NimbeLink Skywire NL-SW-LTE-TC4NAG User manual

Skywire® CAT4 LTE Modem
Windows Networking Guide
NimbeLink Corp
Updated: December 2019
PN 1002202 rev 1 © NimbeLink Corp. 2019. All rights reserved. 1

Table of Contents
Table of Contents 2
Introduction 3
Overview 3
Orderable Part Numbers 3
MBIM on Windows 8/10 3
Overview 3
Skywire Configuration Procedure 3
Install Drivers 3
Preliminary Skywire Setup 4
Configure the USB Interface Composition 4
Configure the PDP Context 5
Enable and Verify Cellular Functionality 6
Query the Cellular Signal Strength 6
Connect the Modem's USB Interface 6
Windows Settings Configuration Procedure 6
Test the Internet Connection 9
Troubleshooting 10
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1. Introduction
1.1 Overview
This application note describes how to use a NimbeLink CAT4 LTE Skywire to
establish an Ethernet over USB connection on a Windows host device.
Windows 8/10 users can use MBIM protocol. See Section 2 for details.
1.2 Orderable Part Numbers
Orderable Device
Cellular Carrier
Network Type
NL-SW-LTE-TC4NAG
AT&T, Verizon
LTE, 3G
NL-SW-LTE-TC4EU
EU Carriers
LTE, 3G, 2G
NL-SWDK
Any
Any
2. MBIM on Windows 8/10
2.1 Overview
The Mobile Broadband Interface Model (MBIM) is a networking protocol created by the
USB Implementers Forum, and is designed for USB-capable networking solutions,
such as cellular modems. MBIM protocol allows a Skywire modem to serve as an
Ethernet over USB Internet connection for a host device running a Windows 8/10 OS.
Note: MBIM mode only supports Windows 8/10 operating systems. Windows 7 users
must use RNDIS in order to implement an Ethernet over USB connection.
2.2 Skywire Configuration Procedure
2.2.1 Install Drivers
First, install the most recent Windows drivers for the Skywire. These drivers are
located at the following link, and are applicable to both NL-SW-LTE-TC4NAG and
NL-SW-LTE-TC4EU Skywire modems:
https://nimbelink.com/Documentation/Skywire/4G_LTE_Cat_4_Telit/Telit_Windows_D
esktop_Drivers_Installer_1.10.0002.zip
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2.2.2 Preliminary Skywire Setup
Ensure that the modem has an activated SIM card inserted into the SIM slot, or that
the modem's soldered-down SIM is active (NL-SW-LTE-TC4NAG modems only).
Power on the modem and allow it to boot up. Open a terminal emulator on the
Windows 8/10 host machine, and connect it to the modem's serial or USB interface.
●SWDK Users:  Refer to the SWDK user manual for detailed setup instructions:
https://nimbelink.com/Documentation/Development_Kits/NL-SWDK/30005_NL-
SWDK_UserManual.pdf
●NL-SW-LTE-TC4NAG Users:  Ensure that the active firmware image
corresponds to the SIM card in use. Section 3.9 of the NL-SW-LTE-TC4NAG
datasheet contains information regarding the dual image firmware:
https://nimbelink.com/Documentation/Skywire/4G_LTE_Cat_4_Telit/1002147_
NL-SW-LTE-TC4NAG_Datasheet.pdf
2.2.3 Configure the USB Interface Composition
Verify that the modem is responsive by issuing:
AT
The modem will respond with:
OK
Before using MBIM protocol, the composition of the modem's USB interface must be
altered in order to provide the proper USB ports to the Windows host PC. To check
the current composition of the USB interface, send the following command to the
modem:
AT#USBCFG?
The modem will respond with something similar to:
#USBCFG: x
If the result code returned by the modem is "#USBCFG: 2", then the USB interface is
already configured properly.
However, if it is not set to the above mode, then the USB configuration must be set.
To do this, issue the following command:
AT#USBCFG=2
The modem will respond with "OK" and then reboot.
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Note:  If the modem's USB path was being used to send AT commands, this port will
unenumerate on the host PC when the modem reboots. After the modem finishes
rebooting, reconnect to the modem's USB interface to continue.
Once the AT interface is responsive again, verify that the correct setting has been
applied:
AT#USBCFG?
The modem should respond with the following if the USB configuration was set
properly:
#USBCFG: 2
Once the correct USB composition has been selected, continue with the MBIM setup
procedure.
Note:  For further information regarding the "  #USBCFG  " command, please refer to the
AT command manual for the chosen modem:
NL-SW-LTE-TC4NAG Modems:
https://nimbelink.com/Documentation/Skywire/4G_LTE_Cat_4_Telit/Telit_LE910Cx_A
T_Commands_Reference_Guide_r2.pdf
NL-SW-LTE-TC4EU Modems:
https://nimbelink.com/Documentation/Skywire/4G_LTE_Cat_4_Telit/Telit-LE910-V2-A
T-Commands-r6.pdf
2.2.4 Configure the PDP Context
A PDP context must be set on the modem before using MBIM protocol. To do so,
issue one of the following commands depending on the modem and firmware:
AT+CGDCONT=1,"IPV4V6","[APN]" // TC4EU, TC4NAG: AT&T FW image
AT+CGDCONT=3,"IPV4V6","[APN]" // TC4NAG: Verizon FW image
Where "[APN]" is replaced with the APN that corresponds to the SIM card that will be
used for the cellular connection. The terminal should respond with "OK".
