Time Division Multiple Access (TDMA)

In TDMA systems, network resources are the time slots available for the
data transmission. Each time slot is assigned to a different user; or multiple time
slots can be assigned to a single user or multiple time slots can be assigned to
multiple users depending on the amount of voice or data traffic transmitted. GSM
telecommunication standard, which is 2G network, uses TDMA technique for
communication.

Frequency Division Multiple Access (FDMA)

In FDMA systems, the whole spectrum is divided into multiple frequency
slots to create the frequency chunks. Network resources are the frequency
chunks available for the data transmission. Each user is assigned a different
frequency chunk to receive and transmit data

Code Division Multiple Access (CDMA)

In CDMA systems, network resources are the number of unique codes
assigned to each user or subscriber. Each subscriber uses assigned code for
data transmission and reception. CDMA 1x and CDMA 1x Advanced technologies
use the same CDMA technique for communication and these standards are used
as 2G technology in North America. 3G communication standard which uses the
CDMA is called WCDMA or UMTS. UMTS standard is used as 3G
communication technology in all over the world.

Orthogonal Division Multiple Access (OFDMA)

This scheme uses time and frequency resources to transmit and receive
data. In other word, this multiplexing technique combines both TDMA and FDMA
multiplexing schemes to transmit data to users. Each user in the network is
assigned specific time and frequency resource grid for communication. This data
transmission technique is used in 4G/LTE, LTE advanced and 5G
telecommunication systems.