Massive MIMO for Future Wireless Communication Networks

Lead Research Organisation: Lancaster University
Department Name: Computing & Communications

Abstract

The spectrum crunch is a global phenomenon, where wireless networks constrained by scarce spectrum resource cannot keep pace with the explosion in mobile broadband use, particularly at a time when smartphones and tablets are becoming even more prevalent and heavily used. Every new opportunity has to be maximally exploited to cope with this spectrum deficit and meet the demands of explosive broadband usage by pushing more data through existing spectrum. Massive multiple-input multiple-output (MIMO), an advanced antenna technology only developed in 2010 offers one such opportunity. Massive MIMO enables a sparse infrastructure network, whereby a single base station (BS) is powerful enough to eliminate inter-cell interference through highly directional beamforming, and hence avoid the need for any cell-to-cell coordination. Initial work, particularly the experiments in have demonstrated the feasibility of massive MIMO. However, there is still lack of insightful understanding of the fundamental limits of massive MIMO, and also there is a large gap in the performance evaluation of massive MIMO under ideal and non-ideal practical conditions. The aim of this project is to establish a unified theoretical framework for the fundamental limits of massive MIMO with various practical constraints, and develop sophisticated signal processing algorithms to realize the concept of massive MIMO in realistic environments. The novelty of this project lies in the fact that advanced mathematical tools, such as random matrix theory and stochastic geometry, will be used to capture the dynamic nature of multi-user wireless channels. Sophisticated signal processing methods, such as game theoretic algorithms and compressed sensing, will be applied to massive MIMO in order to combat the practical constraints, such as frequency selective channel fading and limited channel feedback.

Planned Impact

The total radio spectrum market was worth £52 billion a year according to the Analysys Mason report, and mobile broadband has been identified by as "essential to creating jobs, growing our economy, and a key part of ensuring that Britain wins the global race", since advances in mobile networks will create new opportunities for innovative applications, services and devices. In particular, wireless communications has been recognized as the key enabling technology for the vision that many sectors from health care to energy to transportation have the opportunity to be transformed, by the availability of affordable, reliable, and high-speed connectivity to the Internet. Massive MIMO, the focus of this project, is a promising technology to revolutionize future mobile networks. A successful outcome will pave the way for its use in the next generation of wireless systems as a cost-effective and energy efficient solution with much higher data capacity due to the use of multiple antennas. The objectives of this project fall naturally into the research areas of digital signal processing and radio frequency communications, which are highlighted for growth by EPSRC. In addition to practical solutions, the project also seeks insightful understanding of massive MIMO facilitated by various mathematical tools, which means that this project brings a close interaction between two research themes, information and communication technologies and mathematical sciences.
 
Description The key aim of this project is to apply MIMO to telecommunications and increase the capacity of the next generation of mobile networks.

1.) Recently collaborating with colleagues from Japan, Australia, and the UK, we have identified how to improve the spectral efficiency of massive MIMO systems, where the key idea is to apply the non-orthogonal multiple access (NOMA) principle.

Zhang D, Liu Y, Ding Z, Zhou Z, Nallanathan A, Sato T, (2017). Performance Analysis of Non-Regenerative Massive-MIMO-NOMA Relay Systems for 5G. IEEE Transactions on Communications,
Yu Y, Chen H, Li Y, Ding Z, Song L, Vucetic B, (2017). Antenna Selection for MIMO Non-orthogonal Multiple Access Systems. IEEE Transactions on Vehicular Technology,

2.) In addition, our group has completed the following two works which can be used to improve the spectral efficiency of mobile networks.

Z. Ding, F. Adachi and H. V. Poor, "The Application of MIMO to Non-Orthogonal Multiple Access", IEEE Transactions on Wireless Communications, 2016.
M. F. Hanif, Z. Ding, T. Ratnarajah and G. K. Karagiannidis "A Minorization-Maximization Method for Optimizing Sum Rate in Non-Orthogonal Multiple Access Systems", to be published at IEEE Transactions on Signal Processing, 2016

Both two works are to combine MIMO with the most promising multiple access techniques to be used in 5G networks, non-orthogonal multiple access. Please note that the TWC paper about MIMO-NOMA has been recognized as the most cited paper among all the articles published at IEEE Transactions on Wireless Communications since 2016, and in Feb. 2018, it has been nominated to be awarded the IEEE TWC Best Paper Award.

3.) In the multi-user scenario, how to group users and which user should be paired with whom are key for the performance of the future wireless networks. We have published the following paper at IEEE TVT

Ding Z, Fan P, Poor H, (2015). User Pairing in Non-Orthogonal Multiple Access Downlink Transmissions.

