nRF9160 - mfw 1.3.5 - EARFCN - uplink/downlink

[Achim Kraus]

Using %XMONITOR I get one EARFCN value.

According 3GPP TS 36.101 (V14.3, page 107) there are two EARFCN values, one for the uplink, one for the downlink. The value I get reported with XMONITOR seems to be the one for the downlink. Is there a possibility to get also the uplink value?

The background for that question is band 20, where the uplink range is critical close to an unlicensed range in Germany (862 upper border of band 20 to 863-870 unlicensed in Germany). If it's possible to get that value, it's easier to exclude or consider interference as source of errors.

[Simonr]

Hi Achim

I got an update from the devs on this today. We're in the middle of summer vacation and low on staff, so that's why it's taken some time to get back to you. 

It seems like UL EARFCN is not provided in the AT interface. The UL channel is defined by default TX-RX separation (36.101 / Table 5.7.3-1 and Table 5.7.4-1) or it may be explicitly signaled with SIB2 (SIB2 content can be seen from traces).

36.331 / Ch. 6.3.1:

SystemInformationBlockType2 field descriptions

ul-CarrierFreq
For FDD: If absent, the (default) value determined from the default TX-RX frequency separation defined in TS 36.101 [42, table 5.7.3-1] applies.
For TDD: This parameter is absent and it is equal to the downlink frequency.

Additionally there is restriction for EUTRA on how channel numbers may be configured near band edges.

The channel numbers that designate carrier frequencies so close to the operating band edges that the carrier extends beyond the operating band edge shall not be used. This implies that the first 7, 15, 25,
50, 75 and 100 channel numbers at the lower operating band edge and the last 6, 14, 24, 49, 74 and 99 channel numbers at the upper operating band edge shall not be used for channel bandwidths of 1.4, 3, 5, 10, 15 and 20 MHz respectively.

Best regards,

Simon

[Achim Kraus]

Thanks!