GSM BTS spectrum sector capacity

Hello everyone

I’m trying to figure out out to compute single band and dual band spectrum sector capacity in TRX’s for GSM BTS. I came across the following:

Capacity Single Band= (N900/(fsu * lambdatrx)) – 0,5

Capacity dual band = Capacity single band + (N1800/(fdu1800 * lambdatrx))

Where:

N900 – Amount of 900Mhz spectrum
fsu – sector re-use factor for 900 Mhz
N1800 – Amount of 1800Mhz spectrum
fdu – sector re-use factor of 1800 Mhz

Is anyone able to confirm this? Thank you in advance