dailywireless.org » 700MHZ Goes Live

700MHZ Goes Live

Need a license in the lower 700 MHz band? Cast your bids at the FCC’s Auction 49, starting May 28, in Washington, D.C.

The lower 700 MHz auction will get you a pair of 6 MHz channels in Block C: (710-716 and 740-746 MHz) and a single D Block: (716-722 MHz). The upper 700 MHz auction, yet to be scheduled consists of Block C with a 10 MHz chunk (2 x 5 MHz) at (747-752 MHz and 777-782 MHz) and Block “D” (752-762 MHz and 782-792 MHz).

The 700 MHz band (which once carried television near channel 52), is viewed as prime real-estate for public service radio. That’s because 700Mhz can penetrate buildings. In addition, the 800Mhz public service radio band is filling up and earlier, voice-only radios, lacked interoperability.

Cellular and PCS, Wi-Fi and other types of radios use higher frequencies that lack the ability to penetrate buildings but they generally have more bandwidth. With cell towers everywhere and “push to talk” services becoming available from a variety of cellular providers, cell phones, particularly the handy PTT Nextel, have often been used by public service agencies. Still, penetration of buildings is a problem - and cell phones depend on an operational telephone system. Not good in an emergency.

The concept that Nextel and others like to promote is interoperability along with mobile, high-speed data - using “4G” standards. Some believe “4G” (wireless IP), can deliver 3G services - at one-tenth the cost.

How do they do it? Flarion, Navini and Arraycom, put phased array pencil beams on cell towers, delivering 500 Kbps-1 Mbps over the unlicensed and licensed bands. 3G can’t deliver those speeds (even if 3G service were available). Flarion claims they can handoff to 802.11b wireless LAN - and deliver broadband wireless to police cars, ambulances and fire vehicles over a wide area.

A vision of an IP-based cellular network is being defined by IEEE 802.20. The IEEE standards group would “standardize 4-G” and enable interoperability with automatic roaming and handoff. Flarion and Navini think 802.20 could be a “cellular killer”. Intermec’s 760 rugged Pocket PC can scan driver’s licenses, and use CDMA, GSM or Wi-Fi networks for connections as can a Centrino Toughbook in a patrol car. But with IEEE 802.20 wireless, hand-held computers and laptops could connect faster and cheaper. Everywhere. Voice, data and video. Without cell charges.

Navini Networks and Korea Telecom are trialing a 2.3 GHz system in Seoul. Multi-megabit network speeds, a zero-install plug-and-play experience, and untethered wide-area wireless broadband access anywhere within the coverage area, perhaps 3-5 miles from the tower.

Nextel, the only major U.S. carrier that hasn’t announced a 3G migration plan, has trialed Flarion’s “4G” system.

Nextel started business as a mobile radio service for taxis and truckers. They used central towers at frequencies intertwined with the public safety band at 800 Mhz unlike cellular frequencies which are further separated but use the same 800 Mhz band. In the 1970s, the FCC let Nextel use those channels for the broader public and let them provide cellular-type service. But a report prepared for the FCC by the Washington County dispatch system discribed the interference problem of nearby cell towers using the Nextel frequencies. According to Portland Assistant Police Chief Bruce Prunk, “We’ve had officers frustrated during a shooting because they get a tone.”

The county’s public safety transmitting tower sits high atop Portland’s Council Crest. Four miles away is a fire station that would get garbled signals because of a Nextel site just down the street. Portable radios inside the station actually worked better with its garage door closed because it helped block the Nextel signals. The report, prepared by Joe Kuran, technical systems manager for the dispatch system, concludes that “as Nextel adds sites to improve their coverage . . . public safety deteriorates.” Portland and other cities are considering moving to the 700-megahertz band to be vacated by UHF television stations as they switch to digital broadcasting.

Clark Regional Emergency Services Agency, in Vancouver, WA, has resolved their interference from a Nextel site. “We made some measurements and found that we were getting intermodulation interference in our radios. Our consultant, gave Nextel a frequency set to use on its site and Nextel retuned the site several months ago, and it has been working fine since,” said Rick Lazo, CRESA’s senior communications system technician.”

Nextel’s spectrum realignment plan is being deliberated by the FCC. The proposal calls for Nextel to exchange 16 megahertz of spectrum spread around the 700 MHz, 800 MHz and 900 MHz bands for 6 megahertz in the upper 800 MHz band and 10 megahertz in the 2.1 GHz band. If approved, this would leave Nextel with 16 megahertz of contiguous spectrum in the upper 800 MHz band, on which the carrier could continue to offer its voice service, and 10 megahertz in the 2.1 GHz band to offer 3G services in the future.

Nextel would give a chunk of their current (interfering) band to public service radio in exchange for pieces of the 2.1GHz band. Competing cellular companies think Nextel’s plan is unfair to them.

