CDMA2000 operates in a relatively small amount of spectrum, 1.25 MHz, in most of the frequency bands designated by the International Telecommunication Union (ITU) for the IMT-2000 systems. The smaller 1.25 MHz channel size enables greater spectrum assignment flexibility to (a) incrementally assign channels as the demand for capacity increases, and (b) to facilitate in-band migration deployments which require the clearing of spectrum.
CDMA2000 1X, EV-DO Rel. 0 and Rev. A operate in a paired 2 x 1.25 MHz FDD channel - compared to other 3G technologies which require a much larger 2 x 5 MHz channel. By using a narrower radio channel, operators benefit from greater flexibility and improved cost efficiencies in managing their scarce spectrum resources. EV-DO Rev. B enables operators to aggregate multiple 1.25 MHz channels, up to 15 channels in 20 MHz of spectrum, to deliver the next-generation multi-mega-bits-per-second data connectivity and bandwidth intensive applications more economically.
Currently, CDMA2000 network infrastructure and user devices are available in most of the IMT-2000 frequency bands designated by the ITU, including the 450 MHz, 700 MHz, 800 MHz, 1700 MHz, 1900 MHz, AWS and 2100 MHz bands.
In many cases, the frequency assignment is as important as the broadband technology selection.
Using the lower frequency bands is preferable for broadband-intensive network deployments. The propagation characteristics of the lower (warmer) frequency bands enable RF transmissions to travel greater distances. The increased range provides larger coverage areas. Fewer cell sites require fewer backhaul connections, which leads to lower costs. The lower frequency bands also enable better in-building penetration, better mobile performance, less power consumption and higher average data throughputs in a non-line-of-sight (NLOS) environment.
This is becoming progressively more important as the bandwidth for the backhaul connections must increase to keep up with the growing demand for mobile broadband services.
Spectrum: Bandwidth-Intensive Networks