[Discuss-gnuradio] Software-defined radio advances on several fronts

[Paul Hartke]

Software-defined radio advances on several fronts
Rick Merritt
Sep 30, 2004 (6:09 PM)
URL: http://www.commsdesign.com/showArticle.jhtml?articleID=48800547

SANTA CLARA, Calif. — The IEEE will kick off in November work on a standard
for fixed-access systems that use so-called cognitive radio techniques to
flexibly tap unused swaths of spectrum.

The effort marks a milestone for software-defined radio (SDR), a technology
stepping forward on several fronts, although still dogged by security
concerns.

The IEEE 802.22 working group is expected to define the medium access
control and physical-layer specifications for a so-called cognitive air
interface. The technology would enable fixed, point-to-multipoint systems
working in unused TV spectrum between 54 and 862 MHz to sense and tap
unused spectrum in that space.

The IEEE effort is targeted at a Federal Communications Commission proposal
to open up 300 MHz of unused UHF/VHF spectrum as the first big test of
smart, software-defined radios. The agency is acepting comments until
December on the proposal that includes use of both fixed-access systems
transmitting up to 1W and portable systems transmitting up to 100 milliW.

"This is the first opportunity to use cognitive radio in a commercial
environment and it could give the FCC the impetus to open up other areas of
spectrum to unlicensed devices," said Jeff, Schiffer, a manager of wireless
research at Intel Labs. "Other regulatory bodies around the world will
follow the FCC, and they are watching to see how this turns out," he added.

The agency's move is part of a broader push toward a new regulatory
framework. "The FCC is trying to change from fixed band to policy-based
spectrum management. They look at this as a way to relieves the perceived
shortage of spectrum," said Schiffer.

"This is ideal spectrum for deploying regional networks to provide broadband
service in sparsely populated areas," said Carl Stevenson, interim chair of
the new group, speaking in a prepared draft statement found on the IEEE's
Web site. "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," he added.

Stephenson said the 802.22-based networks, which could propagate signals up
to 40 kilometers, could act as a rural complement to both 802.11 local
networks and 802.16 metropolitan back-haul links. However, Schiffer of
Intel Labs said it's too early to tell what the applications might be for
cognitive radios in the TV spectrum.

Members of the 802.22 group are expected to include chip and wireless
systems makers, TV broadcasters and pubic safety officials.

Momentum for SDR

Both government and private investors are putting money into research for
SDR, spawning a growing pool of promising startups. For it's part, SDR
Forum, a 90-member industry group, is developing a variety of design
guidelines as well as its first industry road map for the technology.

"Our history is hardwired technologies and standards, but our future is
software-defined systems and standards for reconfigurability," said Mark
Cummings, chairman of the SDR Forum in a panel discussion at the GSPx
conference here Thursday (Sept. 30).

The SDR Forum plans to kick off at its annual conference in Phoenix (Nov.
14-19) work on defining an industry road map for SDR. The group is also
creating a more detailed technical definition of a high-level
RF-to-baseband interface it has defined.

Adding a hand, both the Defense Advanced Research Projects Agency and the
National Science Foundation are now providing commercial research grants
for SDR, said Schiffer. "I think you will see some radios emerge in the
near future that can operate in multiple domains," he added.

"The Department of Defense has announced that all new radios it will acquire
in the future will be based on SDR technology," added Cummings.

As a general partner of enVia II (Atherton, Calif.), Cummings also funds
three companies in SDR, including Rfco Inc. (Los Gatos, Calif.), a startup
developing a new hardware RF front-end geared for software-defined radios.

"They have the first fundamentally new radio architecture since
superheterodyne was patented in the 1950s. Some people think this is the
biggest opportunity in semiconductors today," Cummings said.

Software security

Indeed, the technology has many applications. The military wants smart
radios that can flexibly work in whatever country they are deployed. Cell
phone makers want to consolidate the four or more radios that are building
into their handsets and provide bug fixes with downloaded software. And
public safety professionals see SDR as a way to solve interagency
communications problems during a crisis.

Today, public safety agencies use as many as 11 bands ranging from 1.5 MHz
to 4.9 GHz. A recent mock disaster exercise in the San Francisco subway
system failed on some communications tasks when a wireless system run by
one local agency knocked out communications from the first responders who
had their own problems with gear sourced from different vendors.

"Even using a gateway the systems couldn't properly process some calls,"
said John Powell, who chairs an SDR working group for the National Public
Safety Telecommunications Council. "SDR has the potential to relieve the
big issues in communications interoperability in public safety," he added.

However, SDR is still dogged by the threat of hackers. "Our big concern is
someone could download rogue software that could cause interference with
public safety communications," Powell said.

The SDR Forum will post at its Web site within 30 days a document laying out
guidelines for downloading radio software securely. It will also put out a
broad request for information seeking from the industry a laundry list both
of security problems and resources.

One of the ongoing debates in SDR is whether to allow third-party software,
which some people believe could accelerate the growth of the technology,
Cummings said.

"This debate must be fought out in business and political circles. But if we
decide third-party software will move ahead it will have implications for
our security approach," he added.