- This topic has 9 replies, 1 voice, and was last updated 10 years, 4 months ago by ISrar Ahmad.
4th May 2008 at 13:09 #52321RFGuest
I have question about TRX which support 8psk and TRX which support GMSk when it is possible to make cell with one TRX support 8psk and other GMSk with making the BCCH TRX with 8psk and the last two ts as normal TCH it is possible to make it in the hopping list or not if yes there will difference in output power and bad cell performance???????4th May 2008 at 15:01 #52322pixGuest
you are making things too complicated : let the technology works for you 🙂
a TRX is 8PSK-capable when it can transmit GMSK and 8PSK bursts. For instance :
TS0 : BCCH (always GMSK)
TS1 : SDCCH (always GMSK)
TS2/3/4 : PDCH (can be alternatively GMSK or 8PSK)
TS5/6/7 : TCH (only GMSK available, as per today)
TS2/3/4 are defined dynamically as PDCH : you actually define them as TCH, and they’ll be defined as PDCH if some users need PDCH.
1 PDCH can serve several users (max is around 10). There is a multiplexing of the radio blocks. One block for user A can be in GMSK, while the next block for user B will be in 8PSK.
(in my example :
User A does not support 8PSK
User B supports GMSK)
pix5th May 2008 at 01:05 #52323navinGuest
hi all.speech disturb and gets normal during calls many times. some times no problem. happening in all bsc allmost. vendor is alcaltel.5th May 2008 at 06:08 #52324RFGuest
what i mean is that if BCCH TRX is only 8psk and other TRX is GMSK modulation let say if user A first get TCH in BCCH TRX let say TS 7 if user A hop to other TRX with GMSK what will be happen because Edge TRX has lower output power than GMSK modulation by aroung 3dB??????5th May 2008 at 06:50 #52325TYnooGuest
For CS calls nothing will happen as all are in GMSK. By the way, BCCH TRX has to support as well GMSK since BCCH TS and SDCCH are only in GMSK modulations.
In your case, I understand you are talknig about voice call… your TCH will be GMSK from the beginning.
8-PSK average power is lower due to the modulation itself (peak power remains the same). This has no impact on voice coverage, and hardly no impact on EDGE performances.5th May 2008 at 10:55 #52326pixGuest
the timeslot hops to another TRX, but the content of the timeslot remains as it was before :
if i have a GMSK ts on TRX 2 / TS 7, and then there is a hopping to TRX 3 / TS 7 -> this is still GMSK timeslot. You’re talking about BBH, right ?
as i said, you’re making things too complicated. A TRX will work with different modulations (GMSK / 8PSK) for different timselots, within different TDMA frames.5th May 2008 at 12:52 #52327RFGuest
yes it is BBH and as you know if I have Edge service the TRX of this BCCH will not be in hopping list the call remain in BCCH TRX and therefore the whole TS on BCCH TRx will be 8psk modulation5th May 2008 at 20:04 #52328pixGuest
in BBH, the BCCH frequency is in the hopping list. And the timeslot carrying an 8PSK PDCH will be hopping, with other PDCH GMSK and/or other GMSK TCH, etc etc.6th May 2008 at 05:23 #52329RFGuest
NO in my network when a site support edge service the TRX of BCCH will not hop because we tested when BCCH TRX making in hopping list we loss edge service because common carrier ( normal TRX ) not support 8psk .1st December 2010 at 02:09 #52330ISrar AhmadGuest
Normally i face the proble mof inddor coverage in most of the areas when my call is on DCS Hopping, even the RxLev gets Below -100 db, so how can this issue be treated.