Zhu Wen, Hongwei Kong

Keysight Labs

June 2015

mmWave MIMO Channel Sounding for 5G — Technical Challenges and Prototype System

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Amazingly fast

Great service in a crowd

Best experience follows you

Super real-time &

reliable communications

Ubiquitous things communicating

For the User:

5G Overview: Expectations Massive

Growth in Mobile Data

Demand

Massive Growth in No. of Connected

Devices

Exploding Diversity of

Wireless Applications

Dramatic Change in User

Expectations of Network

100X Energy

Efficiency

Reliability

99.999%

1mS Latency

100X

Densification

1000X

Capacity

100X Data

Rates

All founded on a

solid business model

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High

Performance

By overlaying the

contrasting demands

of different types of

service an aggregate

picture of 5G emerges.

5G Possibilities Could this be 5G?

Bit rate

bits / s

109

107

105

103

UE battery life

days

103

102

10

1

Availability

cost and

efficiency

Key:

Public Safety

MTC/IoT

High Performance

Page

1 GHz 10 GHz 100 GHz 1 THz 10 THz 100 THz 1PHz

10 cm 1 cm 1 mm 100 mm 10 mm 1 mm

Wavelength

Frequency Microwave THz Far IR Infrared UV

5G Overview: Opportunities to Innovate

To-do list!

Design

Simulate

Emulate

Calibrate

Validate

mm-Wave

Enabling Technologies

1. New <6GHz PHY/MAC

2. mmWave (Carrier, BW, MU-MIMO)

3. Full Duplex

4. >>400GB/s Fiber

5. Hyper-Fast Data Buses

6. C-RAN & New NW Topologies 100X Energy

Efficiency

Reliability 99.999%

1mS Latency

100X

Densification

1000X

Capacity

100X Data

Rates

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5G Channel Measurement and Modeling Needs

– 5G spectrum choices and standardization

– 5G key technology choices

• Massive MIMO

• mmWave

• Waveform design

• Full duplex

• etc

– 5G network planning

5G channel models not well studied. Channel sounding is needed to address the

gap.

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Channel Sounding: Concept

RF channel the heart of any

wireless system

Channel sounding techniques to understand

the characteristics of RF channel

Tx Rx

RF Channel

𝑥 𝑡 𝑦 𝑡

ℎ 𝑡

𝑦 𝑡 = ℎ(𝑡) ⊗ 𝑥(𝑡)

𝑅𝑥𝑦 𝜏 = 𝐸 𝑥∗ 𝑡 𝑦 𝑡 − 𝜏

= ℎ(𝑡 − 𝜏) ⊗ 𝑅𝑥 𝜏

≈ ℎ 𝑡 − 𝜏 ⊗ 𝛿 𝜏 = ℎ(𝑡)

RF: Radio Frequency

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Channel Sounding for 5G (I)

5G Channel Sounding

mmWave Frequency Band

Ultra-broad Bandwidth

Massive MIMO

System Requirements

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Channel Sounding for 5G (II)

5G Channel

Sounding

Sounding Approach & Architecture

mmWave Frequency

Band

Ultra-broad Bandwidth

Signal Generation & Acquisition

Efficient Data Storage & Streaming

Channel Parameter Estimation Processing

Synchronization and

Calibration

Technical Challenges

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Consideration on 5G Channel Sounding (1)

Sliding Correlator

• Low meas. speed

• Amplitude information only

Wideband Correlation

• Fast meas. speed

• Amp./phase information

Frequency Swept

• Low meas. speed

• Amplitude information only

Sounding Approach & Architecture

Switching @ Tx&Rx

• Slowest

• No cross-interference

Switching @ Tx, parallel receiving

• Fast

• No cross-interference

Parallel transmitting & receiving

• Fastest

• Suffering cross-interference

Sounding Technique

MIMO Sounding Approach

Wideband Correlation

Switching @ Tx, parallel receiving

Advantages

• Fast measurement speed

• MIMO sounding capability

• High measurement performance

• Arbitrary sounding waveform support

Keysight preferred sounding architecture

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Consideration on 5G Channel Sounding (2) mmWave & Ultra-broadband

Wideband Signal Generator Wideband Multi-channel Receiver

Wideband AWG1

mmWave VSG2

Wideband Multi-

channel Digitizer

mmWave Multi-

channel DC3

mmWave Switch

mmWave

Signal

Wideband I/Q

Signal

mmWave

Sounding

Signal

Channel

IF Signal

1AWG: Arbitrary Waveform Generator 2VSG: Vector Signal Generator 3DC: Down-Converter

mmWave

Antenna mmWave

Antenna

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Consideration on 5G Channel Sounding (3) Data Streaming & Storage

