lte world summit 2012 grimley agilent-technologies-m_asterclass-1_wed

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Greater insight. Greater confidence. Accelerate next-generation wireless.

Verify and Visualize your LTE MIMO Beamforming Signals

Craig Grimley, R&D Developer

Electronic Measurement Group, Agilent Technologies

LTE World Summit, May 2012

© Agilent Technologies

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What is MIMO Beamforming ?

Multi-antenna techniques

Introduction to beamforming

What are benefits ?

Benefits for cellular network

Use within LTE transmission modes

What are the test verification challenges ?

Typical TD-LTE eNB test configuration

Agilent 8-Chan N7109A SA + 89600 VSA test solution

Verify and Visualize your

LTE MIMO Beamforming Signals



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Multi-Antenna Techniques

Tx Rx :

SIMO

- Rx diversity

- Rx smart antenna

(beamforming)

- Improved SINR

Tx Rx :

MISO

- Tx diversity

- Tx smart antenna

(beamforming)

- Improved SINR

Tx Rx : :

MIMO

- Tx/Rx diversity

- Tx/Rx smart antenna

(beamforming)

- Spatial multiplexing

- Improved SINR

or

Improved Spectral

Efficiency / Data Rates

Tx Rx

SISO - No diversity protection

against channel fading

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Multi-Antenna Techniques

Tx Diversity • Orthogonally modified redundant copies

transmitted across multiple antenna’s

• Robustness to channel fading / noise

S1 S0

-S1*

Tx0

Tx1 S0*

Frequency domain

Spatial Multiplexing • Simultaneous unique data streams


• Improved spectral efficiency / throughput

S0

S1

Tx0

Tx1

Beamforming • Per antenna weighted signal copies


• Coherent beamforming gain (dB) at receiver

S0.w0

S0.w1

Tx0

Tx1

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Introduction to Beamforming

Relative field strength example

1 Antenna Element

|

-90 deg

-60 deg

-30 deg

0 deg

+30 deg

+60 deg

+90 deg

Main Lobe = omnidirectional

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2 Antenna Elements

Co-polarized 0.5 wavelength separation

0deg phase shift per element

| |

-90 deg

-60 deg

-30 deg

0 deg

+30 deg

+60 deg

+90 deg

Main Lobe = 0deg azimuth

Number of Nulls = 1 Constructive

Interference

Power Gain

Destructive

Interference

Power Null

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3 Antenna Elements



| | |

-90 deg

-60 deg

-30 deg

0 deg

+30 deg

+60 deg

+90 deg


Number of Nulls = 2

Improved

Beam

Selectivity

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4 Antenna Elements



| | | |

-90 deg

-60 deg

-30 deg

0 deg

+30 deg

+60 deg

+90 deg


Number of Nulls = 3

Improved

Beam

Selectivity

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4 Antenna Elements



| | | |

-90 deg

-60 deg

-30 deg

0 deg

+30 deg

+60 deg

+90 deg

Main Lobe = -30deg azimuth

Number of Nulls = 3

Beam

Control

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-90 deg

-60 deg

-30 deg

0 deg

+30 deg

+60 deg

+90 deg

| | | |

4 Antenna Elements





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• Used in many technologies:

radar, sonar, seismology, wireless communications, radio astronomy, acoustics

• Takes advantage of multi-antenna interference patterns

Constructive (in-phase)

interference

Power Gain

Destructive (out-of-phase)

interference

Power Nulling

Antenna array geometry

+

Relative mag / phase

weightings

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• Coherent Beamforming Gain (dB)

Improved SINR observed at UE device

Increased throughput at cell-edge

Increased cell coverage or size

• Spatial Selectivity

Mitigate intra-cell interference

Mitigate inter-cell interference

Improve spectrum efficiency

(SDMA, Space Division Multiple Access)



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eNB3

UE3

UE4

eNB1 eNB2

UE1

UE2

Null

Null

Benefits for Cellular Network

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3GPP Release 8:

TM1: SISO single antenna transmissions

TM2 : Tx Diversity using 2 or 4 antennas

TM3: Open-Loop SU-MIMO (Spatial Multiplexing)

TM4: Closed-Loop SU-MIMO

TM5: Closed-Loop MU-MIMO

TM6: Rank 1 Spatial Multiplexing

TM7: Single Layer Beamforming on Port 5

3GPP Release 9:

TM8: Dual Layer Beamforming on Ports 7 & 8

3GPP Release 10:

TM9: Up to 8 layer transmissions using Ports 7 to 14

LTE DL Transmission Modes

TM7 & TM8 Beamforming

is current TD-LTE

market focus

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Channel coding

Rate matching

Code block

concatenation

110 ,...,, Aaaa

110 ,...,, Bbbb

110 ,...,, rKrrr ccc

)(

1)(

1)(

0 ,...,, iDr

ir

ir r

ddd

110 ,...,, rErrr eee

110 ,...,, Gfff

Transport block

CRC attachment

Code block segmentation

Code block CRC attachment



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LTE Signal Processing (TM7 & TM8) (Adapted from 3GPP 36.211 and 36.212)

