MC7455 does not lock on to UK 5MHz Band 20

IoT Modules MC/EM Series
1

Hello,

I’ve been entrusted to evaluate the following combination for use in rural and semi-rural situations and would be grateful of some direction please.

Router & Modem: CradlePoint CBA850LP6 EU version with MC400LP6 (MC7455 / EM7455) for operation in the UK.

CradlePoint Firmware: v7.0.70

Modem Firmware: 02.30.01.01_GENERIC,002.045_001 only ‘ticked’ Up to date (i.e. none of the USA AT&T, Sprint or Verizon firmwares are ticked)

Antenna: Poynting XPOL2

Cell Network: Three UK but also could be the others; EE, Vodafone & O2

Bands: Band 1 (10MHz), Band 3 (15MHz) & Band 20 (5MHz). All three are available on the nearby semi-rural test tower 1.5km away with 2CA (Bands 3 & 20) offered by the network & this tower & tested successfully with the Huawei B525-23a (B20+B3) & (B3+B20) and others.

Bands 1 & 3 work OK individually but are not setup for CA by the network or this Sierra Wireless modem I believe.

My Issue

Band 20 does not work / lock as it comes up as 10MHz instead of 5MHz. In many of the rural use-cases only Band 20 will be available so we need it to work.

Before I plough through the AT! command reference, are there AT! commands that I can enter into the modem to correct this bandwidth issue and ensure that if the tower is enabled for CA the modem will follow suit?

I have used the CLI ‘Band Selection / Locking’ process a few times and as far as I can see I’ve understood and implemented that OK but haven’t yet tried to force a band to have a particular bandwidth as that shouldn’t normally be necessary - should it?

I look forward to hearing from you.

Thanks in advance.

Steve

2

Hi @stevenma,
You can use AT!BAND to to operate on a set of frequency bands, look up available sets,
create new sets, or return the current selection. Refer the 4117727 AirPrime EM-MC74xx AT Command Reference r4.pdf (1.4 MB) page #24 for more detail.
Note that, 4G LTE support B1,3,20,… but 3G WCDMA supports B1, B2, B3, B4, B5, B8 not B12 so If your device is using 3G it is not able to connect
Please share any concerns you have and help us tick Solution if it is helpful to you guy
Thanks

3

Hi @Vianney,
Many thanks for coming back to me. I’ve done some more reading around this, including of the Command Reference.

  1. We’re generally only interested in 4G LTE, at least until 5G comes along.

  2. We’re in the UK and therefore Europe

  3. Bands created using the command reference:

  • AT!BAND=10,“THREE B1”,0,1 - working OK
  • AT!BAND=11,“THREE B3”,0,4 - working OK
  • AT!BAND=12,“THREE B20”,0,80000 - not working does now see 5MHz bandwidth
  • AT!BAND=13,“THREE B3+B20”,0,80004 - Band 3 only is working. Carrier Aggregation: Not Registered (Obviously because Band 20 is not working!)
  1. Are we missing the L[TE] Band Mask:
    06, Europe 00000000000800C5

to be added to each of the above, particularly:

AT!BAND=13,“THREE B3+B20”,0,80004

which becomes instead:

Hex value: 00000000000800C5 + 0000000000080004 = 1000C9

AT!BAND=13,“THREE B3+B20”,0,1000C9

I haven’t tested this yet but will do so.

Should I also be adding L[TE] Band Mask?:
09, LTE ALL 00000100330818DF

to make:

Hex value: 100330818DF + 1000C9 = 100331819A8

AT!BAND=13,“THREE B3+B20”,0,100331819A8

I haven’t tested this yet but will do so if you think I’ve understood the command correctly.

I look forward to hearing from you.

Thanks,
Steve

4

@Vianney
I tried this, but unfortunately that didn’t see Band 20 either.

AT!BAND=13,“THREE B3+B20”,0,1000C9

Do you have any other suggestions I can try please before I put this combination aside?
Thanks, Steve

5

Hi @stevenma,
I am not sure why you set B3+B20 by including 06, Europe 00000000000800C5. It doesn’t like a valid value so you got error message.

