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time slot allocation on gsm radio

Wallis Dudhnath - 22nd May 2018  (09:24 GMT)

Hi Moses,

This GSM burst is used for the standard communications between the basestation and the mobile, and typically transfers the digitised voice data.

GSM uses a combination of both TDMA and FDMA techniques. The FDMA element involves the division by frequency of the (maximum) 25 MHz bandwidth into 124 carrier frequencies spaced 200 kHz apart as already described.

The carriers are then divided in time, using a TDMA scheme. This enables the different users of the single radio frequency channel to be allocated different times slots. They are then able to use the same RF channel without mutual interference. The slot is then the time that is allocated to the particular user, and the GSM burst is the transmission that is made in this time.

Each GSM slot, and hence each GSM burst lasts for 0.577 mS (15/26 mS). Eight of these burst periods are grouped into what is known as a TDMA frame. This lasts for approximately 4.615 ms (i.e.120/26 ms) and it forms the basic unit for the definition of logical channels. One physical channel is one burst period allocated in each TDMA frame.

VBR/ Wallis Dudhnath

MOSES - 14th May 2018  (11:02 GMT)

Once a time slot is assigned to a user means, whether the same time slot will be associated with the user till he ends his call or any possibilities for change in time slot??

Mohd. Muzammil - 19th July 2003  (11:29 GMT)


The following link on GSM overview explains brusts and burst formats. Hope this helps you.


Nguyen - 18th July 2003  (03:13 GMT)

OK, the TDMA and FDMA are implemented in the GSM. By using FDMA we have 124 carriers.

Each of these carrier frequencies is divided in 8 timeslots, using a TDMA scheme.

The fundamental unit of time in this TDMA scheme is called a burst
period and it lasts approx 0.577 ms. 8 burst periods are grouped
into a TDMA frame (approx 4.615 ms), which forms the basic unit for
the definition of logical channels.
One physical channel is one burst
period per TDMA frame.

Channels for speech and data traffic (TCH) use 26-frame multiframe. Other control channels (such as BCCH, RACH, PCH,...) use 51-frame multiframe.

Pls adv if you have other question.


frededrick - 17th July 2003  (15:23 GMT)

would you tell me all issues regarding timeslot in gsm radios to your knowledge and capacity to keep pace in this growing telecom indusrty.

help me in whichever way your think gonna make it.

Nguyen - 17th July 2003  (14:46 GMT)

Sorry but your question was not so clearly for me. Please describe more concrete, so that other can help you.


frededrick mbogo - 17th July 2003  (11:19 GMT)

how will I assign time slot for a given radio and what are the basics should one need to know regarding this issue?

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