TDMA full form is Time Division Multiple Access uses time instead of frequency. It is used to facilitate channel sharing without interference. Different user shares the same time slot of the complete time available. Each user to allocate a time slot in which the user can access the channel and in each slot, only one user is allowed to transmit or receive.
TDMA was more used by Europe, Japan, and Asian countries, whereas CDMA is widely used in North and South America. But nowadays both technologies are very popular throughout the world.
Advantages of TDMA :
- TDMA can easily adapt to the transmission of data as well as voice communication.
- It has the ability to carry 64 kbps to 120 Mbps of data rates.
- No interference from simultaneous transmission.
- TDMA is the cost-effective technology to convert an analogue system to digital.
- Share a single carrier frequency with multiple users
- Mobile assisted handoff possible
- TDMA provides the user with extended battery life since transmitting the only portion of the time during conversations
- Flexible bit rate
- No frequency guard band required
- No need of a precise narrowband filter
- TDMA separates users according to time ensures that there will be no interference from the simultaneous transmission.
- TDMA allows the operator to do services like fax, voiceband data, SMS as well as applications such as multimedia and video conferencing.
- TDMA offers substantial savings in base-station equipment, space, and maintenance, an important factor as cell sizes grow ever smaller.
- Dual-band 800/1900 MHz.
- It is the only technology that offers an efficient utilization of hierarchal cell structures like pico, micro, and macro.
Disadvantages of TDMA :
- In TDMA each user has a predefined time slot so that users roaming from one cell to another are not allotted a time slot. Thus, if all the time slots in the next cell are already occupied, a cell might well be disconnected. In the same way, if all the time slots in the cell in which a user happens to be in are already occupied, a user will not receive a dial tone.
- It is subjected to multipath distortion. A signal coming from a tower and receive to handset might come from any one of several directions so on the road signal bounced off several different buildings before arriving which can cause interference.
- Network and spectrum planning is intensive.
- Too few users result in ideal channels rural versus urban environment.
- High synchronization overhead.
- Frequency/slot allocation is to be complex in TDMA.
- Equalization was necessary for high data rates.
- Demands high peak power on the uplink in transient mode.
- Signal processing is required for matched filtering and correlation detection.
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