ABSTRACT
The evolution of communication systems from 1G to 3G interestingly shows the use of technology to exploit the three cardinal axes of frequency, time, and code. First-generation systems were based on Frequency Division Multiple Access (FDMA), where each user was assigned a single frequency or a pair of frequencies for full duplex communications. Second-generation systems expanded FDMA to Time Division Multiple Access (TDMA), where each available frequency channel could transmit and receive data from several users by assigning each user data into individual time slots. Finally, thirdgeneration systems introduced Code Division Multiple Access (CDMA), which assigns orthogonal codes to subscribers: this enables them to share the entire available frequency band without interfering with each other.
