Deep Dive-Massive MIMO Basic Principle

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