CIS 6930 Powerline Communications Introduction

Outline • Course nuts and bolts • What is PLC? • Uses of PLC • PLC challenges • Narrowband PLC • In-home broadband PLC • Access broadband PLC • Coexistence

Nuts and Bolts • Class meeting times: • MWF 10, or M 10, W 10 & 11? • Format: Lecture, discussion, presentations • Grading: • Quizzes: 20% • Presentations: 20% • Project: 30% • Exam: 30%

What is PLC? • PLC = powerline communication • Uses existing power distribution wires • PLC has been in use for many decades • Utility company use at very low data rates for control purposes • Very challenging communication environment • High attenuation, low power • Multipath fading, noise • Recent advances in processing power enable high-speed communication

Uses of PLC • Control • Utility company use – plant control, AMR • Vehicular systems – trucks, planes, … • Smart home – security, HVAC, lighting/power, etc. • Industrial remote control • In-home Networks • Power lines become “ethernet” • Multimedia distribution – audio, video, VoIP • Access Networks • Solves “last 100 meters” problem • Necessarily shared

Advantages of Powerline • Access Networks • Penetration of CATV distribution is poor (~80% in US, ~50% in Europe, less elsewhere) • 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 • High Voltage Distribution • Relatively few, long segments • Parallel wires, consistent wiring, few turns • Medium Voltage Distribution • Penetration into neighborhoods • More frequent turns, may have air-gap loops • Low Voltage Distribution • From transformer to offices, residences, plants • Consistent from transformer to meter • Little consistency past meter (turns, gauges, etc.)

Powerline Topologies • High Voltage Distribution • Long segments requires repeaters • Actually not bad for communication • Medium Voltage Distribution • Also requires repeaters • Air-gap loops occur when switch for redundant paths is not terminated – Tx/Rx antennas • Low Voltage Distribution • High attenuation at transformer • Small attenuation at meter (0-10 dB typical) • May have from ~6 customers/transformer (US) to 300 or more (Europe) • May have loops in-home (UK)

Visions • 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/set-top 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) • Those can all be done today! • Future: smart home/smart grid • Every electrical appliance could have PLC capability • Allow real-time monitoring and control • Enable new interactions between devices • Simply plug car into public charger – car “talks” to utility to access account, start electricity flowing

PLC Challenges • Low power (!) signals • Government regulations specify maximum emission levels • Must not interfere with existing uses • High Attenuation • Frequency-selective Fading • Interference • Impulse Noise • 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? • How low power must be • Wires are good antennas • Time variant frequency-selective fading • Changes with load changes • Cyclostationary noise • Less at zero crossings • Severe and frequent impulse noise • 30-60ms duration every 100-200 ms typical • Brush motors, halogen lamps, dimmers, etc.

Narrowband PLC • Smaller bandwidth, usually lower frequency • Inexpensive • Lower data rate • Long used for control applications • CEBus • LONworks • PLC4Trucks

Narrowband PLC - Utilities • Distribution Automation • Intelligent grid • Asset control & monitoring • Load mgmt • AMR • Telesurveillance

In-home Broadband PLC • Advances in processing, algorithms allows higher data rates • ca. 2000 HomePlug 1.1 • Up to 14 Mbps raw rate, 8 Mbps after coding • Up to 6 Mbps TCP/IP throughput • ca. 2005 Panasonic proprietary – video xfer • ca. 2006 HomePlug AV • Up to 200 Mbps raw, 150 Mbps after coding

In-home Broadband PLC • Standardization efforts • HomePlug Powerline Alliance (HPA) • IEEE p1901 • ITU-T G.hn • Support • FCC ruling ca. 2006 • NIST citation • Issues from neighboring PLC networks

Access Broadband PLC • 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) • Standardization efforts • UPA • IEEE p1901 • OPERA • Uncertainty • EMC rules vary or are not established in many countries • Opposition from amateur radio operators • FCC, CISPR

Coexistence • In-home and access broadband PLC operate in same band • Disaster if PLC technologies sabotage each other • Standardization efforts • CENELEC • IEEE p1901 • OPERA

CIS 6930 Powerline Communications Introduction