Imperfect Harmony

"We are within a gnat's eyelash of being the same," said Ted Hoffman, Bell Atlantic Mobile vice president of technology, at November's CDMA Americas Congress in Los Angeles.

What he was talking about were those final niggling issues that separate W-CDMA and cdma2000.

"If we could converge these two standards now, we could be the pre-eminent standard," he predicted. "If we can't do it here, it won't happen in the fourth or fifth generation."

One of the most argued differences is the chip rate. The W-CDMA camp has advocated the 4.096 megachip per second (Mc/s) chip rate, suggesting that the higher chip rate provides more horsepower. On the other hand, the cdma2000 camp wants to retain the familiar 3.686Mc/s. The cdma2000 camp rejects the new chip-rate notion because it claims that it will accommodate fewer carriers and will require a complete change to existing CDMA equipment.

Although filters could help minimize the effect of the different chip rate, it is largely regarded as an unnecessary change.

Since the November CDG Congress, vendors and standards participants have attempted to reduce the differences and resolve the chip debate. Ericsson announced it publicly supported a convergence of W-CDMA and cdma2000, and suggested a compromise chip rate of 3.84Mc/s. Qualcomm continued to argue that such a chip rate does not contribute to a standard that is demonstrably superior in terms of performance, features or cost. It also indicated that it was unaware of any analysis suggesting that 3.84Mc/s was a better solution than 3.686Mc/s. In fact, Qualcomm continues to support the latter because of its evolutionary support of existing CDMA technology.

SO CLOSEAccording to Perry LaForge, CDG executive director, there has been compromise throughout the entire process, resulting in agreement on all but a few technical parameters.

"We originally stated that the ETSI-proposed chip rate of 4.096Mc/s would not work when attempting to implement the system in a 5MHz block of spectrum. It is now recognized that, indeed, this is true. ARIB has studied the chip-rate issue and has concluded that the choice of this parameter value has no bearing on overall performance."

LaForge also said that agreeing on a common chip-rate parameter does not reduce performance, but rather it creates economies of scale.

Other CDMA carriers, such as AirTouch, Bell Atlantic Mobility and Sprint PCS, agreed with this sentiment and encouraged the industry to seek harmonization.

"Harmonization is possible, but it is hard," said Craig Ferrell, AirTouch vice president of strategic technology. "Carriers want it to happen, but it is tough to shove it over the goal line."

Ferrell predicted that if the industry is unable to "shove it over the goal line," it easily could cost this industry more than $50 billion dollars in lost revenues.

The CDG agreed, saying that harmonization provides obvious economies of scale. Areas of savings would include research and development costs, improved deployment costs, cohesive worldwide roaming capabilities and a stronger competitive stance against wireline services.

"It will provide an atmosphere where features and services, not technologies, are the basis of competition," said CDG's LaForge.

CARRIER INVOLVEMENTAt the CDG, Bell Atlantic Mobile announced that it will begin phased introduction of the new high-speed wireless data capabilities based on cdma2000 3G enhancements over its existing cdmaOne network this year. Bell Atlantic Mobile was an early advocate and adopter for CDMA technology and now covers 90% of its subscribers with its digital service.

"Backward compatibility to existing cdmaOne is the linchpin for delivering these advanced services, and that is why we intend to deploy cdma2000 capabilities in our network," said Bell Atlantic Mobile's Hoffman.

He also emphasized that co-existence of 2G and 3G network elements must be assured by components operating at chip rates that are exact multiples of the cdmaOne standard.

Following an extensive testing program, Bell Atlantic Mobile and Lucent Technologies, including Bell Laboratories developers, will make the technology enhancement with minimal upgrades.

"This phase of evolution will allow us to introduce 3G data-rate services quickly and at minimal cost while substantially increasing our current digital voice capacity within our existing spectrum," Hoffman said. "This will give us one of the most competitive cost structures in the world for wireless services."

CARRIER INVOLVEMENTCertainly, the challenges of harmonizing a global standard are many. After all, wireless carriers around the world all started from different points. There has been a lack of a consistent regulatory approach. There have been different focuses on customer and industry benefit issues. Although the 2G environment heated up competition, it also fired up elements of pride and politics. Meanwhile, throughout the compression of standards, carriers by and large have remained quiet on the issue.

However, with vendors coming closer to an agreement, carriers such as Bell Atlantic Mobile and AirTouch are becoming involved and mounting more pressure on the vendor community to make it all work together, lest they lose an important customer.

Meanwhile, ETSI's Special Mobile Group 2 (SMG2) accepted an evaluation of the UWC-136 3G proposal and recognized that the 136HS outdoor technology element is similar to that of the GSM EDGE technology. Also, the 136HS indoor element of the proposal is similar to the wideband TDMA proposal studies within ETSI as a potential candidate for UTRA.

The SMG2 determined that the UWC-136 3G proposal met the requirements of IMT-2000 and is consistent with its understanding of the technologies.

"This is a critical acceptance for the convergence of a TDMA air interface for data up to 384kb/s and paves the way for further cooperation between the UWCC and ETSI," said Chris Pearson, UWCC director of marketing.