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Frequency Planning

APZ - 30th July 2019  (05:28 GMT)

One thing I am not clear, in BCCH planning the carrier spacing between
the cells among intra cells of same site and inter cells of adjcent sites should be 400 Khz , some say
1 Mhz to avoid Co-channel and adjacent channel interference. How about TCH channal assignments ?
In principle, the spacing between
BCCH and TCH of same sites must be
at least 400Khz, Is there any principles of TCH frequency planning
among the cells of same site and inter cells of adjacent cells of adjacent sites ? If have, I would pleasure to learn it

Pix - 12th May 2015  (09:34 GMT)

Hi Mickey

With so many ARFCN available, you don't need to worry. It would be interesting to keep 5 to 8 ARFCN not used, for future TRX extension, or new cell integration.

The way to split the band between BCCH and TCH depends on how many TRX per cell.
My example was for 4 TRX per cell, in which case you give 30% of band to BCCH and 70% of band to TCH.
In your case, with 6 TRX per cell, I would give 20% to BCCH band, 72% to TCH band, and 8% free, reserved for future use.
There is now several automatic frequency planning tools, based on radio measurements. It's usually a tool provided by the vendor (EFO for Ericsson for example). I'm currently using extensively EFO for creating frequency planning on ALU, Huawei, Ericsson on Nokia networks. The results are just incredible.
It's way more efficient to do a FP using such tool rather than doing it manually. And the resulting KPI... well, they are amazing :)

Rgds, Pix.

Mickey - 8th May 2015  (05:57 GMT)

Hey Pix,

Hope you are doing good,Thanks for your valuable answers.

Below you mentioned TCH Freq should be 3 times more than BCCH, does it means, Suppose i have total 75 Channels,And my Avg TRX per cell is 6, then TCH should be 6*3, i.e minimum 18.
I want to know what is the exact calculation for No.of BCCH if there is any Technical Calculation to this.
Can i keep like this : Out of 75 Channels - BCCH 28, TCH 47 (it will also fulfill (No. of TRX * 3) crieria.

What you say ?

Pankaj - 2nd May 2015  (10:12 GMT)

I we have less BCCH frequency available and there is more sites to plan BCCH frequency,then hw could i reduce the inetrference.....???

Shaon - 1st April 2008  (07:30 GMT)

7x21-is it posssible?

ZAPH - 31st March 2008  (07:52 GMT)

can anyone explain what is this 4x3, 7x21, 21x3, 1x3........

is it related to frequency planning as "freq x no.of sites" or something else

plz explain clearly so that funda may be clear in one reading..

thanx

zoy - 30th March 2008  (18:36 GMT)

This tooL ILSA is part of the Asset3G the planning tool of aircom. This tool greatly depends on the planning parameters and radio propagation. Therefore, ILSA needs the ASSET3G.

zoy - 28th March 2008  (15:55 GMT)

Hi Abdel,

Would it be possible to have the ILSA automatic Frequency planning tool from Aircom.

Abdel - 13th February 2008  (19:22 GMT)

Hi pix and Huawei RF,

One guy came up with this proposal to mix up the TCH and BCCH and I don't know why he is trying to use these technique. That is why I asked you guys. Planning manual is a bit difficult but I often use the ILSA automatic Frequency planning tool from Aircom which is part of their enterprise suite. After that I make some adjustments of the ILSA output.
"I didn't really get what you mean by 7x21... may be u mean 21x3?" No I made a mistake we are using fractional reuse 13 pattern.
The distance between our sites are 200-400m.

Pix - 13th February 2008  (13:57 GMT)

Abdel,

It looks like you're going to perform a manual frequency planning, right ? That's why you're trying to find a way to split your frequency band in two parts : BCCH & TCH.

If you choose to alternate BCCH and TCH, as you said, the main problem I can see is that you have to be extra-careful : it might be easy to make a mistake and plan adjacent BCCH/TCH in the same site, or even in the same cell.
Otherwise, if you are extra-careful (and i'm sure you are), this is an interesting approach.

Quite original, but that might actually work, if you can ensure that your C/I stays above -6dB (limit of adjacent interference impacting the radio quality). In other words, you need a good cell planning with sharp borders.

But additionally (that's what everybody is talking about in this post), it is surprising to see as many BCCH's as TCH's frequencies. Unless you have only 2 TRX per cell, this can't work : your BCCH quality is going to be too good, and your TCH quality too bad.

As a rule of thumb, if you plan 1 trx BCCH + 3 trx TCH per cell, you should have 2.5 to 3 times more frequencies for TCH than for BCCH (approx.). For "easy" manual planning, it should be 3 times more.

I hope it helps... regards,
pix

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