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MIMO in 4G Wireless Presenter: Iqbal Singh Josan, P.E., PMP Director & Consulting Engineer USPurtek LLC About the presenter: Iqbal is the founder of training and consulting firm USPurtek LLC, which specializes in providing Professional Engineering Services to telecom operators and network equipment vendors in the domain of Wireless Broadband and Enterprise Networks. Iqbal is a Senior Member of IEEE and a Licensed Professional Engineer, and has 26 years of experience in the industry, having held engineering and project lead positions with multinational companies in the US as well as India. Iqbal can be reached at [email protected]
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MIMO Introduction Realizing Benefits from MIMO Antenna Diversity, Beamforming and SDM Applications of MIMO in WiFi, WiMax and LTE Future of MIMO
MIMO in 4G Wireless
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Introduction Multiple Input Multiple Output
o Multiple Tx & Rx Antennas Multiple radio channels
Tx Rx
1 1
2 2
M N
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Introduction Multiple Input Multiple Output
o Multiple Tx & Rx Antennas Multiple radio channels
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What came before MIMO? SISO
o Single Input Single Output
Tx Rx
1 1
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What came before MIMO? SISO
o Single Input Single Output
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What came before MIMO? SIMO o Single Input Multiple Output
Tx Rx
1 1
2
N
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What came before MIMO? SIMO o Single Input Multiple Output
Tx Rx
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What came before MIMO? MISO o Multiple Input Single Output
Tx Rx
1 1
2
M
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What came before MIMO? MISO o Multiple Input Single Output
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Finally MIMO! MIMO
o Multiple Input Multiple Output
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Interactive Question #1 Which Antenna configuration is depicted by the following figure?
1. SISO 2. SIMO 3. MISO 4. MIMO
Tx Rx
Rx
Rx
Rx
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Promises of MIMO Robust Radio Channel
o Effects of fading and multipath interference mitigated o No breaks in voice calls or data
Higher Throughput o Faster downloads o More Mbps with existing spectrum and power
Enables 4G Wireless Broadband applications o WLAN (IEEE 802.11n/ad) o WiMAX (IEEE 802.16m) o LTEA (3GPP Rel 10)
I Is this handset in your future?
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Realizing MIMO Promises
Antenna Diversity o Receive Diversity o Transmit Diversity
Beamforming Space Division Multiplexing (SDM)
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Multipath Propagation
I 20 30 dB Fading
+ = no signal
Tx Rx
Path 3
Path 2
Path 1
+ =
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Multipath Propagation
I Inter Symbol Interference (ISI)
time
Path 1
Path 2
Path 3
+ +
s1 s2
s1, s2 s2
s1 s2
Tx Rx
Path 3
Path 2
Path 1
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Receive Diversity Mitigates Effects of Multipath Propagation Enhances Signal to Noise Ratio (SNR) SIMO Configuration
Tx Rx
λ/2 λ/2
I Signals combined from multiple antennas
Tx Rx
λ/2 λ/2
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I Selection Combining
Receive Diversity Mitigates Effects of Multipath Propagation Enhances Signal to Noise Ratio (SNR) SIMO Configuration
Tx Rx
λ/2 λ/2
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I Equal Gain Combining
Mitigates Effects of Multipath Propagation Enhances Signal to Noise Ratio (SNR) SIMO Configuration
Receive Diversity
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Tx Rx
I Maximal Ratio Combining
λ/2 λ/2
Receive Diversity Mitigates Effects of Multipath Propagation Enhances Signal to Noise Ratio (SNR) SIMO Configuration
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Transmit Diversity Redundant copies of signal transmitted across space and time Space Time Block Codes (STBC) used
o 50 – 200 ns time delay inserted in transmission paths Mitigates Effects of Multipath Propagation Enhances Signal to Noise Ratio (SNR) MISO Configuration
time
Ant 1
Ant 2
Ant 3
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Interactive Question #2 What is not a benefit of Antenna Diversity?