For this issue, you can help to check:
at!entercnd=“A710”
at!band=?
at!band?
at!selrat=?
at!selrat?
at!lteca=?
at!lteca?
By default, MC7455 supports B20 for LTE so it will be successful to register to network if the operator supports B20. You can also get more information from operator and the distributor of the product
Thanks

6

@stevenma

So just to be clear you are able to set the bands that the unit will attach to. The BW of the bearer is set by the network, you cannot set that on the UE as it is dependent on how the provider has cut the BW up.

Regards

Matt

7

Hi @Vianney

I agree, but I’m trying the various possible solutions.

AT!BAND=?
Response:

image
image903×918 15.1 KB

AT!BAND?
image
image922×185 3.17 KB

AT!BAND=?
image
image238×733 4.86 KB

AT!BAND?
image
AT!LTECA=?
image
AT!LTECA?
image
image322×702 5.85 KB

We expect to be able to use LTEB7: B3, B7, B20, (Bands 3 & 20 are available & previously tested for CA on the test tower and the Three network).

  • What do:
  1. Permitted Bands:
    Empty
    &
  2. Prune_ca_combos:
    Empty
    mean and do I have to correct anything here?

Yes, the operator fully supports Band 20 5MHz as successfully tested with a range of other LTE products.

I look forward to hearing from you further if I am missing something.

Thank you,
Steve

8

@mlw
Yes Matt, that is my understanding. Originally the modem was telling me Band 20 was a 10MHz band which I know is not correct. It does now say 5MHz in the interface so that’s a step forward but the MC7455 will not attach to Band 20 and the CBA850LP6 CradlePoint Router reports; ‘Carrier Aggregation: Not Registered’, presumably because it’s not ‘seeing’ Band 20?

Thanks for jumping in to this thread, it’s appreciated as I’m trying to complete and write-up my evaluation by the end of the week.

Thanks,
Steve

9

@stevenma

How do you know it is not correct? I presume you have another device which is attaching to 3 on B20?

If you send the at!lteinfo? command then it will show you all of the surrounding LTE cell information.

Re the CA point, it may well not show a CA status until you are to the point where the unit is attempting to access SCC’s and the network has subsequently allocated resources for (or the unit) to be able to state that it has access.

Regards

Matt

10

@mlw , @Vianney

Hi Matt,

Yes, a Huawei B525-23a which attaches to Bands 1, 3 & 20 individually and will also CA Bands 3&20.

AT!LTEINFO? (just for Band 20)

Capture4
Capture4866×601 11.2 KB

From the router’s cellular status page:

Capture3
Capture31017×1025 64.4 KB

Yes, I understand that it’s the tower / network’s decision to invoke Carrier Aggregation. My issue though is that the modem isn’t communicating with the tower’s Band 20 as is apparent from the router’s cellular page.

I am starting to wonder, if you can’t see anything obvious, if the tower has an issue with Band 20.

Any other thoughts Matt?

Thanks,
Steve

11

@mlw, @Vianney

I’ve just checked, using my iPhone 6S, and that’s seeing and working fine on the same Band 20 Physical Cell ID 326.

12

@stevenma

So this should get you onto B20.

ati
Manufacturer: Sierra Wireless, Incorporated
Model: MC7455
Revision: SWI9X30C_02.32.11.00 r8042 CARMD-EV-FRMWR2 2019/05/15 21:52:20
MEID: 35907206005151
IMEI: 359072060051519
IMEI SV: 19
FSN: LQ545100810110
+GCAP: +CGSM


OK
at!band?
Index, Name
00, All bands


OK
at!band=?
Index, Name
00, All bands
01, Europe 3G
02, North America 3G
06, Europe
07, North America
08, WCDMA ALL
09, LTE ALL

OK
at!entercnd="A710"
OK
at!band?
Index, Name,                        GW Band Mask     L Band Mask      TDS Band Mask
00, All bands,                      0002000007C00000 00000100330818DF 0000000000000000


OK
at!band=10,"B20",0,80000,0
OK
at!reset
OK
at
OK
at!band?
Index, Name
00, All bands


