ALU Drop Radio

Hi Pix,
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.
Example:
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 🙂

Here what if i keep pref_mark as 0 for all the TRX, or what is recommended?

Hi Pix,
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.

Hi all

ALU
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.

Mania,
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.

Regards

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!

paul,

i didn’t understand your question. What are you asking exactly ?

(ps: ha ha, i never needed to graduate : i work there ! 🙂 )

mania,

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)

regards !
pix

Hi Mania,
Why don’t you opt for DFH(Discrete Freq Hopping) then? because its very similar to BBH and secondly no planning overload 🙂