THE IMPROVEMENT OF MIMO CAPACITY USING SIMPLE TECHNIQUE REALIZED BY BUTLER MATRIX
Keywords:
MIMO Channel Capacity, Array domain processing, Angle domain processing, Eigenbeamforming, Butler matrixAbstract
In the literature, among many techniques improving MIMO capacity (Foschini, 1996; Foschiniet al., 1998; Kermoal et al., 2000; Molisch et al., 2002; Stridh et al., 2000; Telatar, 1995; Tsoulos,2006; Vieira et al., 2006), the concept of eigen-beamforming has been recognized as the best technique to provide an enhanced capacity. However, the expense of this technique is the cost of feedback channel and complexity processing. Therefore, this article aims to present a simple technique based on angle domain processing which does not require a feedback channel and has low complexity. A Butler matrix is chosen for 4 × 4 MIMO systems in order to prove the concept of the proposed system in practice. The simulation and measurement results indicate the enhancement of MIMO capacity when using Butler matrix.
References
Bishwarup, M., and Robert, W.H., (2006).Performance analysis of quantized beamforming MIMO systems. IEEE Transactions on Signal Processing,54(12):4753-4766.
Foschini, G.J., (1996). Layered space–time architecture for wireless communication in a fading environment when using multielement antennas. Bell Labs Technical Journal, 1(2):41-59.
Foschini, G.L., and Gans M.J., (1998). On limit of wireless communications in a fading environment when using multiple antennas. Wireless Personal Communications, 6(3):311–335.
Innok, A., Uthansakul, M., and Uthansakul, P.,(2009). Performance of MIMO capacity using angle domain processing realized by butler matrix. Proceedings of ECTICON;6-9 May, 2009; Pattaya, Thailand,p. 844-847.
Kermoal, J.P., Mogensen, P.E., Jensen, S.H.,Andersen, J.B., Frederiksen, F., Sorensen,T.B., and Pedersen, K.I., (2000).Experimental investigation of multipath richness for multi-element transmit and receive antenna array. IEEE 51st Vehicular Technology Conference Proceedings;15-18 May, 2000; Tokyo, Japan, p.2004–2008.
Liang, S., Matthew, R.M., and Shi J., (2009).Analytical Performance of MIMO Multichannel Beamforming in the Presence of Unequal Power Cochannel Interference and Noise. IEEE Transactions on Signal Processing, 57(7):2721-2735.
Liberti, J. C., and Rappaport, J. T. S., (1999).Smart Antennas for Wireless Communications. IS-95 and Third Generation CDMA Applications, 528p.
Li, H., Bergmans, J.W.M., and Willems,F.M.J., (2007). Low-complexity LMMSE based MIMO-OFDM channel estimation via angle-domain processing. IEEE Transactions on Signal Processing,55(12):5668–5680.
Li, H., Chin, K.H., Bergmans, J.W.M., and Willems F.M.J., (2008). Pilot-aided angle-domain channel estimation techniques for MIMO-OFDM system.IEEE Transactions on Vehicular Technology, 57(2):906–920.
Molisch, A.F., Steinbauer, M., Toeltsch, M.,Bonek, E., and Thoma, R.S., (2002).Capacity of MIMO systems based on measured wireless channel. IEEE Journal on Selected Areas in Communications,20(3):561–569.
Promsuvana, N., and Uthansakul, P., (2008)Feasibility of adaptive 4 × 4 MIMO system using channel reciprocity in FDD mode. 14th Asia-Pacific conference on communications; 14-16 October,2008; Akihabara, Tokyo, Japan.
Sirikiat, L.A., Jun, Z., Eric, O., and Joonsuk,K., (2006). Subspace beamforming for near-capacity performance. IEEE Transactions on Signal Processing,56(11):5729-5733.
Stridh, R., Ottersten, B., and Karlsson, P.,(2000). MIMO channel capacity of a measured indoor radio channel at 5.8Ghz. Conference Record of the Thirty-Fourth Asilomar Conference on Signals,Systems and Computers; 29 October- 1November, 2000; PACIFIC GROVE,CALIFORNIA, USA, p. 733-737.
Telatar, I.E., (1995). Capacity of multiantenna Gaussian channels. AT&T Bell Laboratories,Tech. Memo., 43(2):773-775.
Tse, D., and Viswanath, P., (2005). Fundamentals of Wireless Communication. Published in the United States of America by Cambridge University Press, New York,p. 290-330.
Tsoulos, R.G., (2006). MIMO systems Technology for Wireless Communications. Theelectrical engineering and applied signal processing Series, Taylor and Francis Group, USA, 378p.
Vieira, R.D., Brandao, J.C.B., and Siqueira,G.L., (2006). MIMO measured channels:Capacity results and analysis of channel parameters. International Telecommunications Symposium: 3-6 September,2006; p. 152–157.
Xiayu Z., Yao X., Jian L., and Petre S.,(2007). MIMO transmit beamforming under uniform Elemental Power Constraint. IEEE Transactions on Signal Processing, 55(11):5395-5406
