More than a year after the Internet burst into the wireless space, the big story in mobile data continues to be how the industry is responding to this communications phenomenon.
While circuit-switched cellular still is the standard for wireless data connectivity-offering near-universal access for dial-up wireless communications-we’re becoming a packet-switched world driven by the Internet and the access it provides to the larger world of computer networking.
Circuit-switched data transmission requires setting up a dedicated two-way link while packet-switching breaks up the transmission into small data packets that share the channel with other packets or, in some cases, voice transmissions.
“If the Internet trend continues, packet will assume a dominant role because it is so congruent with the Internet,” noted Kendra VanderMeulen, vice president and general manager of AT&T Wireless Services Inc.’s Wireless Data Division.
The Internet’s Transmission Control Protocol/Internet Protocol provides a common set of rules so different networks and devices can communicate. And accommodating TCP/IP gives wireless carriers an advantage in attracting the applications developers that mobile data ultimately needs to succeed.
“It’s much easier to get a market started by springboarding off what is already popular,” said Ira Brodsky, president of Datacomm Research Co. “There’s tremendous value in being compatible with what people are already doing.
“Having an IP-based data network is definitely an advantage in attracting and working with developers. You can’t sell a solution that is alien to them,” he said.
AT&T’s VanderMeulen quickly seized on the term “Wireless IP” to characterize the Cellular Digital Packet Data networks being rolled out by her company and a number of other cellular carriers.
CDPD is based on IP and optimizes it for wireless transmission by reducing the protocol’s inherent “chattiness” that wastes bandwidth and drives up cost.
CDPD expansion
At the end of the first quarter, CDPD networks in 113 U.S. markets covered nearly 50 percent of the population, or about 123 million people. These include both commercial and test markets, some of which are confined to core business districts.
In addition, 17 international markets have CDPD installations.
With help from the Telecommunications Act of 1996, interoperability agreements have been signed between the “Big Four” CDPD carriers-Ameritech Cellular Services, AT&T Wireless Services, Bell Atlantic Nynex Mobile and GTE Mobilnet Inc.-plus a few others.
Smart phones
Although almost all wireless networks-packet radio, narrowband personal communications services, digital cellular and broadband PCS-accommodate the Internet’s most pervasive application, e-mail, the emergence of devices with native IP support allows two-way access to richer data resources residing on Internet and corporate intranet computer servers. This provides more mission-critical applications for the user and gives the carrier an opportunity to hold on to its core market-the business user.
Smart phones containing their own IP addresses have been introduced by Pacific Communications Sciences Inc. and Samsung Electronics Co. Inc. for CDPD networks.
Mitsubishi Wireless Communications Inc. just premiered another smart phone model called the MobileAccess 110.
Having IP on the handset “extends applications to a user while they’re in motion. It’s simply not available to them if they don’t have IP,” said Joy Maguire, senior manager, product management and marketing, for Mitsubishi’s Personal Mobile Communications Division.
“The CDPD footprint does cover most of the United States, although it may be fringe coverage out in the suburbs,” she said. “That’s why we will support Circuit Switched-CDPD this fall.”
CS-CDPD is a hybrid technology developed by GTE Mobilnet that allows CDPD applications to access the network in areas where CDPD base stations have not been installed.
“It extends CDPD functionality where CDPD is not yet deployed,” said Chuck Napier, GTE’s group manager for data market management. “The hybrid solution takes the coverage issue out of the decision for the user.
“It makes it easier to sell and support the users. But we retain all the advantages of CDPD including security and authentication,” he said.
GTE calls its CS-CDPD network Extended Wireless Packet Data. It went commercial Feb. 3, and is available nationwide for dial-in using an 800 number.
“We maintain a centrally located enhanced Mobile Data Intermediate System to handle CDPD transmissions. We can grow it by adding new modem banks, it’s not base-station dependent,” Napier said.
Thus far, Comcast Cellular Communications is the only other carrier that has announced it will implement a CS-CDPD network.
Going digital
CDPD and CS-CDPD are overlays to the existing analog cellular network but at some point may be mapped over to emerging digital cellular and PCS networks.
“The (CS-CDPD) specification is built for transparency over different airlinks including digital PCS,” said Napier.
Datacomm’s Brodsky said, “The mobile IP software interface developed by the CDPD group will allow people to develop applications for the CDPD networks now and run them, with only minimal changes, on circuit-switched digital networks later that use CDPD for packet routing.”
Circuit-switched access imposes a dial-delay penalty, so users don’t get the full benefit of using a sessionless, IP-based network.
But, “As digital evolves the differences will begin to fade,” Brodsky said. “Call set-up time over digital will get faster.”
Apps developers
“CDPD is the only wireless packet protocol that is truly open,” noted Brodsky. “Customers are more comfortable with a cellular-based solution. It provides ubiquity in coverage; it’s been around for a long time; it’s a solid platform.”
Stability and familiarity are important in luring applications developers into the wireless space.
“They looked at the limitations of TCP/IP over the airlink-its chattiness-but they concluded the tradeoff is worthwhile. What everybody is working on is being compatible with IP but not bringing all the IP stuff over the air,” Brodsky said.
He points to the UP.Link software platform developed by Unwired Planet Inc. that optimizes Web-based content for wireless transmission. UP.Link has been licensed to a number of carriers, handset manufacturers and Internet companies.
Boulder, Colo.-based CellPort Labs Inc. is using Internet protocols to make applications development easier, faster and cheaper for the automotive market: some 600 million vehicles in use worldwide.
“The Internet has become an applications enabler,” said Michael Braitberg, the company’s chief technology officer. “Its development tools hide TCP/IP networking complexities, offering simplified communications with HyperText Transfer Protocol and HyperText Markup Language formatting.”
By using standard Internet protocols and TCP/IP applications development tools, CellPort’s MobileWeb developer kit reduces development complexity, drastically cuts development time and costs, and opens a host of new mobile networking opportunities and applications, he said.
The company said the MobileWeb kit has encouraged a wide range of companies to begin experimenting with wireless data including applications for public safety, intelligent transportation systems, vehicle fleet management, highway maintenance vehicles, agricultural combine instrumentation, cargo ships and next generation consumer vehicles.
Last week, the Silicon Valley-based Daimler-Benz Research and Technology Center premiered an Internet-ready Mercedes E420 demonstration car equipped with the MobileWeb controller and server, several computers, three flat-panel display screens, a palmtop computer docking station and a Global Positioning System navigation receiver. The device also features a Sega Saturn g
ame machine.
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