This paper evaluates the performance of different configurations of MIMO antenna operating in the 5G band with the effect of user's hand in data mode and suggests an optimized configuration to mitigate hand effects. A dual-band four-element MIMO antenna is used. All antenna elements (AEs) are identical planar inverted-F antenna (PIFAs) with a lower frequency band (LB) from 3.3 to 3.8 GHz and an upper frequency band (UB) from 5.2 to 6 GHz. In addition, four different configurations to place the AEs on the chassis are selected including worst and optimized configurations as well two intermediate cases. Results show that similar values of ECC are produced for both cases without and with user hand. These values are less than 0.20 on most frequency range, except the worst case configuration which has some high ECC values close to unity. Unlike ECC, TE is severely affected by user's hand as well as by the different configuration. TE of each AE under hand effect is degraded differently according to the thickness of hand tissue that covers it. TE in the optimized configuration without user's hand ranges between 50 and 95% in both frequency bands. However, this range deteriorates when user's hand effect is considered, between 40% and 15% in LB, and from 35% to 41% in the UB. Multiplexing efficiency analysis reveals that MIMO performance is mainly determined by TE, and the impact of the low ECC is insignificant. This indicates that improving the performance depends on improving the TE of AEs and optimizing their positions on the chassis to reduce interaction with user's hand. Moreover, the loss in ergodic capacity due to user's hand compared with free space is increased from 5 to 40% in the LB, and it is more stable in the UB and ranging between 12 and 17%.
2. Astely, D., E. Dahlman, A. Furuskar, Y. Jading, M. Lindstrom, and S. Parkvall, "LTE: The evolution of mobile broadband," IEEE Commun. Mag., Vol. 47, No. 4, 44-51, 2009.
3. Fan, W., X. Carreno, P. Kyosti, and J. O. Nielsen, "Over-the-air testing of MIMO-capable terminals," IEEE Vehicular Technology Magazine, Vol. 10, No. 2, 38-46, June 2015.
4. Yanakiev, B., J. O. Nielsen, M. Christensen, and G. F. Pedersen, "On small terminal antenna correlation and impact on MIMO channel capacity," IEEE Trans. Antennas Propag., Vol. 60, No. 2, 689-699, 2012.
5. Gesbert, D., M. Shafi, D. Shiu, P. J. Smith, and A. Naguib, "From theory to practice: An overview of MIMO space-time coded wireless systems," IEEE J. Sel. Areas Commun., Vol. 21, No. 3, 281-302, 2003.
6. Song, H. J., et al., "Evaluation of vehicle-level MIMO antennas: Capacity, total embedded e±ciency, and envelope correlation," 2014 IEEE-APS Topical Conference on Antennas and Propagation in Wireless Communications (APWC), 89-92, 2014.
7. Nielsen, J. O., B. Yanakiev, S. C. Del Barrio, and G. F. Pedersen, "Channel models for capacity evaluation of MIMO handsets in data mode," IET Microwaves, Antennas Propag., Vol. 11, No. 1, 1-9, 2017.
8. Harrysson, F., A. Derneryd, and F. Tufvesson, "Evaluation of user hand and body impact on multiple antenna handset performance," 2010 IEEE Antennas and Propagation Society International Symposium (APSURSI), 1-4, 2010.
9. Zhekov, S. S., A. Tatomirescu, E. Foroozanfard, and G. F. Pedersen, "Experimental investigation on the effect of user's hand proximity on a compact ultrawideband MIMO antenna array," IET Microwaves, Antennas Propag., Vol. 10, No. 13, 1402-1410, 2016.
10. Holopainen, J., O. Kivekas, J. Ilvonen, R. Valkonen, C. Icheln, and P. Vainikainen, "Effect of the user's hands on the operation of lower UHF-band mobile terminal antennas: Focus on digital television receiver," IEEE Trans. Electromagn. Compat., Vol. 53, No. 3, 831-841, 2011.
11. Abbasi, Q. H., H. El Sallabi, E. Serpedin, K. Qaraqe, A. Alomainy, and Y. Hao, "Ellipticity statistics of ultra wideband MIMO channels for body centric wireless communication," 2016 10th European Conference on Antennas and Propagation (EuCAP), IEEE, 2016.
12. Helander, J., K. Zhao, Z. Ying, and D. Sjoberg, "Performance analysis of millimeter-wave phased array antennas in cellular handsets," IEEE Antennas Wirel. Propag. Lett., Vol. 15, 504-507, 2016.
13. Zhao, K., J. Helander, D. Sjoberg, S. He, T. Bolin, and Z. Ying, "User body effect on phased array in user equipment for the 5G mmWave communication system," IEEE Antennas Wirel. Propag. Lett., Vol. 16, 864-867, 2017.
