- Research Article
- Open Access
Cholesky Factorization-Based Adaptive BLAST DFE for Wideband MIMO Channels
EURASIP Journal on Advances in Signal Processing volume 2007, Article number: 045789 (2007)
Adaptive equalization of wireless systems operating over time-varying and frequency-selective multiple-input multiple-output (MIMO) channels is considered. A novel equalization structure is proposed, which comprises a cascade of decision feedback equalizer (DFE) stages, each one detecting a single stream. The equalizer filters, as well as the ordering by which the streams are extracted, are updated based on the minimization of a set of least squares (LS) cost functions in a BLAST-like fashion. To ensure numerically robust performance of the proposed algorithm, Cholesky factorization of the equalizer input autocorrelation matrix is applied. Moreover, after showing that the equalization problem possesses an order recursive structure, a computationally efficient scheme is developed. A variation of the method is also described, which is appropriate for slow time-varying conditions. Theoretical analysis of the equalization problem reveals an inherent numerical deficiency, thus justifying our choice of employing a numerically robust algebraic transformation. The performance of the proposed method in terms of convergence, tracking, and bit error rate (BER) is evaluated through extensive computer simulations for time-varying and wideband channels.
Foschini GJ, Golden GD, Valenzuela RA, Wolniansky PW: Simplified processing for high spectral efficiency wireless communication employing multi-element arrays. IEEE Journal on Selected Areas in Communications 1999,17(11):1841-1852. 10.1109/49.806815
Al-Dhahir N, Sayed AH: The finite-length multi-input multi-output MMSE-DFE. IEEE Transactions on Signal Processing 2000,48(10):2921-2936. 10.1109/78.869048
Lozano A, Papadias C: Layered space-time receivers for frequency-selective wireless channels. IEEE Transactions on Communications 2002,50(1):65-73. 10.1109/26.975751
Ginis G, Cioffi JM: On the relation between V-BLAST and the GDFE. IEEE Communications Letters 2001,5(9):364-366. 10.1109/4234.951378
Zhu X, Murch RD: Layered space-frequency equalization in a single-carrier MIMO system for frequency-selective channels. IEEE Transactions on Wireless Communications 2004,3(3):701-708. 10.1109/TWC.2004.826322
Tubbax J, van der Perre L, Donnay S, Engels M: Single-carrier communication using decision-feedback equalization for multiple antennas. Proceedings of IEEE International Conference on Communications (ICC '03), May 2003, Anchorage, Alaska, USA 4: 2321–2325.
Kalbasi R, Dinis R, Falconer D, Banihashemi AH: Hybrid time-frequency layered space-time receivers for severe time-dispersive channels. Proceedings of the 5th IEEE Workshop on Signal Processing Advances in Wireless Communications (SPAWC '04), July 2004, Lisbon, Portugal 218–222.
Dinis R, Kalbasi R, Falconer D, Banihashemi AH: Iterative layered space-time receivers for single-carrier transmission over severe time-dispersive channels. IEEE Communications Letters 2004,8(9):579-581. 10.1109/LCOMM.2004.835339
Voulgarelis A, Joham M, Utschick W: Space-time equalization based on V-BLAST and DFE for frequency selective MIMO channels. Proceedings of IEEE International Conference on Acoustics, Speech, and Signal Processing (ICASSP '03), April 2003, Hong Kong 4: 381–384.
Komninakis C, Fragouli C, Sayed AH, Wesel RD: Multi-input multi-output fading channel tracking and equalization using Kalman estimation. IEEE Transactions on Signal Processing 2002,50(5):1065-1076. 10.1109/78.995063
Coon J, Armour S, Beach M, McGeehan J: Adaptive frequency-domain equalization for single-carrier multiple-input multiple-output wireless transmissions. IEEE Transactions on Signal Processing 2005,53(8):3247-3256.
Mailaender L: Linear MIMO equalization for CDMA downlink signals with code reuse. IEEE Transactions on Wireless Communications 2005,4(5):2423-2434.
Dam HH, Nordholm S, Zepernick H-J: Frequency domain adaptive equalization for MIMO systems. Proceedings of the 58th IEEE Vehicular Technology Conference (VTC '03), October 2003, Orlando, Fla, USA 1: 443–446.
Maleki-Tehrani A, Hassibi B, Cioffi JM: Adaptive equalization of multiple-input multiple-output (MIMO) channels. Proceedings of IEEE International Conference on Communications (ICC '00), June 2000, New Orleans, La, USA 3: 1670–1674.
Choi J, Yu H, Lee YH: Adaptive MIMO decision feedback equalization for receivers with time-varying channels. IEEE Transactions on Signal Processing 2005,53(11):4295-4303.
Rontogiannis AA, Kekatos V, Berberidis K: A square-root adaptive V-BLAST algorithm for fast time-varying MIMO channels. IEEE Signal Processing Letters 2006,13(5):265-268.
Rontogiannis AA, Kekatos V, Berberidis K: An adaptive decision feedback equalizer for time-varying frequency selective MIMO channels. Proceedings of the 7th IEEE Workshop on Signal Processing Advances in Wireless Communications (SPAWC '06), July 2006, Cannes, France
Haykin S: Adaptive Filter Theory. Prentice-Hall, Englewood Cliffs, NJ, USA; 2002.
Golub GH, van Loan CF: Matrix Computations. John Hopkins University Press, Baltimore, Md, USA; 1996.
Rontogiannis AA, Theodoridis S: New fast QR decomposition least squares adaptive algorithms. IEEE Transactions on Signal Processing 1998,46(8):2113-2121. 10.1109/78.705419
Pan C, Plemmons R: Least squares modifications with inverse factorization: parallel implications. Journal of Computational and Applied Mathematics 1989,27(1-2):109-127. 10.1016/0377-0427(89)90363-4
Luetkepohl H: Handbook of Matrices. John Wiley & Sons, New York, NY, USA; 2000.
Selection procedures for the choice of radio transmission technologies of the UMTS In Tech. Rep. 101.112. ETSI, Sophia Antipolis, France; 1998.
About this article
Cite this article
Kekatos, V., Rontogiannis, A.A. & Berberidis, K. Cholesky Factorization-Based Adaptive BLAST DFE for Wideband MIMO Channels. EURASIP J. Adv. Signal Process. 2007, 045789 (2007) doi:10.1155/2007/45789
- MIMO Channel
- Equalization Problem
- Cholesky Factorization
- Recursive Structure
- Autocorrelation Matrix