Unwiring the Last Mile
Portable Broadband Wireless

Company	Technology	Trials/Deployment
Arraycomm	Proprietary TDMA	Sydney, Mitsubitsi
BeamReach	Proprietary OFDM	Verizon
Broadstorm	802.16a	Churchill, Manitoba
Flarion	Proprietary OFDM	S. Korea, SK Telecom
IP Wireless	UMTS TD-CDMA	Jacksonville, Auckland
Monet Networks	1xEV-DO	Duluth, Korea
Navini	Proprietary S-CDMA	Daytona, S. Texas (5K sq mi)
Soma Networks	W-CDMA	Chiloquin, OR, NTT
Tantivy	I-CDMA (IS-95 CDMA)	SK Shinsegi (S Korea)
Vivato	802.11b	Pre-trial

A division of Northrop Grumman said that it is petitioning the FCC to free up more spectrum at 700 MHz so that the Department of Homeland Security and public-safety agencies can set up advanced wireless communications systems, The Washington Post reports in its Wednesday edition.

Northrop Grumman’s information technology division, last month asked the FCC to consider reallocating 10 megahertz of spectrum in the 700-megahertz frequency range for public-safety use, so that those airwaves can be developed for a more advanced network to handle high-speed Internet, video and voice calls simultaneously, the Post reported.

“While the commercial world continues to move toward third-generation broadband wireless technologies, the public safety and law enforcement community is prevented from taking advantage of any updated applications because the present public safety spectrum allocation cannot be used to deploy advanced broadband services,” said Royce Kincaid, program manager, wireless initiatives, with Northrop Grumman IT TASC. “The situation is especially hazardous to first responders given their paramount role in homeland security and fighting terrorism.”

The company has specifically requested comment on adding 10 MHz of spectrum, located below 3 GHz, preferably at 747-752 and 777-782 MHz, or elsewhere in the 700 MHz band.

Northrop is hoping to eventually profit from the federal government’s increasing appetite for a more sophisticated, faster way to coordinate the communications between various branches of the government. FCC officials declined to comment on the proposal, the Post reported.

Whether “4G” systems as defined by IEEE 802.16e and IEEE 802/20 will be utilized by public service applications remains to be seen. Still, if workers need broadband at remote locations or in vehicles, there isn’t a lot of choice.

Forrester estimates the capital expenditure for 3G is 15 times higher than for 2.5G systems. Europe will need 700,000 3G base stations, each costing between $189,000 to $473,000. Nearly 70 percent of the 385 million people of Western Europe have cell phones, while the US has close to 170 million using cell phones, about half the population.

President Bush’s FY 2003 budget request includes $3.5 Billion for first responders. The single biggest portion of that amount, $1.4 billion, is designated for enhancing communications.

The Federal Emergency Management Agency is expected to spend most of the $1.4 billion in the form of grants to state and local governments.

Input forecasts the following specific examples of FY 2003 federal spending:

$32.8 million – U.S. Forest Service radio communications
$14.7 million – U.S. Forest Service national fire plan-radio
$6.1 million – U.S. Secret Service radio program
$3.4 million – Bureau of Alcohol, Tobacco and Firearms tactical radio communications

The TDD Coalition
Time Division Multiple Access is another concept that ought to be thrown in the hopper.

Two different paired frequencies (duplex) are used for cellular and 3G systems. One channel coming in, one going out. When 2.5-3 G cellular is used for data, a fully loaded downlink and a low loaded uplink is typical. Hence, most of the uplink spectrum cannot be used. It’s wasteful and expensive. Time Division Duplex (TDD), uses a single frequency band. Both voice and data can use TDD - you get an “effective” two channel duplex system - on one.

Smart antennas increase the spectrum efficiency, range and reliability of wireless networks. They’re easier to utilize using a single channel.

When time division and smart antennas are applied at both the transmitter and the receiver, it’s called multiple-input, multiple-output (MIMO).

TDD operation is based on a periodically repeated TDMA frame in the radio channel. The frame is subdivided to a number of timeslots. Within this time domain subdivision the transmission direction from downlink to uplink can be changed and meet the required symmetry of any service - voice or data, low or high speed data.

The TDD Coalition includes companies like Adaptive Broadband, Aperto Networks, ArrayComm, BeamReach Networks, CALY Networks, Clearwire Technologies, Harris Corporation, IPWireless, LinkAir, Malibu Networks, Navini, Radiant Networks, Raze Technologies and others.

The 802.20 spec apparently supports both single channel (like Wi-Fi) and duplex (like cellular) communications.

It will be interesting to see who bids on the 700 MHz channels today. They are likely to have considerable impact in the coming years.

The Northrop proposal is likely to spark opposition from television broadcasters, who don’t have to give up the spectrum until at least 2007. The National Association of Broadcasters said its members won’t be rushed off the airwaves. They want to get paid off - even though they were given the spectrum at no charge because they operate in the “public service”.

Right.