5G mmWave MIMO Channel Sounding Technical Challenges and Test Approaches Sheri DeTomasi 5G Solutions Program Manager Sept 2015
5G mmWave MIMO Channel Sounding Technical Challenges and Test Approaches
Sheri DeTomasi
5G Solutions
Program Manager
Sept 2015
Page Page Topics
– Channel sounding fundamental
– Channel sounding approaches
– 5G Channel sounding technical challenges
– 5G channel sounding measurements
– Summary
Keysight 5G
Channel Sounding 2
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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 Goals and Key Performance Indicators
Keysight 5G
Channel Sounding
mm-Wave
100X Energy
Efficiency
Reliability
99.999%
1mS Latency
100X
Densification
1000X
Capacity
100X Data
Rates 5G air interface technology investigations
• mmWave channels
• Waveform design
• Massive MIMO
• Full duplex
Channel behavior is not well understood
for mobile multiple-access
communications at mmWave. Channel
sounding is needed to characterize new
potential 5G air interfaces
Amazingly fast
Great service in a crowd
Super real-time &
reliable communications
Ubiquitous “things”
communicating
New
Market Demands
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What is Channel Sounding?
The RF channel is the heart of any radio-communication system and must be
characterized with parameters such as path loss, delay, absorption, reflection,
multipath, fading, Doppler, all which can affect the performance of the overall system
Channel sounding is required to understand the characteristics of RF channel
Tx Rx
Channel
𝑥 𝑡 𝑦 𝑡
ℎ 𝑡
𝑅𝑥𝑦 𝜏 = 𝐸 𝑥∗ 𝑡 𝑦 𝑡 − 𝜏
= ℎ(𝑡 − 𝜏) ⊗ 𝑅𝑥 𝜏
≈ ℎ 𝑡 − 𝜏 ⊗ 𝛿 𝜏 = ℎ 𝑡
* RF: Radio Frequency
𝒚 𝒕 = ℎ(𝑡) ⊗ 𝑥(𝑡)
Received Signal convolution
h(t) CIR extraction requires post or real-time signal processing
like using cross correlation processing technique here in this formula
CIR
Channel Impulse Response
Keysight 5G
Channel Sounding 4
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Driving, impacting the overall R&D
• Antenna design SISO, MIMO, ARAY
• Power Amplifier & Receiver
• BB Signal Processing & Algo.
• Form factor
• Material
Channel Sounding Contribution in Wireless System Design
Keysight 5G
Channel Sounding
RF
Channel
Wireless
Communication system
CIR Measurement (using channel sounding)
Channel Modeling
Channel Emulation &
Simulation
Channel Related Research
Channel
Parameters
Channel Models
RAN
UEs
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The Role of Channel Modeling
Keysight 5G
Channel Sounding
The many inputs to developing a channel model
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Channel Sounding Contribution in Wireless System Design
Keysight 5G
Channel Sounding 7
Page Page Topics
– Channel sounding fundamental
– Channel sounding approaches
– 5G Channel sounding technical challenges
– 5G channel sounding measurements
– Summary
Keysight 5G
Channel Sounding 8
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How can Channel Sounding be Implemented? Sounding Approach & Architecture
Sliding Correlator
• Low measurement speed
• Some only have amplitude information
Frequency Swept
• Low measurement speed
• Amplitude/phase information
Wideband Correlation
• Fast measurement speed
• Amplitude/phase information
Sounding Techniques
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Channel Sounding 9
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How can Channel Sounding be Implemented?
