Tri-Diagonalizing Approach on Frequency Domain Equalization in a Doubly-Selective Channel

Frequency-domain equalization (FDE) has been studied for suppressing inter-symbol interference (ISI) due to frequency selective fading in single carrier systems. When a highmobility terminal is assumed in the system, channel transition within an FFT block cannot be ignored. Then, the ISI reduction performance of FDE degrades since cyclicity of the channel matrix is lost. To solve this problem, we extend the conventional diagonal matrix in FDE to a tri-diagonal matrix. In addition, a simple procedure without strict calculation in tri-diagonalization is proposed. The proposed technique is applied to FDE and frequency-domain turbo equalization (FDTE). The results of numerical analysis show a remarkable improvement by the tri-diagonalization. When the normalized Doppler frequency is 0.0015, the bit error rate (BER) floor is decreased to less than 0.01 in the FDE case; and about 2.8 dB gain at the BER of 0.001 is obtained in the FDTE case.

[2]  Geert Leus,et al.  Receiver Design for Single-Carrier Transmission Over Time-Varying Channels , 2007, 2007 IEEE International Conference on Acoustics, Speech and Signal Processing - ICASSP '07.

[3]  Philip Schniter,et al.  Low-complexity equalization of OFDM in doubly selective channels , 2004, IEEE Transactions on Signal Processing.

[4]  P. Schniter,et al.  Iterative frequency-domain equalization for single-carrier systems in doubly-dispersive channels , 2004, Conference Record of the Thirty-Eighth Asilomar Conference on Signals, Systems and Computers, 2004..

[5]  Kimmo Kansanen,et al.  Wireless broadband single-carrier systems with MMSE turbo equalization receivers , 2005 .

[6]  Justin P. Coon,et al.  Channel and noise variance estimation and tracking algorithms for unique-word based single-carrier systems , 2004, ISWCS.

[7]  Toshihiko Nishimura,et al.  Subblock processing in MMSE-FDE under fast fading environments , 2008, IEEE Journal on Selected Areas in Communications.

[8]  Andrew C. Singer,et al.  Turbo equalization: principles and new results , 2002, IEEE Trans. Commun..

[9]  Sven-Gustav Häggman,et al.  Intercarrier interference self-cancellation scheme for OFDM mobile communication systems , 2001, IEEE Trans. Commun..

[10]  Luc Deneire,et al.  Training sequence versus cyclic prefix-a new look on single carrier communication , 2001, IEEE Communications Letters.

[11]  David Falconer,et al.  Frequency domain equalization for single-carrier broadband wireless systems , 2002, IEEE Commun. Mag..

[12]  Thomas Mayer,et al.  A different look on cyclic prefix for SC/FDE , 2002, The 13th IEEE International Symposium on Personal, Indoor and Mobile Radio Communications.