In Code-Division Multiple Access (CDMA), how is data for every call transmitted?

In Code-Division Multiple Access (CDMA), data for every call is transmitted using a unique key for encoding. This method involves assigning a unique spreading code to each call, enabling multiple calls to occupy the same frequency space simultaneously without interfering with each other. By encoding the data with a unique code, the transmission can be distinguished from others, allowing the receiver to decode the information accurately, even in a crowded spectrum.

This approach leverages the principle of spreading the signal over a larger bandwidth than the minimum required, providing better resistance to interference and eavesdropping. As a result, multiple users can share the same frequency channel effectively, making CDMA particularly efficient in terms of spectrum usage.

The other options do not accurately describe how CDMA functions: time slots are characteristic of Time Division Multiple Access (TDMA), separating frequencies pertains to Frequency Division Multiple Access (FDMA), and digital signaling describes a method of transmitting data that is not specific to CDMA's unique code encoding system.