- This topic has 31 replies, 1 voice, and was last updated 10 years, 7 months ago by Mania.
30th July 2010 at 11:05 #63770biodunGuest
pls can anyone help me with stuffs on Atoll+wiamx+TEMS.thnks30th July 2010 at 16:49 #63771ALUGuest
DFH is a type of SFH in which
no of Frequencies >= no of TRX
You dont have to assign a complete hopping group to each cell like in normal SFH.Its more of similar to BBH.Kindly note that its not necessarily used for cells which have little amount of TRX.Its equally beneficial for high configuration cells aswell.
Consider Frequency Band from 500-532(TCH) and 534-550(BCCH)ARFCN and a 4-TRX cell.
Lets just say that you are implementing DFH with
NO of Frequencies=No of TRX
So, you can have a scenario like:
Cell A= 534, 500,531,515
Cell B= 550, 504,512,518
Cell C= 546, 506,510,520
So, you see here the plan is just like BBH except for the fact that the whole BCCH TRX doesnt hop.Its more beneficial when you assign more frequencies than the no of TRXs.So, mostly for low configuration sites(2-TRX) , you can assign 4 frequencies and reap the advantage of DFH 🙂
I was curious about a statement of urs that
“most calls will be allocated on 2nd trx ” why do u say that? Has Alcatel removed the parameter “pref-mark” in your Release or you dont like playing with it(pm)? 😛
You are right about the SDCCH 🙂30th July 2010 at 18:11 #63772pixGuest
ok about dfh, it’s clear 🙂
the pref mark is fantastic, as long as you don’t have GPRS traffic… so no, i don’t like playing with it. Anyway, default behaviour is fine, no need to play with pref mark in this situation.
en_ma_selection is sufficient too (cf. other thread) to put MS on the hopping TRXs rather than on the BCCH TRX.
thanks for the enlightening discussion 🙂
pix30th July 2010 at 18:33 #63773MickeyGuest
Here what if i keep pref_mark as 0 for all the TRX, or what is recommended?30th July 2010 at 18:37 #63774pixGuest
i used to keep 0 for all TRXs, that’s what i would recommend on a standard network.
only in some case of exotic use of SFH (different MA list per TRX) or in case of faulty TRX troubleshooting, changing the trx pref mark is interesting.
(just my opinion…)
pix1st August 2010 at 16:23 #63775ALUGuest
Well i personally feel that apart from Faulty TRX troubleshooting ,prefmark can be very useful at times even if u r having normal SFH(1*1 or 1*3).At places where the azimuths are not standardized and hopping frequencies are very much interfered due to overlapping of coverage area of diff cellshaving same FHS(and there r plenty of such cases in my current network and operator doesn’t allow redesign :P)…you cannot do much as whenever the call goes on hopping, the Rxqual degrades(6,7).So, simple solution is to push traffic to the BCCH TRX by just change of PM 🙂
Vice versa is also applicable at certain cases.2nd August 2010 at 06:02 #63776ManiaGuest
Just curious from the below discussion.
|How can FH (Frequency hopping increase coverage area) also coverage area of the cell usually defined by BCCH TRX (for call setup and handover).
Also ALU you case seems ideal for BBH trial and should be good for your network then why not proceed for BBH? should have great improvement in KPIs6th August 2010 at 06:01 #63777PixGuest
are you saying That Prefmark is useful to avoid calls going on anything else than bcch trx? Well, ok i call that a very specific situation 🙂 as mania said it might be Time to use bbh.
the initial access is done on bcch ts0 but it is so short that even with low rxlev it could go through. But call setup (sdcch) and call (tch) are long and require a good average lev. Freq diversity can help improving lev by fighting rhe fast fading.
Regards6th August 2010 at 09:21 #63778paulGuest
My network is using FSH 1×3, not BBH, only few sites are using BBH (outside inner city).
Well, as we know, FSH means that the frequency which will not be hoped is only the BCCH frequency, which mean it’s located in TRX-1 (Usually). Other TRXs (2,3,4), the frequencies are hoped (Each of TRX 2,3,4 has different MALIST).
In my network, sector 1 & 3 will be hoped periodically based on MAIO 0,2,4 and sector 2 MAIO 1,3,5.
Your explanations is related to BBH, if I’m not wrong 🙂 But my case is in FSH (Frequency Synthesize Hopping).
Based on my experience, if I extend MALIST by adding some frequecny channel from BCCH range Frequency and change the MAIO, it improved the performance (SD Drops, Drop Call). And even though like that (Putting BCCH frequency in MALIST),it seems no inner interference happened. It’s true, you can try it.
Any idea Pix?
By the way, if you are from France, it seems that you graduated from ALCATEL University :):):)
Paul7th August 2010 at 17:31 #63779ALUGuest
yes pix, its really helpful in certain scenarios and as suggested by you & Mania, we are going for BBH…just waiting for Operator to finalize the details and go ahead with the plan!9th August 2010 at 06:09 #63780ManiaGuest
Hi pix (though he is on leave):) / anyone with info.
regarding your previous explaination on how FH can improve coverage
“the initial access is done on bcch ts0 but it is so short that even with low rxlev it could go through. But call setup (sdcch) and call (tch) are long and require a good average lev. Freq diversity can help improving lev by fighting rhe fast fading.”
Then how come we prefer keeping SDCCH on BCCH TRXs, here the concept is that keep SDCCH on BCCH as it would be cleaner (and is planned cleaner). seems like the two concepts are contridictory to each other.14th August 2010 at 14:44 #63781pixGuest
i didn’t understand your question. What are you asking exactly ?
(ps: ha ha, i never needed to graduate : i work there ! 🙂 )
trx1 provides better rxqual due to better frequency planning
trx 2, 3… provide better rx lev due to frequency diversity (if FH is activated), but this is not always true, and hard to quantify anyway.
if bbh is activated, trx1 can also get frequency hopping (except ts0)
so why SDCCH and BCCH on TRX1 : because rxqual is better, therefore less interference. (that’s a measurable improvement, whereas freq diversity is hard to measure)
pix16th August 2010 at 04:29 #63782ManiaGuest
You Just added valuble gems to my vault. 🙂
@ ALU: Glad to be of help, hope I was in your network, my current opperator is severely undermining BBH implementation even when we have shown great improvement, just because of Planning overload added by BBH.17th August 2010 at 16:44 #63783ALUGuest
Why don’t you opt for DFH(Discrete Freq Hopping) then? because its very similar to BBH and secondly no planning overload 🙂17th August 2010 at 18:47 #63784pixGuest
dfh requires as much planning effort than the bbh, since you need to assign a specific FHS to each sector 🙂