UCL Discovery
UCL home » Library Services » Electronic resources » UCL Discovery

Analog-Digital Beamforming in the MU-MISO Downlink by use of Tunable Antenna Loads

Li, A; Masouros, C; Sellathurai, M; (2017) Analog-Digital Beamforming in the MU-MISO Downlink by use of Tunable Antenna Loads. IEEE Transactions on Vehicular Technology 10.1109/TVT.2017.2776563. (In press). Green open access

[img]
Preview
Text
LI.Ang.Analog.Digital.Beamforming.pdf - Published version

Download (2MB) | Preview

Abstract

We investigate the performance of multi-user multiple-input-single-output (MU-MISO) downlink in the presence of the mutual coupling effect at the transmitter. Contrary to traditional approaches that aim at eliminating this effect, in this paper we propose a joint analog-digital (AD) beamforming scheme that exploits this effect to further improve the system performance. A jointly optimal AD beamformer is firstly obtained by iteratively maximizing the minimum received signal-to-interference-plus-noise ratio (SINR) in the digital domain, followed by an optimization on the load impedance of each antenna element in the analog domain. We further introduce a decoupled low-complexity approach, with which existing closed-form beamforming schemes can also be efficiently applied. For the consideration of hardware imperfections in practice, we study the case where the analog load values are quantized, and propose a sequential search scheme based on greedy algorithm to efficiently obtain the desired quantized load values. Moreover, we also investigate the imperfect channel state information (CSI) scenarios, where we prove the optimality for closed-form beamformers, and further propose the robust schemes for two typical CSI error models. Simulation results show that with the proposed schemes the mutual coupling effect can be exploited to further improve the performance for both perfect CSI and imperfect CSI.

Type: Article
Title: Analog-Digital Beamforming in the MU-MISO Downlink by use of Tunable Antenna Loads
Open access status: An open access version is available from UCL Discovery
DOI: 10.1109/TVT.2017.2776563
Publisher version: http://doi.org/10.1109/TVT.2017.2776563
Language: English
Additional information: This work is licensed under a Creative Commons Attribution 3.0 License. For more information, see http://creativecommons.org/licenses/by/3.0/.
Keywords: MIMO, beamforming, mutual coupling, optimization, imperfect CSI
UCL classification: UCL > Provost and Vice Provost Offices
UCL > Provost and Vice Provost Offices > UCL BEAMS
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science > Dept of Electronic and Electrical Eng
URI: https://discovery.ucl.ac.uk/id/eprint/10041095
Downloads since deposit
96Downloads
Download activity - last month
Download activity - last 12 months
Downloads by country - last 12 months

Archive Staff Only

View Item View Item