ScramblingModulation

mapper

Layer

mapperPrecoding

Resource element

mapper

OFDM signal

generation

Resource element

mapper

OFDM signal

generationScrambling

Modulation

mapper

layers antenna portscodewords

Cell-specific RS (Reference Signal)

Can be weighted to produce sector wide common control Broadcast pattern

Possible when Num Physical Ports > Num CRS Ports

Cell-specific RS Broadcast pattern

PDSCH (Data)

Channel encoded and mapped onto 1 or 2 codewords (layers)

BF precoding is non-codebook based

BF precoding can vary per RB & per Subframe (TTI)

UE-specific RS (Reference Signal)

Mapped to associated TM7 / TM8 PDSCH RB allocations

Same BF precoding as per associated PDSCH RB

UE-specific RS

UE-specific pattern

UE1

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LTE Signal Processing (TM7 & TM8) (Adapted from 3GPP 36.211 and 36.212)

TM7

Single Layer

UE-specific RS

Port 5

TM8

Dual Layer

UE-specific RS

Port 7

Port 8

Common

Cell-specific RS

Port 0

Port 1

Port 2

Port 3

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A1 A2 A3 A4

A5 A6 A7 A8



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Typical TD-LTE eNB Test Configuration

UE1

Uplink feedback

(SRS, CQI, PMI, RI)

UL RF

Channel

Emulator

2x8

DL RF

Channel

Emulator

8x2

~10dB

CAL

Coupler

eNB

RRH

eNB

BB

CAL

Ant 1

Ant 2

Ant 3

Ant 4

Ant 5

Ant 6

Ant 7

Ant 8

A1, A2, A3, A4 = +45 degree polarization

A1 A2 A3 A4

A5, A6, A7, A8 = -45 degree polarization

A5 A6 A7 A8

Common customer problem, need to verify:

RF Circulator

RF Atten

~0.5 * RF carrier wavelength spacing

eNB RF antenna calibration accuracy

BB beamforming weighting algorithm correctness

RF & EVM modulation quality for MIMO single or

dual layer

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UE1


RF Splitter

Uplink feedback

(SRS, CQI, PMI, RI)

UL RF

Channel

Emulator

2x8

RF Circulator

RF Atten

DL RF

Channel

Emulator

8x2

~10dB

CALIBRATION REFERENCE

SIGNAL RF SOURCE & SPLITTER

Agilent

8-Chan

N7109A

Analyzer

Agilent 89600B VSA

~20dB

CAL

Coupler

eNB

RRH

eNB

BB

CAL

Ant 1

Ant 2

Ant 3

Ant 4

Ant 5

Ant 6

Ant 7

Ant 8



A1 A2 A3 A4

A5 A6 A7 A8


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DL RF

Channel

Emulator

8x2

~10dB

UE1



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RF Splitter

Uplink feedback

(SRS, CQI, PMI, RI)

UL RF

Channel

Emulator

2x8

RF Circulator

RF Atten

CALIBRATION REFERENCE

SIGNAL RF SOURCE & SPLITTER

CAL

Coupler

eNB

RRH

eNB

BB

CAL

Ant 1

Ant 2

Ant 3

Ant 4

Ant 5

Ant 6

Ant 7

Ant 8



A1 A2 A3 A4

A5 A6 A7 A8


Agilent

8-Chan

N7109A

Analyzer

~20dB

Agilent 89600B VSA

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Agilent 8-Chan N7109A SA + 89600 VSA

8 Channel

RF Spectrum

8 Channel

RF Time

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IQ

Constellations

UE-specific

RS Weights

Cell-specific RS

Weights &

Impairments

UE-specific &

Common Broadcast

Antenna Beampatterns

EVM

Metrics

Detected

Resource

Allocations

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Agilent 8-Chan N7109A SA + 89600 VSA Ant Group 0

pattern

Ant Group 1

pattern

8 Channel

UE-specific RS

Mag/Phase Weights

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Ant Group 1 Cell-RS Weights

8 Channel

Cell-RS

MIMO

Impairments

& Weights

Ant Group 0

pattern

Ant Group 1

pattern

Ant Group 0 Cell-RS Weights

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LogMag (dB)

IQ Polar

Beamforming Gain (dB)

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Provides an 8-channel phase coherent measurement solution to enable

verification and visualization of TD-LTE base station RF antenna

beamforming signals.

TD-LTE (TM7 & TM8) measurement solution

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Application Note: http://www.agilent.com/find/LTE-Forward

Youtube Video: http://www.youtube.com/watch?v=mj58aSOZ1Kc

8-Chan N7109A: http://www.agilent.com/find/N7109A

89600 VSA: http://www.agilent.com/find/89600

LTE: http://www.agilent.com/find/LTE

For more information…

http://www.agilent.com/find/LTE-Forward



http://www.youtube.com/watch?v=mj58aSOZ1Kc

http://www.youtube.com/watch?v=mj58aSOZ1Kc

http://www.agilent.com/find/N7109A



http://www.agilent.com/find/89600

http://www.agilent.com/find/89600

http://www.agilent.com/find/LTE

http://www.agilent.com/find/LTE

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Thank you !

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