Currently this paper has been one of the most cited paper in IEEE TVT and in Feb. 2018, it has already attracted 224 citations within two years.

4.) In addition, an information theoretic study of NOMA has also been completed and submitted to IEEE Access

P. Xu, Z. Ding, X. Dai and H. V. Poor, "NOMA: An Information Theoretic Perspective", IEEE Access, 2015

5. ) The investigator has also collaborated with researchers from Princeton University and Queen Mary University of London on an important application of wireless power transfer to non-orthogonal multiple access, which can essentially provide incentives for user cooperation and prolong the lifetime of energy constrained networks.

Y. Liu, Z. Ding, M. Elkashlan, and H. V. Poor, "Cooperative Non-Orthogonal Multiple Access with Simultaneous Wireless Information and Power Transfer", IEEE Journal on Selected Areas in Communications, 2016.
Exploitation Route For our completed works, we have put the preprints on the open access website, arXiv, and also Professor Zhiguo Ding's home page.

In addition, we are currently working with colleagues from Princeton University, Queen Mary University of London, and China Mobile for a collaboration on a magazine paper, which shall provide a high level and laymen introduction to our work.

Prof. Zhiguo Ding has been invited to provide a plenary talk at AICWC-2015 and 2017. This is a high profile workshop, in which 15 world class researchers were invited and 12 of them are IEEE Fellows. Prof. Zhiguo Ding has also been invited to deliver keynote speech at
- The IEEE VTC-2017 Workshop on Non-orthogonal Multiple Access, Sydney, Australia
- The IEEE 2017 International Workshop on 5G Multiple Access, Toronto, Canada.
- The IEEE 2017 Symposium on Computers and Communications, Crete, Greece.

Prof. Zhiguo Ding has been invited to provide a tutorial at Globecom-2017, PIMRC-2017 ICC-2017, EUCNC-2017, VTC-Spring-2017, BSC-2016, ICCC-2016, and VTC-2016.
Sectors Digital/Communication/Information Technologies (including Software)
 
Description The explosive growth in mobile broadband demand started with the launch of the first smartphones, which spurred demand for multimedia streaming, social networking and fast Web browsing. Global wireless data traffic will average 78% growth through 2016, with a nearly 60-fold increase in the use of wireless services and applications by 2015, according to Cisco Visual Networking Index: Global Mobile Data Traffic Forecast Update http://www.cisco.com/en/US/solutions/collateral/ns341/ns525/ns537/ns705/ns827/white_paper_c11-520862.pdf. In UK, Analysis-Mason estimates the economic value of radio spectrum at approx. £50B in 2011, see:http://tinyurl.com/oug5yzq. Particularly the mobile-broadband penetration per inhabitant has reached 56%, which is well above the fixed wired broadband penetration of 31.6%. UK carriers are now shifting their focus to 4G networks, in particular the LTE standard, which features much faster upload and download speeds. Tablets and smartphones are chewing up more and more bandwidth. Market analysts see annual bandwidth demand growing 75% or more. It is increasingly clear that the rapid demand growth cannot be accommodated by current mobile networks for long due to the limited availability of radio spectrum, which motivates the studies of more bandwidth efficient physical layer techniques. This project is proposed at a time when massive MIMO has been envisioned to bring fundamental breakthroughs to the design of mobile communication networks, where spectrum can be more efficiently utilized and interference is tackled more effectively. Initial theoretical studies and prototyping of massive MIMO systems have shown order of magnitude spectral efficiency improvements in communications, which is the reason why it has been considered as a key technology to meet the rapid demand growth of future mobile broadband networks given the constraint of scarce bandwidth resources. Building on conventional smart antenna technologies, the key idea of massive MIMO is to deploy a large number of antennas at the base station to significantly increase data throughput and link range without requiring additional radio spectrum resources. The proposed studies of massive MIMO is beneficial for the research community to get a better understanding of the fundamental limits of this newly developed concept, and hence provide guidelines for the efficient design of practical next generation telecommunication systems with high spectral and energy efficiency. In addition to telecommunication networks, there are wider applications of massive MIMO technology. For example, in context of wireless sensor networks, the use of massive MIMO can shift the computational complexity to data fusion centres, and hence enable the use of low-cost energy-constrained sensors, which is crucial to the energy constrained scenarios such as structural health monitoring, disaster prevention, undersea exploration, assisted navigation, etc. The immediate industrial beneficiaries of this project are companies involved in developing mobile broadband systems and robust wireless sensor networks for the purpose of environmental monitoring or tactical surveillance. The whole UK economy and society will benefit indirectly, as the project aims at improving our security and defence as well as building on the UK's reputation for providing state-of-the-art communication solutions. Areas of high value to society that will also directly benefit from this research also include education and training. In addition to the researchers directly involved in the project, there will be wider benefits to students at both Universities, from involvement in cutting edge research which will feed through into teaching activities. Both teams have a good history of collaboration with industry and use research to inform teaching at higher levels. In addition, the application of massive MIMO to 5G networks has also been considered, where the spatial degrees of freedom were found to be useful for the design of non-orthogonal multiple access and grant free transmission in machine types of communications.
Sector Digital/Communication/Information Technologies (including Software)
Impact Types Societal,Economic
 
