CIS 6930 Powerline Communications Introduction c 2013 Richard

CIS 6930 Powerline Communications Introduction (c) 2013 Richard Newman

Outline Course nuts and bolts What is PLC? Uses of 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 PLC has been in use for many decades Uses existing power distribution wires 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

Control Uses of PLC 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, Vo. IP 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 3 rd 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 d. B 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/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) 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 d. B or worse – can’t adapt to worse case noise!

What is peculiar to PLC? How low power must be Time variant frequency-selective fading Changes with load changes Cyclostationary noise Wires are good antennas Less at zero crossings Severe and frequent impulse noise 30 -60 ms 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 PLC 4 Trucks

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 Home. Plug 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 Home. Plug AV Up to 200 Mbps raw, 150 Mbps after coding

In-home Broadband PLC Standardization efforts Home. Plug Powerline Alliance (HPA) IEEE p 1901 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 p 1901 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 p 1901 OPERA