Powerline Communications: Channel Characterization and Modem Design Yangpo Gao Helsinki University of Technology yangpo.gao@nokia.com 2005-10-18

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

Introduction

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

PLC Technology Background

PLC Technologies Three network levels Efficient coupling High voltage (110–380 kV) Medium voltage (10–30 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

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.

Standardizations PLC standardization bodies International National Regional National

Channel Measurement and Modeling

Transmission Line Theory A piece of mains cable can be modeled as following figure Attenuation constant phase Characteristic impedance Propagation constant R : resistance . L : inductance. G : conductance C : capacitance

Channel Measurement Setup Equipment: Network Analyzer (NA) Coupling Circuit Coupling circuit Conductive coupling High pass filter Galvanic isolation Over Voltage protection

PLC Cable Measurements Rapid fluctuation caused by impedance mismatch Maximum of 4 dB attenuation difference @ 100 MHz Cable transversal Cable Type Size (mm2) Vulcanize rubber cable (three-wire) 0.75 1 PVC/PVC cable (three-wire) PVC/PVC cable (two-wire) 0.5

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

Channel Responses Frequency Domain Time Scenario 1 Scenario 2

PLC Channel Modeling According to PLC channel multipath phenomenon, channel can be modeled as:

Disturbance over PLC

PLC Noise Noise Classification: Our concentration 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

Noise Measurement setup Equipment: Oscilloscope Spectrum Analyzer Coupler

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

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

Other Disturbance NEXT Formation FEXT Formation NEXT (Near End crosstalk) FEXT (Far End crosstalk). NEXT Formation FEXT Formation

DMT Based PLC Modem Design

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

DMT Based PLC Modem Design Simulation environment: MATLAB SimuLink MATLAB DSP Blockset Simulated channel response Expected result Bit Error Rate (BER)

Simulation and Performance Optimized bit loading algorithm Modem performance PLC vs AWGN Signal spectrum after PLC channel Signal spectrum before PLC channel

Publications Related to My Thesis

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

Any Questions? Thank You!