In this paper, we report the design and evaluation of a compact 108-element base station antenna array for massive multi-input multi-output (MIMO) system using a 3-port multimode antenna as a unit element. Of these three ports, port 1 and port 2 have orthogonally polarized broadside radiation pattern with measured peak gain of 6.5 dBi and impedance bandwidth of 254 MHz (2.268 GHz-2.522 GHz) and 238 MHz (2.248 GHz-2.486 GHz), respectively, while port 3 has monopole-like radiation pattern having measured peak gain of 1.21 dBi and impedance bandwidth of 102 MHz (2.376 GHz-2.478 GHz). Mutual coupling among all the ports is kept as less than -14 dB. Design of 108 elements massive MIMO antenna array is evaluated as a base station antenna for multiuser urban street grid scenario in MIMO-OFDM downlink system, which is further modeled using Wireless World Initiative New Radio II (WINNER II) Channel models in MATLAB. Parameters like Singular value spread and Dirty Paper Coding (DPC) sum capacity was calculated and compared with i.i.d channel model. For 4 users case using same frequency and time resource, singular value spread and DPC sum capacity for presented antenna array converges to 7 dB and 11.6 bps/Hz at 10 dB SNR, respectively.
2. Marzetta, T. L., "Noncooperative cellular wireless with unlimited numbers of base station antennas," IEEE Transactions on Wireless Communications, Vol. 9, No. 11, 3590-3600, Nov. 2010.
3. Rusek, F., D. Persson, B. K. Lau, E. G. Larsson, T. L. Marzetta, O. Edfors, and F. Tufvesson, "Scaling up MIMO: Opportunities and challenges with very large arrays," IEEE Signal Processing Magazine, Jan. 2013.
4. Ngo, H. Q., E. G. Larsson, and T. L. Marzetta, "Energy and spectral efficiency of very large multiuser MIMO systems," IEEE Transactions on Communications, Vol. 61, No. 4, 1436-1449, 2013.
5. Antonino-Daviu, E., et al., "Design of a multimode MIMO antenna using the theory of characteristic modes," Radioengineering, Vol. 18, No. 4, Dec. 2009.
6. Sarrazin, J., Y. Mah, S. Avrillon, and S. Toutain, "A new multimode antenna for MIMO systemsusing a mode frequency convergence concept," IEEE Transactions on Antennas and Propagation, Vol. 59, No. 12, Dec. 2011.
7. Rajo-Iglesias, E., O. Quevedo-Teruel, and M. Sanchez-Fernandez, "Compact multimode patch antennas for MIMO applications," IEEE Antennas and Propagation Magazine, Vol. 50, No. 2, Apr. 2008.
8. Waldschmidt, C. and W. Wiesbeck, "Compact wide-band multimode antennas for MIMO and diversity," IEEE Transactions on Antennas and Propagation, Vol. 52, No. 8, Aug. 2004.
9. Gao, X., et al., "Massive MIMO performance evaluation based on measured propagation data," IEEE Transactions on Wireless Communications, Mar. 2015.
10. Vishwanath, S., N. Jindal, and A. Goldsmith, "Duality, achievable rates, and sum rate capacity of Gaussian MIMO broadcast channels," IEEE Transactions on Information Theory, Vol. 49, No. 10, 2658-2668, Oct. 2003.
11. Jindal, N., et al., "Sum power iterative water-filling for multi-antenna gaussian broadcast channels," IEEE Transactions on Information Theory, Vol. 51, No. 4, Apr. 2005.