How to configure the frequency not defined in 3GPP ?

It is possible to define a non standard LTE frequency band or to over-ride standard bands. This is done by adding custom_freq_band object to the eNodeB configuration file. It should contain the following fields. If the uplink information is not provided, it is assumed to be the same as the downlink (TDD band).

band
dl_earfcn_min
dl_earfcn_max
dl_freq_min
ul_earfcn_min
ul_earfcn_max
ul_freq_min

The carrier frequency in the uplink and downlink is designated by the E-UTRA Absolute Radio Frequency Channel Number (EARFCN) in the range 0 – 262143. The relation between EARFCN and the carrier frequency in MHz for the downlink and uplink is given by the following equations (cf. 36101 3GPP spec):

F_downlink = F_{DL_Low} + 0.1 (N_DL - N_{DL_Offset})

F_uplink = F_{UL_Low} + 0.1 (N_UL - N_{UL_Offset})

Where,

N_DL is downlink EARFCN
N_UL is uplink EARFCN
N_{DL_Offset} is offset used to calculate downlink EARFCN
N_{UL_Offset} is offset used to calculate uplink EARFCN

An example is shown below:

custom_freq_band: { band: 90, dl_freq_min: 730, dl_earfcn_min: 250000, dl_earfcn_max: 250149, ul_freq_min: 700, ul_earfcn_min: 251000, ul_earfcn_max: 251149, },

In this example, a FDD LTE band 90 is defined with DL frequency range of 730 to 745 MHz and DL EARFCN range of 250000 to 250149. F_{DL_Low} is 730 MHz and N_{DL_Offset} is 250000.