Professor Mark Beach's presentation (without videos) on the University of Bristol's Massive MIMO activities as given at the IET's 'Towards 5G Mobile Technology – Vision to Reality' event, January 25th 2017.

1. Massive MIMO:
A Key Enabler for sub-6GHz Wireless Connectivity
Professor Mark Beach (and colleagues)
Communication and Networks Group,
University of Bristol, Bristol. UK
http://www.bristol.ac.uk/engineering/research/csn/
IET Towards 5G Mobile Technology – Vision to Reality
Wednesday 25th January 2017

2. Communication Systems & Networks Group
University of Bristol © CSN Group 2017
Summary
• 5G and why Massive MIMO
• Multiple Access through
Massive MIMO
• Test-bed architecture
• Field Trials exploring gains in
Spectrum Efficiency
• Need for Power Control
• Initial Mobility Trials
• Open Research Questions
2

3. Communication Systems & Networks Group
University of Bristol © CSN Group 2017
5G: The Networked Society
• Broadband experience: everywhere; anytime
• Smart vehicles, transport & infrastructure
Target Specs:
• 10Gbit/s Peak, 100Mbit/s where ever needed
• X100 – x1000 Capacity
• X10 battery life
• Reduced Latency (1ms)
• 5G Requires
• New Spectrum …… Millimetre wave bands
• Enhanced Spectrum Efficiency .. Massive MIMO for sub-6GHz
3

4. Communication Systems & Networks Group
University of Bristol © CSN Group 2017
What is Massive MIMO & Why?
4
Basestation or Access Point
> 50 (M) antennas serving a few (K) users (simultaneously)
Simple Signal Processing, power and spectrum efficient (sub-6GHz)

5. Communication Systems & Networks Group
University of Bristol © CSN Group 2017
Some Clarity on Definitions
5
Millimetre Wave 5G Access:
Massive Arrays for
Beamforming Array Gain
Analogue Phase control
Sub 6GHz: Massive Arrays with
Signal Processing per element for
enhanced Spectrum Efficiency

6. Communication Systems & Networks Group
University of Bristol © CSN Group 2017
Massive MIMO and Capacity Gain
6
Ultimate Spatial
Resolution
• Increased spectral efficiency and network capacity
• Accurate spatial multiplexing for multiple access
• Same Radio Channel, Same time (slot)
Time
Space
Uplink Downlink
Uplink
Uplink
Uplink
Downlink
Downlink
Downlink
Cellular View

7. Communication Systems & Networks Group
University of Bristol © CSN Group 2017
NI Based ‘BIO’ Massive MIMO test-bed
• 128 Programmable
Radio Heads
• 20MHz Bandwidth
• ‘LTE’ like interface
• 1.2 – 6.0GHz Carrier
• 3.51GHz used
• 4 Racks of 32 Radios
• Data consolidation
• Channel processing
• 24 Clients
• Massive MIMO signal
processing supporting
• 12 clients
7

8. Bristol is Open (BIO):
Open Programmable City
Not for Profit Joint Venture Bristol City Council & University of Bristol
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9. Communication Systems & Networks Group
University of Bristol © CSN Group 2017
Massive MIMO subsystem architecture
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Distributed FPGA Processing with PCIe links
Embedded
Computer

10. Communication Systems & Networks Group
University of Bristol © CSN Group 2017
First System Deployment
10
• Indoor Atrium (University of Bristol, Merchant Venturers
Engineering Building
• 5.4m Linear Array with half-wavelength spacing
• LOS Conditions

11. Communication Systems & Networks Group
University of Bristol © CSN Group 2017
First System Deployment (March 2016)
11
• Client Separation 2.5 - 6 Wavelengths
• Equal Transmit Power

12. Communication Systems & Networks Group
University of Bristol © CSN Group 2017
Our first results (10th March 2016):
12
Eigen
Structure
Individual Spatial Stream Rx Magnitude
Power Delay profiles
Frequency Domain profiles
12 streams of 256 QAM!
http://www.bristol.ac.uk/news/2016/march/massive-mimo.htmlCOST IRACON TD(16)0185 Paul Harris

13. Communication Systems & Networks Group
University of Bristol © CSN Group 2017
Lots of Antennas 𝑯𝑯 𝑯
(12 users, scaled by N)
13
Scenario 2 (12.5m Straight Line)

