NRF9160 Band Lock causes network registration failure

[GJSea]

Hi,

In order to speed up network registration times I'm trying to do a band lock to 13,4 (Verizon & ATT within USA), so I'm issuing the below AT command which responds with OK

AT%XBANDLOCK=2,1000000001000

However when doing the subsequent AT+CFUN=1 the response is +CEREG: 2,"FFFE","FFFFFFFF",7

Removing the AT%XBANDLOCK and the modem responds properly with a response of +CEREG: 2,"910F","066E8210",7 followed by +CEREG: 5....

Any idea why the band lock causes network registration failure?

Thanks!

[Sigurd]

Hi,

Are you sure that band 13 and 4 are available ?

If you test with the at_client sample, and LTE Link Monitor, what band are you connecting on ?

[GJSea]

Hi Sigurd,

Interesting it is band 17 it is connecting to. I thought in the USA we only needed to specify Bands 4 and 13 for ATT and Verizon in order for the NRF9160 to connect to.

So my question is now, what are the list of bands we should support if the want the NRF9160 to connect broadly across the US on either ATT or Verizon networks?

Thanks!

[Sigurd]

Hi,

On Verizon we have certified band 4 and 13. See this page and this page.

AFAIK, AT&T is using LTE on band 2,4,5,12 and 17

[GJSea]

Thanks Sigurd, so to be realistic we need to specify all of those bands in the BANDLOCK mask otherwise there is the potential the device won't connect to the network if a specific available tower is only broadcasting one of those bands?

Will adding more bandlock bands then cause the scan/registration time to increase?

[Sigurd]

Hi GJSea,

I asked internally, and to our knowledge AT&T has M1 deployed in US on bands 2,4/66,12/17 and Verizon on 4 and 13. AT&T requires that bands 2,4(66),12(17) are supported by any Cat-M1 module. B17 as a standalone band will be phased out and is required by AT&T to be supported through B12 MFBI feature.

 If you want to maximize coverage then all of those will need to be left enabled.

GJSea said:

so to be realistic we need to specify all of those bands in the BANDLOCK mask otherwise there is the potential the device won't connect to the network if a specific available tower is only broadcasting one of those bands?

That is correct. E.g. a AT&T tower could in theory only support e.g. band 17.

GJSea said:

Will adding more bandlock bands then cause the scan/registration time to increase?

Yes, but not in all cases (the device remembers the bands previously camped on).

[GJSea]

Great thanks Sigurd for the clarification!