Update on BPL From the Radio User’s Vantage Point

1. Update on BPL From the Radio User’s Vantage Point

2. BPL’s Interference Potential • NTIA study in 2004 of BPL concluded that BPL did have a significant local interference potential on those frequencies it shared with other users • FCC Report and Order on Broadband over Power lines (BPL) acknowledged the interference potential of BPL and established the rules to minimize the impact of BPL on licensed radio services

4. Part 15subpart G BPL requirements • FCC certification • Prohibited from using twelve aeronautical frequency bands • Prohibited from deploying near specific government and commercial radio installations • BPL industry must maintain an advance notice database, open to the public

5. Part 15subpart G BPL requirements • BPL operators are required to consult with local public service entities before deployment and must respond within 24 hours to any interference reports from them • BPL vendors and operators are cautioned to avoid locally used frequencies • No additional restrictions were placed on any licensed service

6. How are things progressing?

7. TECHNOLOGY UPDATE • Orthogonal Frequency Division Multiplexing (OFDM) • large number of carriers • frequencies can be avoided by turning off the carriers in the band of interest. This is the basis of ‘notching’

8. HomePlug – Final Specification

9. Problems with ‘notching’ • Quantization noise • The (sin x)/x tail from the summation of adjacent carriers • Lack of linearity resulting in intermodulation distortion • Does not solve ingress problem

10. Ingress • Underplayed by the BPL industry • As little as 5 watts from a nearby, legal transmitter can choke off a BPL signal • Basic requirement of Part 15 devices: a Part 15 device must accept any interference it receives, even if it causes undesired effects.

11. Fundamental Overload • Strong signals may overwhelm a receiver's ability to reject them. • If the interfering frequency is similar to that of the desired signal, it may not be possible to remove the transmitted signal with a high-pass or low-pass filter because the desired signal will be removed, as well.

12. Fundamental Overload • A hardware notch filter, installed at the receiver, can reduce the interfering signal to a level that can be handled properly by the receiver. • Steep hardware notch filters are expensive to implement.

13. Certified Equipmentas of 11-7-06 • Ambient Technologies • Corinex • Current Technologies

14. CURRENT TECHNOLOGIES • Medium voltage BPL carriers between 32 and 48 MHz • 4 to 20 MHz used on low voltage following the Homeplug standard • Only active when there is actual data traffic • Homeplug standard was worked out in cooperation with the ARRL in 2000

15. MOTOROLA • Wireless Canopy system to bring the broadband signal to the LV connection • 4 to 20 MHz used on low voltage following the Homeplug standard • Fixed, hardware filters protect the Motorola LV link from interference from nearby amateur transmitters in all bands

16. Motorola at ARRL • In August 2005, the Motorola system was installed at the main ARRL station, W1AW. • seven 1KW W1AW transmitters operating at the same time, on seven different frequencies with antennas clustered around the building carrying the Powerline LV signals, no interference in the Amateur bands was detected either to or from the Motorola BPL system

17. Motorola at ARRL • The BPL system, however, was “loud and clear” on other spectrum

18. DS2 CHIP SET • Used by Corinex and Ambient • OFDM with fully programmable masking • At tests at the ARRL lab earlier this year, the latest DS2 reference design was shown to be capable of achieving 40dB notches • Very few new generation DS2 based systems are in the field in the U.S.

19. BPL database • 53 active or pending BPL deployments, 27 of which have not been verified as operating and may not be as of yet • 7 active deployments have unresolved interference • 2 exhibit noise levels high enough to constitute harmful interference, but have as yet not been reported as such.

20. BPL database • 26 BPL deployments are listed as shut down. • 13 of these had unresolved interference complaints pending that were only resolved when the system was shut down. • 3 exhibited harmful levels of interference but were shut down by the operators before complaints were filed

21. BPL database • Most of the BPL installations to date are extremely small test deployments, with well under 1000 homes passed • All but two of the shut down BPL deployments are in this class.

22. BPL database • Two large deployments in place • Current Technologies deployment in Cincinnati at 60,000 homes passed • Main.Net deployment in Manassas, Virginia at 12,500

23. BPL database • Two large deployments pending, using certified equipment. • 2 million homes to be passed in Dallas/ Ft. Worth with Current Technologies equipment. • 6000 homes to be passed in North Carolina with Ambient equipment.

24. RECENT FIELD EXPERIENCE • CINCINNATI • Current Technologies • Passes 60,000 homes • Uses 31 to 48MHz on the MV lines and 4 to 30Mhz and the Homeplug standard for the low voltage side. • No interference complaints have been filed

25. RECENT FIELD EXPERIENCE • CINCINNATI • Interference to HF users is confined to within 200 feet of the home and involves a slight increase in background noise, squawks and short bursts of noise • Shortwave bands are more heavily affected

26. RECENT FIELD EXPERIENCE • Manassas • Decided to install Main.Net BPL system in October 2003 • Initial high level of interference between 2 and 30 MHz • Equipment operated close to amateur radio frequencies with poor or non existent notching

27. RECENT FIELD EXPERIENCE • Manassas • ISP now replacing the Main.Net first generation equipment with second-generation equipment • Situation improved but several interference complaints still outstanding. • Acceptable noise levels difficult to maintain

28. RECENT FIELD EXPERIENCE • Manassas • System still operates near amateur radio frequencies. • As little as 5 watts from a nearby transmitter can cause distress to the BPL system.

29. OBSERVATIONS • Vendors are taking care to avoid locally used aeronautical, public service and amateur frequencies • Best interference performance is with systems that avoid 2 to 30 MHz on MV lines

30. OBSERVATIONS • Ingress will be a problem for systems operating near locally used frequencies • Data handling capacity of BPL limited when compared to wireless, cable and fiber • We are at a low point in the Solar Cycle and have yet to see the effects of increased propagation.

31. Questions to pose to the BPL vendors • How does your technology deal with interference issues- both from and to BPL? • What solutions do you have if notching doesn’t work? • What do you consider to be legitimate interference?

32. Questions to pose to the BPL vendors • Is your product Certified under the new FCC rules • Does the implementation notch all of the NTIA bands and frequencies that may be in use locally?

33. Questions to pose to the BPL vendors • If the answer doesn’t include Amateur Radio, expect interference complaints if it is deployed where fixed or local Amateur operation is likely

34. Moving Forward • BPL is particularly challenging because it is attempting to use a resource in a manner it was never designed to do. • BPL can co-exist by completely avoiding locally used frequencies.

35. Moving Foward • BPL will never have the bandwidth of cable, wireless or fiber but may have enough for some utility uses. • Local radio amateurs can help with EMC assessment.