In multiuser detection techniques, the maximum likelihood multiuser detector provides the best performance in DS-CDMA systems with impulsive ambient noise. But the high complexity makes it impractical. And therefore, effective sup-optimal detectors in non-Gaussian noise are needed. In this paper, we present two-layer perceptron neural network with back propagation training algorithm as a multiu...

In this paper, we present different linear and nonlinear iterative data detection schemes for the asynchronous direct-sequence code-division multiple access (DS-CDMA) systems employing orthogonal signalling formats and long scrambling codes. Compared to the conventional receiver and other noncoherent multiuser detectors, coherent multiuser detection schemes achieve much better performance provi...

| Suboptimum multiuser detection has attracted wide attentions recently. In this paper, we consider a suboptimum multiuser detector which is based on the maximum signal-to-interference and noise ratio (SINR) criterion. Analysis indicates that this multiuser detector is equivalent to the MMSE detector. To further improve the performance of the detection, a decision-feedback strategy has been int...

In this paper, a new spreading scheme, which consists of two stages of spreading, is considered for DS-CDMA systems. The data of a user is spread first with a long signature sequence and then with a short signature sequence. The scheme combines the advantages of the two types of spreading techniques and allows us to suppress MAI by performing both beamforming and multiuser detection efficiently...

In code-division multiple-access systems, simultaneous multiuser accessing of a common channel is made possible by assigning a signature waveform to each user. Knowledge of these waveforms enables the receiver to demodulate the data streams of each user, upon observation of the sum of the transmitted signals, perturbed by additive noise. Under the assumptions of symbol-synchronous transmissions...

{This paper evaluates the performance of decision-feedback multiuser detectors with coding for CDMA channels. A combined multiuser detection/soft-decision decoding scheme is proposed which allows total control over the reliability of decision-feedback mechanism. Its performance is compared to that of conventional detection and linear-decorrelation detection with soft-decision decoding. Simulati...

In this letter, we propose a combined scheme of minimum mean square error (MMSE) detection and successive interference cancellation (SIC) for multiuser space-time block coded orthogonal frequency division multiplexing (STBC-OFDM) systems. With the same complexity order, the proposed scheme provides significant bit error rate (BER) performance improvement over the linear MMSE multiuser detector....

Direct-sequence code-division multiple access (DS-CDMA) is a popular wireless technology. In DS-CDMA systems, all of the users' signals overlap in frequency and time and cause multiple access interference (MAI). Multiuser detection schemes are used to detect the users’ data in the presence of MAI. in this paper, a comparison study of linear multiuser detectors in the presence of MAI, under the ...

This document augments contribution T1E1.4/99-120 by investigating the QAM transmission methods used for higher-speed Home-phone LANs (HPL), specifically 2-10 Mbps with symbol rates of 2-4 MHz. While higher speed, these newer HPL transmission methods are suggested to be easier for multiuser detection with respect to the pulse position modulation schemes used for earlier Home PNA 1.0 networks, b...

An iterative multiuser detection scheme is proposed for DS-CDMA system. An iterative multiuser detection has a partial parallel interference cancellation (PIC) detector and serially concatenated codes. Taking the expectation value of a coded bit the partial PIC detector produces a metric, which becomes an input to the decoders. It is shown that the proposed iterative multiuser detector has near...