E******* Cell Utilization

[lechela]

Could anybody give me the formula for calculating cell TCH utilization in E******* system which includes both full rate (FR) and half rate (HR) please

[lechela]

anybody have information on this?

[senjamir]

Hi,

Try to use this one.

100*((TFTRALACC/TFNSCAN)+(THTRALACC/THNSCAN))*TAVASCAN/TAVAACC


Hope it helps. (",)

Br,
Sen


anybody have information on this?

[lechela]

Thanks Sen but using this formula sometimes gives utilization of more than 100%. Is there another formula that we can use?

[Ghost78]

Dear Lechela;

to calculate cell utilization, you have to use this formula:
TCH utilization= carried Traffic / nominal Traffic * 100

carried Traffic equals to the real traffic the cell has carried in BH in Er, in general you can extract this info from Business Object if you are using it.
Nominal Traffic, is calculated considering some parameters which are : accepted HR penetration, GOS, and TCH numbers, this is done using erlangB table.

let me show you one example to understand:

consider one cell having 4 TRXs and carrying in BH 35.47 Er
in normal config of this cell we got 29 TCH channels "4*8-1(BCCH)-2(SDCCH)".
if we consider that this cell has also 3 TS configured as Fixed PDCH.
and if we do our dimensioning at 40% of HR penetration and accepting a grade of service of 2% we will got

the number of channels we will get is (29(TCH)-3(FPDCH))*1.25(HR penetration)=32.5, we round it to 33 channels.
If we take ErlangB table in row corresponding to 33 channels and we see in column indicating Gos of 2% we will find a nominal traffic of 24.63 Er

so TCH utilization=35.47/24.63*100=144.03%

so under the conditions you put "40% HR and 2% of GOS" this cell needs an expansion.

this is what i'm using to do my calculation, if you have other question, don't hesitate.

B.R

[lechela]

Thanks a lot for the explanation Ghost78, it makes perfect sense