Roaming SIM card

Legacy Legacy AirPrime modules
1

Hi,

We are investigating using a roaming SIM card with our product (which uses the Q64 modem). When the network selection is automatic (AT+COPS=0), the system remains connected to the home network even if the signal strength is very low. We had an example last week where the signal strength on the Vodafone network was -103, and the signal strength on the O2 network was -79dBm. But the system remained connected to Vodafone.

The CCED command only seems to show neighbouring cells of the current network.

Is there any way of scanning all available networks to find out the signal strength of each so that we can manually select the best?

Thanks

Andrew

2

Hi Andrew,

It is expected to select and camp on home network even it is not the best signal.

However, the new Network Scan library available in Open AT Application Framework 2.51 serves exactly your requirement to scan all networks with signal strength info.

Below example for reference:

AT+NWKSCAN

PLMN:“SmarToneVodafone”,MCC:454,MNC:06,CellNb:4,MeanPower:33
1:Arfcn:114,Bsic:11,Lac:140,RxLev:40,Qual:0,Status:SUITABLE
2:Arfcn:103,Bsic:3,Lac:140,RxLev:33,Qual:6,Status:SUITABLE
3:Arfcn:95,Bsic:32,Lac:140,RxLev:32,Qual:0,Status:SUITABLE
4:Arfcn:107,Bsic:8,Lac:140,RxLev:30,Qual:5,Status:SUITABLE

PLMN:“CSL”,MCC:454,MNC:00,CellNb:4,MeanPower:32
1:Arfcn:36,Bsic:9,Lac:1131,RxLev:39,Qual:0,Status:LOW PRIORITY
2:Arfcn:72,Bsic:9,Lac:1131,RxLev:34,Qual:0,Status:LOW PRIORITY
3:Arfcn:659,Bsic:39,Lac:1131,RxLev:29,Qual:0,Status:SUITABLE
4:Arfcn:655,Bsic:11,Lac:1131,RxLev:29,Qual:0,Status:SUITABLE

PLMN:“PCCW”,MCC:454,MNC:16,CellNb:4,MeanPower:28
1:Arfcn:868,Bsic:11,Lac:48,RxLev:49,Qual:0,Status:SUITABLE
2:Arfcn:866,Bsic:14,Lac:48,RxLev:27,Qual:0,Status:SUITABLE
3:Arfcn:813,Bsic:37,Lac:48,RxLev:20,Qual:0,Status:SUITABLE
4:Arfcn:865,Bsic:34,Lac:48,RxLev:16,Qual:4,Status:SUITABLE

PLMN:“3(2G)”,MCC:454,MNC:04,CellNb:3,MeanPower:29
1:Arfcn:78,Bsic:38,Lac:8850,RxLev:35,Qual:0,Status:SUITABLE
2:Arfcn:80,Bsic:8,Lac:8850,RxLev:26,Qual:0,Status:SUITABLE
3:Arfcn:67,Bsic:32,Lac:8850,RxLev:26,Qual:0,Status:SUITABLE

PLMN:“China Mobile HK”,MCC:454,MNC:12,CellNb:2,MeanPower:36
1:Arfcn:756,Bsic:1,Lac:170,RxLev:42,Qual:0,Status:SUITABLE
2:Arfcn:879,Bsic:8,Lac:170,RxLev:31,Qual:0,Status:SUITABLE

OK

Not sure whether you use AT command only or also with OpenAT, maybe worth to look into the Layer 3 service.

Hope it helps.
L

3

Lotam,

Thanks very much for your response. I’m using a Q64 modem - would it be possible to upgrade this to use the Open AT framework? If so, can you point me at some information which describes how to do this?

Thanks very much

Regards

Andrew