14. Zhang, S., X. Chen, I. Syrytsin, and G. F. Pedersen, "A planar switchable 3-D-coverage phased array antenna and its user effects for 28-GHz mobile terminal applications," IEEE Trans. Antennas Propag., Vol. 65, No. 12, 6413-6421, 2017.
15. Li, Y. and G. Yang, "Dual-mode and triple-band 10-antenna handset array and its multiple-input multiple-output performance evaluation in 5G," Int. J. RF Microw. Comput. Eng., Vol. 29, No. 2, e21538, 2019.
16. Li, Y., Y. Luo, and G. Yang, "12-port 5G massive MIMO antenna array in sub-6 GHz mobile handset for LTE bands 42/43/46 applications," IEEE Access, Vol. 6, 344-354, 2018.
17. Rohani, B., K. Takahashi, H. Arai, Y. Kimura, and T. Ihara, "Improving channel capacity in indoor 4 x 4 MIMO base station utilizing small bidirectional antenna," IEEE Trans. Antennas Propag., Vol. 66, No. 1, 393-400, 2018.
18. Di Paola, C., I. Syrytsin, S. Zhang, and G. F. Pedersen, "Investigation of user effects on mobile phased antenna array from 5 to 6 GHz," 2018 IEEE 12th European Conference on Antennas and Propagation (EuCAP), 5 pages, April 2018.
19. Ying, Z., "Antennas in cellular phones for mobile communications," Proc. IEEE, Vol. 100, No. 7, 2286-2296, 2012.
20. Andersen, J. B., L. Fellow, J. O. Nielsen, and G. F. Pedersen, "Absorption related to hand-held devices in data mode," IEEE Trans. Electromagn. Compat., Vol. 58, No. 1, 47-53, 2016.
21. Syrytsin, I., S. Zhang, G. Pedersen, K. Zhao, T. Bolin, and Z. Ying, "Statistical investigation of the user effects on mobile terminal antennas for 5G applications," IEEE Trans. Antennas Propag., Vol. 65, No. 12, 6596-6605, 2017.
22. Recioui, A. and H. Bentarzi, "Genetic algorithm based MIMO capacity enhancement in spatially correlated channels including mutual coupling," Wirel. Pers. Commun., Vol. 63, No. 3, 689-701, 2012.
23. Recioui, A. and H. Bentarzi, "Capacity optimization of MIMO wireless communication systems using a hybrid genetic-taguchi algorithm," Wirel. Pers. Commun., Vol. 71, No. 2, 1003-1019, 2013.
24. Recioui, A., "Application of a galaxy-based search algorithm to MIMO system capacity optimization," Arab. J. Sci. Eng., Vol. 41, No. 9, 3407-3414, 2016.
25. Zhao, K., Mobile antenna systems for 4G and 5G applications with user body interaction, KTH Royal Institute of Technology, 2017.
26. Khan, R., A. Abdullah Al-Hadi, P. J. Soh, M. T. Ali, S. S. Al-Bawri, and Owais, "Design and optimization of a dual-band sub-6 GHz four port mobile terminal antenna performance in the vicinity of user's hand," Progress In Electromagnetics Research C, Vol. 85, 141-153, 2018.
27. Haraz, O. M., M. Ashraf, and S. Alshebeili, "Single-band PIFA MIMO antenna system design for future 5G wireless communication applications," 2015 IEEE 11th International Conference on Wireless and Mobile Computing, Networking and Communications (WiMob), 608-612, 2015.
28. Moradi Kordalivand, A., T. A. Rahman, and M. Khalily, "Common elements wideband MIMO antenna system for WiFi/LTE access-point applications," IEEE Antennas Wirel. Propag. Lett., Vol. 13, 1601-1604, 2014.
29. Tian, R., B. K. Lau, and Z. Ying, "Multiplexing efficiency of MIMO antennas with user effects," 2012 IEEE Antennas and Propagation Society International Symposium (APSURSI), 1-2, 2012.
30. Tian, R., B. K. Lau, and Z. Ying, "Multiplexing efficiency of MIMO antennas in arbitrary propagation scenarios," 2012 6th European Conference on Antennas and Propagation (EUCAP), 373-377, 2012.
31. Zhao, K., E. Bengtsson, Z. Ying, and S. He, "Multiplexing efficiency of high order MIMO in mobile terminal in different propagation scenarios," 2016 10th European Conference on Antennas and Propagation (EuCAP), 1-4, 2016.
32. Tian, R., B. K. Lau, and Z. Ying, "Multiplexing efficiency of MIMO antennas," IEEE Antennas Wirel. Propag. Lett., Vol. 10, 183-186, 2011.
33. Goldsmith, A., Wireless Communications, Cambridge University Press, 2005.
34. De Flaviis, F., L. Jofre, J. Romeu, and A. Grau, "Multiantenna systems for MIMO communications," Synth. Lect. Antennas, Vol. 3, No. 1, 1-250, 2008.