CELLULAR > UMTS > Frequency

Frequency

UMTS must operate in a frequency band defined by 3GPP TS 25.104. In FDD mode, the paired bands must have a minimum of 30MHz separation between the UL/DL. The Up-Link (UL) refers to the transmission from the phone to the base station, and is always the lower frequency, since the phone has a lower output power than the base station, and lower frequencies help the signal travel farther.

Values taken from 3GPP TS25.104

UARFCN 

The UARFCN (UTRA Absolute Radio Frequency Channel Number) is the channel number representing the full 5 MHz UMTS carrier. Only 3.84MHz is used for transmission, while the 116 kHz acts as a built-in guard-band to adjacent UARFCN's (580kHz + 3840kHz + 580kHz = 5MHz). If an operator owns the adjacent frequency bands, it is possible to reduce the size of the UMTS carrier from 5MHz to 4.4 or 4.2 MHZ, but this is not recommended.

The UARFCN channel number is calculated according to it's frequency. If no offset is used, the frequency is simply multiplied by 5 to get the UARFCN (ex:  2132.8 MHZ * 5 = UARFCN 10664) If an offset is used the offset must be first subtracted from the frequency.

RadioRaiders UARFCN Calc 

In order to quickly translate the Down-Link UARFCN to it's actual frequencies, RadioRaiders developed an on-line calculator  to quickly perform the calculation. Just enter the DownLink UARFCN and frequency bands and other info will be returned.

Enter DL UARFCN:

Frequency Band:
DL (U)ARFCN:
DL Frequency: MHz
UL Frequency: MHz
UL (U)ARFCN:

 

Theres also a downloadable version of the tool (.exe) that should work on any version of Windows. You may need .NET installed, which you can download for free from Microsoft here:

http://www.microsoft.com/net/Download.aspx

Download RadioRaiders UARFCN calc here:

Note: Correction to tool made on 04.Feb.2009, previous version had error in Bands X to XIII. Please download new version.

Screen-shot of UARFCN calc: