Steven J. Crowley, P.E.
Archive for the ‘Unlicensed’ Category
Google has filed an application with the FCC to conduct drone tests in New Mexico. The company has sought confidential treatment of its application form and exhibits. All we have to go by now is one exhibit that’s been redacted for public consumption. Google provides some detail, and we can try to infer some more.
Last month I wrote about the Jarvinian Wireless Investment Fund and its application to the FCC to test its proposed terrestrial low-power service (TLPS). TLPS would use both the upper 2.4 GHz unlicensed band and Globalstar’s terrestrial-use spectrum (2473-2495 MHz all in all). That test would take place in Cambridge, Massachusetts.
Jarvinian is back with a second application, similar to the first, but with testing taking place at three locations in Silicon Valley (Sunnyvale and Cupertino, California). The supporting technical exhibit appears essentially the same. Different is the equipment to be used. The Cambridge application specified 50 Linksys WRT54GL access points, 10 Ubiquity UniFi access points, 10 Ubiquity XR2 client cards, and 10 Ubiquity SR-71-12 client cards. The Silicon Valley application specifies 10 TP-LINK TL-WA5110G access points, 20 TP-LINK TL-WR1043ND access points, and 20 Ubiquity SR-71-12 client cards.
This application was received by the FCC on March 6. The Cambridge application was received February 13 and is still pending.
At its February 20 meeting, the FCC will likely adopt a Notice of Proposed Rulemaking as a first step toward increasing the amount of spectrum available in the 5 GHz band for unlicensed devices. Up to 195 MHz might be made available, which is a 35% increase over the present 555 MHz. Chairman Genachowski announced this initiative at CES in January. A leading application for new spectrum would be IEEE 802.11ac, which could have four instead of the current two 160 MHz-wide channels.
Here it is: At 600 MHz, interference travels farther than it does at higher frequencies, all else equal.
FCC Chairman Julius Genachowski yesterday announced an initiative to make 195 MHz of more spectrum available for Wi-Fi in the 5 GHz band.
The last time more spectrum for Wi-Fi was made available in this range was in 2003, when an FCC increased the then 300 MHz bandwidth to 555 MHz. As the document in that last link shows, the 5 GHz band is not as neat as the 2.4 GHz band, with other services, such as radar, requiring protection. These coexistence issues will have to be looked at again.
This summarizes a selection from 215 applications for the Experimental Radio Service received by the FCC during October, November, and December 2011. These are related to AM broadcasting, FM broadcasting, spread spectrum on HF and VHF, unmanned aerial vehicle control, electronic warfare support, small satellites, white space technology, video production, managed access, TV interference, RFID, and radar. The descriptions are listed in order of the lowest frequency found in the application.
This summarizes a selection of applications for the Experimental Radio Service received by the FCC during April and May 2011. These are related to TV white space, electromagnetic compatibility testing, train control, point-to-multipoint communications, satellite communications, radar, unmanned aerial vehicles, GPS, ultra-wideband, mobile satellite service, UMTS, mobile broadband picocells, wireless backhaul, and IEEE 802.11p. The descriptions are sorted by frequency.
This summarizes a selection of applications for the Experimental Radio Service received by the FCC during December 2010. These are related to FM broadcasting, Positive Train Control, TV white space, mobile satellite terminals, GSM, UMTS, through-the-wall surveillance radar, troposcatter communications, millimeter-wave propagation, flight test telemetry, Doppler weather radar, and air-to-air military radar.
Unlicensed wireless may disrupt the broadband service market in Boston. Communications engineer Brough Turner and his partners have founded netBlazr, a new business broadband service that takes advantage of cheap metropolitan fiber and uses unlicensed wireless technology from Ubiquiti Networks that can operate with various Wi-Fi protocols, and a proprietary one, in a mesh configuration. In the netBlazr network the devices operate at an aggregate data rate of 100 Mbps with 50-500 meters per hop. Throughput per user is 10 Mbps.
In Boston, Verizon charges about $2,200 per month for symmetrical 10 Mbps business service via fiber; netBlazr charges $189 per month for equivalent service using its hybrid fiber/wireless system. Less-expensive shared plans, including one that’s free, are available for businesses with lower-priority traffic.
The FCC finalized its white-space rules today, acting on petitions for reconsideration of its earlier decisions. It issued an 88-page Second Memorandum Opinion and Order that explains its decisions and includes the final white-space rules. A much-shorter press release was also issued.
At least one FCC observer has noted an uncharacteristic level of hype in today’s announcements. The FCC calls it “super Wi-Fi,” and adds the “potential uses of this spectrum are limited only by the imagination.”
Over two years ago, Google called it “Wi-Fi on Steroids.” It was later picked up by the popular press. Not all agree; it’s “Wi-Fi on Crutches” according to one who dares to consider the realities of physics and economics.
I’ll call it “Wi-Fi on Caffeine,” at least with respect to better range and coverage — if not data rates — compared with current Wi-Fi equipment. This is partly due to operation in the UHF-TV band instead of the 2.4 GHz band. In major markets and their suburbs, there will be few or no channels available for white space use. In rural areas and other less dense areas, the technology will be a good fit with Wireless Internet Service Providers (WISPs) and other longer-distance applications.
Cellular operators would like some of the white space on a licensed basis for backhaul in rural areas. They didn’t get it today, but the FCC is actively considering it and we may hear more on that by the end of the year. No way are all these vacant channels going to be occupied by internet services in the most rural areas, so the proposal of the operators makes sense.
In IEEE 802, Working Groups 802.22 and 802.11 are working on standards that can be used by equipment in these applications; 802.22 may be the one with longer range. Working Group 802.19 is trying to facilitate coexistence between the two. Now, there are asymetric interference effects, which is causing friction between the two groups beyond the normal competition. (802.22 takes the harder interference hit.)
There will be other standards and equipment as well. The white space concept is international, but unique to each area of the world.
Equipment is not easy; it’s challenging to develop sufficiently-broadband power amplifiers and antennas, and to meet the emission mask in a cost-effective manner.
Another challenge is developing a business plan when 120 MHz of TV spectrum could be taken away under the National Broadband Plan.
The FCC recently issued an order denying reconsideration petitions in its ultra-wideband (UWB) proceeding. That effectively ends the 12-year UWB rulemaking process. Mitchell Lazarus recounts how UWB became bogged down at the FCC and in a failed standardization attempt in IEEE 802.
UWB, as authorized by the FCC, operates across 3.1 to 10.6 GHz, with very low power at any one frequency; its tendency to cause or receive interference is very low.
IEEE 802 attempted to create a UWB standard in IEEE 802.15.3a but did not, as neither of two competing proposals reached the necessary voting threshold for approval. One of the competing proposals, Multi-band Orthogonal Frequency Division Multiplexing (MB-OFDM), has since seen some consumer success in Wireless USB, which is based on a platform maintained by the WiMedia Alliance; data rates are up to 480 Mbps at a range of about 10 feet.
UWB was eventually standardized in IEEE 802.15.4a, where it exists as an alternative physical-layer to standard IEEE 802.15.4-2006, a standard for very low power, low data rate devices. (The IEEE 802.15.3 family is for higher data rates with higher power consumption.) It uses what was the other competing proposal in 802.15.3a, Direct Sequence UWB (DS-UWB). This standardized form of UWB has been commercialized for asset tracking and other location services, but not yet for consumer applications.
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