Multiuser detection and channel estimation algorithms for M-ary DS-CDMA systems in multipath Rayleigh fading channels
نویسندگان
چکیده
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 provided that the channels are accurately estimated. To this end, we proposed several channel estimation algorithms to estimate multipath Rayleigh fading channels. Different data detection and channel estimation schemes are compared in terms of the BER performance. Based on the numerical results, some recommendations are made on how to choose multiuser detectors and channel estimation algorithms in practical CDMA systems.
منابع مشابه
Bit Error Performance for Asynchronous Ds Cdma Systems Over Multipath Rayleigh Fading Channels (RESEARCH NOTE)
In recent years, there has been considerable interest in the use of CDMA in mobile communications. Bit error rate is one of the most important parameters in the evaluation of CDMA systems. In this paper, we develop a technique to find an accurate approximation to the probability of bit error for asynchronous direct–sequence code division multiple–access (DS/CDMA) systems by modeling the multipl...
متن کاملCoherent Detection for DS/CDMA System with M -Ary Orthogonal Modulation in Multipath Fading Channels
In this letter, we propose the channel estimation technique in the uplink of a DS/CDMA system with M -ary orthogonal signaling over multipath fading channels. The channel estimation is carried out using the maximum correlator output of RAKE receiver. With the estimated channel parameters, the RAKE receiver can coherently combines the received multipath signals, resulting in a significant perfor...
متن کاملCommunication Theory Joint data detection and estimation of time-varying multipath rayleigh fading channels in asynchronous DS-CDMA systems with long spreading sequences
In this paper, we present a joint approach to data detection and channel estimation for the asynchronous direct-sequence code-division multiple access (DS-CDMA) systems employing orthogonal signaling formats and long scrambling codes. Our emphasis is placed on different channel estimation algorithms since the performance of a communication system depends largely on its ability to retrieve an ac...
متن کاملIterative Demodulation of M-Ary Orthogonal Signaling Formats in Coded DS-CDMA Systems with Soft Interference Cancellation and Channel Estimation
The system under study is a convolutionally coded and orthogonally modulated DS-CDMA system over timevarying frequency-selective Rayleigh fading channels in multiuser environments. Iterative soft demodulation and decoding using the Turbo principle can be applied to such a system to increase the system capacity and performance. To combat multiple access interference (MAI), we incorporate the int...
متن کاملLong codes for generalized FH-OFDMA through unknown multipath channels
A Generalized Frequency Hopping (GFH) OFDMA system is developed in this paper as a structured long code DS-CDMA system in order to bridge frequency hopped multi-carrier transmissions with long code DS-CDMA. Through judicious code design, multiuser interference is eliminated deterministically in the presence of unknown frequency-selective multipath channels. Thanks to frequency hopping, no singl...
متن کامل