What is TDMA Cell Phone Technology?

Compare TDMA Technology Versus CDMA

There are three main cellular technologies: Older Analog/FDMA, Modern TDMA, Newer CDMA

TDMA is the leading digital technology in cellular phones today.

Time Division Multiple Access (TDMA) is one of several technologies used in digital wireless transmissions that increases the efficiency of the network by allowing a greater number of simultaneous transmissions. Networks using TDMA assign 6 timeslots for each frequency channel. Devices using the wireless network send bursts of information that are reassembled at the receiving end.

TDMA builds on FDMA (Frequency Division Multiple Access) by dividing conversations by frequency and time. Since digital compression allows voice to be sent under 10 kilobits per second (equivalent to 10 kHz), TDMA can fit three digital conversations into a FDMA/Analog channel (which is 30 kHz). By sampling a person’s voice for, say 30 milliseconds, then transmitting it in 10 milliseconds; the system is able to offer 3 timeslots per channel in a round-robin fashion. This technique allows compatibility with FDMA while enabling digital services and easily boosting the system by 3 times capacity. This leads to increase calls, more users on the network and better cellular quality.

While TDMA is a good digital system, it is still somewhat inefficient since it has no flexibility for varying digital data rates (high quality voice, low quality voice, pager traffic) and has no accommodations for silence in a telephone conversation. In other words, once a call is initiated, the channel/timeslot pair belongs to the phone for the duration of the call. TDMA also requires strict signaling and timeslot synchronization. A digital control channel provides synchronization functionality as well as adding voice mail and message notification. Due to the digital signal, TDMA phones need only broadcast at 600 milliwatts.

Compared to analog FDMA transmissions, TDMA offers a cellular carriers a efficient bandwidth option. TDMA is more secure, and has better quality of voice transmissions over longer and shorter distances. The newer CDMA(Code Division Multiple Access) technology is more advanced than basic FDMA. Due to lower cost savings compared to CDMA, TDMA is the digital transmission of choice in today's cellular world. TDMA is more popular with cellular carriers and manufactures and is the adopted digital standard for most phones. TDMA can be viewed as modern technology, FDMA/Analog as older technology.