Presentation by Professor Mark Beach at the IEEE PIMRC 2016 COST IRACON Workshop on 4th September 2016 in Valencia, Spain.

1. Massive MIMO: Bristol - Lund Joint Field Trial
Experiments and Record Breaking Spectrum
Professor Mark Beach
Communication and Networks Group,
University of Bristol, Bristol. UK
http://www.bristol.ac.uk/engineering/research/csn/
IEEE PIMRC 2016 COST IRACON Workshop
Sunday 4th September 2016, Valencia, Spain

2. Communication Systems & Networks Group
University of Bristol © CSN Group 2016
Summary
• 5G and why Massive MIMO
• Multiple Access through
Massive MIMO
• Test-bed architecture
• Field Trials exploring gains in
Spectrum Efficiency
• Power Control … why and how
• Open Research Questions
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3. Communication Systems & Networks Group
University of Bristol © CSN Group 2016
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
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4. Communication Systems & Networks Group
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What is Massive MIMO & Why?
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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 2016
Refined Definition
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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 2016
Massive MIMO and Capacity Gain
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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

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University of Bristol © CSN Group 2016
More than just beamforming
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8. Communication Systems & Networks Group
University of Bristol © CSN Group 2016
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

9. Bristol is Open (BIO):
Open Programmable City
Not for Profit Joint Venture Bristol City Council & University of Bristol

10. Communication Systems & Networks Group
University of Bristol © CSN Group 2016
Massive MIMO subsystem architecture
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11. Communication Systems & Networks Group
University of Bristol © CSN Group 2016
Division of Labour
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MIMO 0
U
S
R
P
U
S
R
P
U
S
R
P
U
S
R
P
U
S
R
P
U
S
R
P
U
S
R
P
U
S
R
P
MIMO 1 MIMO 2 MIMO 3
Subcarriers 0-299
16 antennas
Subcarriers 300-599
16 antennas
Subcarriers 600-899
16 antennas
Subcarriers 900-1199
16 antennas
Downlink
Uplink• 8 USRPs / Subsystem
• 8 Subsystems
Single RRH
Subsystem

12. Communication Systems & Networks Group
University of Bristol © CSN Group 2016
Initial System Deployment
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• Indoor Atrium (University of Bristol, Merchant Venturers
Engineering Building
• 5.4m Linear Array with half-wavelength spacing
• LOS Conditions

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University of Bristol © CSN Group 2016
Initial System Deployment
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• Client Separation 2.5 - 6 Wavelengths
• Equal Transmit Power

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University of Bristol © CSN Group 2016
128 element, 5.4m long array
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15. Communication Systems & Networks Group
University of Bristol © CSN Group 2016
Some initial results (10th March 2016):
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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

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University of Bristol © CSN Group 2016
𝑯𝑯 𝑯
for 12 users with scaled N
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Scenario 2 (12.5m Straight Line)

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University of Bristol © CSN Group 2016
Alternative view of channel hardening
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Eigenvalue
𝐈 𝐓𝐡 = 44%
Eigenvalue
𝐈 𝐓𝐡 = 16%
• M = 32 & UEs =12
• No movement
• M = 112 & UEs =12
• With motion between array & users

18. Communication Systems & Networks Group
University of Bristol © CSN Group 2016
Motion & channel hardening
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Eigenvalue
𝐈 𝐓𝐡 = 16%
• M = 112 & UEs =12
• With motion between array & users

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University of Bristol © CSN Group 2016
CDF Plots of Singular Value Spreads
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Scenario 1-3 in ascending order of LOS distance
LOS worst
scenario for
32 elements

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University of Bristol © CSN Group 2016
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
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http://www.wired.com/2016/04/facebooks-massive-new-antennas-can-beam-internet-miles/

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University of Bristol © CSN Group 2016
2nd Deployment (Wed 11th May 2016)
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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

22. Communication Systems & Networks Group
University of Bristol © CSN Group 2016
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

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University of Bristol © CSN Group 2016
Uplink Power Control
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COST IRACON TD(16)0184 Wael Boukley Hasan

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Power Control in action
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University of Bristol © CSN Group 2016
Initial Results
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On-going: Mobility Trials & Analysis
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28. Communication Systems & Networks Group
University of Bristol © CSN Group 2016
Open Research Questions
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Scalability, Multi-cell – massive MIMO
(Pilot Contamination), Power Control
Integration with Software Enabled Networks
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

29. Communication Systems & Networks Group
University of Bristol © CSN Group 2016
Acknowledgements and Thanks to …
• Academic Colleagues at Bristol: Andrew Nix, Evangelos Mellios, Angela Doufexi and
Simon Armour
• Post Graduate Students: Paul Harris, Siming Zhang, Henry Brice, Benny Chitambira,
Wael Boukley Hasan & Fred Wiffen
• Academic Colleagues Ove Edfors, Fredrik Tufvesson & Liang Liu, post graduates Steffan
Malkowsky, Joao Vieira, Erik Bengtsson,….. at Lund University
• NI Staff Leif Johansson, Karl Nieman Ian Wong & James Kimery
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Any Questions?

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Frame Schedule
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