Abstract
In this work an enhanced semi-blind channel estimator is presented for multicarrier CDMA systems with multiple transmit and receive antennas. The novel scheme is based on embedded pilots that are characterized as virtual users and their number is determined in a dynamic fashion according to the propagation channel conditions. The superimposed code-multiplexed pilots are used initially for channel estimation before the despreading operation, thus achieving per subcarrier estimation using the known unique multi-layer pattern of the virtual users. Afterwards, the estimation is enhanced by using the despread pilots. Furthermore, an iterative scheme is incorporated in channel estimation process minimizing the effect of multiuser interference and operates either in interference cancellation, or in virtual user mode. The proposed architecture is evaluated for spatial diversity systems (space- frequency block coded) with two transmit and up to four receive antennas operating in realistic propagation channels for various modulation and coding schemes. The results demonstrate a significant performance improvement especially as the channel is dominated by its time variant characteristics. The dynamic assignment of spreading codes in the payload and the pilots offers to the system realistic flexibility and adaptivity in demanding channels achieving concurrently maximization of the real overall system throughput, while maintaining low overhead and complexity burden.
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References
Foschini, G. J., & Gans, M. J. (1998). On the limits of wireless communications in a fading environment when using multiple antennas. Wireless Personal Communications, 6, 311–335. Kluwer.
Thoma R. S., Hampicke D., Richter A., Sommerkorn G., Trautwein U. (2001) MIMO vector channel sounder measurement for smart antenna system evaluation. European Transaction on Telecommunications ETT 12(5), 377–391. (Special Issue on Smart Antennas).
6th Framework program information society technologies, 4-MORE project, IST-2002-507039, Online Available: http://www.ist-4more.org.
Poor H. (1985) An introduction to signal detection and estimation. Springer, New York
Makrakis, D., & Feher, K. (1987). A novel insertion-extraction technique based on spread spectrum techniques. In Proceedings of the miami techicon, pp. 129–132, USA.
Hoeher, P., & Tufvesson, F. (1999). Channel estimation with superimposed pilot sequence. In Proceedings of IEEE global telecommunications conference, GLOBECOM (Vol. 4, pp. 2162–2166). Brazil.
Bohlin, P., & Tapio, M. (2004). Performance evaluation of MIMO communication systems based on superimposed pilots. In Proceedings of IEEE ICASSP 04, Montreal, Canada.
Budianu C., Tong L. (2002) Channel estimation for space-time orthogonal block codes. IEEE Transactions on Signal Processing 50(10): 2515–2528
Coldery M., Bohlin P. (2008) Training based MIMO systems: Part II–improvements using detected symbol information. IEEE Transactions on Signal Processing 56(1): 296–303
Qin W., Peng Q.-C. (2008) Time-varying channel estimation and symbol detection using superimposed training in OFDM systems. Wireless Personal Communications 47: 293–301
Pirak, C., Wang, Z. J., Liu, K. J. R., & Jitapunkul, S. (2006). Adaptive channel estimation using pilot-embedded data-bearing approach for MIMO-OFDM systems. IEEE Transactions on Signal Processing, 54(12).
Chapalain, N., Mottier, D., & Castelain, D. (2005). Performance of uplink SS-MC-MA systems with frequency hopping and channel estimation based on pilot symbols. In IEEE 16th international symposium on personal indoor and mobile radio communications 2005, PIMRC 2005 (Vol. 3, pp. 1515–1519).
Cariou, L., & Helard, J.-F. (2005). Superimposed pilot-based channel estimation for MIMO OFDM code division multiplexing uplink systems. In Proceedings of from 5th international workshop of multi-carrier spread-spectrum (pp. 247–256). Oberpfaffenhofen, Germany.
Schoeneich, H., & Hoeher, P.-A. (2006). Iterative pilot-layer aided channel estimation with emphasis on interleave-division multiple access systems. EURASIP Journal on Applied Signal Processing, Article ID 81729 (pp. 1–15).
