can anyone explain these SDCCH terms ?

[coursekec]

i am new to RF and confused about the following terms

SDCCH/8, SDCCH/4 ... Does SDCCH/8 refers that 1 TS of SDCCH is shared by 8 users or is it something else ?

Optimization gurus please help..

thanks in advance..

[forumuser-2008]

SDCCH/4 is combination with BCCH

SDCCH/8 is separate timeslot which consist of 8 subslots and 8 subscribers can use it in the same time.

Thanks

[senjamir]

The combined SDCCH/4 is only implemented on timeslot 0 of the BCCH carrier

SDCCH/8 is a non combined multiframe in which you can use 8 timeslot

[coursekec]

thanks for the replies...i've one confustion. how many subscribers is supported by SDCCH/4 at a time and what is the duration of the timeslot in both the cases ?

[senjamir]

thanks for the replies...i've one confustion. how many subscribers is supported by SDCCH/4 at a time and what is the duration of the timeslot in both the cases ?

Hi,

Both timeslot have the same duration for any service such as call attempts, loc up and SMS.

Normally sms will occupy the SD slot for 6-7 seconds (MHT - Planning perspective)
SDCCH/4 - means 4 sub SD in SD channel
SDCCH/8 - means 8 sub SD in SD channel

Hope this might help. :)

Br,

Sen

[avatar]

Hi,
attached document contains guideline on SDCCH dimensioning for the GSM system, hopefully you will find it useful

[firstmaxim]

i am new to RF and confused about the following terms

SDCCH/8, SDCCH/4 ... Does SDCCH/8 refers that 1 TS of SDCCH is shared by 8 users or is it something else ?

Optimization gurus please help..

thanks in advance..
When a timeslot is assigned exclusively for SDCCH channels (used for call setup, location updating, periodic registration, SMS), then we refer to it as SDCCH/8, meaning there are 8 subchannels. Normally 1 SDCCH is assigned for every 2 carrier, but then accuracy of assignment will depend on actual SDCCH traffic of cell).

When there is a single carrier cell, we will combine the SDCCH with the BCCH. Here we will have 4 SDCCH subchannels, SDCCH/4. This ofcourse comes at the cost of reduced CCCH.

Regards