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Channel Sounding
Switching @ Tx & Rx
• Slowest measurement speed
• Serial measurement requires stable measurement environment
• No need for phase coherence
• No cross-interference
Switching @ Tx & parallel receive
• Fast measurement speed
• Multi-channel phase coherence needed in Rx
• No cross-interference
Parallel transmit & receive
• Fastest measurement speed
• Multi-channel phase coherence needed in Tx&Rx
• Suffering cross-interference
Most research has been SISO
5G requires MIMO characterization to include spatial information
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Page Page Topics
– Channel sounding fundamental
– Channel sounding approaches
– 5G Channel sounding technical challenges
– 5G channel sounding measurements
– Summary
Keysight 5G
Channel Sounding 11
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Key Requirements for 5G Channel Sounding
5G Key Requirements
mmWave Frequency Band
Ultra-broad Bandwidth
Massive MIMO
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Channel Sounding
New 5G
Channel Models
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Technical Challenges
Keysight 5G
Channel Sounding
Goal: Understand characteristics of new RF
Channels in mmWave Technical Challenges
1. Sounding approach & architecture
2. Signal generation and capture
- mmWave frequency band
- Ultra-broad bandwidth
- Multi-channel
3. Data capture & storage
4. Channel parameter estimation
processing
5. Calibration and synchronization of
the measurement system
Tx Rx
RF Channel
𝑥 𝑡 𝑦 𝑡
ℎ 𝑡
28 GHz, 38 GHz, 72 GHz
BW 500 MHz, 1 GHz, 2 GHz
Measurements:
• Path loss, absolute path delay,
power delay profile (PDP)
• AoA / AoD
• Doppler Shift
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Consideration on 5G Channel Sounding
Keysight 5G
Channel Sounding
1. Sounding Approach & Architecture
Sliding Correlator
• Low meas. speed
• Amplitude information only
Frequency Swept
• Low meas. speed
• Amplitude/phase information
Wideband Correlation
• Fast meas. speed
• Amplitude/phase information
Switching @ Tx & Rx
• Slowest
• No cross-interference
Switching @ Tx, Parallel Receive
• Fast
• No cross-interference
Parallel Transmit & Receive
• Fastest
• Adds cross-interference
Sounding Techniques
MIMO Sounding Approaches
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Consideration on 5G Channel Sounding
Keysight 5G
Channel Sounding
1. Sounding Architecture
Advantages
• Fast measurement speed
• MIMO sounding capability
• High measurement performance
• Arbitrary sounding waveform support
Keysight recommended sounding
architecture
Use wideband
signal generation
and analysis
Use switched Tx and
parallel Rx
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Consideration on 5G Channel Sounding
Keysight 5G
Channel Sounding
2. mmWave, Ultra-broad Bandwidth, MIMO
Wideband Signal Generator Wideband Multi-channel Receiver
Wideband AWG1
mmWave Vector
Signal Generator
Wideband Multi-
channel Digitizer
mmWave Multi-
channel
Downconverter
mmWave Switch
mmWave
Signal
Wideband I/Q
Signal
mmWave
Sounding
Signal
Channel
IF Signal
1AWG: Arbitrary Waveform Generator
mmWave
Antenna
mmWave
Antenna
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Consideration on 5G Channel Sounding
Keysight 5G
Channel Sounding
3. Data Capture & Storage
Sounding
signal
CIR1
Transmitting period 𝑇𝑝
Effective
CIR Data
Max. delay
spread 𝑇𝑑
Transmitting signal
length 𝑇𝑠
Raw Sounding Data 32GB/s 2
Effective Raw Data
1 CIR: Channel Impulse
Response 2 1GSa/s sampling rate,
𝑇𝑝 = 100𝑢𝑠, 𝑇𝑠 = 20𝑢𝑠, 𝑇𝑑 = 5𝑢𝑠
Effective Raw Data 8GB/s 2
1.6GB/s 2
Real-time data analysis reduces memory and
disk space requirements
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Consideration on 5G Channel Sounding
Keysight 5G
Channel Sounding
4. Channel Parameter Estimating Algorithms
SystemVue
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Consideration on 5G Channel Sounding
– The various channel parameter estimation algorithms can be categorized
with 3 types
• Beamforming Based: simple, but poor performance
• Subspace Based: good performance, but limit on the detected
number of paths
• Maximum likelihood based: widely used due to high performance and
strong capability
– ML Based SAGE: Space-Alternating Generalized Expectation
maximization
• High accuracy
• No limit on the maximal estimating path number
• Joint channel parameter estimation: Path, Delay, Doppler, AoA/AoD
Keysight 5G
Channel Sounding
4. Channel Parameter Estimating Algorithms
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Consideration on 5G Channel Sounding
Synchronization
- Precise timing thorough GPS
clocks and triggering
System-Wide Calibration
- System impulse response
- IQ imbalance
- Multi-channel amplitude,
phase, delay
- System delay
- Power
- Antenna
Wideband Signal Generator Wideband
Multi-channel
Receiver
Wideband AWG1
mmWave VSG2 mmWave Multi-
channel DC3
Rubidium
Clock
Rubidium
Clock
I/Q Mismatch
Calibration
AWG
Acquisition
Trigger
Wideband Multi-
channel Digitizer
Channel Parameter
Estimation Algorithm
5. Synchronization and Calibration
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Channel Sounding 20
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Synchronization and Calibration Requirements for Wideband Sounding System
Measurement
Matrices
Synchronization & Calibration
LO
sync
Signal
Gen&Acq.
