Abstract
This work pertains to the use of superimposed training for channel estimation in orthogonal frequency division multiplexing (OFDM) based systems. An iterative time domain Least Squares based channel estimator is proposed. The estimator is generalized to provide scope for exploiting the coherence time and the coherence bandwidth of the channel. By exploiting the periodicity of the training sequences in the time domain and inserting zeros instead of data at some of the training sequence subcarrier locations depending on the desired estimation accuracy, a controlled superimposition technique is proposed. This method includes the flexibility to trade off between bandwidth efficiency and performance without any change in the structure of the channel estimator. The mean squared estimation error (MSEE) performance of such a system is mathematically analyzed and a training sequence selection criterion optimizing the same is proposed. The simulation performance of the scheme is presented in terms of the MSEE and also its impact on the bit error rate is shown. Such a scheme is attractive in high data rate scenarios in closed loop OFDM systems.
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Orozco-Lugo A. G., Lara M., McLernon D. (2004) Channel estimation using implicit training. IEEE Transactions on Signal Processing 52(1): 240–254
Tugnait J. K., Meng X. (2006) On superimposed training for channel estimation: Performance analysis, training power allocation, and frame synchronization. IEEE Transactions on Signal Processing 54(2): 752–765
Ghogho M., McLernon D., Alameda-Hernandez E., Swami A. (2005) Channel estimation and symbol detection for block transmission using data-dependant superimposed training. IEEE Signal Processing Letters 12(3): 226–229
Orozco-Lugo A. G., Lara M., McLernon D. (2004) Channel estimation using implicit training. IEEE Transactions on Signal Processing 52(1): 240–253
Chen N., Zhou G. T. (2006) Superimposed training for OFDM: A peak-to-average power ratio analysis. IEEE Transactions on Signal Processing 54(6): 2277–2287
Ohkubo, N., & Ohtsuki, T. (2003). Added pilot semi-blind channel estimation for OFDM packet transmission. In Proceedings of the IEEE-GLOBECOM (pp. 878–882).
Ho, C. K., Farhang-Boroujeny, B., & Chin, F. (2001). Added pilot semi-blind channel estimation scheme for OFDM in fading channels. In Proceedings of the IEEE-GLOBECOM (pp. 3075–3079).
Balasubramanian, S., Farhang-Boroujeny, B., & John Mathews, V. (2004). Pilot embedding for channel estimation and tracking in OFDM systems. In Proceedings of the IEEE-GLOBECOM (pp. 1244–1248).
Josiam K., Rajan D. (2007) Bandwidth efficient channel estimation using super-imposed pilots in OFDM systems. IEEE Transactions on Wireless Communications 6(6): 2234–2245
Alameda-Hernandez E., McLernon D. C., Orozco-Lugo A. G., Lara M., Ghogho M. (2007) Frame/training sequence synchronization and DC-offset removal for (data dependant) superimposed training based channel estimation. IEEE Transactions on Signal Processing 55(6): 2557–2569
Li C.-P., Hu W.-W. (2007) Super-imposed training scheme for timing and frequency synchronization in OFDM systems. IEEE Transactions on Broadcating 53(2): 574–583
Ohno S., Giannakis G. B. (2002) Optimal training and redundant precoding for block transmissions with applications to wireless OFDM. IEEE Transactions on Communications 50(12): 2113–2123
Sari H., Karam G., Jeanclaude I. (1995) Transmission techniques for digital terestrial TV broadcasting. IEEE Communications Mgazine 33(2): 101–109
Mobile WiMAX-Part I: A technical overview and performance evaluation, WiMAX Forum (2006).
Proakis, J. G., & Manolakis, D. G. (1996). Digital Signal Processing (3rd ed., pp. 345–350). New Delhi: PHI Press.
Rappaport, T. (2002). Wireless Communications: Principles and Practice (2nd ed., pp. 203–204). New Delhi: PHI Press
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Nair, J.P., Raja Kumar, R.V. Data Aided Iterative Channel Estimation in OFDM Systems Using a Controlled Superimposition of Training Sequences. Wireless Pers Commun 68, 1241–1254 (2013). https://doi.org/10.1007/s11277-012-0506-9
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DOI: https://doi.org/10.1007/s11277-012-0506-9