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Journal Radioengineering №3 for 2010 г.
Article in number:
Adaptive Channel Estimation for MIMO-OFDM Wireless Systems
Keywords: channel estimation OFDM MIMO adaptation interpolation
Authors:
V.B. Manelis, I.V. Kaioukov
Abstract:
A lot of attention has also been recently paid to high-speed transmission and high-capacity systems based on MIMO-OFDM technologies. To achieve high interference stability, coherent M-PSK and M-QAM modulation schemes are applied. Potential advantages of these modulation schemes could be implemented with high channel estimation accuracy only. Channel estimation accuracy is a crucial aspect in the design of MIMO-OFDM systems. Channel estimation algorithm for MIMO-OFDM systems based on separable interpolation in frequency and time domains (21D interpolator) is proposed. Proposed original channel estimation algorithm includes Doppler frequency and path profile length (multipath delay spread) estima-tions, which performed using the pilot symbols for all pairs of receive and transmit antennas. Since all channel propagation signals in MIMO system pass through the same scatters, delay path profile for all channels is also the same. We use this MIMO system feature to improve the channel statistics estimation. Proposed interpolation order rule consists in comparison normalized Doppler frequency estimate of MIMO-OFDM system with normalized multipath delay spread estimate. If the first is more than the second, relative channel variations speed in time domain is more rapid than in frequency domain. So interpolation in frequency domain is implemented first, and then in time domain. Otherwise inter-polation order is reverse. Adaptive selection of interpolation order provides estimation accuracy improving, especially for long channels (urban area) or for high sub-scriber speed (future mobile communication systems will have to support high user mobility). Simulation of the proposed algorithm showed, that performance gain in comparison with the alternative fixed order algorithms takes place for subscriber speed more 40 km/h and channel impulse response length more 4 us. This gain can reach 34 dB. The proposed algorithm with adaptive interpolation order has prospects for different MIMO-OFDM systems (IEEE std. 802.16хх, LTE etc) operating in rapid time-variant multipath environments.
Pages: 25-31
References
  1. Cimini L.J. Jr. Analysis and simulation of a digital mobile channel using orthogonal frequency division multiplexing // IEEE Trans. Commun. 1985. V. COMM-33. P. 665-675. July.
  2. Van Nee R., Prasad R. OFDM Wireless Multimedia Communications. Artech House, Boston-London, 2000.
  3. Foschini G. J. and Gans M. J. On limits of wireless communications in a fading environment when using multiple antennas // Wireless Personal Commun. 1998. V. 6. No. 3. P. 311-335.
  4. Golden G. D., Foschini C. J., Valenzuela R.A. and Wolniansky P. W. Detection algorithm and initial laboratory results using V-BLAST space-time communication architecture // Electron. Lett. 1999. V. 35. P. 14-16. Jan.
  5. IEEE Std 802.16e, Part 16: Air Interface for Fixed and Mobile Broadband Wireless Access Systems, Sep. 2004.
  6. Sandell M. and Edfors O. A comparative study of pilot-based channel estimators for wireless OFDM. Div. Signal Processing, Lulea Univ. Technology, Lulea, Sweden, Res. Rep. TULEA 1996:19, Sept. 1996.
  7. Ye Li, Cimini J. Leonard, Jr, and Sollengerger Nelson R. Robust Channel estimation for OFDM Systems with Rapid Dispersive Fading Channels // IEEE Transaction on Communications. 1998. V. 46. No. 7. P. 902-915. July.
  8. Morelli M., Mengali U. A Comparison of Pilot-Aided Channel Estimation Methods for OFDM Systems IEEE // Transactions on Signal Processing. 2001. V. 49. No.12. December. P. 3065-3073.
  9. Wang X., Liu K. J. R. OFDM Channel Estimation Based on Time-Frequency Polynomial Model of Fading Multipath Channels // IEEE GLOBECOM 2001 San Antonio, Texas, USA, November 25-29. 2001.
  10. Манелис В.Б., Каюков И.В. Эквалайзеры в широкополосных системах радиосвязи // Мобильные системы. 2007. № 2. С. 30-35.
  11. Kaioukov I. V., Manelis V. B., Cleveland J. R. Channel Estimation for MIMO-OFDM Systems in Rapid Time-Variant Environments Based On Channel Statistics Estimation, GLOBECOM 2006 // IEEE Global Telecommunications Conference. 2006. V. 25. No. 1. November. P. 2752-2756.
  12. Каюков И. В., Манелис В. Б. Оценка канала распространения в мобильных системах связи // Тез. докл. 7-й междунар. НТК «Радиолокация, навигация, связь» Воронеж. 2001. Т.2. C. 958-965.
  13. Choi Y-S., Ozdural O. C., Liu H. and Alamouti S. A maximum likelihood doppler frequency estimator for OFDM systems, ICC 2006 // IEEE International Conference on Communications. 2006. V. 29. N. 1. June. P. 4556 - 4560.
  14. Yucek T. and Arslan H. Delay spread and time dispersion estimation for adaptive OFDM systems, WCNC 2006 // IEEE Wireless Communications and Networking Conference. 2006. V. 7. No. 1. April. P. 1433-1438.
  15. Zhu X., Murch R. D. Performance analysis of maximum likelihood detection in a MIMO antenna system // IEEE Transactions on Communications. 2002. V. 50. No. 2. Feb. P. 187-191.
  16. Spatial Channel Model Text Description, SCM Text V7.0, Spatial Channel Model AHG (Combined ad-hoc from 3GPP & 3GPP2), August 19, 2003.