Massive MIMO wireless networks: Theory and methods

Lead Research Organisation: University College London
Department Name: Electronic and Electrical Engineering


Spectrum is a precious but scarce natural resource. In the UK, Ofcom will free up the analogue TV spectrum at 800MHz (together with the available 2.6GHz band) for 4G, which has already raised £2.34 billion for the national purse. According to Ofcom, the amount of data Britons consume on the move each month has already hit 20 million gigabytes, mainly due to users' engagement of video, TV and films while on the move. It is also a common understanding for the mobile operators that by 2020 a 1000 times increase in the system capacity will be needed to avoid mobile networks grinding to a halt. Maximising spectral efficiency, which is limited by interference and fading for wireless networks including 4G, is therefore a major issue. An emerging idea, which is championed by Alcatel-Lucent and has already received serious consideration by vendors and operators is that of a massive MIMO antenna system. This technology has the potential to unlock the issue of spectrum scarcity and to enhance spectrum usage tremendously by enabling simultaneous access of tens or hundreds of terminals in the same time-frequency resource.

In order for massive MIMO technology to attain its utmost potential, it is important that various challenges in terms of channel estimation and acquisition due to pilot contamination, fast spatial-temporal variations in signal power and autonomous resource allocation, in particular in the presence of simultaneous access of a large number of users need to be addressed. The focus of this project is on tackling these fundamental challenges, by advancing aspects of information theory, estimation theory and network optimisations. In particular, we will contribute in terms of modelling massive MIMO channels underpinned by heterogeneous correlation structures; performing information theoretic analysis in terms of random matrix theory through shrinkage estimators; robust precoder design for massive MIMO in the presence of channel estimation errors; developing novel channel estimation technique in the presence of severe pilot contamination; and proposing and analysing game theoretic algorithms for autonomous resource allocation and pilot assignments. All the concepts and algorithms developed will be integrated and the radio link layer performance will be assessed using a simulation reference system based on LTE-Advanced standards and its evolution towards 5G. Industrial partners will be engaged throughout the project to ensure industrial relevance of our work.

Planned Impact

This project will use a number of strategies to maximise both the academic and industrial impact of the research. It involves three academic partners, University College London, King's College London and Loughborough University, who will meet regularly to review the progress of the project and to ensure that the deliverables from every work packages are fully exploited and correctly integrated within other work packages. Research results from each Work Package will be documented and published in international conferences and journals.

In order to maximise the quality and industrial relevance of the research, the industrial partners Thales and Three UK and other relevant industries attached to mVCE will be engaged throughout the project. They will provide guidance and steering during the project to ensure that the results can be applied to real world systems. The final work package will focus on demonstration of important concepts and results achieved in the programme. The project partners Thales, Three UK and mVCE will also facilitate routes for potential commercial exploitation of important results and breakthroughs achieved in the project.

The project will provide wider dissemination of the results through several means. Firstly, a project website will be setup to describe the research and to record major findings from each work package. Secondly, two workshops will be organised in the second and the third years of the programme to exchange knowledge with other major UK and international researchers. The investigators current involvement with multimillion funded mVCE and EPSRC/DSTL University Defence Research Collaboration in Signal Processing for the Networked Battlespace will also be used as a vehicle for wider dissemination of results.
Description Our work funded on this grant are mainly three-fold:
1. We have proved that conventional algorithms are unfeasible in massive MIMO enabled wireless networks, and the use of them will result in severe throughput imbalance. Therefore, we have proposed new transmission designs to solve this issue;
2. We have demonstrated that massive MIMO can significantly improve the secrecy of wireless communications, which can efficiently protect users from malicious eavesdropping;
3. We have proposed a novel massive MIMO enabled wireless powered cellular network architecture, such that massive MIMO can be applied to wireless-power user equipment over long distances.
Exploitation Route Our contributions can help researchers understand how massive MIMO technology can be implemented to enhance capacity, secrecy and wireless harvested energy. Our modeling and analysis are general, which can be used to study other practical scenarios. Our proposed designs are important guidelines for research and practical deployment.
Sectors Digital/Communication/Information Technologies (including Software),Energy