In this manuscript, a novel multiport matching method is devised to directly maximize the mean capacity with rigorous consideration of the mutual coupling effects of the matching network. In the RF front end of the real communication circuits, the mutual couplings always exist. In this paper, 1) a theoretical capacity upper bound of the 2-by-2 MIMO system with a matching network using the water-filling as the power allocation rule is analytically derived for the first time, 2) the Genetic Algorithm is employed to optimize the parameters of the matching network for the maximization of the mean capacity, 3) a coupled microstrip lines structure is devised to implement the matching network of the real MIMO receiving circuits by this matching method. The numerical results in the last section demonstrate that an optimized matching network obtained using our novel MPM method is capable to enhance the performance of the MIMO systems in a range of different indoor environments. This verifies that our method is not only effective but also practical.
1. Wallace, J. W. and M. A. Jensen, "Mutual coupling in MIMO wireless systems: A rigorous network theory analysis," IEEE Trans. on Wireless Commun., Vol. 3, No. 4, 1317-1325, Jul. 2004. doi:10.1109/TWC.2004.830854
2. Lau, B. K., J. B. Anderson, G. Kristensson, and F. Molisch, "Impact of matching network on bandwidth of compact antenna arrays ," IEEE Trans. on Antennas and Propagat., Vol. 54, No. 11, 3225-3238, Nov. 2006.
3. Fei, Y., Y. Fan, B. K. Lau, and J. S. Thompson, "Optimal single-port matching impedance for capacity maximization in compact MIMO arrays ," IEEE Trans. on Antennas and Propagat., Vol. 56, No. 11, 3566-3575, Nov. 2008.
4. Tsen, W.-F. and H. J. Li, "Optimal impedance matching for capacity maximization of MIMO systems with coupled antennas and noisy amplifiers," Progress In Electromagnetics Research C, Vol. 15, 23-36, 2010. doi:10.2528/PIERC10050301
6. Wang, H. G. and L. Wang, "A novel numerical model for simulating three dimensional MIMO channels with complex antenna arrays," IEEE Trans. on Antennas and Propagat., Vol. 57, No. 8, 2439-2451, Aug. 2009. doi:10.1109/TAP.2009.2024481
7. Wang, H. G. and C. H. Chan, "The implementation of multilevel Green's function interpolation method for full-wave electromagnetic problems ," IEEE Trans. on Antennas and Propagat., Vol. 55, No. 5, May 2007. doi:10.1109/TAP.2007.895576
8. Shi, Y., X. Luan, J. Qin, C. Lv, and C.-H. Liang, "Multilevel Green's function interpolation method solution of volume/surface integral equation for mixed conducting/bi-isotropic objects," Progress In Electromagnetics Research, Vol. 107, 239-252, 2010. doi:10.2528/PIER10060209
9. Bertoni, H. L., Radio Propagation for Modern Wireless Systems, Prentice Hall, NJ, 2000.
10. Liu, Z.-Y. and L.-X. Guo, "A quasi three-dimensional ray tracing method based on the virtual source tree in urban microcellular environments," Progress In Electromagnetics Research, Vol. 118, 397-414, 2011. doi:10.2528/PIER11041602
11. Reza, W. A., M. S. Sarker, and K. Dimyati, "A novel integrated mathematical approach of ray-tracing and genetic algorithm for optimizing indoor wireless coverage," Progress In Electromagnetics Research, Vol. 110, 147-162, 2010. doi:10.2528/PIER10091701
12. Sarker, M. S., A. W. Reza, and K. Dimyati, "A novel ray-tracing technique for indoor radio signal prediction," Journal of Electromagnetic Waves and Applications, Vol. 25, No. 8-9, 1179-1190, 2011. doi:10.1163/156939311795762222
13. Chen, S.-H. and S.-K. Jeng, "An SBR/image approach for radio wave propagation in indoor environments with metallic furniture," IEEE Trans. on Antennas and Propagat., Vol. 45, No. 1, 98-106, Jan. 1997. doi:10.1109/8.554246
14. Telatar, I. E., "Capacity of multi antenna Gaussian channels," AT&T Bell Labs. Internal Tech. Memo., Jun. 1995.
15. Chiurtu, N., B. Rimoldi, and E. Telatar, "On the capacity of multi-antenna gaussian channels," IEEE International Symposium on Information Theory, Washington, DC, Jun. 24-29, 2001.
16. Pozar, D. M., Microwave Engineering, 3rd Ed., 226-227, 2004.
17. Wolpert, D. H. and W. G. Macready, "No free lunch theorems for optimization," IEEE Transactions on Evolutionary Computation, Vol. 1, No. 1, 67-82, Apr. 1997. doi:10.1109/4235.585893
18. Kirkpatrick, S., C. D. Gelatt, and M. P. Vecchi, "Optimization by simulated annealing," Science, Vol. 220, No. 4598, 671-680, 1983. doi:10.1126/science.220.4598.671
19. Fulginei, F. R. and A. Salvini, "Comparative analysis between modern heuristics and hybrid algorithms," COMPEL: The International Journal for Computation and Mathematics in Electrical and Electronic Engineering, Vol. 26, No. 2, 259-268, 2007. doi:10.1108/03321640710727629
20. Siakavara, K., "Novel fractal antenna arrays for satellite networks: Circular ring Sierpinski carpet arrays optimized by genetic algorithms," Progress In Electromagnetics Research, Vol. 103, 115-138, 2010. doi:10.2528/PIER10020110
21. Dadgarnia, A. and A. A. Heidari, "A fast systematic approach for microstrip antenna design and optimization using ANFIS and GA," Journal of Electromagnetic Waves and Applications, Vol. 24, No. 16, 2207-2221, 2010. doi:10.1163/156939310793699037
22. Gaorga, I. Z. and A. K. Johnson, "Coupled transmission line networks in an inhomogeneous dielectric medium," IEEE Transactions on Microwave Theory and Techniques, Vol. 17, No. 10, 750-753, Oct. 1969.
23. Kirschning, M. and R. H. Jansen, "Accurate wide-range design equations for the frequency-dependent characteristic of parallel coupled microstrip lines," IEEE Transactions on Microwave Theory and Techniques, Vol. 27, No. 1, 83-90, Jan. 1984. doi:10.1109/TMTT.1984.1132616
24. Wang, L. and H. G. Wang, An analytical three dimensional correlation model for array with antennas having arbitrarily oriented directions, IEEE Asia Pacific Microwave Conference, Hong Kong, Dec. 2008.
25. Wang, L. and H. G. Wang, "Regular polyhedron antenna array design and simulation for MIMO systems," PIERS Proceedings, 1487-1490, Beijing, China, Mar. 23-27, 2009.
26. Gray, R. M., Toeplitz and Circulant Matrices: A Review, 2006.