Marty Cooper, the acknowledged father of cellular radio, has bracketed 25 of his 40-year career in the wireless industry by pioneering new ways to use particular frequency bands and give more people access to a richer array of services. In the early 1970s there was trunked mobile radio and then the metropolitan array of antennas and handoff schemes that allowed true cellular services to emerge; now there is a new technology that packs more bits into a hertz than conventional techniques.

To be sure, the problems to be solved have changed in a quarter century, but Cooper said there's definitely a common thread between the two stages of his career. In both cases, wireless traditionalists accepted the limitations imposed by traditional uses of a frequency band but Cooper considered all such barriers artificial.

Cooper spent 29 years at Motorola Inc. in a variety of engineering and executive posts promoting early paging and cellular systems. Although many in the wireless industry are aware that Cooper went on to found the smart antenna pioneer company ArrayComm Inc. — he is its chairman chief executive — few realize how much ArrayComm's mid-1999 shift in focus reflects the same motivations Cooper followed in the early days of cellular radio.

ArrayComm originally developed its IntelliCell model of adaptable antennas for more efficient siting of antennas as new Personal Communication Service networks were rolled out in the 1.9-GHz band. The concept has won strong adherents in Japan's PHS network, but its penetration of North American and European markets has been spotty at best.

That didn't stop Cooper. At the September PCS show in New Orleans, ArrayComm introduced its new technology, i-Burst, which uses the same techniques as IntelliCell to provide broadband access capabilities in unpaired frequency bands, which provides more bits per hertz than traditional MMDS or LMDS broadband radio concepts.

Cooper is straightforward. "There's never been a real shortage of spectrum, only a scenario where the regulatory bodies created de facto scarcity," Cooper said. "In the mobile radio business, the traditional response to artificial scarcity has been to continue to split channels and reduce quality. My entire career has revolved around applying emerging technologies like sectorization and smart antennas to solve the problem of spectral efficiency, broadening a service to more users without reducing quality."

In the late 1960s and early 1970s, Cooper was in the team at Motorola that proposed broadening specialized mobile radio by having licensed users share base stations-trunking-that allowed more private companies to apply for SMR licenses by reducing costs. The concept was so heretical in Motorola's mobile radio organization that Cooper almost got fired for his troubles.

Between his stints in trunked and cellular radio, Cooper was active in paging network development and introduced the PageBoy II in 1970. The experience in one- and two-way paging later gave him the insight to apply adaptive antenna technology to paging systems after he founded ArrayComm.

Cooper was instrumental in conducting the first cellular trials in New York City in April 1973 and placed the first call from a Manhattan base station to rivals in Bell Labs in New Jersey, just to chide them about Motorola's lead. In October, Cooper helped a New York Times photographer find the original base station used in those trials, still in the same corner of the building where it was installed 26 years ago.

At the time, AT&T was proposing to the FCC that 75 MHz of spectrum be reserved for the company's sole use in building cellular infrastructure; the decade cellular radio took to become commercialized is largely the fault of rival companies trying to abuse regulatory agencies in favor of closed cellular systems

Many of the frustrations faced in promoting cellular radio were reruns of the problems Cooper faced in promoting trunked mobile radio, with many frustrations faced before the first cellular service emerged in Chicago in 1983. Cellular radio allows mobile users-both fast ones in moving vehicles and slow ones in urban environments-to shift to different bands as they move from sector to sector. Unlike the closed world of trunked radio and SMR, where users can communicate with each other but not with the public switched telephone network, the cellular infrastructure was designed from the beginning to be an extension of the phone network, using the North American numbering plan to allow wired and wireless users to telephone each other.

Cooper said he was constantly hearing from naysayers in Motorola in the early days, including a regional sales director for trunked radio who insisted that "no one would pay the 15 percent premium for a mobile radio service of this variety." Aggravations about the viability of cellular were one of the reasons Cooper elected to leave Motorola, whereupon he founded Cellular Business Systems Inc., later sold to Cincinnati Bell.

In the same way that switching centers allowed open interfaces to the PSTN, each succeeding generation of cellular standards-Advanced Mobile Analog Service (AMPS), GSM European digital service, time division multiple access (TDMA) and code division multiple access (CDMA) U.S. digital service, the 1.9-GHz PCS equivalents of 800-MHz digital cellular service and the nascent global third-generation (3G) standard-have successively moved the world closer to open interfaces that allow multiple manufacturers of handsets and base stations to function in a formerly closed world.

The whole issue of competing air interfaces, such as GSM, TDMA and CDMA, did very little to help the spectral efficiency problem, Cooper said, but accomplished plenty in helping to break down the walls of the formerly closed mobile radio market.

