Transcript CIS 6930 Powerline Communications

CIS 6930
Powerline Communications
Introduction
(c) 2013 Richard Newman
Outline
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Course nuts and bolts
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What is PLC?
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Uses of PLC
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PLC challenges
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Narrowband PLC
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In-home broadband PLC
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Access broadband PLC
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Coexistence
Nuts and Bolts
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Class meeting times:
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MWF 10, or M 10, W 10 & 11?
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Format: Lecture, discussion, presentations
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Grading:
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Quizzes: 20%
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Presentations: 20%
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Project: 30%
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Exam: 30%
What is PLC?
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PLC = powerline communication
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PLC has been in use for many decades
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Uses existing power distribution wires
Utility company use at very low data rates for
control purposes
Very challenging communication environment
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High attenuation, low power
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Multipath fading, noise
Recent advances in processing power enable
high-speed communication
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Control
Uses of PLC
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Utility company use – plant control, AMR
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Vehicular systems – trucks, planes, …
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Smart home – security, HVAC, lighting/power, etc.
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Industrial remote control
In-home Networks
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Power lines become “ethernet”
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Multimedia distribution – audio, video, VoIP
Access Networks
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Solves “last 100 meters” problem
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Necessarily shared
Advantages of Powerline
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Access Networks
–
Penetration of CATV distribution is poor (~80% in US, ~50%
in Europe, less elsewhere)
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Penetration of telephone distribution is better (>95% in US,
>90% Europe, less in 3rd world)
–
But DSL only works well close to exchanges
–
Power distribution exceeds phone distribution (>99% in US,
>95% Europe, >90% most countries)
In-home Networks
–
Cable often has 1-2 outlets per home, usually 0-1 outlet per
room
–
Phone usually has only one (or a pair of adjacent) outlets per
room, and only in a few rooms
–
Power outlets are ubiquitous, usually 6-7 per room, and
spaced according to national regs.
Power Distribution Networks
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High Voltage Distribution
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Relatively few, long segments
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Parallel wires, consistent wiring, few turns
Medium Voltage Distribution
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Penetration into neighborhoods
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More frequent turns, may have air-gap loops
Low Voltage Distribution
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From transformer to offices, residences, plants
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Consistent from transformer to meter
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Little consistency past meter (turns, gauges, etc.)
Powerline Topologies
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High Voltage Distribution
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Long segments requires repeaters
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Actually not bad for communication
Medium Voltage Distribution
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Also requires repeaters
Air-gap loops occur when switch for redundant paths is not
terminated – Tx/Rx antennas
Low Voltage Distribution
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High attenuation at transformer
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Small attenuation at meter (0-10 dB typical)
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May have from ~6 customers/transformer (US) to 300 or
more (Europe)
May have loops in-home (UK)
Visions
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Imagine networking your PCs, laptops, printers,
cable/DSL modem, etc. by simply plugging
them into power outlets
Imagine repositioning your wireless AP for
improved reception by simply moving a device
the size of a deck of cards to a different outlet
Imaging streaming HDTV from DVD/PVR/settop box to any display without adding new wires
Imagine moving your telephone to any location
by changing where it is plugged in
Visions (con't)
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Those can all be done today!
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Future: smart home/smart grid
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Every electrical appliance could have PLC
capability
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Allow real-time monitoring and control
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Enable new interactions between devices
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Simply plug car into public charger – car “talks” to
utility to access account, start electricity flowing
PLC Challenges
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Low power (!) signals
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Government regulations specify maximum emission
levels
Must not interfere with existing uses
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High Attenuation
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Frequency-selective Fading
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Interference
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Impulse Noise
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Hidden Nodes
Hair Dryer Noise on Power Line
noise spike
packet
SNR of -10 dB or worse – can’t adapt to worse case noise!
What is peculiar to PLC?
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How low power must be
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Time variant frequency-selective fading
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Changes with load changes
Cyclostationary noise
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Wires are good antennas
Less at zero crossings
Severe and frequent impulse noise
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30-60ms duration every 100-200 ms typical
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Brush motors, halogen lamps, dimmers, etc.
Narrowband PLC
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Smaller bandwidth, usually lower frequency
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Inexpensive
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Lower data rate
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Long used for control applications
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CEBus
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LONworks
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PLC4Trucks
Narrowband PLC - Utilities
Distribution Automation
 Intelligent grid
 Asset control & monitoring
 Load mgmt
AMR
Telesurveillance
In-home Broadband PLC
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Advances in processing, algorithms allows
higher data rates
ca. 2000 HomePlug 1.1
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Up to 14 Mbps raw rate, 8 Mbps after coding
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Up to 6 Mbps TCP/IP throughput
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ca. 2005 Panasonic proprietary – video xfer
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ca. 2006 HomePlug AV
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Up to 200 Mbps raw, 150 Mbps after coding
In-home Broadband PLC
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Standardization efforts
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HomePlug Powerline Alliance (HPA)
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IEEE p1901
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ITU-T G.hn
Support
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FCC ruling ca. 2006
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NIST citation
Issues from neighboring PLC networks
Access Broadband PLC
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Longer impulse response times mean lower
efficiency (Cyclic Prefix in OFDM)
Longer, straight wires mean higher emissions,
interference
Similar techniques as used in in-home PLC
PHY still work, after modifications
Access PLC network is shared
Access Broadband PLC (con't)
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Standardization efforts
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UPA
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IEEE p1901
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OPERA
Uncertainty
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EMC rules vary or are not established in many
countries
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Opposition from amateur radio operators
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FCC, CISPR
Coexistence
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In-home and access broadband PLC operate in
same band
Disaster if PLC technologies sabotage each
other
Standardization efforts
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CENELEC
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IEEE p1901
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OPERA