Deep dive par t: 1 Basic Principle of Massive MIMO
Background
50years ago，Shanon give the capacity formula：
PT C log2 1 N 0
bit s/Hz/s
System capacity is near to the maximum limitation through Turbo and LDPC code used.
In future, capacity improving depends on MIMO which spatial multiplexing will be used
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Multi Input Multi Output (MIMO) MIMO：improve system performance by using multiple antennas. Multi Antennas development driven MIMO using spreadly.
1T1R
2T2R
8T8R
4T4R
Multiple antennas: obtains gain of diversity, array, spatial multiplexing and interference control HUAWEI TECHNOLOGIES CO., LTD.
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Gain from Multi-Antenna Diversity Gain
Array Gain——Improve SINR
Interference Rejection
Multiplexing Gain
Array Gain
Spatial diversity——decrease the fluctuation of SINR Spatial multiplexing——improve capacity Interference cancelling——improve SIR
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MultiAntenna Gain
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LTE TDD Transmission Mode Transmission Mode
Transmission Scheme
2Tx Support
4Tx Support
TM1
Single-antenna port, port 0
Y
Y
TM2
Transmit Diversity
SFBC
SFBC+FSTD
TDD or FDD, Ports 0-3
TM3
Open-Loop Spatial Multiplexing
2 Layer
4 Layer
TDD or FDD, Ports 0-3
TM4
Closed-Loop Spatial Multiplexing(SM)
2 Layer
4 Layer
TDD or FDD, Ports 0-3
TM5
Multi-user MIMO
Y
Y
TDD or FDD, Ports 0-3
TM6
Closed-loop Rank = 1 Precoding
Y
Y
TDD or FDD, Ports 0-3
TM7
Single Layer Beamfoming( port 5 )
N
Y
TDD preferred, Ports 5
TM8 (R9)
Dual Layer Beamfoming( port 7,8 )
N
Y
Comments TDD or FDD, Port 0
TDD preferred, Ports 7-8 SU & MU MIMO
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LTE TDD MIMO and Beam-forming SISO, SIMO
SDMA = Space Division Multiple Access
Beam-forming R8(TM7)，R9(TM8)
TM7/8
TM1
For Up-link vMIMO and DL MU-BF
Open-Loop-MIMO
Closed-Loop-MIMO
MU-MIMO = Multi-user MIMO
Null of the beam
TM2
TM3
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TM4
TM6
TM5
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Beam-forming principle(1)
Single Antenna，cannot beam forming
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2 antennas，a beam can be obtained but fat.
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Beam-forming principle(2)
4 antennas, a main beam can be obtained
4 antennas, a main beam direction can be
and direct to 0 deg.
changed to 30 deg.
3 antennas，a main beam can be obtained.
Beam forming：by weighted on Tx channel，beam with direction can be obtained, and direction can be changed by different weighted value. • More antenna，beam will be more narrow，the energy will more focus on UE. HUAWEI TECHNOLOGIES CO., LTD.
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Massive MIMO Physical
Logical
8T8R: H8V1
16T16R: H16V1
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32T32R: H16V2
64T64R: H16V4
64T64R: H16V4
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128T128R: H16V8
Key technology Capacity improving by Massive MIMO 3D MIMO
MU BF
More antenna brings more capacity by MU BF
More antenna bring better SINR by BF More antenna bring less interference by narrow beam Maximum 5x capacity improved by Massive MIMO
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Massive MIMO Average Capacity Gain Impact Factors User Distributions
User Locations
Traffic Patterns Mobility
Large packets & constant data (downloading, video)
Distributed at different places (lower correlation) or Gathered at same spot (higher correlation)
Multipath
Cell center (high SINR) or cell edge (low SINR)
UE Types
Small packets & burst data (SNS, web pages…) Smartphone (no antenna gain) or CPE (higher antenna gain) Rich scattered multipath scenario or not
MU-BF pairing prefers: constant larger packets, lower correlation, rich multipath, higher SINR and low mobility HUAWEI TECHNOLOGIES CO., LTD.
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Stationary, low speed or high speed mobility
Factors to effect Performance
- Traffic Load & Signal Quality
Traffic Load
Low traffic load: only BF link gain
Heavy traffic load: both MU-BF gain and BF link gain
Link Quality
In low SINR region, the link-level BF gain is the main factor to improve the throughput
In middle and high SINR region, the MUBF layer is the main factor to improve the throughput
High Capacity Region
Coverage Region
Capacity gain size of Massive MIMO grows with load increasing
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Cell throughput of Massive MIMO grows with the SINR increasing
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Factors to effect Performance
- User Distribution
Pairing number depends on the usage of Massive MIMO beams.