OK
at!band=?
Index, Name
00, All bands
01, Europe 3G
02, North America 3G
06, Europe
07, North America
08, WCDMA ALL
09, LTE ALL
10, B20		//New profile with just B20 enabled

OK
at!band=10		//Set it to the bands
OK
at!reset		//Then reset it for the profile to take effect
OK
at!band?
Index, Name
10, B20


OK
at!entercnd="A710"
OK
at!band?
Index, Name,                        GW Band Mask     L Band Mask      TDS Band Mask
10, B20,                            0000000000000000 0000000000080000 0000000000000000


OK
at+creg?
+CREG: 0,3

OK
at+cops=?
+cops: (1,"3","3","23420",7),(3,"EE","EE","23430",7),(3,"O2 - UK","O2 - UK","23410",7),(3,"234 32","234 32","23432",7),(3,"vodafone UK","voda UK","23415",7),,(0,1,2,3,4),(0,1,2)

OK
at+cgdcont?
+CGDCONT: 1,"IP","3internet","0.0.0.0",0,0,0,0
+CGDCONT: 15,"IP","internet","0.0.0.0",3,2,0,0
+CGDCONT: 2,"IP","everywhere","0.0.0.0",0,0,0,0
+CGDCONT: 3,"IPV4V6","three.co.uk","0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0",0,0,0,0

OK
at+cgdcont=1,"IP","three.co.uk"
OK
at+creg?		//For some reason my 3 SIM is messing around today
+CREG: 0,3

OK
at!lteinfo?		//Regardless the unit is on B20 in emergency mode
!LTEINFO:
Serving:   EARFCN MCC MNC   TAC      CID Bd D U SNR PCI  RSRQ   RSRP   RSSI RXLV
         6225 234  30 11340 00805C0D 20 2 2   4 346 -11.0  -86.1  -60.8  35

IntraFreq:                                          PCI  RSRQ   RSRP   RSSI RXLV
                                                346 -11.0  -86.1  -60.8  35
                                                347 -16.7  -93.5  -67.9  35
                                                417 -15.2  -93.9  -69.7  35
                                                133 -13.4  -93.5  -71.1  35

InterFreq: EARFCN ThresholdLow ThresholdHi Priority PCI  RSRQ   RSRP   RSSI RXLV

WCDMA:     UARFCN ThreshL ThreshH Prio PSC   RSCP  ECN0 RXLV


OK
at!reset
OK
at+creg?
+CREG: 0,3

OK

Regards

Matt

13

@mlw

Thank you Matt, that looks promising. I shall implement later on and update you.

Regards,
Steve

14

@mlw
Unfortunately that didn’t work Matt. I’ll update this thread as soon as I can test again with all of the responses.
Thanks, Steve

15

@mlw
Hi Matt,
As I say above, I couldn’t get the modem working with your commands which I followed to a tee.

I can set Band 20 OK, I could do that before:
at!band?

Index, Name, GW Band Mask L Band Mask TDS Band Mask
10, B20, 0000000000000000 0000000000080000 0000000000000000

but I also get the same as you here:

at+creg?
+CREG: 0,3

at!lteinfo? also returns a similar result to you however, there is no registration with the mobile network.

If I check at+creg? when I’m operating on the working Band 3 I get:

at+creg?
+CREG: 0,1

I’ve done a lot of reading in this and other fora then carefully tried a range of other alternate settings in the modem and router, all without Band 20 registration success.

Incidentally, “3internet” has always been the APN I’ve had success with and which provides a dynamic public IP address.

If you have other suggestions I could try I’d be pleased to hear them.

Thank you,
Steve

16

@stevenma

So that is an active reject from the network, if the SIM with that APN works when it is set with the other bands enabled then the network is clearly doing something to stop it. I suspect i might be that it does not want units with the 7455’s IMEI on B20.

Regardless, if the unit can see the network and the SIM worked previously then it is trying to attach, the reject is on the network.

Regards

Matt

17

Thanks Matt, I’d started to think it was the network but needed your help to confirm same. A colleague has spoken to Three and ordered a replacement SIM although I’m not certain we’ll get the issue fixed in one go. I’ve also got an EE SIM coming and they’re on the same tower.
Thanks for your help.
Rgds, Steve