1) Time division multiple access (TDMA) is a digital transmission technique that allows multiple users to access the same radio frequency channel by allocating unique time slots to each user. 2) TDMA divides each cellular channel into three time slots to increase data capacity and enables features like voice, fax, SMS, and multimedia services. 3) The efficiency of TDMA is measured by the percentage of transmitted data containing user information rather than overhead, and the number of TDMA channels provided is calculated by multiplying the number of TDMA slots per channel by the total available channels.