A multicarrier architecture based upon the affine Fourier transform

Recently, innovative multicarrier schemes have been proposed that exploit the transmission of chirp-shaped waves e/sup -j2/spl pi/ct2/ by optimally choosing the chirp parameter c on the basis of the channel characteristics and are more robust to time-varying channels than ordinary OFDM schemes. This concept was applied to continuous-time and to discrete-time systems. In the present paper, we aim at developing those ideas using the affine Fourier transform (AFT), which is a very general formulation of chirp transforms. We present a multicarrier modulation based upon the discrete form of the AFT that is therefore inherently discrete and strictly invertible. Moreover, it allows to define a circular prefix concept that is coherent with the chirp nature of the transmission. The system can be efficiently implemented by adding a simple phase-correction block to standard OFDM modulators/demodulators and can effectively combat interchannel interference when the propagation channel is made of few multipath components affected by independent frequency offsets. Our discrete-time multicarrier scheme is an improved version of Martone's approach (as we also show by simulation results), and exhibits analogous characteristics to Barbarossa's continuous-time system.

[1]  Tomaso Erseghe,et al.  Unified fractional Fourier transform and sampling theorem , 1999, IEEE Trans. Signal Process..

[2]  Marc Moeneclaey,et al.  BER sensitivity of OFDM systems to carrier frequency offset and Wiener phase noise , 1995, IEEE Trans. Commun..

[3]  John M. Cioffi,et al.  Multi-tone transmission for asymmetric digital subscriber lines (ADSL) , 1993, Proceedings of ICC '93 - IEEE International Conference on Communications.

[4]  Desmond P. Taylor,et al.  A Statistical Model for Indoor Multipath Propagation , 2007 .

[5]  J. Ortega.  Matrix Theory: A Second Course , 1987 .

[6]  Cagatay Candan,et al.  The discrete fractional Fourier transform , 2000, IEEE Trans. Signal Process..

[7]  Yih-Fang Huang,et al.  Pilot assisted synchronization for wireless OFDM systems over fast time varying fading channels , 1998, VTC '98. 48th IEEE Vehicular Technology Conference. Pathway to Global Wireless Revolution (Cat. No.98CH36151).

[8]  J.A.C. Bingham,et al.  Multicarrier modulation for data transmission: an idea whose time has come , 1990, IEEE Communications Magazine.

[9]  A.A.M. Saleh,et al.  A Statistical Model for Indoor Multipath Propagation , 1987, IEEE J. Sel. Areas Commun..

[10]  Sergio Barbarossa,et al.  Chirped-OFDM for transmissions over time-varying channels with linear delay/Doppler spreading , 2001, 2001 IEEE International Conference on Acoustics, Speech, and Signal Processing. Proceedings (Cat. No.01CH37221).

[11]  Soo-Chang Pei,et al.  Closed-form discrete fractional and affine Fourier transforms , 2000, IEEE Trans. Signal Process..

[12]  Nicola Laurenti,et al.  A unified framework for the fractional Fourier transform , 1998, IEEE Trans. Signal Process..

[13]  B. Hirosaki,et al.  An Orthogonally Multiplexed QAM System Using the Discrete Fourier Transform , 1981, IEEE Trans. Commun..

[14]  Levent Onural,et al.  Convolution, filtering, and multiplexing in fractional Fourier domains and their relation to chirp and wavelet transforms , 1994 .

[15]  Luis M. Correia.  Wireless flexible personalised communications : COST 259 : European co-operation in mobile radio research , 2001 .

[16]  Z. Zalevsky,et al.  The Fractional Fourier Transform: with Applications in Optics and Signal Processing , 2001 .

[17]  Leonard J. Cimini,et al.  Analysis and Simulation of a Digital Mobile Channel Using Orthogonal Frequency Division Multiplexing , 1985, IEEE Trans. Commun..

[18]  Massimiliano Martone,et al.  A multicarrier system based on the fractional Fourier transform for time-frequency-selective channels , 2001, IEEE Trans. Commun..