TDMA:
Time division multiple access (TDMA) is a channel access method for shared medium (generally radio) networks. It permits several users to share the similar frequency channel by dividing the signal into different time slots. The users transfer in rapid succession, one after the other, each using his own time slot. This permits multiple stations to
Share the similar transmission medium (e.g. radio frequency channel) while using only a part of its channel capacity. TDMA is used in the digital 2G cellular systems like Global System for Mobile Communications (GSM), IS-136, Personal Digital Cellular (PDC) and iDEN, and in the Digital Enhanced Cordless Telecommunications (DECT)
Standard for portable phones. It is also used extensively in satellite systems, and combat-net radio systems.
FDMA:
Frequency Division Multiple Access or FDMA is a channel access method used in multiple-access protocols as a channelization protocol. FDMA gives users an individual allocation of one or various frequency bands, permitting them to utilize the allocated radio spectrum without interfering with each other. Multiple Access systems coordinate access among multiple users. The users may also share access by different methods such TDMA, CDMA, or SDMA. These protocols are utilized differently, at dissimilar levels of the theoretical OSI model.