Turbo Equalization with Cancelation of Nonlinear Distortion for CP-Assisted and Zero-Padded MC-CDM Schemes
; Araújo, T.
IEEE Transactions on Communications Vol. 57, Nº 7, pp. 2185 - 2189, August, 2009.
ISSN (print): 0090-6778
Journal Impact Factor: 2,070 (in 2008)
Digital Object Identifier: 10.1109/TCOMM.2009.08.070485
n this paper, we consider MC-CDM schemes (MultiCarrier Code Division Multiplexing) where clipping techniques are employed to reduce the envelope fluctuations of the transmitted signals. Both CP-assisted (Cyclic Prefix) and ZP (Zero-Padded) MC-CDM schemes are studied. We develop frequency-domain turbo equalizers combined with an iterative estimation and cancelation of nonlinear distortion effects, with relatively low complexity since they allow FFT-based (Fast Fourier Transform), frequency-domain implementations.
Our performance results show that the proposed receivers allow significant performance improvements at low and moderate SNR (Signal-to-Noise Ratio), even when strongly nonlinear transmitters are employed. The receiver for ZP MC-CDM is of special interest for systems where the duration of the channel impulse response is not a small fraction of the duration of the MC-CDM blocks, being suitable to MC-CDM systems with very large blocks (hundreds or even thousands of subcarriers), since they do not require the inversion nor the multiplication of large matrixes.