U900 _ UARFCN Calculation

[khurrambilal01]

Hi Experts we have done refarming on 900 band and are launching 3rd carrier on U900 layer,

I just need to confirm one thing for UARFCN calculation, We are using 4.2Mhz band for U900 with 1 X 200khz channel on both sides to be used as guard band.
The start frequency for 4.2Mhz band is ARFCN 24 and ending is ARFCN 44.

The middle frequency comes out to be 34 ARFCN = 941.8Mhz, to calculate DL UARFCN 941.8-340 = 601.8 X 5 = 3009 UARFCN DL,

I have two questions:

1) While calculating UARFCN we should multiply 601.8 with 5 or 4.2?
2) If we have to multiply by 5 then considering 5 Mhz we have two middle frequencies, 33 & 34 which result in UARFCN DL 3008 & 3009, Which one to use?

With 4.2 Mhz we are using 2 guard band frequencies one 200khz on each side. Guard frequencies ARFCN 23 & 45.

[Philippe]

The UARFCN is defined in 3GPP TS25.101.
In 900MHz band called band VIII at 3GPP, the DL UARFCN is computed
as UARFCN DL = 5 * (FDL -340) with FDL the downlink frequency in MHz, 340 being a specific offset used for band VIII (it would be 0 for band I 2100MHz).

This is the 3GPP definition. It is not dependent on the fact you are using 4.2MHz.

If your 2 guard bands are GSM ARFCN 23 (939.6MHz) and ARFCN 45 (944), it means your 3G frequency will be (944-0.1)-(939.6+0.1)= 4.2MHz width (OK) with central frequency being (944+939.6)/2=941.8MHz which corresponds to UARFCN DL =5*(941.8-340)=3009. So 3009 is well the right UARFCN to use in your case.

[omarGSMUMTS]

right philipe !