CDMA

 CDMA (Code Division Multiple Access) is a digital cellular network technology used to transmit voice, data, and other digital signals over wireless networks. Unlike GSM, which uses TDMA and FDMA, CDMA allows multiple users to share the same frequency at the same time by encoding each user's signal with a unique code. 

CDMA operates by spreading each user's signal over a wide range of frequencies, which are then combined and transmitted over the air. The receiver uses the same unique code to decode the signal and separate it from the other signals in the transmission. This allows for many users to share the same bandwidth and frequency range, increasing the overall capacity of the network.

CDMA has been widely used in the United States, but it has been largely replaced by newer technologies such as 3G, 4G LTE, and 5G. However, some countries still use CDMA for their cellular networks.