Virginia Tech hopes to smarten up experimental cognitive radios so that ad hoc communications networks can adapt to aid in disaster relief and battlefield communications, reports EE Times
By sharing a distributed knowledge base, Virginia Tech’s “cognitive engine” will serve as the communication system’s “brain” by sensing unused bandwidth, avoiding interference, adapting to changing circumstances and optimizing network performance. At the same time, the engine will help maintain the autonomy of individual cognitive-radio nodes.
Virginia Tech researchers have applied for a patent on their cognitive engine, which will also work with existing hardware, said Charles Bostian, director of Virginia Tech’s Center for Wireless Telecommunications. “We are going to see if we can use vacant TV channels for Wi-Fi-like services without interfering with other emergency services that are already operating there.”
Cognitive radios are “smarter” than software-defined radios because they give radios the ability to decide which bands to use based on availability, location and experience.
If successful, Virginia Tech’s cognitive engine will be able to coordinate the frequency assignments and communication protocols of ad hoc networks so existing radios do not interfere with existing emergency broadcasts.
In 2003, the FCC issued an RFP to add artificial intelligence to cognitive radios. The upgrade would allow the new radios to sense dead zones, interference and usage patterns as well as adapt to changing real-time circumstances.
The FCC is looking to enable the 6-MHz-wide licensed spectrum in the UHF band, currently assigned to TV broadcasters, to be reused in secondary markets. This proposal would set power levels up to 8 dB higher than those currently allowed in those bands, thereby greatly increasing range and coverage area.
The FCC requires that 802.11a radios using the mid (5.4 GHz band) detect radar signals and avoid interfering with them. Startup Adaptix announced the launch of a broadband wireless product line (point-to-multipoint, non-line-of-sight, last-mile access and backhaul solutions) that is said to use SDR techniques and is based on 802.16e.
Last year, the IEEE 802.22 was designated to develop a standard. The 802.16 faction argued that cognitive radio work should be under its tent, rather than in a separate group, but was defeated. So the quest to turn 802.22 into a real 700 Mhz alternative is underway.
The first focus of IEEE 802.22 is on rural fixed wireless access. “This is ideal spectrum for deploying regional networks to provide broadband service in sparsely populated areas,” said Carl Stevenson, chair of the new group, in a statement. Our goal is to equal or exceed the quality of DSL or cable modem services, and to be able to provide that service in areas where wireline service is economically infeasible, due to the distance between potential users.
In fixed networks, 802.22-based technologies could achieve 40 kilometer range and complement local Wi-Fi and 802.16 backhaul, he said.
The 700 MHz Band Coalition is congratulating itself for defeating a proposal to allow unlicensed devices to operate in the unused portions of the TV broadcast bands. Thanks to the efforts of the Rural 700 MHz Licensees and QUALCOMM they were successful in “helping to convince the FCC that it should NOT propose unlicensed operations anywhere in the 700 MHz band”.
Keeping the 700 MHz band off the table in the Unlicensed NPRM should be viewed as a significant victory for the 700 MHz band industry on the whole. The Rural 700 MHz Licensees took a firm stand against any proposal allow unlicensed devices to use Lower 700 MHz Band spectrum, raising the following arguments: “It would be extremely unfair to current licensees and long-form applicants from Auction No. 44, and disruptive to applicants and potential bidders in Auction No. 49, for the FCC to change the rules in the middle of the game by permitting unlicensed devices to operate on any of the Lower 700 MHz Band channels. These licensees and applicants have invested a significant amount of time, effort and money in securing the exclusive right to provide spectrum-based services in a given geographic area using Lower 700 MHz Band C-Block channels, and all of them must make significant further investment in order to turn these spectrum rights into a viable business.
If the Commission were to allow other individuals or businesses to use these same frequencies on an unlicensed basis, it would undercut the nascent auction winners, and discourage any future investment in licensed operations using Lower 700 MHz Band channels.
“Free”, unlicensed frequencies are anethema to license holders — even though licenses, by definition, avoid interference and allow greater power and range. Sprint/Nextel, which owns large tracks of the 2.5GHz band, might argue that WiFi at 2.4 and 5 GHz should be banned, too — for the public good!
The 700 MHz Band Coalition, apparently, is unconcerned about protecting the interests of public — protecting the interests of their high roller license-holding membership (such as Charles Townsend’s Aloha Partners) appears to be their game plan.
