Deep Dive-Massive MIMO Basic Principle

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Deep dive part: 1

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Background



_{50years ago，Shanon give the capacity formula：}



_{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

bit s/Hz/s

1 log

0 2

















N

P

C

T

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Multi Input Multi Output (MIMO)

MIMO：improve system performance by using multiple antennas.

1T1R 2T2R 4T4R 8T8R

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Gain from Multi-Antenna

 Array Gain——Improve SINR

 Spatial diversity——decrease the fluctuation

of SINR

 Spatial multiplexing——improve capacity  Interference cancelling——improve SIR

Diversity Gain Interference Rejection Array Gain Multiplexing Gain Multi-Antenna Gain

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LTE TDD Transmission Mode

Transmission

Mode

Transmission Scheme

2Tx

Support

4Tx

Support

Comments

TM1 Single-antenna port, port 0 Y Y TDD or FDD, Port 0

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

TDD preferred, Ports 7-8 SU & MU MIMO

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Open-Loop-MIMO Closed-Loop-MIMO

TM2 TM3 TM4 TM6 TM5

TM1 TM7/8

MU-MIMO = Multi-user MIMO SISO, SIMO Beam-forming

R8(TM7)，R9(TM8)

Null of the beam

LTE TDD MIMO and Beam-forming

For Up-link vMIMO and DL MU-BF SDMA = Space Division Multiple Access

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Beam-forming principle(1)

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Beam-forming principle(2)

3 antennas，a main beam can be obtained.

4 antennas, a main beam can be obtained and direct to 0 deg.

4 antennas, a main beam direction can be changed to 30 deg.

Beam forming：by weighted on Tx channel，beam with direction can be obtained, and direction can be

changed by different weighted value.

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Massive MIMO

8T8R: H8V1 16T16R: H16V1 32T32R: H16V2 64T64R: H16V4 128T128R: H16V8

Logical

Physical

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Key technology Capacity improving by Massive 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

UE Types Traffic Patterns Multipath Mobility User Distributions

Small packets & burst data (SNS, web pages…)

Distributed at different places (lower correlation) or Gathered at same spot (higher correlation)

Cell center (high SINR) or cell edge (low SINR)

Smartphone (no antenna gain) or CPE (higher antenna gain)

Stationary, low speed or high speed mobility Large packets & constant data

(downloading, video)

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Factors to effect Performance

- Traffic Load & Signal Quality

 _{Low traffic load: only BF link gain}

 Heavy traffic load: both MU-BF gain and BF link gain

Capacity gain size of Massive MIMO grows with load increasing

Traffic Load

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

Cell throughput of Massive MIMO grows with the SINR increasing

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 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 Higher user dispersion brings more valid beams

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If the antenna height isn’t enough, it will be mainly covered by one vertical beam, which isn’t good for MM capacity

If the coverage target is far from site, users distribute in fewer horizontal beams, which isn’t good for MM capacity.

√

High Antenna

X

Low Antenna

Distance

Short distance More beams Long distance Fewer beams

Antenna Height

UE Distance

Factors to effect Performance

- Antenna Height & UE Distance

UE in different beams

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Vertical Parameter Design

Antenna Pattern Introduction

Antenna pattern setting is flexible and suitable for different scenarios:

 Pattern: 13 Types

 Electrical Down tilt: -15°~15°

No. Horizontal l HPBW Vertical HPBW Antenna Gain(dBi) (±1) Tilt 0° (+-)3° (+-)6° (+-)9° (+-)12° (+-)15° 1 90 8 14.08 14.04 13.91 13.69 13.32 12.81 2 65 8 15.97 15.94 15.82 15.58 15.18 14.62 3 45 8 17.62 17.4 17.2 16.88 16.42 15.75 4 25 8 19.74 19.61 19.36 18.98 18.47 17.71 5 90 17 11.07 11.03 10.92 10.69 10.33 9.82 6 65 17 12.96 12.89 12.74 12.46 12.1 11.66 7 45 17 14.5 14.41 14.45 14.23 13.88 13.38 8 25 17 16.73 16.62 16.42 16.42 15.71 15.14 9 15 17 19.74 19.63 19.4 19.1 18.67 18.1 10 65 35 9.95 - - - - -11 45 35 11.52 - - - - -12 25 35 13.76 - - - - -13 15 35 16.77 - - - -

-Parameter Design

C o vh β S 𝛽 = 2 × tan−1₍ 𝐶𝑜𝑣ℎ 2 × 𝑆 ) Horizontal HPBW: C o v v β S α h B 𝛼 = tan−1( ℎ𝐵𝑇𝑆 − 𝐶𝑜𝑣𝑣 2 𝑆 ) Tilt: Vertical HPBW:

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Massive MIMO DL Coverage Analysis

AAU Design No Cable Loss TxPower CableLoss TxAntennaGain PropagationLoss ShadowFadingMargin InterferenceMargin PenetrationLoss RxAntennaGain

• Flexible broadcast beam

• Beamforming boosted service beam

AAU Design No Cable Loss RxPower CableLoss RxAntennaGain PropagationLoss ShadowFadingMargin InterferenceMargin PenetrationLoss TxAntennaGain

• Flexible broadcast beam

RxPower TxPower

Massive MIMO Antenna Gain is the Most Distinguished Difference compared with Normal Macro.

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Huawei is Key Contributors of Massive MIMO Standard & Patent

› 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;

Essential Patent Example

Architecture：Modular AAS Design

Algorithm：L2 Adaptive Traversal pairing CPRI：Massive MIMO Compression

Others：Panel Base station Heat Radiating

Leading 3GPP Study & Work in Massive MIMO

related AAS/Channel modeling/Scenario/Pilot improvement etc… Acquired 50+ key patents in Massive MIMO

Engineering Pilot Design L2 Schedule CPRI Channel BF Antenna Array Architecture

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