Holographic MIMO Communications: What is the benefit of closely spaced antennas?
Abstract: Holographic MIMO refers to a (possibly large) array with a large number of individually controlled and densely deployed antennas. The objective of this paper is to provide further insight into the use of closely spaced antennas in the uplink and downlink of a multi-user Holographic MIMO system. To this end, we utilize multiport communication theory, which ensures physically consistent uplink and downlink models. We first consider a simple uplink scenario with two side-by-side half-wavelength dipoles, two users, and single-path line-of-sight propagation, and show both analytically and numerically that the array gain and average spectral efficiency strongly depend on the directions from which the signals are received and on the array matching network used. The numerical results are then used to extend the analysis to more practical scenarios involving larger arrays of dipoles (arranged in a uniform linear array) and a larger number of users. The case where the antennas are densely packed in a space-constrained factor form is also considered. It is found that the spectral efficiency increases with decreasing antenna spacing only for arrays of moderate size, e.g. in the order of a few wavelengths. In comparison, larger arrays with closely spaced antennas show only marginal improvements in spectral efficiency compared to half-wavelength arrays.
- T. L. Marzetta, “Noncooperative cellular wireless with unlimited numbers of base station antennas,” IEEE Trans. Wireless Commun., vol. 9, no. 11, pp. 3590–3600, Nov. 2010.
- E. Björnson, J. Hoydis, and L. Sanguinetti, “Massive MIMO networks: Spectral, energy, and hardware efficiency,” Foundations and Trends® in Signal Processing, vol. 11, no. 3-4, pp. 154–655, 2017.
- L. Sanguinetti, E. Björnson, and J. Hoydis, “Toward massive MIMO 2.0: Understanding spatial correlation, interference suppression, and pilot contamination,” IEEE Trans. Commun., vol. 68, no. 1, pp. 232–257, Jan. 2020.
- E. Björnson, L. Sanguinetti, H. Wymeersch, J. Hoydis, and T. L. Marzetta, “Massive MIMO is a reality - what is next?: Five promising research directions for antenna arrays,” Digital Signal Processing, vol. 94, pp. 3 – 20, Nov. 2019.
- S. Hu, F. Rusek, and O. Edfors, “Beyond Massive MIMO: The potential of data transmission with large intelligent surfaces,” IEEE Trans. Signal Proc., vol. 66, no. 10, pp. 2746–2758, May 2018.
- A. Li and C. Masouros, “Exploiting constructive mutual coupling in P2P MIMO by analog-digital phase alignment,” IEEE Trans. Wireless Commun., vol. 16, no. 3, pp. 1948–1962, March 2017.
- C. Masouros, J. Chen, K. Tong, M. Sellathurai, and T. Ratnarajah, “Exploiting transmit correlation and mutual coupling in MIMO transmitters,” in European Wireless Conference, 2014, pp. 1–6.
- X. Chen, S. Zhang, and Q. Li, “A review of mutual coupling in MIMO systems,” IEEE Access, vol. 6, April 2018.
- T. L. Marzetta, “Super-directive antenna arrays: Fundamentals and new perspectives,” in Asilomar Conference on Signals, Systems, and Computers, 2019, pp. 1–4.
- L. Han, H. Yin, and T. L. Marzetta, “Coupling matrix-based beamforming for superdirective antenna arrays,” in IEEE Int. Conf. Commun., 2022, pp. 5159–5164.
- N. Deshpande, M. R. Castellanos, S. R. Khosravirad, J. Du, H. Viswanathan, and R. W. H. J. au2, “A generalization of the achievable rate of a MISO system using bode-fano wideband matching theory,” 2023.
- M. Akrout, V. Shyianov, F. Bellili, A. Mezghani, and R. W. Heath, “Super-wideband Massive MIMO,” IEEE J. Sel. Areas Commun., vol. 41, no. 8, pp. 2414–2430, Aug. 2023.
- R. Janaswamy, “Effect of element mutual coupling on the capacity of fixed length linear arrays,” IEEE Antennas Wirel. Propag. Lett., vol. 1, pp. 157–160, March 2002.