sync
Multi-ch
phase&
cal
System
IR cal
Antenna
cal
System
power
cal
System
delay cal
AWG
I/Q cal
SISO PDP(relative
delay) Yes Yes Yes
PDP (absolute
delay) Yes Yes Yes Yes Yes
Doppler freq. Yes Yes Yes Yes
MIMO PDP(relative
delay) Yes Yes Yes
PDP(absolute
delay) Yes Yes Yes Yes Yes
Doppler freq. Yes Yes Yes Yes
AoA/AoD
using antenna
array
Yes Yes Yes Yes Yes Yes
Keysight 5G
Channel Sounding 21
Page Page Topics
– Channel sounding fundamental
– Channel sounding approaches
– 5G Channel sounding technical challenges
– 5G channel sounding measurements
– Summary
Keysight 5G
Channel Sounding 22
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Channel Sounding Measurements
CIR (Channel Impulse Response)
• PDP (Power Delay Profile): path delay, path loss
• AoA/AoD (Angle of Arrival/Departure)
• Doppler shift
Instant parameters
• AS (Angular Spread) of AoA/AoD
• PAS (Power Angular Spectrum)
• Doppler spectrum
• Correlation matrix
• Rician K factor
Statistics parameters & modeling
Keysight 5G
Channel Sounding
Tx Rx
RF Channel
𝑥 𝑡 𝑦 𝑡
ℎ 𝑡
28 GHz, 38 GHz, 72 GHz
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Measurement System
Keysight 5G
Channel Sounding
Keysight 5G Channel Sounding Reference Solution
Software
System
Data capture and
storage IO control software
for calibration and synchronization
Transmitter
Config&Control
Receiver
Config&Control
RT autocorrelation of CIR
in FPGA
Parameter Estimation
Algorithm
Channel
Measurement
Results
M9703A, 1 GHz BW,
interleaving
N5173B 40 GHz LO
10MHz GPS
Ref Clk
E8267D PSG with
IQ inputs
M8190 2GHz BW
10MHz GPS
Ref Clk
33511A AWG for
Sync Trigger
M9362A-D01 40 or 50 GHz
Down Convertors
1x
4 o
r 1
x8
Sw
itc
h
Ch
an
nel
1x
4 o
r 1
x8
MIM
O
Signal generation
and capture
Up to 44 GHz
Up to 1 GHz BW
Up to 8x8 MIMO
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Channel Sounding Signal Processing
Transmitter Receiver Channel
Sounding
Signal@TX
0 1000 2000 3000 4000 5000 6000 7000 8000 9000 10000-1.5
-1
-0.5
0
0.5
1
1.5
Received Signal
(huge amount of
data)
Cross-correlator &
data truncation
(Real-time pre-
processing in
M9703A FPGA)
CIR
(greatly reduced
amount of data)
0 1000 2000 3000 4000 5000 6000 7000 8000 9000 100000
0.005
0.01
0.015
0.02
0.025
0.03
0.035
0.04
0.045
0 50 100 150 200 250 300 350 4000
0.01
0.02
0.03
0.04
0.05
0.06
0.07
Processing
Algorithms
(SAGE, ESPRIT,
etc.)