Sounding

signal

CIR1

Transmitting period 𝑇𝑝

Effective

CIR Data

Max. delay

spread 𝑇𝑑

Transmitting signal

length 𝑇𝑠

Raw Sounding Data 25.6GB/s 2

Effective Raw Data

1 CIR: Channel Impulse Response 2 3.2GSa/s with 4 channels and 2Byte/sa, 𝑇𝑝 = 100𝑢𝑠, 𝑇𝑠 = 20𝑢𝑠, 𝑇𝑑 = 5𝑢𝑠

Effective Raw Data 6.4GB/s 2

1.28GB/s 2

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Consideration on 5G Channel Sounding (4) Parameter Estimating Algorithms

Algorithm Consisten

cy

Coherent

Signals

Estimation

Performance

Computations Max Num. of

Path

Beamforming

Based

Bartlett L=1 No Poor 1-D search

Capon No No Poor 1-D search

Subspace

Based

MUSIC1 Yes No;

Yes for ROOT-

MUSIC

Good EVD,

1-D search

< Num. of Rx

ESPRIT2

Yes No;

Yes for TLS-

ESPRIT and

Unitary-

ESPRIT

Good EVD < Num. of Rx

ML Based SAGE3

Yes Yes Good Iterative,

1-D search

No limitation

1MUSIC: MUltiple SIgnal Classification 2ESPRIT: Estimating Signal Parameter via Rotation Invariance 3SAGE: Space-Alternating Generalized Expectation maximization 4EVD: Eigen-Value Decomposition

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Consideration on 5G Channel Sounding (5) Synchronization & Calibration

Wideband Signal Generator Wideband Multi-channel Receiver

Wideband AWG1

mmWave VSG2

Wideband Multi-

channel Digitizer

mmWave Multi-

channel DC3

mmWave

Sounding

Signal

Rubidium

Clock

Rubidium

Clock

I/Q Mismatch

Calibration

Antenna

Calibration

Multi-channel

Calibration

System Impulse

Response

Calibration

Power

Calibration

LO LO

AWG

Acquisition

Trigger

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mmWave MIMO Channel Sounding System Architecture Prototype for 5G Channel Sounding

E8267D

mmWave

Signal

Source

M8190 12GHz

BW AWG

Rubidium Clock

ANT Transmitter PA

M9703A

8CH

Digitizer

Rubidium Clock

M9362

50 GHz 4CH Digital

Convertor

E8257D 67GHz LO

ANT

BPF

33512

AWG

Receiver LNA

L4450A Digital

I/O Switch

Controller

85332B 50GHz

SP4T Switch

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Prototype mmWave Sounding System: Phase I SISO mmWave Channel Sounding

Prototype mmWave Channel Sounding Channel Emulator (for

validation)

mmWave Sounding Signal

mmWave Multi-path Fading Signal

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Prototype mmWave Sounding System: Phase II 4x4 mmWave Channel Sounding

Transmitter Receiver

• 4x4

• CF: 28GHz

• BW: 1GHz

• Size: 2 mobile carts,

838mm(L)*585mm(W)

*920mm(H) for each

• Power consumption:

Tx ~1KW; Rx~800W

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Phase II 4x4 Sounding System Validation Preliminary Results

AoA, AoD, PDP validation results

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Scale to 60GHz mmWave System

M8190 wide

BW AWG

Rubidium

Clock

HJ5418B

N5173B

13.75 GHz LO

Rx

PA

LNA BPF

Rubidium

Clock

AWG

E8267D 10.625GHz 3rd

LO

N5152A 57~65GHz

Up-converter

Tx N1999A 57~65GHz

Down-converter

5GHz IF Input

5GHz IF Output

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Scale to 94GHz mmWave System

M8190 wide

BW AWG

Rubidium

Clock

HJ5418B

N5173B

LO

Rx

PA

LNA BPF

Rubidium

Clock

AWG

E8267D

E257DV10:

75~110GHz, 6x

Multiplier

Tx N9029AV10 SA

frequency extension

module

15GHz Input

1~5GHz IF Output

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Summary

– Channel sounding and modeling important for 5G

– 5G channel sounding challenges

– Keysight mmWave MIMO channel sounding research

– How to scale the prototype solution to address different needs