Description A tutorial about Non-Orthogonal Multiple Access 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Public/other audiences
Results and Impact Multiple access in 5G mobile networks is an emerging research topic, since it is key for the next generation network to keep pace with the exponential growth of mobile data and multimedia traffic. Non-orthogonal multiple access (NOMA) has recently received considerable attention as a promising candidate for 5G multiple access. The key idea of NOMA is to exploit the power domain for multiple access, which means multiple users can be served concurrently at the same time, frequency, and spreading code. Instead of using water-filling power allocation strategies, NOMA allocates more power to the users with poorer channel conditions, with the aim to facilitate a balanced tradeoff between system throughput and user fairness. Recent industrial demonstrations show that the use of NOMA can significantly improve the spectral efficiency of mobile networks. Because of such a superior performance, NOMA has been also recently proposed for downlink scenarios in 3rd generation partnership project long-term evolution (3GPP-LTE) systems, and the considering technique was termed multiuser superposition transmission (MUST). In this tutorial, we will provide a progress review for NOMA, including an information theoretic perspective of NOMA, the interaction between cognitive radio and NOMA, the design of MIMO and cooperative NOMA, and the impact of practical constraints, such as imperfect channel state information and limited feedback, on the performance of NOMA.
Year(s) Of Engagement Activity 2016
URL http://infotheory.ca/bsc2016/index.php/tutorials/
 
Description A tutorial about Non-Orthogonal Multiple Access 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Public/other audiences
Results and Impact Multiple access in 5G mobile networks is an emerging research topic, since it is key for the next generation network to keep pace with the exponential growth of mobile data and multimedia traffic. Non-orthogonal multiple access (NOMA) has recently received considerable attention as a promising candidate for 5G multiple access. The key idea of NOMA is to exploit the power domain for multiple access, which means multiple users can be served concurrently at the same time, frequency, and spreading code. Instead of using water-filling power allocation strategies, NOMA allocates more power to the users with poorer channel conditions, with the aim to facilitate a balanced tradeoff between system throughput and user fairness. Recent industrial demonstrations show that the use of NOMA can significantly improve the spectral efficiency of mobile networks. Because of such a superior performance, NOMA has been also recently proposed for downlink scenarios in 3rd generation partnership project long-term evolution (3GPP-LTE) systems, and the considering technique was termed multiuser superposition transmission (MUST). In this tutorial, we will provide a progress review for NOMA, including an information theoretic perspective of NOMA, the interaction between cognitive radio and NOMA, the design of MIMO and cooperative NOMA, and the impact of practical constraints, such as imperfect channel state information and limited feedback, on the performance of NOMA.
Year(s) Of Engagement Activity 2006
URL http://www.ieeevtc.org/vtc2016fall/tutorials.php#tut_4
 
Description Why IoT Needs 5G - an interview by IEEE Spectrum 
Form Of Engagement Activity A press release, press conference or response to a media enquiry/interview
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Public/other audiences
Results and Impact When 5G, the fifth generation of wireless communications technology, arrives in 2020, engineers expect that it will be able to handle about 1000 times more mobile data than today's cellular systems. It will also become the backbone of the Internet of Things (IoT), linking up fixed and mobile devices-vending machines and cars alike-becoming part of a new industrial and economic revolution, some say. A new architecture, new communication technologies, and new hardware will make this transformation possible. A research team comprising Zhiguo Ding at Lancaster University and researchers at China's Southwest Jiaotong University have took stock of the recent research and future needs of 5G in a review last month in Science China [pdf]. In a Skype interview Ding spoke to Spectrum about his views on how 5G will take shape in the near future.
Year(s) Of Engagement Activity 2015
URL http://spectrum.ieee.org/tech-talk/computing/networks/5g-taking-stock