Kaiser, S. (2003). Space frequency block codes and code division multiplexing in OFDM systems. In IEEE global telecommunications conference, GLOBECOM’03 (Vol. 4, pp. 2360–2364).
Zhu H., Farhang-Boroujey B., Schegel C. (2003) Pilot embedding for joint channel estimation and data detection in MIMO communication system. IEEE Communication Letters 7(1): 30–32
Portier, F., Sand, S., & Helard, J.-F. (2006). Iterative channel estimation for orthogonal STBC MC-CDMA systems over realistic high-mobility MIMO channels. In Proceedings of IEEE PIMRC-06 (pp. 14–16). Helsinki, Finland.
Sand, S., Raulefs, R., & Dammann, A. (2005). Iterative channel estimation for MIMO MC-CDMA. In Proceedings of 5th international workshop on multi-carrier spread-spectrum and related topics (MC-SS 2005), Oberpfaffenhofen, Germany.
Cariou, L., & Helard, J.-F. (2005). A simple and efficient channel estimation for MIMO OFDM code division multiplexing uplink systems. In IEEE 6th workshop on signal processing advances in wireless communications, SPAWC-05 (pp. 176–180).
Tarokh V., Seshadri N., Calderbank A. R. (1998) Space-time codes for high data rate wireless communication: Performance criterion and code construction. IEEE Transactions on Information Theory 44: 744–765
Lee, Y.-N., Ashikhmin, A., & Chen, J.-T. (2008). Impact of soft channel construction on iterative channel estimation and data decoding for multicarrier systems. IEEE Transactions on Wireless Communications, 7(7).
Wo, T., Hoeher, P.-A., Scherb, A., & Kammeyer, K.-D. (2006). Performance analysis of maximum-likelihood semiblind estimation of MIMO channels. In Proceedings of IEEE 63rd vehicular technology conference, VTC06-Spring (Vol. 4, pp. 1738–1742). Australia.
3GPP TR 25.996 v6.1.0 (2003–2009). Spatial channel model for multiple input multiple output simulations, Sep 2003, www.3gpp.org.
Baum, D., Salo, J., Del Galdo, G., Milojevic, M., Kyosti, P., & Hansen, J. (2005). An interim channel model for beyond-3G systems. In Proceedings of IEEE VTC 2005 Spring, Stockholm.
6th Framework program, information society technologies, wireless world initiative new radio (WINNER), IST-2003-507581, Online Available: http://www.ist-winner.org.
Skentos N., Marousis A., Kanatas A., Constantinou P. (2007) Experimental multipath component characteristics for short range urban propagation environments. European Transactions on Telecommunications ETT 18(6): 595–603
Agilent Technologies, Advanced Design Systems (ADS) 2009 www.agilent.com/find/eesof-ads.
Portier, F., Baudais, J.-Y., & Helard, J.-F. (2004). Performance of STBC MC-CDMA systems over outdoor realistic MIMO channels. In IEEE 60th vehicular technology conference, VTC 04 Fall (Vol. 4, pp. 2409–2413). Los Angeles, USA.
Wehinger J., Mecklenbrauker C. (2006) Iterative CDMA multiuser receiver with soft decision-directed channel estimation. IEEE Transactions on Signal Processing 54(10): 3922–3934
Taoka H., Higuchi K., Sawahashi M. (2006) Experiments on space diversity effect in MIMO channel transmission with maximum data rate of 1Gbps in downlink OFDM radio access. European Transactions on Telecommunications 17: 611–622
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Marousis, A.D., Skentos, N.D. & Constantinou, P. An Enhanced Embedded-Pilot Channel Estimation Architecture for MIMO MC-CDMA Systems. Wireless Pers Commun 59, 713–739 (2011). https://doi.org/10.1007/s11277-010-9933-7
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DOI: https://doi.org/10.1007/s11277-010-9933-7