CDMA Group: Hold On There
By Joseph Palenchar -- TWICE, 8/19/2002
Costa Mesa, Calif. — The CDMA Development Group (CDG) took issue with the GSM camp's claims of superior voice capacity, and one carrier member contended that its CDMA 1X network has already exceeded the voice-capacity limits ascribed to it by 3G Americas.
The carrier, Korea's SK Telecom, said its capacity exceeds analog capacity by 25.7 times, exceeding 3G America's estimate that 1X is limited to 17 times analog capacity. SK also said its capacity exceeds the 19-times gain that GSM is expected to offer when Adaptive Multirate (AMR) codec and Dynamic Frequency and Channel Allocation (DFCA) are implemented. (See story above.)
Specifically, said SK CTO Myung Sung Lee, SK "has increased to more than 231 Erlangs in 10 MHz spectrum" compared to the 170 promised by GSM's AMR and DFCA technologies. With the launch, SK achieved a more than 70 percent increase in voice capacity, he said.
U.S. carrier Leap Wireless also disputes the 3G Americas estimates. The 2G CDMA carrier is rolling out CDMA 1X, and chief technology officer Mark Kelley said, "It is fundamentally impossible to operate Leap's Cricket flat-rate 'all-you-can-talk' wireless service using technologies other than CDMA."
Leap found GSM would use up as much as five times the spectrum that 2G CDMA would, he said. What Leap is doing with 10MHz of spectrum would require 45MHz if the company opted for GSM, he claimed.
Leap's 2G CDMA network consistently sees 20 Erlangs per sector per 1.25MHz of spectrum, or "at least five times the realistic capacity of GSM systems," CDG said.
Leap is now using CDMA2000 1X in a few markets and, in initial tests, is enjoying almost twice the voice capacity of 2G CDMA, CDG continued. "Moreover, earlier in the year, Leap tested new CDMA technology that would push the capacity another 50 percent, which the company will be adopting when it becomes commercially available."
Advancements in Selectable Mode Vocoder (SMV), Smart Antennas and Receive Diversity "will continue to make CDMA far more efficient than other technologies for years to come," CDG added.
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