The number of Massive MIMO valid beams is based on User Dispersion.
Lower user dispersion causes fewer valid beams
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Higher user dispersion brings more valid beams
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Factors to effect Performance Antenna Height If the antenna height isn’t enough, it will be mainly covered by one vertical beam, which isn’t good for MM capacity
High Antenna
- Antenna Height & UE Distance UE Distance If the coverage target is far from site, users distribute in fewer horizontal beams, which isn’t good for MM capacity.
√ Distance
UE in different beams Low Antenna
X Short distance
UE in same beam
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More beams
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√
Long distance Fewer beams
X
Vertical Parameter Design Antenna Pattern Introduction
Parameter Design
Antenna pattern setting is flexible and suitable for different scenarios: Pattern: 13 Types Electrical Down tilt: -15°~15° β No.
𝐶𝑜𝑣ℎ ) 2×𝑆
Tilt:
β
α
hBTS
S
No.10~No.13’s vertical beam is wide and antenna gain is not much different
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𝛽 = 2 × tan−1 (
Covv
1 2 3 4 5 6 7 8 9 10 11 12 13
Horizontal Vertical l HPBW HPBW Tilt 0° 90 8 14.08 65 8 15.97 45 8 17.62 25 8 19.74 90 17 11.07 65 17 12.96 45 17 14.5 25 17 16.73 15 17 19.74 65 35 9.95 45 35 11.52 25 35 13.76 15 35 16.77
Antenna Gain(dBi) (±1) (+-)3° (+-)6° (+-)9° (+-)12° (+-)15° 14.04 13.91 13.69 13.32 12.81 15.94 15.82 15.58 15.18 14.62 17.4 17.2 16.88 16.42 15.75 19.61 19.36 18.98 18.47 17.71 11.03 10.92 10.69 10.33 9.82 12.89 12.74 12.46 12.1 11.66 14.41 14.45 14.23 13.88 13.38 16.62 16.42 16.42 15.71 15.14 19.63 19.4 19.1 18.67 18.1 -
Horizontal HPBW:
Covh
S
𝛼 = tan−1 (
Vertical HPBW: β = tan−1(
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ℎ𝐵𝑇𝑆 − 𝐶𝑜𝑣𝑣 2 ) 𝑆
ℎ𝐵𝑇𝑆 𝐶𝑜𝑣𝑣 − ℎ𝐵𝑇𝑆 ) + tan−1 ( ) 𝑆 𝑆
Massive MIMO DL Coverage Analysis Downlink Coverage
Uplink Coverage
TxAntennaGain
RxAntennaGain
• •
•
Flexible broadcast beam Beamforming boosted service beam
TxPower
Flexible broadcast beam
RxPower PropagationLoss
PropagationLoss
CableLoss
CableLoss
AAU Design No Cable Loss
AAU Design No Cable Loss
ShadowFadingMargin
InterferenceMargin
ShadowFadingMargin
InterferenceMargin RxPower
PenetrationLoss
TxPower PenetrationLoss
RxAntennaGain
Massive MIMO Antenna Gain is the Most Distinguished Difference compared with Normal Macro.
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TxAntennaGain
Huawei is Key Contributors of Massive MIMO Standard & Patent Leading 3GPP Study & Work in Massive MIMO related AAS/Channel modeling/Scenario/Pilot improvement etc…
Acquired 50+ key patents in Massive MIMO
Engineering
Channel
Pilot Design
CPRI
L2 Schedule ›
› ›
AAS: » Leading 3GPP RAN4 R11（RP-111349） AAS initialization: performance and system impact study; » R11 SI, R12 WI，R13 WI reporter, leading standard definition, convener of RAN4 AAS AdHoc meeting. 3D channel modeling: provide field test channel & Ray tracing simulation result as major input of standard; 3D MIMO SI: proposed proactive cell shaping concept, leading SRS/DMRS improvement study items.
Architecture
Antenna Array
Essential Patent Example Architecture：Modular AAS Design Algorithm：L2 Adaptive Traversal pairing
CPRI：Massive MIMO Compression Others：Panel Base station Heat Radiating
About 90% Standard proposals and Patents for Massive MIMO were proposed by Huawei . HUAWEI TECHNOLOGIES CO., LTD.
BF
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Thank you