1. Diversity Gain 2. Enhanced Signal to Noise Ratio 3. Increased Bandwidth 4. Redundant Copies of Signal
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Beamforming Controls shape and direction of radio signals Used on Transmit or Receive Antenna Arrays Extends range of radio signals in a direction
o Signals from multiple antennas add up constructively to maximize receiver gain
Mitigates Effects of Multipath Propagation
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Beamforming Controls shape and direction of radio signals Used on Transmit or Receive Antenna Arrays Extends range of radio signals in a direction
o Signals from multiple antennas add up constructively to maximize receiver gain
Mitigates Effects of Multipath Propagation
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Space Division Multiplexing (SDM) Different signals transmitted and received simultaneously over same RF bandwidth Exploits spatial separation provided by MIMO Configuration Achieves Higher Throughput Ideal for RF channels with High Signal to Noise Ratio (SNR)
Tx Rx
1 1
2 2
M N
M X N MIMO λ/2
λ/2
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Space Division Multiplexing (SDM) Signal Path Coefficients (h11….hMN) represent amplitude and phase response for each signal path
o Determined during training sequence – Tx generates known training signal – Rx processes training signal to estimate path responses
Tx Rx
1 1
2 2
M N
M X N MIMO
h11
h1N h21
h22
hM2
hMN
λ/2
λ/2
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Space Division Multiplexing (SDM) MIMO channel represented as matrix of signal path coefficients, H Receivers use H1 to spatially demultiplex the original transmitted signals
o T = H1 R
I Received Signals
I MIMO Channel I Transmitted
Signals
Rx1
Rx2
RxN
• •
•
₌ h11 h21 • • hM1
h21 h22 • • hM2
• • • • •
• • • • •
hM1 hM2 • • hMN
Tx1
Tx2
TxM
• •
•
R H T
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Interactive Question #3 Which technique will you recommend when the radio channel is very noisy (SNR is low)?
1. Space Division Multiplexing (SDM) 2. Transmit Antenna Diversity 3. Space Time Block Codes (STBC) 4. Time Division Multiplexing (TDM)
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Multiplexing Rate in MIMO
Base Station
1 1
2 2
3
Single User
3 X 2 MIMO Multiplexing Rate = 2
Multiplexing Rate o Number of distinctive data streams that can be received correctly and simultaneously
– For MxN MIMO, it is the min (M,N)
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Multiplexing Rate in MIMO Multiplexing Rate
o Number of distinctive data streams that can be received correctly and simultaneously
– For MxN MIMO, it is the min (M,N)
Base Station
1 1
2 2
3
3 X 2 MIMO Multiplexing Rate = 2
Single User
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Multiplexing Rate in MIMO
Base Station
1 1
2 2
3
Single User
3 X 2 MIMO Multiplexing Rate = 2
Multiplexing Rate o Number of distinctive data streams that can be received correctly and simultaneously
– For MxN MIMO, it is the min (M,N)
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Multiplexing Rate in MIMO
Base Station
1 1
2 2
3
Single User
3 X 2 MIMO Multiplexing Rate = 2
Multiplexing Rate o Number of distinctive data streams that can be received correctly and simultaneously
– For MxN MIMO, it is the min (M,N)
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Multiplexing Rate in MIMO
Base Station
1 1
2 2
3
Single User
3 X 2 MIMO Multiplexing Rate = 2
Multiplexing Rate o Number of distinctive data streams that can be received correctly and simultaneously
– For MxN MIMO, it is the min (M,N)
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Multiplexing Rate in MIMO
Base Station
1 1
2 2
3
Single User
3 X 2 MIMO Multiplexing Rate = 2
Multiplexing Rate o Number of distinctive data streams that can be received correctly and simultaneously
– For MxN MIMO, it is the min (M,N)
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Multiplexing Rate in MIMO
Base Station
1 1
2 2
3
3 X 2 MIMO Multiplexing Rate = 2
Single User
Multiplexing Rate o Number of distinctive data streams that can be received correctly and simultaneously
– For MxN MIMO, it is the min (M,N)
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Diversity Gain in MIMO For narrow band system with slow fading
o Product of M & N
Base Station
1 1
2 2
3
Single User
3 X 2 MIMO Diversity Gain = 6
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Trade Off is Possible For 5x4 MIMO oCase 1: Reliable Mode
– Multiplexing Rate = 2 – Diversity Gain = 3x2 = 6
Multiplexing & Diversity Combo
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Multiplexing & Diversity Combo
Trade Off is Possible For 5x4 MIMO oCase 2: High Rate Mode
– Multiplexing Rate = 3 – Diversity Gain = 2x1 = 2
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MIMO in WiFi
IEEE 802.11n standard has adopted MIMO o Antenna Diversity upto 4 x 4 o Tx Beamforming o Space Division Multiplexing (SDM)
2.4/5 GHz ISM band o 20/40 MHz Bandwidth
PHY Data rates upto 600 Mbps o Throughput > 200 Mbps
Extended Range o Indoor 70 m o Outdoor 250 m
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MIMO in WiFi Antennas for Access Point o Narrowband Monopole
λ/2 λ/2
λ / 4
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MIMO in WiFi Antennas for Access Point o Multiband Compact
Top View
2.4 GHz 5 GHz
RF Cable
Ground
Multiband Antenna Element
Antenna Element
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MIMO in WiFi Antennas for Portable Devices
o Tradeoffs between design, performance and placement
Antenna Feed Point
Ground Plane
Antenna Configuration: Case1
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MIMO in WiFi Antennas for Portable Devices
o Tradeoffs between design, performance and placement
Antenna Feed Point
Ground Plane
Antenna Configuration: Case2
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Interactive Question #4 What is the recommended physical separation between Antenna elements of a MIMO system?
