411 research outputs found
IB-DFE receiver techniques for CP-assisted block transmission within DS-CDMA and MC-CDMA systems
MC-CDMA (MultiCarrier Code Division
Multiple Access), currently regarded as a promissing
multiple access scheme for broadband communications, is
known to combine the advantages of an OFDM-based (Orthogonal
Frequency Division Multiplexing), CP-assisted
(Cyclic Prefix) block transmission with those of CDMA
systems. Recently, it was recognised that DS-CDMA (Direct
Sequence) implementations can also take advantage
of the beneficts of the CP-assisted block transmission
approach, therefore enabling an efficient use of FFT-based
(Fast Fourier Transform), chip level FDE (Frequency-
Domain Equalisation) techniques.
In this paper we consider the use of IB-DFE (Iterative
Block Decision Feedback Equalisation) FDE techniques
within both CP-assisted MC-CDMA systems with
frequency-domain spreading and DS-CDMA systems. Our
simulation results show that an IB-DFE receiver with
moderate complexity is suitable in both cases, with excellent
performances that can be close to the single-code
matched filter bound (especially for the CP-assisted DSCDMA
alternative), even with full code usage
IB-DFE receivers with space diversity for CP-assisted DS-CDMA and MC-CDMA systems
Multi-Carrier Code Division Multiple Access (MC-CDMA), currently regarded as a promising multiple access scheme for broadband communications, is known to combine the advantages of an Orthogonal Frequency Division Multiplexing (OFDM)-based, Cyclic Prefix (CP)-assisted block transmission with those of CDMA systems. Recently, it was recognised that DS-CDMA (Direct Sequence) implementations can also take advantage of the benefits of the CP-assisted block transmission approach, therefore enabling an efficient use of Fast Fourier Transform (FFT)-based, chip level Frequency-Domain Equalisation (FDE) techniques. When employing a linear FDE with both MC-CDMA and DS-CDMA, the FDE coefficients can be optimised under the Minimum Mean Squared Error (MMSE) criterion, so as to avoid significant noise enhancement. The residual interference levels can be very high, especially for fully loaded scenarios, since the FDE/MMSE does not perform a perfect channel inversion.
This paper deals with CP-assisted DS-CDMA systems and MC-CDMA systems with frequency-domain spreading. We consider the use of Iterative Block Decision Feedback Equalisation (IB-DFE) FDE techniques as an alternative to conventional, linear FDE techniques, and derive the appropriate IB-DFE parameters in a receiver diversity context. Our performance results show that IB-DFE techniques with moderate complexity allow significant performance gains in both systems, with bit error rate (BER) that can be close to the single-code matched filter bound (MFB) (especially for the CP-assisted DS-CDMA alternative), even with full code usage. Copyright © 2007 John Wiley & Sons. Ltd
A computationally efficient multi-mode equaliser based on reconfigurable frequency domain processing
Frequency-Domain Turbo Equalisation in Coded SC-FDMA Systems: EXIT Chart Analysis and Performance
In this paper, we investigate the achievable performance of channel coded single-carrier frequency division multiple-access (SC-FDMA) systems employing various detection schemes, when communicating over frequency-selective fading channels. Specifically, three types of minimum mean-square error (MMSE) based frequency-domain (FD) turbo equalisers are considered. The first one is the turbo FD linear equaliser (LE). The second one is a parallel interference cancellation (PIC)-assisted turbo FD decision-feedback equaliser (DFE). The final one is the proposed hybrid interference cancellation (HIC)-aided turboFD-DFE, which combines successive interference cancellation (SIC) with iterative PIC and decoding. The benefit of interference cancellation (IC) is analysed with the EXtrinsic Information Transfer (EXIT) charts. The performance of the coded SC-FDMA systems employing the above-mentioned detection schemes is investigated with the aid of simulations. Our studies show that the IC techniques achieve an attractive performance at a moderate complexity
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