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Member
Reputation: 238
why 8 time slots?
Hi freinds
i have next doubt .......
why were limited to 8 time slots not more?, and similarly 26 tdma frame,
52 frame for Control channels?
any specific reason .......
regards
Plannerguy
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2009-05-29 10:58 PM
# ADS
Circuit advertisement
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why 8 TS.
the reason is certainly related to the fact that the speech is put in frame of 20ms. And when the GSM was invented, 20ms could be encoded/compressed/etc. into 4x0.577 ms.
20ms => 4x0.577ms = 2.3ms
each 20ms, one user needs 2.3ms.
So during 20ms on the air, only 8 calls can be multiplexed.
20/2.3 = 8.7
The remaining is used for in band signalling (sacch).
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Member
Reputation: 18
@zeaboll
Can you explain deeply about 4*0.577ms in 20ms.
I don't undersatand.
Tks!!!!111
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Member
Reputation: 38
why 8 TS
Bandwidth of GSMK filter is 67.5 Hz and the output of the mobile is at 270.333
270/67.5 = 4 i.e. -4 channels in UL and 4 channels in DL thus giving us 8 timeslot per TRX.
Regards,
Amit
agarwalamit081@gmail.com
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Member
Reputation: 22
for reason of 8 ts, i don't know
Last edited by m2m; 2009-09-16 at 01:59 AM
Reason: duplicate post
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Member
Reputation: 22
There are 2 types of multiframe 26 multiframe, and 51 multframe.
in 1 super frame there are 51 - 26 frame multiframe and
also in 1 super frame there are 26 - 51 frame multiframe
The reason why we need to have different between 26 and 51 due to the concept of sliding multiframe, to let mobile during idle can detect BSIC of neighboring cells
If u like my answer thanks and reputation would be great
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Member
Reputation: 91
Originally Posted by
zaebolll
why 8 TS.
the reason is certainly related to the fact that the speech is put in frame of 20ms. And when the GSM was invented, 20ms could be encoded/compressed/etc. into 4x0.577 ms.
20ms => 4x0.577ms = 2.3ms
each 20ms, one user needs 2.3ms.
So during 20ms on the air, only 8 calls can be multiplexed.
20/2.3 = 8.7
The remaining is used for in band signalling (sacch).
the reason is related to bandwith capacity no more
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