A Sampling of Current Issues: BPL, >275 GHz, & Airborne Cell Phones

Andrew Clegg National Foundation Broadband over Power Lines

• The provision of consumer broadband internet access using existing medium- and low-voltage power lines • FCC Definition (Part 15.3): – Access broadband over power line (Access BPL). A carrier current system installed and operated on an electric utility service as an unintentional radiator that sends radio frequency energy on frequencies between 1.705 MHz and 80 MHz over medium voltage lines or low voltage lines to provide broadband communications and is located on the supply side of the utility service’s point of interconnection with consumer premises. Access BPL does not include power line carrier systems as defined in Section 15.3(t) of this part or In-House BPL systems as defined in Section 15.3(gg) of this part.

Passive Service Allocations in the 1.705 – 80 MHz Range • 13.360 – 13.410 MHz (exclusive primary Radio Astronomy) • 25.550 – 25.670 MHz (exclusive primary Radio Astronomy) • 37.5 – 38 MHz (Radio Astronomy secondary to Land Mobile) • 73.0 – 74.6 MHz (exclusive primary Radio Astronomy) BPL Regulatory Action • NTIA produces Phase I report on the potential for interference to Federal government radio services in the 1.7 – 80 MHz band from Access BPL (NTIA Report 04-413, April 2004) – Recommends modifications to Part 15 measurement guidelines; frequency agility; and registration • FCC issues Report and Order addressing Access BPL (FCC 04-245, adopted 10/14/2004). – Generally, Access BPL is allowed intentional radiator Part 15 limits throughout the band, with some exceptions – Modifies measurement guidelines – Requires frequency agility – Requires registration through a clearing house administrator Protections We Asked For

• Access and In-House BPL emissions should be excluded from all radio astronomy bands in the 1.705 – 80 MHz range • BPL systems must be coordinated in the NRQZ • All US311 RA sites should be protected to Rec 769 levels from Access and In-House BPL fundamental and unwanted emissions Protections We Got

• No Access BPL use of 73.0 – 74.6 MHz on overhead medium voltage power lines within 29 km of VLBA sites, or on overhead low voltage lines or underground power lines within 11 km of the VLBA sites. –HUH???? • We have asked for a revision… What to Look For

• FCC response to a number of appeals for modifications to the rules, including ours • NTIA Phase II study – Unwanted emissions – Aggregation – Ionospheric propagation Aeronautical Use of CMRS

• FCC rules specifically prohibit the use of cellular phones aboard aircraft (47 CFR 22.925) • Not an FAA rule • Applies to commercial and general aviation • Rule is based upon interference concerns • PCS phones are not specifically prohibited • Most airlines prohibit use of any type of mobile phone aboard their aircraft by policy (except their own air-ground and satellite phones) because of interference concerns to aircraft electronic equipment Aeronautical Use of CMRS: Recent FCC Activity • FCC releases NPRM on “Amendment of the Commission’s Rules to Facilitate the Use of Cellular Telephones and other Wireless Devices Aboard Airborne Aircraft” (FCC 04-288, released 2/15/2005) • Comments were due April 11 • Reply comments due May 9 • Broad inquiry • 800 MHz only? • Technical standards to limit interference to terrestrial systems? • Must be in communication with a pico-cell onboard aircraft (not direct communication with ground) • Other uses of 800 MHz spectrum aboard aircraft? Impact on Passive Services

• 800 MHz band used at multiple RA observatories, even though it is not a RA band • Restriction on cellular handset use on observatory grounds allows limited use of this band for observing • Cellular A block includes 824 – 835 MHz (mobile-to-base) paired with 869 – 880 MHz (base-to-mobile) • Second harmonic of mobile-to-base band covers the 1660.5 – 1668.4 MHz exclusive passive allocation to Radio Astronomy and Research Aeronautical Use of CMRS: Estimate of Interference Levels on Ground • Assume lowest power class defined for GSM BTS/mobile stations (0 dBm per GSM 05.05 spec) • Assume 20 dB average attenuation of signals propagated outside of the plane • Assume average slant-range path of 5 miles • Assume average number of visible planes =10 • Assume average number of users per GSM carrier aboard plane = 7 (fully loaded GSM BCCH channel) • Assume noise-equivalent bandwidth of ~200 kHz • Expected spectral power flux density on ground: -30 dBW – 20 dB – 89 dBm^2 + 10 dB – 53 dBHz = -182 dB(W/m^2/Hz) = Rec 769 (spectral line) + 55 dB • Single aircraft at 100 mile slant range exceeds Rec 769 by 19 dB • For harmonic and out-of-band emissions (-13 dBm/MHz), Rec 769 level is exceeded by 44 dB for #users = 7 Sidebar: The redundant “43 +10logP” rule

• This rule is a widely quoted restriction on unwanted emissions from various active services. • The rule is typically applied in the following manner: • The power of any emission outside of the authorized operating frequency ranges must be attenuated below the transmitting power (P) by a factor of at least 43 + 10log(P) dB [24.238(a)] • Now, if you start out with a power 10log(P) (in dBW), and attenuate it by an amount (in dB) of 43 + 10log(P), what you get (in dBW) is: • Limit (dBW) = 10log(P) – [43 + 10log(P)] = -43 dBW ¾ In other words, the “43 + 10log(P)” limit always reduces to -43 dBW (= -13 dBm), regardless of P Above 275 GHz • The International Table of Frequency Allocations presently extends to an upper limit of 275 GHz. • Footnote 5.565 to the Table notes the interest of the radio astronomy service in frequencies between 275 and 1 000 GHz for spectral line observations and research. • Resolution 950 (WRC-03) considers the use of the frequencies between 275 and 3 000 GHz, and invites the ITU-R: • to conduct the necessary studies in for consideration by WRC- 10 with a view to the modification of No. 5.565 or the possible extension of the Table of Frequency Allocations above 275 GHz, including advice on the applications suitable for such bands. • Resolution 803 (WRC-03) establishes the consideration of frequency allocations between 275 GHz and 3 000 GHz as item 2.2 of the preliminary agenda for WRC-10. • Through Working Party 7D, we are presently attempting to establish specific bands of interest to Radio Astronomy in the range 275 – 3 000 GHz, in anticipation of possible future WRC activity Above 275 GHz • Bands of interest are based upon a list of spectral lines of astrophysical interest established in ITU-R Recommendation RA.314 (below 1 000 GHz) • Spectral lines of interest above 1 000 GHz have, to date, been based upon line data from NIST. • Plan to work through the IAU to establish a more complete and accurate list of spectral lines above 1 000 GHz • Bands are being established without regard to atmospheric attenuation • Document in WP7D is “living,” and will be continually updated. • There are some politics involved in extending allocations above 275 GHz