interference cancellation system employing an adaptive LMS technique is introduced. Simulation results for the proposed system show appreciable improvements over the parallel interference cancellation techniques that employ either hard decision or partial cancellation.

The effect of block, convolutional and turbo coding on the probability of error and the capacity are investigated for CDMA low Earth orbit (LEO) satellite systems. The model employed assumes a contaminated Gaussian traffic model. The conventional Gaussian distribution can be considered as a special case.

A system formed by N identical nonparametric detectors and a fusion center is studied. The detectors transmit their decisions to the fusion center. The detectors are based either on the signs (sign test) or on the signs and the ranks of the observations (Wilcoxon test). It is concluded that the performance is almost unchanged when the product of the number of detectors by the number of samples received by each of them is constant. The asymptotic performance is also derived, and it is shown that it is equivalent to the centralized situation as the number of samples increases without limit.

Studies the performance advantage offered by the wideband multipath RAKE structure receiver in a cellular radio direct sequence code division multiple access system (CDMA). The base to mobile link is modeled as a Nakagami fading frequency selective channel. The performance of a RAKE structure receiver employing coherent reception with maximal ratio combining in a frequency selective channel is analyzed and compared with the flat fading case. The degradation in the performance of the receiver as a result of imperfect channel estimation is also studied.

A detector with multinomial input (MN) previously derived for on-off communication systems is generalized to include binary antipodal signals with arbitrary shapes. The proposed detector is distinguished by its simpler implementation. No multiplications are needed and it has a relatively good performance. Results of numerical examples are obtained under Gaussian and non-Gaussian noise environments for different numbers of quantization levels. Solutions for M-ary signaling are also discussed.>

In previous studies by V.G. Hansen (1973) and by Hansen and J.H. Sawyers (1980), performance models were developed for the smaller of (SO) and greater of (GO) constant false alarm rate (CFAR) detectors processing a single sweep (or single pulse). Here, performances of the SO and GO detectors are derived when M pulses are incoherently integrated in a homogeneous environment. This situation is fitted to the case of a radar system processing M sweeps per range bin.>

Bit error rate (BER) is analyzed theoretically for diversity reception in Nakagami fading environment using anM-branch maximal ratio combiner (MRC). Coherent and incoherent reception of frequency shift keying (FSK) are considered, using the multiple branch diversity system for both identical and different diversity branch fading parameters. The effect of correlation is also considered for the dual diversity case. The results are extended to include coherent phase shift keying (CPSK) and differential phase shift keying (DPSK).

The effect of preemphasis/deemphasis on the noise power output of FM detectors for SSB-FM is studied. Two cases are considered: namely, when the modulating signal is assumed to be sinusoidal and when it is a Gaussian random process. For both cases the noise is assumed to be stationary and Gaussian. For a sinusoid modulating signal, the improvement of(S/N)_{0}for SSB-FM detectors is obtained when the modulation index β lies in the interval (0.1-12.0) with negligible improvements for higher β. For a Gaussian modulating signal, improved results are obtained for a modulation index in the interval (0.1-0.6).

The asymptotic relative efficiencies (ARE) of generalized sign (GS), Mann-Whitney (MW), modified Savage (MS), and modified rank squared (MRS) two-sample nonparametric detectors are compared with those of the mean and median parametric detectors. The signal is assumed to be nonfluctuating, and the background noise is assumed to be lognormal or to be characterized by a contaminated normal distribution. It is shown that using the asymptotic relative efficiency measure the performance of nonparametric detectors increases appreciably as the noise distribution deviates from normality.