Powerline Communications: Channel Characterization and Modem Design

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Powerline CommunicationsChannel
Characterization and Modem Design

• Yangpo Gao
• Helsinki University of Technology
• yangpo.gao_at_nokia.com
• 2005-10-18

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Thesis Contents

• Table of Contents
• Introduction
• PLC Technology Background
• Channel Measurement and Modeling
• Disturbance over PLC
• DMT Based PLC Modem Design
• Conclusion
• Reference
• This thesis is part of project PLC controlled
  LEDs for general lighting system, which is
  sponsored by TEKES

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Introduction
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History of PLC and Motivation of Thesis

• What is PLC
• PLC Powerline Communications
• Using powerline as transmission medium for data
  communication
• History of PLC
• From high voltage (HV) low voltage (LV)
• Low data rate high data rate
• Control application multimedia data
  applications
• Motivation
• Cheap the last mile solution
• However, worse channel than other wired network
• Channel characterization reliable
  communications

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PLC Technology Background
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PLC Technologies

• Three network levels
• High voltage (110380 kV)
• Medium voltage (1030 kV)
• Low voltage (230/400 V, in the USA 110 V) (my
  thesis range)
• Efficient coupling
• Inductive coupling
• Conductive coupling
• Modulation and error correction
• OFDM, DMT
• CDMA
• FEC

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EMC Issues

• EMC --Electromagnetic compatibility
• The ability of a device or system to function
  satisfactorily in its electromagnetic environment
  without introducing intolerable electromagnetic
  disturbances in the form of interferences to any
  other system in that environment, even to itself.
  

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Standardizations

• PLC standardization bodies

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Channel Measurement and Modeling
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Transmission Line Theory

• A piece of mains cable can be modeled as
  following figure

R resistance . L inductance. G
conductance C capacitance
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Channel Measurement Setup

• Equipment
• Network Analyzer (NA)
• Coupling Circuit
• Coupling circuit
• Conductive coupling
• High pass filter
• Galvanic isolation
• Over Voltage protection

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PLC Cable Measurements
Cable Type Size (mm2)
Vulcanize rubber cable (three-wire) 0.75
Vulcanize rubber cable (three-wire) 1
PVC/PVC cable (three-wire) 0.75
PVC/PVC cable (two-wire) 0.5
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PLC Channel Measurements

• Scenario 1 Internet access and
  distribution
• Scenario 2 Home networking

Scenario 1 Network topology is known, or easy to
estimate. Channel is simple, and has few
multipath components Scenario 2 Network
topology is unknown or it is hard to define.
Channel acts as black box. A lot of multipath
components
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Channel Responses
Scenario 1
Scenario 2
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PLC Channel Modeling

• According to PLC channel multipath phenomenon,
  channel can be modeled as

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Disturbance over PLC
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PLC Noise

• Noise Classification
• Colored background noise
• Narrowband noise
• Periodic impulsive noise, asynchronous to the
  main frequency
• Periodic impulsive noise, noise, synchronous to
  the main frequency
• Asynchronous impulsive noise
• Our concentration
• Colored background noise
• Asynchronous impulsive noise

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Noise Measurement setup

• Equipment
• Oscilloscope
• Spectrum Analyzer
• Coupler

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Colored Background Noise

• Quasi-Static behavior
• Statistic information is extracted in table
• Can be modeled as

s b c
Max -94 -80 -0.4
Min -124 -100 -0.6
Average -105 -90 -0.5
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Random Impulsive Noise

• Caused by frequency bursts generated by
  electrical devices connected to the powerline.
• Statistic information is extracted

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Other Disturbance

• NEXT (Near End crosstalk)
• FEXT (Far End crosstalk).

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DMT Based PLC Modem Design
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DMT Technology

• Discrete Multi-tone Modulation (DMT)
• Advantages
• Multicarrier technology combat frequency
  selective fading
• Dynamic bit loading based on SNR efficient
  spectrum utilization
• High channel capacity

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DMT Based PLC Modem Design

• Simulation environment
• MATLAB SimuLink
• MATLAB DSP Blockset
• Simulated channel response
• Expected result
• Bit Error Rate (BER)

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Simulation and Performance
Optimized bit loading algorithm
Signal spectrum before PLC channel
Signal spectrum after PLC channel
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Publications Related to My Thesis
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Publications

• More information can be found in my publications
• Channel modeling and modem design for broadband
  power line communications, Proceeding of ISPLC
  2004, April, Spain
• Broadband characterization of indoor powerline
  channel, Proceeding of ISPLC 2004, April, Spain
• Broadband Characterization of Indoor Powerline
  Channel and Its Capacity Consideration,
  Proceeding of ICC 2005, May, Korea

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Any Questions?

• Thank You!