Broadband Over Power Line

1
Broadband Over Power Line

• National Telecommunications and
• Information Administration
• U.S. Department of Commerce
• May 25, 2005

2
Scope

• BPL in the Context of Power Line Emissions
• Findings Of NTIA BPL Phase 1 Study
• Subsequent Technical Findings
• Framework of FCC BPL Rules
• NTIAs On-going Study Priorities
• ___________
• See www.ntia.doc.gov, publications, NTIA BPL
  Phase 1 Report andComments to FCC

3
BPL in the Context of Power Line Emissions

• Without BPL, power line emissions exceed FCC Part
  15 field strength limits and interfere in some
  cases
• Diagnosis and repair of noise emissions can be
  time-consuming and costly
• Some federal radio operators routinely police
  local power lines for noise emissions, diagnose
  high emission levels, and work cooperatively with
  the utility or electricity user to eliminate
  interference

4
Some Receiver Antennas are Close to Power Lines
5
NTIA BPL Study Findings

• NTIA Coordinated its studies with FCC/OET
• BPL (and other) power line radiated emissions do
  not emanate from a point source
• Multiple points sources (impedance
  discontinuities)
• Traveling wave modes of high radiation intensity
• Measurements modeling
• Radiation and local groundwave propagation -
  Numerical Electromagnetics Code (NEC) ver. 4.1
• Local spacewave propagation toward aircraft
  Matlab model using NEC radiation predictions
• HF ionospheric propagation - VOACAP software
• Phase 1 study addressed potential local
  interference

6
Example NEC Analysis(Spatial Distribution of E
Field)
7
Distances From BPL Power Lines Within Which
Interference Is Likely
LOW MODERATE MODERATE - HIGH
Land Mobile Station 125 m 55 m
Fixed or Base Station (for Mobile) 770 m 450 m
Maritime Shipborne Station 135 m 85 m
Aircraft 6 km alt in Flight 12 km alt. 33 km gt 50 km 12 km -
Desired Signal Level
Service
8
NTIA Phase 1 Study Findings

• Many interference prevention and mitigation
  techniques exist advance consultations and BPL
  frequency agility
• Greatest interference risks stem from compliance
  measurement provisions
• In situ measurement procedures not well defined
  (ANSI C63 and CISPR 16 22)
• Irregular spatial distribution of field strength
  greatly complicates compliance measurements

9
Subsequent Study Findings

• Relatively high levels of field strength are
  spatially confined
• A practical compliance measurement procedure for
  Access BPL systems can reliably identify the
  field strength level that is not exceeded at 80
  of possible receiver antenna locations at the
  specified measurement distance from the radiating
  structure this is the procedure that was
  specified in the FCC Report Order
• Ionospheric propagation and aggregation of BPL
  emissions is not a near-term issue millions of
  BPL devices can be deployed before the onset of
  any such interference problem
• ? Should not delay rulemaking for further study

10
Framework of FCC BPL Rules

• Access BPL emission frequencies must be fungible
• Access BPL devices are subject to certification
• In-House BPL compliance measurement procedures
  improved via requirement to measure along outdoor
  power service lines

11
NTIAs On-Going Study Priorities

• Update interference risk analyses based on new
  FCC rules for Access BPL systems
• Provide additional guidance
• Prevention of interference
• Suspected interference
• Prevention of significant noise floor increase
  via ionospheric propagation