LOS ANGELES-Ever since PrimeCo Personal Communications L.P. launched service in 11 markets last month, many Code Division Multiple Access proponents believe the technology has passed its first test-widespread deployment. Now the challenge, most say, will be for carriers to maintain high voice quality while increasing network capacity.
Motorola Inc. said it will begin early next year testing in conjunction with a mobile vendor an 8 kilobit-per-second enhanced variable rate vocoder designed to deliver voice quality that is equivalent to the 13 kbps vocoder without compromising capacity. Other manufacturer members of the CDMA Development Group have been conducting laboratory and some field testing as well, said Perry LaForge, executive director of the CDG.
The reason for launching CDMA has not been for capacity reasons. Emphasis has been on call quality and services, said Thomas Hulsebosch, senior product manager for the digital system division of Motorola Inc.’s Cellular Infrastructure Group. “We traded off some of the capacity of CDMA for the toll line vocoder. But that cost us in terms of capacity of a single cell site and in terms of range. If you look at a system that is deployed with 13 [kbps] compared with 8 [kbps], you may need 20 to 50 percent more cell sites.”
The 8 kbps EVRC was developed by the Telecommunications Industry Association and has been standardized, said LaForge. It is known as Interim Standard 127. Subjective listening tests have shown the vocoder is statistically equivalent to toll quality as well as 13 kbps, said Hulsebosch.
DDI Corp., one of Japan’s leading cellular operators, said its affiliate cellular company, Kansai Cellular, will use the 8 kbps EVRC when it launches CDMA service by early 1998 near Osaka, Japan. Osaka is one of the most competitive regions in Japan, and DDI expects Kansai Cellular to reach the network capacity limit in 1997.
“I suspect that EVRC will hit big internationally first. The capacity advantage is critical to many international companies,” said Motorola’s Hulsebosch.
Motorola plans to test and evaluate its first office application in mid-1997 with plans to offer commercial products to its customers shortly after.
Adopting the 8 kbps EVRC in North America will depend on how fast carriers want to deploy it, said Hulsebosch. “All of the operators who have deployed 13 will take a closer look at it. It’s easy to add to the existing system. Carriers aren’t locked in. We can easily support multiple vocoders with infrastructure and start selling better, smaller and lighter phones.”
LaForge said North American operators are committed to 13 kbps at this point because voice quality is still better, although capacity is slightly compromised. Carriers will most likely deploy the 8 EVRC for marketing reasons, he said.
“We’re not in a rush. It’s attractive to go back to 8 kbps, but you can always run 13 at lower rates,” said Craig Farrill, vice president of strategic technology for AirTouch Communications Inc., a Motorola customer that now operates commercial systems in Los Angeles and San Diego using 13 kbps.
Ameritech Cellular Services, which has plans to roll out CDMA service using the 13 kbps vocoder in its Chicago cellular market during the second quarter next year and personal communications services in Cleveland and Indianapolis by late 1997, said it is studying the vocoder’s development and will make sure it matches the quality of the 13 kbps vocoder.
Qualcomm Inc. fully backs 13 kbps vocoder but said it also is testing the 8 kbps EVRC. “The 13 is probably the best vocoder around but the 8 does very, very well,” said Dr. Irwin Jacobs, chairman and chief executive officer of Qualcomm.
