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Dear all, dear Pix!
Anoter question about Alcatel BSS 🙂
As I know, BS_PC is inhibited on BCCH frequency (B9 – Introduction to radio fine tuning, page 84 ), but I’ve noticed in RNO (QoS rep. Alc_Mono_Power …) that it works even on BCCH tre. And it’s not a unique cell – there are a lot of cells like that. Or maybe PC is inhibited only on BCCH timeslot?BR,
I think you are using BBH hopping ?
In this case, one timeslot in the BCCH TRE is using different frequencies, not only BCCH.Only the timeslots which are carried onto the BCCH frequency are emiotted at full power.
If BBH is enabled, then those timeslots will change each TDMA frame.
Only TS0 of TRX1 is at full power all the time.
Other TS will be at full power only when they’re hopping onto the bcch frequency.If there are 4 TRX, the TS5 of TRX1 will be transmitted at (one letter = 1 TDMA frame)
H-L-L-L-H-L-L-L-H-L-L-L-H-L-L-L…H = max power
L = “power controlled” powerDear Pix,
Yes, we use BBH for 900MHz cells and Synthesizer hopping (RH) for 1800MHz cell. We saw this situation in both cases. But as I remember in BBH each tre emits its own frequency permanently and MS is leaping between tres? In RH our BCCH also doesn’t hop – so, I became confused 🙁In case of RH:
BCCH TRE is always emitting at full power. So BS TXPWR always = Max. But MS TXPWR can be decreased (thx to UL PC).In case of BBH:
the MS doesn’t hop between different TRX : each TS will hop onto different frequencies. This is called “synthetized” BBH 🙂 it’s alcatel-lucent solution.
therefore, in bbh, even the bcch trx will lower its power, during the TDMA frames emitted onto non-BCCH frequencies.Dear Pix,
great shame on me 🙁 I had different point of view about BBH (particulary in Alcatel) :((
Therefore some more questions:)
in case of TCH-tre:
We have FHS1 for TSs from 1 to 7 (the same MAIO) and FHS2 for TS0 (and corresponding MAIO). FHS2 containes less frequences than FHS1 (without BCCH). So TSs from 1 to 7 must be emitted on the same frequency within one frame, aren’t they? And during one frame tre emits two frequencies – one while TS0 and another – while the rest of TSs, doesn’t it? Can we say that certain connection is served by one certain carrier unit/tre (if we have no intracell HO)in this cell?Hi Ivann,
We have FHS1 for TSs from 1 to 7 (the same MAIO) and FHS2 for TS0 (and corresponding MAIO). FHS2 containes less frequences than FHS1 (without BCCH). So TSs from 1 to 7 must be emitted on the same frequency within one frame, aren’t they?
— YES
And during one frame tre emits two frequencies – one while TS0 and another – while the rest of TSs, doesn’t it?
—- YES
Can we say that certain connection is served by one certain carrier unit/tre (if we have no intracell HO)in this cell?
— If MS is allocate on the TRX3 / TS5 then it will stay there (unless call release or handover). Physically, the call is always handled by the same TRE. But each TDMA frame, the frequency used is modified. Basically, the same TS is used, but with different frequencies.
The frequencies are changing within the same timeslot 🙂Dear Pix, thanks a lot for your patience 🙂
So there is no much difference between BBH and RH (except BCCH-tre, of course) – they use same principle (basically).
But now I can’t understand this part of “Alcatel BSS description”:
… Synthesized Frequency Hopping functions in a similar fashion to Baseband
Frequency Hopping, but is performed at a different location. Instead of
switching each time slot between traffic channels, the channel assigned to a
time slot is assigned to a fixed Carrier Unit (or TRE).
The Carrier Unit/TRE changes frequency with each TDMA frame in accordance
with the HSN algorithm selected, in the same manner as above. Thus, instead
of the channel hopping from one fixed transceiver to another, the transceiver
itself hops from one frequency to another, in both cases, according to the
algorithm and parameters selected.
Synthesized Frequency Hopping has the advantage of allowing an FHS to
contain one more frequency than the number of Carrier Units/TREs in the
system. This is particularly useful in some microcellular applications where only
one transceiver is available for Frequency Hopping.
Note: Normally, in both Frequency Hopping schemes (Baseband and Synthesized),
time slot 0 (TS0) is not available for Frequency Hopping. This is because
it carries the BCCH, which must always be at maximum power and on a
frequency known to mobile stations in Idle mode in the cell…And questions:
1) What does it mean – “Instead of switching each time slot between traffic channels”? In BBH we have a certain TS on certain tre – and each frame this TS is emitted on different frequencies the procedure is similaar to RH,as I understand.
2) “Thus, instead
of the channel hopping from one fixed transceiver to another, the transceiver
itself hops from one frequency to another, in both cases, according to the
algorithm and parameters selected.” It sounds like that: in BBH channel (and consequently – MS) hops between different transceivers. But maybe I’m not right :(((Ivann,
How old is this document ??
This is not true anymore !
Or if it is true, it means I’m wrong… and i just can’t be wrong about this 🙂 I need some time to find the proof though…
hello i saw your discussion and i like it ,
i would like to ask what is the immediate assignment success rate for alcatel b9.
need your supportit’s probably equivalent to the Alcatel-Lucent indicator called “SDCCH ASSIGNMENT UNSUCCESS RATE”.
Thank u pix can i have detail formula for SDCCH ASSIGNMENT UNSUCCESS RATE
Dear Pix,
I trust you more than any of docs 🙂
This document is called “BSS system description”, the part of “B9 Field Procedure Documentation”. The question is important to me bacause this book is reffered very often by my colleagues (and by me too – before 🙂
Thanks a million for your help !!!Dear Pix
I hope I didn’t look impolite or incredulous in this discussion 🙂
I’m really grateful to you :)))Ivann, you’re really nice, no problem at all 🙂
The BBH in ALU is just as what I said :
in BTS product description:
Synthesizer frequency hopping
Synthesizer frequency hopping (or so-called radio frequency hopping) is supported by the whole
BTS range, its use being optional. Two frequency hopping modes are available:– Standard RF hopping mode: A cell with N TRXs can have N-1 TRXs hopping (the TRX carrying
the BCCH is not hopping), on M frequencies (M usually > N).
– Pseudo baseband RF hopping mode: A cell with N TRXs can have all its N TRXs hopping on N
frequencies.————
conclusion : it’s pseudo BBH 🙂i won’t look further, because i’m sure of what i’m saying. In old alcatel docs, this wasn’t true (G1 BTS didn’t work this way, G2 neither, perhaps)
Your doc is not updated, probably alcatel didn’t care about updating it… you can raise the concern to your TPM, so alcatel updates this doc…
The truth about BBH in Alcatel became a revelation in our department 🙂
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