cdmaOne networks were the first mobile networks to use Code Division Multiple Access (CDMA) for offering mobile services. cdmaOne is actually the commercial name for Interim Standard 1995, also known as IS-95, which made use of the CDMA technology for the air interface. The standard IS-95 has two variants; IS-95A and IS-95B. Let’s have a look at the frequency bands below.
The frequency band used by IS-95A (cdmaOne) can either be 824 to 894 MHz or 1850 to 1990 MHz with separate frequency bands for the uplink and the downlink. The carrier frequencies used in IS-95 have a bandwidth of 1.25 MHz. The peak data rates of up to 14.4 kbps can be achieved from IS-95A, while the technology enhancements in IS-95B can allow up to 115 kbps. IS-95 provided capacity advantages for its ability to accommodate more users per MHz of bandwidth.
cdmaOne frequency band vs. GSM and D-AMPS frequencies
cdmaOne was introduced in the same era as GSM (Global System for Mobile Communications) and D-AMPS (Digital-Advanced Mobile Phone System). Both GSM and D-AMPS used a combination of Frequency Division Multiple Access (FDMA) and Time Division Multiple Access (TDMA) to offer cellular services. The original GSM networks used 890 to 915 MHz for the uplink and 935 to 960 MHz for the downlink. This frequency band was later extended in order to add 10 MHz to both the uplink and the downlink. The extended band is known as Extended GSM or E-GSM and ranges from 880 to 915 MHz for the uplink and 925 to 960 MHz for the downlink. D-AMPS, on the other hand, uses 824 to 849 MHz for the uplink and 869 to 894 MHz for the downlink.
Is CDMA2000 different from cdmaOne?
CDMA2000 was the 3G upgrade path for cdmaOne networks. cdmaOne was the commercial name for IS-95 while CDMA2000 was the commercial name for IS-2000. CMDA2000 uses the same carrier bandwidth of 1.25 MHz and is both circuit-switched and packet-switched. Just like cdmaOne was launched in the same era as GSM and D-AMPS, CDMA2000 was introduced in the same era as UMTS (Universal Mobile Telecommunications System).
The power consumption in IS-95 networks is low which allows users to make phone calls in decent quality even when the signal strength is not at that great. Due to low power consumption in these networks, the coverage is a bit wider which means that the cell size is a bit bigger. It also means that a lesser number of cells can do a good enough job. IS-95 networks also have a soft handover (also sometimes called handoff) which means that the calls are less likely to be dropped.