The Federal Communications Commission (FCC) is set to approve modifications
in the rules governing spread spectrum technologies used by fixed wireless
(Wi-Fi) operators, amendments which open the door to new systems and
improve the transmission of broadband data.
It’s expected the rule changes to Part 15, three years in the making, will
give wireless Internet service providers (WISPs) a much-needed boost in
deploying effective high-speed Internet systems in their communities.
Part 15 rules govern the equipment specifications of systems running on the
unlicensed 2.4 GHz band, one of several “free” bands open for public use —
others include the 915 MHz and 5.7 GHz bands.
Because the spectrum is available for anyone to utilize, the FCC set up
rules to ensure equipment running in the “free” bands don’t interfere with
adjacent licensed bands. One of those rules was establishing the two
spread spectrum technologies allowed to operate in the unlicensed
band: direct-sequence spread spectrum (DSSS) and frequency-hopping spread
spectrum (FHSS). By their very nature, the two technologies cause very
little interference problems.
Part 15 rules determine what makes a spread spectrum technology truly
spread spectrum. For example, the rules stipulate a minimum number of hops
a FHSS signal must take on its 2.4 GHz route.
FHSS systems in the 2.4 GHz spectrum will get a boost in the Part 15
revamp, lowering the minimum number of hops to 15, provided the system uses
no more than 125 milliwatts (mW) of power.
DSSS systems also get a break in the new rules, with the elimination of the
processing gain requirement of 10db. Adopted 11 years ago to prevent
equipment makers from making systems that used more bandwidth power than
needed, the industry has matured to a point where the requirement might not
be necessary any more, the FCC concludes.
The Part 15 amendment opens the 2.4 GHz spectrum to other technologies,
which technically aren’t spread spectrum technologies but have the same
The FCC is set to remove that restriction to allow deployment of the new
systems almost immediately, provided they obey the rules and meet FCC
certification standards. Last May, the FCC issued a waiver to
manufacturers who wanted to get their equipment certified before the
amendment is formally adopted, though commissioners blocked the application
of a Wi-LAN, Inc., technology, wideband orthogonal frequency division
Part 15 rules for spread spectrum systems have been in effect for more than
15 years, and have undergone several amendments to incorporate new
technologies benefiting the wireless community. Recent advances with
802.11b and Bluetooth products show the unlicensed band will continue to
thrive in tomorrow’s wireless world.
“The Commission’s spread spectrum rules have been a tremendous success,”
reads the further notice of proposed rule making (FNPRM). “A wide variety
of devices have been introduced under these rules for business and consumer
use including cordless telephones and computer local area networks (LANs).”
The FNPRM was issued last year to garner “last-minute” opinions from
interested parties, a process that’s lasted almost a year to the date. The
amendment was first initiated in November, 1999.
The FCC has been treading water in the unlicensed band debate, as more and
more companies (with the millions and billions they’ve invested) go public
on the airwaves. FCC Chairman Michael Powell told attendees at a recent
convention 802.11 was heading
for a “meltdown” as the playing field quickly filled up with competitors.