Issue with Verizon LTE on MC7750

Hi,

We have an embedded MC7750 modem and we are trying to connect to verizon’e LTE netowrk but we are not able to connect it. We are using Connection manger sample application of Sierra Wireless SDK “SLQS03.01.03.tar.gz”. We are able to connect with CDMA gracefully and it is working fine. But we ware not able to enstablish connection with LTE. We have been informed by Verizon that the SIM card is activated for LTE connection and try with the below listed APNs to get it working.

Following is our configurations and set-up detail:

Host operating system : Linux 2.6.32
Model: MC7750
Sierra Wireless SDK : “SLQS03.01.03.tar.gz”
Sample Application used : Connection Manager for ARM
QMI drivers : SierraLinuxQMIdriversS2.11N2.16.tar.gz
APN tried : VZWINTERNET , ne01.VZWSTATIC, so01.VZWSTATIC

Though we are using SDK (C Code) to get more information about the device state we tried following AT commands on modem port and also listed it’s o/p.

ATi9
Manufacturer: Sierra Wireless, Incorporated
Model: MC7750
Revision: 33, SWI9600M_03.05.10.06ap r5595 carmd-en-10527 2012/11/12 15:07:45
3GPP Release 8
+GCAP: +CIS707-A, CIS-856, CIS-856-A, +CGSM, +CLTE1, +MS, +ES, +DS, +FCLASS

AT!GSTATUS?
!GSTATUS:
Current Time: 11751 Temperature: 29
Bootup Time: 10324 Mode: ONLINE
System mode: HDR PS state: Attached
CDMA band: US Cellular CDMA chan: 777
Subnet mask: 64 Color code: 195
PN offset: 315
Sector ID: 0080:0580:0000:0013:180A:F8E1:1901:5602
IMS reg state: Full Srv

RSSI (dBm): -95 ECIO (dB): -11
IO (dBm): -91 SINR (dB): 2
RX1 (dBm): Unavailable
OK

OK
AT!ENTERCND=“A710”
OK

AT!SELRAT?
!SELRAT: 03, Automatic
OK

Please provide some guideance or inputs where we can debug/change the code.

Thanks !

Hi,

FW 03.05.10.06 is not Verizon approved firmware and may cause this issue, please contact your distributor or FAE to get the approved FW 3.5.10.9 and this problem should gone.

Thx

Hi Iotam,

Thanks for your inputs. To debug this problem, now we have connected the same modem and SIM card on the dev-kit of Sierra Wireless and attached it with Windows machine so that we can isolate the issue specific to our Lninux environemtn, if any.

We downloaded the “FlashTool_MC7750_03.05.10.09_00_vzw_033.011_000.zip” from the Sierra Wireless web-site. Using this tool, we could upgrade the modem firmware successfully.

Then, we used AirCard Watcher Winodws based tool to test connectivity. Followings are our observation.

We are using default “VZaccess” profile with “VZWINTERNET” APN name and “IPv4v6” PDP type with no Username and Password.

  1. When we change the User Option -> Network -> Radio Technology [ Selection Mode : CDMA] [ Duration : Persistent] [ Radio Technology : LTE] then we get the “Request Failed” error at bottom in red color.

  2. When we change the User Option -> Network -> Radio Technology [ Selection Mode : CDMA] [ Duration : Persistent] [ Radio Technology : 3G] then we get the “Operation Successful” message at bottom. And with this setting we can perform connect/disconnect number of times and everything works fine.

  3. When we change the User Option -> Network -> Radio Technology [ Selection Mode : CDMA] [ Duration : Persistent] [ Radio Technology : 2G/3G] then we get the “Operation Successful” message at bottom. And with this setting we can perform connect/disconnect number of times and everything works fine.

  4. When we enable the AirPlande mode and disable it then at very first time we get connected with LTE succesfuly but if we do disconnect and again try to connect then it doesn’t work out.

Please suggest where we are missing or provide guidance on this.

Thanks !

Hi ronakd,

First… to be honest, I don’t have chance to use Windows Watcher with Verizon LTE before…

But based on your description, you configured “Selection Mode: CDMA”, I guess better way is to set it to “Auto” or something equivalent…
Also, are you using the latest watcher/driver for your test?

If possible, please check with your distributor or FAE for info.
Thx

Hi Iotam,

There are three options available for Mode Selection, which are “Auto”, “UMTS” and “CDMA”. We tried selecting “Auto” mode also, but the behavior is same.

We double checked that we are using latest software/driver for Windows. Here, we are not able to identify whether the issue is with Verizon or issue is with Sierra Wireless Modem/SDK. So, whom should we contact in this scenario.

Thanks in anticipation.

Thanks !