CDMA: Code-Division Multiple Access what is it?
TELUS Mobility’s digital PCS network, the most extensive in Canada, is based on
CDMA technology. As the term implies,
CDMA is a form of multiplexing, which allows numerous signals to occupy a single transmission channel, optimizing the use of available bandwidth. The technology is used in ultra-high-frequency wireless phone systems, such as TELUS Mobility’s, in the 800-MHz and 1.9-GHz bands.
how does it work?
CDMA employs analog-to-digital conversion in combination with spread spectrum technology. Audio input is first digitized into binary elements. The frequency of the transmitted signal is then made to vary according to a defined pattern, so it can be intercepted only by a receiver whose frequency response is programmed with the same code, so it follows exactly along with the transmitter frequency. There are trillions of possible frequency-sequencing codes; this enhances privacy and makes cloning difficult.
The
CDMA channel is nominally 1.23 MHz wide.
CDMA networks use a scheme called soft handoff, which minimizes signal breakup as a handset passes from one cell to another. The combination of digital and spread-spectrum modes supports several times as many signals per unit bandwidth as analog modes.
about TELUS Mobility’s CDMA network:
Prior to the merger of TELUS Mobility and Clearnet, TELUS Mobility operated a
CDMA network with Nortel infrastructure in Alberta and British Columbia, while Clearnet’s national
CDMA network operated on Lucent equipment. These networks are now being rationalized, with TELUS Mobility’s network supported by Nortel in Alberta and B.C., and Lucent infrastructure in the rest of Canada. This allows redeployment of Lucent equipment for, among other possibilities, the buildout of new markets outside Alberta and B.C.
Linear Mode