- T. Svantesson and A. Ranheim, “Mutual coupling effects on the capacity of multielement antenna systems,” in IEEE International Conf. Acoustics, Speech, and Signal Processing, vol. 4, 2001, pp. 2485–2488 vol. 4.
- J. Wallace and M. Jensen, “Mutual coupling in MIMO wireless systems: a rigorous network theory analysis,” IEEE Trans. Wireless Commun., vol. 3, no. 4, pp. 1317–1325, July 2004.
- M. T. Ivrlac and J. A. Nossek, “Toward a circuit theory of communication,” IEEE Trans. Circuits Syst. I: Regular Papers, vol. 57, no. 7, pp. 1663–1683, July 2010.
- ——, “The multiport communication theory,” IEEE Circuits and Systems Magazine, vol. 14, no. 3, pp. 27–44, 2014.
- H. Yordanov, M. T. Ivrlac, P. Russer, and J. A. Nossek, “Arrays of isotropic radiators-a field-theoretic justification,” in Proc. ITG/IEEE Workshop on Smart Antennas, 2009.
- M. T. Ivrlac and J. A. Nossek, “Receive antenna gain of uniform linear arrays of isotrops,” in IEEE Int. Conf. Commun., 2009, pp. 1–6.
- T. Laas, J. A. Nossek, and W. Xu, “Limits of transmit and receive array gain in massive MIMO,” in IEEE Wireless Communications and Networking Conference, 2020, pp. 1–8.
- M. T. Ivrlač and J. A. Nossek, “On the diversity performance of compact antenna arrays,” in Proc. 30th Gen. Assembly Int. Union Radio Sci.(URSI), 2011, pp. 1–4.
- T. Laas, J. A. Nossek, S. Bazzi, and W. Xu, “On reciprocity in physically consistent TDD systems with coupled antennas,” IEEE Trans. Wireless Commun., vol. 19, no. 10, pp. 6440–6453, Oct. 2020.
- B. Tadele, V. Shyianov, F. Bellili, and A. Mezghani, “Channel estimation with tightly-coupled antenna arrays,” in IEEE International Conference on Acoustics, Speech and Signal Processing, 2023, pp. 1–5.
- V. Shyianov, M. Akrout, F. Bellili, A. Mezghani, and R. W. Heath, “Achievable rate with antenna size constraint: Shannon meets Chu and Bode,” IEEE Trans. Commun., vol. 70, no. 3, pp. 2010–2024, March 2022.
- H. Nyquist, “Thermal agitation of electric charge in conductors,” Phys. Rev., vol. 32, pp. 110–113, Jul 1928.
- H. Rothe and W. Dahlke, “Theory of noisy fourpoles,” Proceedings of the IRE, vol. 44, no. 6, pp. 811–818, 1956.
- W. Kahn and H. Kurss, “Minimum-scattering antennas,” IEEE Trans. Antennas Propag., vol. 13, no. 5, pp. 671–675, Sept. 1965.
- K. F. Warnick, B. Woestenburg, L. Belostotski, and P. Russer, “Minimizing the noise penalty due to mutual coupling for a receiving array,” IEEE Trans. Antennas Propag., vol. 57, no. 6, pp. 1634–1644, June 2009.
- R. R. Müller, B. E. Godana, M. A. Sedaghat, and J. B. Huber, “On channel capacity of communication via antenna arrays with receiver noise matching,” in 2012 IEEE Information Theory Workshop, 2012, pp. 396–400.
- B. Friedlander, “The extended manifold for antenna arrays,” IEEE Trans. Signal Process., vol. 68, pp. 493–502, Jan. 2020.
- B. Friedlander, “Localization of signals in the near-field of an antenna array,” IEEE Trans. Signal Process., vol. 67, no. 15, pp. 3885–3893, Aug. 2019.
- K. Kurokawa, “Power waves and the scattering matrix,” IEEE Trans. Microw. Theory Tech., vol. 13, no. 2, pp. 194–202, 1965.
Paper Prompts
Sign up for free to create and run prompts on this paper using GPT-5.
Top Community Prompts
Collections
Sign up for free to add this paper to one or more collections.