"Traditionally, carriers in this market defined what was important and only developed the services that were of financial interest to them," he said. "In the old world, where a half-dozen infrastructure manufacturers were the only ones that mattered, you identify the specific market and design an optimum system for that market."

The hype from the GSM and 3G development communities, particularly in Europe, tried to address that closed world by talking of service universality. It was a good step toward making cellular services ubiquitous, Cooper said, but the drive for a universal scaled service also had pitfalls since "the desire to create a universal market means that you define all service markets sub-optimally."

It was Cooper's musings about these competing market drivers during his years at Cellular Business Systems that were instrumental in defining the original business plan for ArrayComm, which was founded in San Jose, Calif., in 1992. Smart antenna concepts developed by ArrayComm's founders originally were applied in the two-way paging market, but the bulk of the 1990s was spent in efforts to bring antenna adaptivity to voiceband markets.

The ArrayComm technology employs spatial division multiple access, in which arrays of antennas are used at each site and parallel DSP processors are used to define a virtual channel for best reception. The receiver antennas then can lock into a moving handset transmission, directing the energy to reduce overall system-level interference. By allowing channel reuse and cutting power dissipation, the IntelliCell arrays allow a metropolitan cellular or PCS system to be designed with fewer antenna sites.

"We had the rather naive view in the mid-1990s that we had such a killer technology, the world would automatically beat a path to our door," Cooper said.

ArrayComm had trouble getting its antenna networks established outside the Japanese Personal Handyphone market, which led Cooper to ponder the issue of service variability. Whether developers consider voice or data services, the notion that a single service will fit all needs is false, Cooper said. In fact, in a paper developed last year for the 25th anniversary of cellular technology, Cooper argued that there will be no unified cellular industry in a few years, only optimized handset businesses for services such as teen-specific GoPhones, E911 SOSphones, etc.

As ArrayComm executives looked at the potential for wireless data applications for IntelliCell, Cooper said the development team observed a huge gap between the slow, unreliable cellular circuit and packet services such as GPRS and IS-95B and the fixed multipoint broadband services such as MMDS and LMDS.

The combination of physical antenna arrays and DSP processors allowed for the development of a service that could utilize packet switching over arrays of antennas. Frequency bands for transmit and receive did not need to be paired and the service was incredibly miserly in its use of frequency windows, Cooper said. The only sacrifice ArrayComm developers had to make in designing i-Burst was that the system would not work with high-mobility end terminals. Cooper said he anticipated the users of most data systems offering speeds of more than several hundred kilobits per second would either be walkabout users in a portable environment or users in a fixed location, not those driving cars.

"We have a pipe of 40-Mbit/second capacity which can be segmented the way a service provider wishes it to be," Cooper said. "By using only a 10-MHz window of unpaired spectra, we make the service very attractive. Tradeoffs for the type of service you aim for are inevitable and we didn't think a multi-megabit data service for the high-mobility market was a necessity near term."

ArrayComm plans to develop and manufacture the chip sets for handling data access in the subscriber terminal and also will develop base stations and antenna arrays for the i-Burst network. However, the company will not pursue entire infrastructure buildouts without a partner. And the changing nature of the Internet access business makes a retail sales-channel partner for handsets and subscriber services as crucial as OEM partners. But, Cooper said he has the retail angle all lined up, though details of what kind of service and handset the partner may be looking at remain secret.

"The market I like the most is an Internet box appropriate for this type of broadband wireless network, and I don't think the appropriate consumer appliance exists today," Cooper said. The model of many different services that Cooper assumes will dominate in our 3G future means that a variety of subscriber terminals will have to be enabled through simple chip-set and reference-design support. Cooper said he's staying clear of defining the end-user terminals for this market since "the biggest troubles I got into in my past were in introducing specific terminals for an emerging market."

The introduction of i-Burst is more than just a sideline for ArrayComm. Although the company will continue to manufacture and upgrade its antenna array systems for voiceband PCS and 3G markets, the future for ArrayComm lies in developing new data and multiservice networks using the underlying smart antenna technology. Prototypes are running in ArrayComm's lab and market trials were slated to start at the very end of 1999, using an experimental FCC license. ArrayComm and its partners expect to have the spectrum they need in 2001 and pledge to have a commercial service in North America by 2002, with networks in Japan and Europe to follow.

Cooper said that despite the years and radical infrastructure changes between the era of trunked and cellular radio and the current eve of wireless broadband access services, he sees an obvious continuity in his life's work.

"I've always wanted to solve problems by approaching old constraints from a new perspective," he said. "Most of the problems I've wanted to solve centered on communications portability and the phony scarcity of spectrum. There's a lot of common ground in the Motorola and ArrayComm work."

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