14. Communication Systems & Networks Group
University of Bristol © CSN Group 2017
CDF Plots of Singular Value Spreads
14
Scenario 1-3 in ascending order of LOS distance
LOS worst
scenario for
32 elements
Paul Harris et al, ‘LOS Throughput Measurements in Real-Time with a 128-Antenna
Massive MIMO Testbed’ IEEE Globecom, Wasington DC, Dec 2016

15. Communication Systems & Networks Group
University of Bristol © CSN Group 2017
Facebook & Massive MIMO (13th April 2016)
• ARIES (Antenna Radio
Integration for Efficiency in
Spectrum)
• Rural wireless Internet
• Specifications & Efficiency
• 96 antenna element array
• 24 users
• 71 bits/s/Hz
15
http://www.wired.com/2016/04/facebooks-massive-new-antennas-can-beam-internet-miles/

16. Communication Systems & Networks Group
University of Bristol © CSN Group 2017
2nd Deployment (Wed 11th May 2016)
16
22 users running 256 QAM in 20MHz Channel
Using same frame structure as before:
• 145.6 bits/s/Hz
• Sum rate of 2.915 Gbps
http://spectrum.ieee.org/tech-talk/telecom/wireless/5g-researchers-achieve-new-spectrum-efficiency-record
http://www.bris.ac.uk/news/2016/may/5g-wireless-spectrum-efficiency.html
User
Inactive
User
Inactive
128 element (32 x 4)
dual polar patch array

17. Communication Systems & Networks Group
University of Bristol © CSN Group 2017
Why Power Control?
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User
1
User
2
User
3
… User
K
ReceivedPower
• Users communicate using:
• Same Radio Channel
• At the same time (slot)
ONLY separated through spatial-
temporal signal processing
• Due to finite dynamic range
• Near-far effect (like CDMA)
• For Massive MIMO exploit
• Channel Hardening
• (Minimise) Mutual Interference
Within Power Control Algorithm

18. Communication Systems & Networks Group
University of Bristol © CSN Group 2017
Channel Hardening
• The experiment environment where only 32 antennas were active at the
BS for the measurements.
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19. Communication Systems & Networks Group
University of Bristol © CSN Group 2017
Motion & channel hardening
Eigenvalue
𝐈 𝐓𝐡 = 16%
• M = 112 & UEs =12
• With motion between array & users
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20. Communication Systems & Networks Group
University of Bristol © CSN Group 2017
4 UEs
4 UEs 4 UEs
Massive MIMO Array
20
2nd Deployment with Power Control

21. Communication Systems & Networks Group
University of Bristol © CSN Group 2017
4
UEs 4
UEs
4
UEs
Massive MIMO Array
21
COST IRACON TD(16)0184
Wael Boukley Hasan
2nd Deployment with Power Control

22. Communication Systems & Networks Group
University of Bristol © CSN Group 2017
On-going: Mobility Trials & Analysis
22
@Bristol @Lund

23. Communication Systems & Networks Group
University of Bristol © CSN Group 2017
Open Research Questions
23
Scalability, Multi-cell – massive MIMO
(Pilot Contamination), Power Control
Integration using Software-defined networking (SDN)
Antenna Element Design, Polarisation,
Array Geometry, Planning Tools
Algorithm Optimisation: Dense Urban Vs Rural,
plus Specialist Deployments
U
E
1
U
E
2
Reduced
SINR
700MHz
Control
plane
3.5GHz
m-MIMO
Data-plane

24. Communication Systems & Networks Group
University of Bristol © CSN Group 2017
Acknowledgements and Thanks to …
• Academic Colleagues at Bristol: Andrew Nix, Evangelos Mellios, Angela Doufexi and
Simon Armour
• Post Graduate Students: Paul Harris, Wael Boukley Hasan, Siming Zhang, Henry Brice,
Benny Chitambira, & Fred Wiffen
• Academic Colleagues at Lund University: Ove Edfors, Fredrik Tufvesson & Liang Liu,
post graduates Steffan Malkowsky, Joao Vieira, Erik Bengtsson,…..
• NI Staff Leif Johansson, Karl Nieman Ian Wong & James Kimery
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Any Questions?

25. Communication Systems & Networks Group
University of Bristol © CSN Group 2017
CSN & Uni Lund “Video of the month”
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http://www.bristol.ac.uk/engineering/research/csn/
https://www.youtube.com/watch?v=wPPMrr4rHmo