Extracted
Channel
Parameters
Sounding
Signal@RX
Post-
processing
by user
Effective data
length is much
shorter than
receive signal
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Keysight 5G
Channel Sounding
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1 Channel Parameter Estimations in Keysight SystemVue
3
Block diagram of the actual
measurement setup 2
Setting options before the post processing of measurement parameter
– CIR/AoA/AoD/Dopppler frequency/Pathdelay/Pathloss
4
Measurement
Parameters
5G Channel Sounding Measurements
Keysight 5G
Channel Sounding 26
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MIMO 8x8 Dual Polarization: 5.8GHz
– Waveform
– PDP
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Channel Sounding 27
– Multiple Path Parameter
– Mirror Spectrum = NO
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MIMO 8x8 Dual Polarization: 5.8GHz
– PDP V
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Channel Sounding 28
– Multiple Path Parameter
– Mirror Spectrum = NO
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5 Result Display of Measurement Parameters
5G Channel Sounding Measurements
Keysight 5G
Channel Sounding 29
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5G Channel Sounding Measurements
Keysight 5G
Channel Sounding
4x4 mmWave MIMO Channel Sounding
Transmitter Receiver
– 4x4
– CF: 28GHz
– BW: 1GHz
– Size: 2 mobile carts,
838mm(L)*585mm(W)*92
0mm(H) for each
– Power consumption: Tx
~1KW; Rx~800W
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5G Channel Sounding Measurements
Keysight 5G
Channel Sounding
90 GHz SISO System
M8190 5GHz
BW AWG
Rubidium
Clock
N5173B
LO
Rx
PA LNA BPF
Rubidium
Clock
AWG
E8267D
N9029AVxx-UDC
Tx N9029AV10 SA
frequency extension
module
15GHz Input
1~5GHz IF Output
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Page Page Topics
– Channel sounding fundamental
– Channel sounding approaches
– 5G Channel sounding technical challenges
– 5G channel sounding measurements
– Summary
Keysight 5G
Channel Sounding 32
Page © 2015 Keysight Technologies
5G Channel Sounding Summary
Keysight 5G
Channel Sounding
- Channel sounding and modeling is critical in 5G research
- Key technical challenges need to be resolved to produce accurate
and repeatable results
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1. Sounding approach & architecture
2. Signal generation and capture
- mmWave frequency band
- Ultra-broad bandwidth
- Multi-channel
3. Data capture & storage
4. Channel parameter estimation
processing
5. Calibration and synchronization of
the measurement system
1. Wide-band correlation with MIMO capability to
extract spatial parameters
2. Use metrology grade test equipment that has
sufficient frequency, sample rate, resolution,
and has support for multi-channel
3. Decimate data or use real-time processing for
better data management
4. Choose algorithm that provides good channel
parameter estimations w/ MIMO
5. Ensure precise timing and synchronization
and calibration to ensure accurate, repeatable
results
Addressing Technical Challenges
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Keysight Test Solutions for 5G Research
Keysight 5G
Channel Sounding 34
Up to 16 channels
Up to 40 channels
Up to 104
channels
Wideband
RF/µW/mmWave Sub-6 GHz MIMO Channel Sounding
mmWave, BW, MIMO Massive MIMO
Receiver
Signal Generation & Analysis Phase Coherent Signal
Generation & Analysis
SystemVue Simulation
Software with 5G Library
Signal Studio Software
with Custom 5G
89600 VSA Software with
Custom OFDM/Demod
Transmitter Receiver
Page Page Thank You
– www.keysight.com/find/5G
– www.keysight.com/find/solution-5GSounding
– www.keysight.com/find/solution-5Gtestbed
Find more recourse like application notes, videos,
brochure, configurations
Keysight 5G
Channel Sounding
Keysight Solutions Unrivaled performance. Half the
time to insight.
35
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3 Setting options before the post processing of measurement
parameter – CIR/AoA/AoD/Doppler frequency/Pathdelay/Pathloss
5G Channel Sounding Measurements
Keysight 5G
Channel Sounding 36
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Completing the Solution
– Software development services based
on the SystemVue platform to create
custom sounding signals and channel
parameter extractions
– Productivity services to complete the
project delivered by Keysight application
experts. Can provide addition
configuration, integration, consulting.
Find out more:
http://literature.cdn.keysight.com/litweb/pdf
/5989-0099EN.pdf?id=393341
– Extended support and training
Keysight 5G
Channel Sounding
Keysight Professional Services
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