1. λ/4 2. Depends on the wireless standard 3. Minimum λ/2 4. Does not matter
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MIMO in WiMax IEEE 802.16m has full featured MIMO o Antenna Diversity o Beamforming o Space Division Multiplexing (SDM)
2.32.4, 3.33.4 GHz (country specific) o 510 MHz Bandwidth
Enhanced Throughput o 1 Gbps for fixed stations o 100 Mbps for mobile stations
Single or Multi User MIMO o SUMIMO o MUMIMO
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MIMO in LTEA 3GPP Rel 10 (LTEA) has full featured MIMO o Antenna Diversity o Beamforming o Space Division Multiplexing (SDM)
22 Freq. bands covering 6983600 MHz o Scalable Bandwidth (20100 MHz)
Enhanced Throughput o 1 Gbps Downlink o 500 Mbps Uplink
Single or Multi User MIMO o SUMIMO o MUMIMO
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SUMIMO Single User gets the benefit of full
Throughput
Base Station
1 1
2 2
3
3 X 2 MIMO
Single User
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SUMIMO
1
1
2
2
3
3 X 2 MIMO
Base Station
Single User
Single User gets the benefit of full Throughput
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MUMIMO Multiple Users share full Throughput
1 1
2 2
3
Base Station Multiple
Users
3
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A Glimpse of the Future Massive MIMO & WiGig (IEEE 802.11ad)
o 60 GHz unlicensed band – 4 channels of 2 GHz each
o Upto 7 Gbps data rates o mm Wave MIMO Antenna Arrays
– small λ ( 5 mm) means very small antenna
λ /2 = 2.5 mm Distance between elements
1 cm
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A Glimpse of the Future
256 elements
16 elements
Massive MIMO & WiGig (IEEE 802.11ad) o 60 GHz unlicensed band
– 4 channels of 2 GHz each o Upto 7 Gbps data rates o mm Wave MIMO Antenna Arrays
– small λ ( 5 mm) means very small antenna
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Bibliography
“An Introduction to MUMIMO Downlink” IEEE Communications Magazine, October 2004 “MIMOOFDM based air interface” IEEE Communications Magazine, January 2005 “Downlink MIMO in LTEA” IEEE Communications Magazine, February 2012 “Understanding IEEE 802.11n amendment” IEEE Circuits and Systems Magazine 1Q 2008 “Advancement of MIMO in WiMax” IEEE Communications Magazine June 2009 “MIMO in WiMax and LTE” IEEE Communications Magazine May 2010 “MIMOOFDM Wireless Systems” IEEE Wireless Communications August 2006 “Antennas for WiFi Connectivity” Proceedings of the IEEE July 2012 “Overview of Mobile WiMax – Technology and Evolution” IEEE Communications Magazine October 2008 The ARRL Handbook for Radio Communications, 2010
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Questions And Answers
A copy of the slides from this seminar will be made available to you Information to claim 1 PDH and Certificate of Completion
o Visit http://bit.ly/mimoforum where you will be required to
– complete a feedback form – respond to a problem statement from this seminar
and your Certificate of Completion will be emailed to you within 2 business days
Presenter: Iqbal Singh Josan, P.E., PMP, USPurtek LLC
o [email protected] o LinkedIn: http://www.linkedin.com/in/iqbalsinghjosan o Twitter: @uspurtek
Visit us at http://uspurtek.com to learn more about our upcoming webinars and onsite training services
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Upcoming Free Webinars
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Upcoming Free Webinars
Antenna Engineering: Part 2 of 2 o Saturday, Nov 10, 2012 12:00 PM Eastern Time, Duration: 60 min
Learn about the Antenna Design Process and Measurements of Impedance, Gain and Field Patterns in the Near and Far Field Understand RF Site Surveys for Wireless LAN and Cellular Networks Learn about different Antenna Diversity techniques and Diversity Combiners Learn about techniques to expand Wireless System Capacity, such as Frequency Reuse, Cell Splitting and Cell Sectoring Understand Flexible Frequency Reuse in 4G LTE networks Learn about overlay macrocell networks and Femto Cells in 4G LTE Understand MIMO techniques with diversity, beamforming and Space Division Multiplexing Understand applications of MIMO in WiFi, WiMax and LTE
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