References
- Elijah O, Leow CY, Rahman TA, et al. A comprehensive survey of pilot contamination in massive MIMO – 5G system. IEEE Commun Surv Tutorials. 2016;18:905–923. doi: 10.1109/COMST.2015.2504379
- Lu L, Li GY, Swindlehurst AL, et al. An overview of massive MIMO: benefits and challenges. IEEE J Sel Topics Signal Process. 2014;8:742–758. doi: 10.1109/JSTSP.2014.2317671
- Li Q, Niu H, Papathanassiou A, et al. 5G network capacity: key elements and technologies. IEEE Veh Technol Mag. 2014;9:71–78. doi: 10.1109/MVT.2013.2295070
- Prasad N, Zhang H, Zhu H, et al. Multi-user MIMO scheduling in the fourth generation cellular uplink. Proceedings of the Asilomar Conference on Signals, Systems, and Computers; 2013. p. 1855–1859,
- Hossain E, Hasan M. 5G cellular: key enabling technologies and research challenges. IEEE Instrum Meas Mag. Jun. 2015;18:11–21. doi: 10.1109/MIM.2015.7108393
- Ngo HQ, Larsson E, Marzetta T. Energy and spectral efficiency of very large multiuser MIMO systems. IEEE Trans Commun. 2013;61:1436–1449. doi: 10.1109/TCOMM.2013.032713.120408
- Bjornson E, Sanguinetti L, Hoydis J, et al. Optimal design of energy-efficient multi-user MIMO systems: is massive MIMO the answer? IEEE Trans.Wireless Commun. 2015;14:3059–3075. doi: 10.1109/TWC.2015.2400437
- Das G, Sharma A, Gangwar RK. Dielectric resonator based circularly polarized MIMO antenna with polarization diversity. Microw Opt Technol Lett. 2018;60:685–693. doi: 10.1002/mop.31033
- Constantine J, Tawk Y, Barbin SE, et al. Reconfigurable antennas: design and applications. Proc IEEE. 2015;103:424–437. doi: 10.1109/JPROC.2015.2396000
- Tripathi S, Mohan A, Yadav S. A compact frequency–reconfigurable fractal UWB antenna using reconfigurable ground plane. Microw Opt Technol Lett. 2017;59:1800–1808. doi: 10.1002/mop.30631
- Nikolaou S, Kingsley ND, Ponchak GE, et al. UWB elliptical monopoles with a reconfigurable band notch using MEMS switches actuated without bias lines. IEEE Trans Antennas Propagat. 2009;57:2242–2251. doi: 10.1109/TAP.2009.2024450
- Iqbal J, Illahi U, Sulaiman MI, et al. Mutual coupling reduction using hybrid technique in wideband circularly polarized MIMO antenna for WiMAX applications. IEEE Access. 2019;7:40951–40958. doi: 10.1109/ACCESS.2019.2908001
- Staszek K, Odrobina S, Wincza K, et al. Broadband matrix-type feeding networks for two-beam antennas with constant beamwidth and efficient aperture utilization. J Electromagn Waves Appl. 2018;33:236–248. doi: 10.1080/09205071.2018.1536565