Although public safety gained a victory this fall when the FCC opted for open standards in issuing guidelines for the licensed 4.9 GHz band set aside for public-safety data communications, equipment vendors continue to push ahead with divergent plans.

The FCC recently acted to accommodate 802.11a (5 GHz) standards-based technologies in the 4.9 GHz band to pave the way for lower-cost mobile broadband wireless systems for public safety, which historically has been hamstrung by expensive and proprietary two-way communications systems.

Specifically, the commission adopted two emission masks limiting interference potential for the band, one for low-power and one for high-power operations. Systems using the high-power DSRC-C mask can output 33 dBm, while systems using the low-power DSRC-A mask can output 20 dBm. The FCC also called for some additional filtering.

Motorola had advocated a tighter mask that favored its technology at 4.9 GHz to reduce the possibility of interference for first responders' mission-critical data communications — something the FCC approved a year ago before opening the item for reconsideration. However, public-safety officials said the tighter mask would prevent commercial vendors from participating, leaving law-enforcement entities with limited — and generally more expensive — equipment choices for their 4.9 GHz services.

But regardless of the relaxed emission mask, it still appears the dominant public-safety wireless vendor has plans for a proprietary system.

“We are glad emission masks are in line with what we looked for,” said Steve Devine, patrol frequency coordinator for the Missouri Highway Patrol and chairman of the National Public Safety Telecommunications Council's 4.9 GHz Task Force. “But Motorola and MeshNetworks still indicate they are going in different directions, using the tighter emission mask anyway. Those are all business decisions.”

Motorola, which recently announced plans to acquire MeshNetworks, always has argued high-power 4.9 GHz gear offers better support of advanced services such as high-speed handoffs and full-motion video, as well as better range. The thinking is that a proprietary system such as MeshNetworks' peer-to-peer network is compatible with all power levels in the 4.9 GHz band, while 802.11-based systems can accommodate only low-power applications with a decreased range.

“Motorola will certainly participate in and support any standards developed, but we also view the ability to provide high-speed, full-motion services as important to customers, which calls for us to provide standards plus,” said Mike Fabbri, director of wireless broadband solutions for Motorola. “802.11 hasn't been established for 4.9 GHz, and we would expect a standard to develop, but we also think there are features and capabilities that need to be supported.”

Motorola's acquisition of MeshNetworks, a developer of mobile mesh networking and position-location technologies that allow customers to deploy IP-based wireless broadband networks, is a key component of the company's 4.9 GHz strategy, said Fabbri. In September, the FCC granted MeshNetworks licenses to deploy several experimental mobile mesh networks, giving the company the ability to conduct nationwide trials of the network in the 2.5 GHz and 4.9 GHz bands.

MeshNetworks designs proprietary mobile mesh systems and also offers an 802.11-based software mesh product. Motorola licenses the MeshNetworks Enabled Architecture product line as well as its 802.11-based mobile mesh software solution called MeshConnex. Fabbri said Motorola will support solutions in the lower-power mask but desires to offer proprietary high-power solutions as a way to differentiate itself and better serve its customers.

“What's the point if you just use the same unlicensed 802.11 technology?” Gary Grube, corporate vice president and chief technology officer with Motorola's government and enterprise sector, recently told MRT. “We understand the way customers will use these things, and we think the mission-critical aspect of this is super important.”

Motorola recently announced an agreement with the city of Tulsa, Okla., to provide a test bed for Motorola's 4.9 GHz hotspot technology, which uses higher-power capabilities and will allow city workers to bring their high-speed data office applications into vehicles. A target date for commercial release of the Motorola/MeshNetworks product for the 4.9 GHz band has not been announced.

“The city will be using applications that take advantage of the broadband pipes such as the ability to stream video to or from a vehicle,” said Fabbri. “The technology lends itself to high-bandwidth and video.”

Yet Nortel Networks, one of the vendors that lobbied the FCC for an emission mask compatible with 802.11a technology, says 802.11a-based networks in the 4.9 GHz band will offer the performance and applications public safety desires.

“What Motorola was pushing for was a mask with narrow bandwidth and higher in power, but wider bandwidth and lower power have the same amount of performance. That's what this mask allows,” said Todd Etchiesen, director of Nortel's wireless mesh networks business management unit. “The infrastructure is all about cost-effectiveness of broadband, delivering bits in a cost-effective way. That's where the value is.”

Nortel earlier this year teamed with PacketHop, which provides mobile mesh networking software that forms ad hoc broadband wireless networks via standard IP radio-equipped devices, to jointly market Nortel's infrastructure and PacketHop's software client technology. Users that have already been investing in devices for the 2.4 GHz Wi-Fi band can incorporate PacketHop's software to support mission-critical applications, said Michael Howse, PacketHop's president and CEO.

“We enable off-the-shelf radios to become mission-critical devices,” said Howse, whose company founded the 4.9 GHz Open Standards Coalition that includes Cisco Systems, Nortel and Tropos Networks. Devices, in effect, are turned into routers that can send and receive packets and are survivable because they don't require backhaul access in order to function, he said.

PacketHop's software uses Layer 3 routing and can operate across any IP-based computer, Howse said. The company also offers a suite of applications such as multicast video, location tracking and a “white board” feature that enables diagramming on maps that can be transmitted to other first responders. The company also will introduce an instant-messaging capability that will allow first responders to provision groups for one-to-one or multiple sessions, as well as sharing data information.

“We actually have proven to decrease the amount of voice traffic running over traditional networks,” Howse said. A recent test of the PacketHop's technology, known as the Golden Gate Safety Network Project, deployed in the San Francisco Bay area, decreased voice traffic by 70%, he said.

PacketHop's equipment also will be interoperable with access points supplied by a number of vendors, including Cisco and Tropos, Howse said. Commercial availability is expected in the first quarter of 2005.

“You can stay current using a whole range of software and devices. That's a whole new paradigm for public safety,” said David Thompson, vice president of marketing with PacketHop.

When it comes to standards, the challenge for public-safety entities now is to determine what solution best serves their interests.

“Motorola will try and fragment the market,” predicted Howse. “It's hard to teach an old dog new tricks.”

For its part, Motorola promises “to be very competitive and provide the strongest value for the dollar,” said Fabbri.

4.9 GHz eligibility and licensing requirements

  • Designated for public safety only
  • Public-safety entities can enter into sharing agreements or other arrangements with entities such as power and railroad companies
  • Geographical licensing scheme is based on a public-safety entity's legal jurisdiction area of operation
  • Frequencies must be shared among licensees
  • An unlimited number of base stations are allowed, provided environmental considerations are taken into account

Source: FCC