[MKT]

It is said that in GSM the power of BCCH TRX is kept high in comparison to other TRX’s. Why?.. I/we know it but How?
As the hardware is same and the RF signal has to pass through the same path for all TRX’s.

[pix]

hello,

the BCCH TRX emits at maximum power all the time. That is what we know 🙂
It means that, on each timeslot of the BCCH TRX :
1. No power control downlink
2. No downlink DTX
3. Even if there is no data to transmit, the timeslots will be filled with dummy bits.

Other TRX can have PC, DTX, etc.

Regards,
Pix

[NK]

Hi! MKT,

BCCH power is kept high because BCCH carrier is used as HO reference.So its power must remains constant.

Regards,
NK

[Klumzy]

Hello,

I need to add a question for the below discussion.
For a type of hopping (synthesized frequency hopping), the BCCH freq is assigned to a certain BCCH and never hops.
But for other type of hopping (Base band hopping), BCCH freq hops for TN1 to TN7, only TN0 on the BCCH TRX never hops.
My question is that during the interval of time during which TN1 to TN7 are transmitted, how will the power control act. on which TRXs PC will be enabled and on which TRX will it be disabled? keeping in mind that BCCH freq hops as well on all TRXs.

Thanks in advance guys:)

[Pix]

Klumzy,

It’s simple : the TS’s which are using the BCCH frequency will be sent at maximum power.

Note :
For one MS receiving DL TCH with DL PC : once in a while it will receive a TS with max power and other times, it will receive a TS with “controlled” power. The average DL rxlev will be “increased” by this mechanism.

There is, therefore, a parameter that allows the MS to NOT take into account the TS “with BCCH freq”in the averaging. (in alcatel, it’s called PWTC, if I remember correctly)

Regards,
Pix

[raja]

hi pix,
kindly tell why we use BCCH and how and where we use i mean on which TRXS thanx
waiting fir ur kind response

Raja

[Abdel]

Hi Raja,

The BCCH is the broadcasting channel and it is a downlink logical channel. It broadcasts the sytstem information to all subscribers under it’s coverage. This includes the MNC,MCC,CI,Frequency, BSIC,C1,C2, LAI, RXlev,neighbouring list… and etc. Ussually the BCCH is used on the first TRX on timeslot 0.
Abdel

[raja]

thanx abdel can u tell plz. the the function of these dedicated control channel SDCCH SACCH and FACCH

BR

RAJA

[PC]

HI
pls explain me what is recmoded power for BCCH and TCH and so if increse the power BCCH and TCH as vis vers so what will hapen to Rx qul and C/I

[awahma]

@pix
Its not PWTC rather PWRC and it is effective for BBH only as BCCH timeslots 1 to 7 are included in hopping sequence.

[Pix]

Hello,

the question (from almost 3 years ago……) was about BBH.
And it was PWRC, you are right : PWTC is the name of the place I used to live in, 3 yrs ago :))) What a funny mistake to read 3 yrs after.

Cheers, and thanks for the correction,
Pix

[Author]

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