FSO with RF Protection for Carrier-Class All-Weather Broadband Wireless Links May 2004

1. FSO with RF Protection for Carrier-Class All-Weather Broadband Wireless Links May 2004 R.T. Carlson, Ph.D. CTO, fSONA Communications Corp

2. SONAbeam -S The SONAbeam™ Advantage - Superior Quality. Premium Reliability. • Superior Design; Rigorous Qualification • Military/carrier-grade with 15 year product lifetime • System test –40C to 60C; Subsystem test -50C to 85C • Telcordia (Bellcore) standards-based design and test • Engineered for High-Rel 24/7 Operations • Electronics operate only 10°C above ambient: low-stress • Subsystems >200 yr MTBF. Telecom-grade power. • 20-40 times more laser power than other FSO systems • Adaptive laser power control operates laser at low power in clear weather for low stress and enhanced reliability • Superior Environmental Capabilities • Completely sealed housing (tested submerged underwater) • Cast aluminum housing with rigid multi-point attachment • Precision pointing in 120km/hr wind; survive >160 km/hr • Lasers actively cooled to 25°C, even in desert conditions • Dual/Quad Transmitter Redundancy • Multiple redundant and independent lasers, laser drivers, laser coolers, & cooler controllers SONAbeam -M

4. SONAbeam FSO Attenuation in Heavy Rain: - much less than at EHF frequencies

5. SONAbeam link in multi-hour intense rain:Example below:50-100 mm/hr, 900m link loss of link

6. SONAbeam Extreme Rain Performance Summary(900m Test in Costa Rica - ITU Rain Region P) • Calibrated rain gauge measured rain rates up to 180 mm/hr • Only 1 rain outage: 3.5 min in very extreme 156-180 mm/hr rain. • Heaviest rain events: DateMax RateTimeLink StatusMargin 14 Sept 120 mm/hr 15:26 Link Up 10 dB 17 Sept 120 mm/hr 13:03 Link Up 3 dB 25 Sept 132 mm/hr 15:33 Link Up 3 dB 28 Sept 96 mm/hr 16:21 Link Up 12 dB 1 Oct 180 mm/hr 13:36 Down 3.5 min 0 dB • 6 Oct 96 mm/hr 11:18 Link Up 12 dB 8 Oct 96 mm/hr 16:32 Link Up 10 dB • SONAbeam rain-performance model has been validated for extreme rain rates of up to 132 mm/hr.

7. NOAA: Number of days/year moderate to heavy fog occurs with visibility < 400m

8. Example of Costa Rica Tests –900m Link Fog Outages • A few fog events caused 900m link outages. • All of the fog outages were very late at night, midnight to 4 AM. • Late-night fog outages: DateTime PeriodFog Outage 16 Sept 2 AM 38 minutes 21 Sept Midnight 22 minutes 22 Sept 3 AM 15 minutes 23 Sept 12 and 2 AM 100 minutes 30 Sept 4 AM 20 minutes • Fog outages were rare, and occurred at hours not an issue for business services or non-emergency applications.

9. Limitations to EHF as Stand-alone Links • 60-90 GHz frequencies have very severe rain-fade attenuation. • 74/84 GHz frequency bands will be point-to-point licensed; Licensing puts constraints on competing service providers. • While interference is mitigated at EHF, it is not eliminated (especially at hubs). Hence, 74/84 GHz licensing to mitigate interference issues. • BER is impacted by dispersion due to multiple scattering in rain. This is often overlooked in rain performance projections, with just rain attenuation used in calculations. • Pointing wander is a well-known phenomenon at EHF frequencies due to refractive index variations, especially early morning and evening. Also antenna oscillation in wind gusts with large, high-gain antennas • But 60 GHz and 74/84 GHz represent an ideal EHF solution to complement FSO, with fallback to RF in heavy fog conditions.

10. Protected Links with FSO and RF We address here very broadband point-to-point wireless transmission for backbone links, spurs, and premium access: OC-12, Gigabit Ethernet, and OC-48 • Protected, all-weather links are essential at >OC-12 bandwidth • Fully 1:1 redundant, with automatic fail-over • Required for SLAs with fiber-quality assurance Rather than ‘which technology?’, the best solution is both: • FSO and RF are complementary broadband wireless technologies for heavy rain & fog penetration Carrier studies have concluded that the equipment cost of protected FSO/RF is not a significant cost factor for OC-12 and greater bandwidths

11. fSONA 1000 meter test range: SONAbeam/EHF Protected Link, GigE

12. Architecture of Protected FSO/RF Link: Indoor Rack-mount SONAswitch APS

13. SONAswitch APS for RF Protection of SONAbeam FSO Links(DS-3 to OC-48; 45-2500 Mbps)

14. SONAswitch APS - Graphical User Interface

15. SONAswitch APS - Hitless Switching Example 1000m Testbed in Light Fog - May 11, 2004

16. Summary of SONAswitch APS Results: Protection Switching in 15 microsec • Three protection-switching events due to fog: - First: RF active for 13.75 minutes - Second: RF active for 0.5 minute - Third: RF active for 0.3 minute • Total of 36 GigE frames impacted by these six protection-switching/switchback events. (2.2 µ sec per per 256-byte frame) SONAswitch APS switching time < 15 microsec 3000x faster than SONET APS spec (50 millisec)

17. Gigabit Ethernet FSO with RF Protection – New installation in Wash. DC area Installation and link commissioning, May 17-20: • 910 meter FSO/RF-protected link in Falls Church, VA • For a U.S. Gov’t. organization as proof-of-concept testbed • SONAbeam 1250-M with 60 GHz RF backup • Gigabit Ethernet test set, 1250 Mbps full-duplex, 256-byte frames, 100% utilization (450,000 frames/sec) • SONAswitch for automatic protection switching and log files

18. Expectations for 850m Wash DC Testbed Expect to achieve annual link availability of 1.000000 • Protected link provides redundancy for high-rel requirements • FSO and EHF are complementary broadband technologies, employed for all-weather link operation: • Expect FSO up circa 99.9%, with RF backup active circa 0.1% • FSO down in heavy fog, with link running on RF protection • RF down, FSO up in heavy rain - incl. 100 mm/hr thunderstorms • RF down in wet snow, FSO up in worst snowstorms

19. Protected Broadband Wireless Solution- using complementary SONAbeam & EHF technologies

20. SONAbeam 2500-M for OC-48 Apps • Over the past nine months fSONA built and tested a 2.5 Gbps (OC-48) system using our proven 1550nm InGaAs semiconductor laser and APD technology • 4 links built: two links for delivery to a U.S. Govt. agency • Government acceptance tests performed April 11, 2004. • Tests performed on fSONA 5000 meter rooftop test range • Acceptance test results, SONAbeam 2500-M: 5 km FastE test, 20 minutes, no packet errors 5 km OC-3 test, 20 minutes, zero bit errors 5 km OC-12 test, 20 minutes, zero bit errors 5 km GigE test, 20 mnutes, no packet errors 5 km OC-48 test, 20 minutes, zero bit errors

21. Summary and Conclusions • FSO and RF technologies are complementary and very well suited for protection of each other (SONAbeam up in heavy rain; RF up in heavy fog) • SONAbeam GigE FSO successfully demonstrated on 1000m test range with 60 GHz EHF backup link • SONAswitch APS provides hitless protection switching 3000 times faster than SONET APS spec • U.S. govt. agency performed acceptance test of 2.5 Gbps SONAbeam 2500-M, April 2004. • Protected links with 2.5 Gbps SONAbeam and 74/84 GHz radio are projected for future apps.

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