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Time Division Multiple Access (TDMA)

 

 

Introduction

Time Division Multiple Access

 

Definition

Time Division Multiplex Access (TDMA). Type of multiplexing where two or more channels of information are transmitted over the same link by allocating a different time interval ("slot" or "slice") for the transmission of each channel, that is, the channels take turns to use the link. Some kind of periodic synchronizing signal or distinguishing identifier usually is required so that the receiver can tell which channel is which. See also TDM.

 

Additional Information

Time division multiple access (TDMA) is a channel access method for shared medium networks. It allows several users to share the same frequency channel by dividing the signal into different time slots. The users transmit in rapid succession, one after the other, each using its own time slot. This allows multiple stations to share the same 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 such as 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, combat-net radio systems, and PON networks for upstream traffic from premises to the operator. For usage of Dynamic TDMA packet mode communication, see below.

 

 

 

 

 

TDMA frame structure showing a data stream divided into frames and those frames divided into time slots.

 

 

TDMA is a type of Time-division multiplexing, with the special point that instead of having one transmitter connected to one receiver, there are multiple transmitters. In the case of the uplink from a mobile phone to a base station this becomes particularly difficult because the mobile phone can move around and vary the timing advance required to make its transmission match the gap in transmission from its peers.

 

TDMA characteristics

 

  • Shares single carrier frequency with multiple users
  • Non-continuous transmission makes handoff simpler
  • Slots can be assigned on demand in dynamic TDMA
  • Less stringent power control than CDMA due to reduced intra cell interference
  • Higher synchronization overhead than CDMA
  • Advanced equalization may be necessary for high data rates if the channel is "frequency selective" and creates Intersymbol interference
  • Cell breathing (borrowing resources from adjacent cells) is more complicated than in CDMA
  • Frequency/slot allocation complexity
  • Pulsating power envelope: Interference with other devices

 

Reference


Wikipedia TDMA Definition.

 
Version history
Revision #:
2 of 2
Last update:
‎08-23-2017 12:57 PM
Updated by:
 
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