Issue the following AT command to ensure that the PDP context was set as intended:
AT+CGDCONT?
In the response from the modem to the above command, verify that the APN and PDP
context have been set correctly.
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2.2.5 Enable and Verify Cellular Functionality
Ensure that the modem has its cellular functionality enabled. Issue this command:
AT+CFUN=1
The modem should respond with "OK", and cellular functionality will now be enabled.
2.2.6 Query the Cellular Signal Strength
To verify that everything is working as it should be, query the cellular signal strength
seen by the modem. Enter the following command:
AT+CSQ
The modem will respond with something similar to "+CSQ: x,y", where "x" and "y" are
replaced with positive integer values that represent an encoding for the RSSI and
RSRQ of the modem, respectively.
● If the modem is receiving a valid cellular signal, the value of "x" will be between
0 and 31, and the value of "y" will be between 0 and 7.
● If the modem is not receiving a cellular signal (or can't determine if it is) the
response to the signal strength query will be: "+CSQ: 99,99".
○ In this case, verify that the hardware is set up properly, and that cellular
functionality has been enabled. Then try the "AT+CSQ" command again.
● See the AT command manual for translations from the reported integer values
to units of "dBm" for RSSI, and "dB" RSRQ.
2.2.7 Connect the Modem's USB Interface
As mentioned previously, MBIM protocol can only be used over USB. Connect the
modem's USB interface to the Windows 8/10 host machine if it is not already
connected.
SWDK Users:  The modem's USB port can be connected to the host PC by inserting a
mini USB cable to SWDK port, J5.
2.3 Windows Settings Configuration Procedure
After completing each of the steps in Section 2.2, the modem is now set up to use
MBIM protocol for the Ethernet to USB connection. The next step is to configure the
Windows Cellular settings.
Press the Windows key, and search for: "Change cellular settings"  . In the search
menu, click on the result with the same name. The window that opens should look
like:
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If the box that says "Let Windows manage this connection"  is checked, uncheck it.
Then click on the link that says "Advanced options"  . A new window will open that looks
something like this:
Contained within this window is some information about the modem, including: IMSI,
IMEI, manufacturer information, firmware revision, etc. There is also a setting for the
APN that will be used for the cellular connection.
Note:  The APN and IP Type settings (e.g. IP vs. IPV4V6 vs. IPV6) in the Windows
Cellular settings must  match the settings that were configured on the modem in
Section 2.2.4  . Failure to do so can result in the MBIM session failing when it is started.
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
To configure the APN for the connection, click the button that says: "Add an APN"  .
This will open a new window that looks something like this:
Populate each of the fields in this new window according to the instructions below. A
sample configuration profile for an NL-SW-LTE-TC4NAG modem with an AT&T SIM is
filled out in the image above:
● Enter a memorable name in the "Profile name"  field so that the APN profile is
easy to distinguish from any other profiles.
● In the "APN"  field, enter the same APN that was provided to the Skywire when
setting the PDP context in Section 2.2.4
● If a username and password is required for the APN, add it accordingly.
● The "IP Type"  field should be set to the same selection made when configuring
the modem's PDP context.
○ It is recommended to set this parameter to "IPV4V6"  on both the modem
and in the Windows settings.
● The APN type will usually default to "Internet"  .
○ Try the connection with "APN type"  set to "Internet"  first, but experiment
with the other settings if this does not work.
After all of the relevant fields have been filled out, check the box that says "Apply this
profile  ", and press the grey button that says "Save"  to save the configuration.
Navigate back to the top level of the Windows Cellular Settings menu by pressing the
back arrow in the top left corner of the current window twice.
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2.4 Test the Internet Connection
First, ensure that all other sources of Internet connectivity are disabled. Remove any
LAN cables from the PC, and disable Wi-Fi in the Windows settings.
To enable the cellular connection, press the button that says "Connect  " at the top level
of the Windows Cellular Settings. The menu should look something like this:
To test the connection, open a Windows Command Prompt by pressing the Windows
key, and searching for "cmd"  . Test the connection by pinging Google's DNS server:
ping 8.8.8.8
If the MBIM connection is functioning properly, the Command Prompt window should
look something like this:
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2.5 Troubleshooting
Section 2.5 contains some solutions for common difficulties that may arise during the
MBIM setup procedure:
If the connection fails with the error message shown below:
This issue is usually caused by one of two things:
1. The user has not entered a custom APN setting.
a. Follow the instructions in Section 2.4 to add an APN setting for the
connection.
2. The modem has an active PDP context.
a. If the modem's PDP context has been activated with the "AT#SGACT"
command, the above error message will be received.
b. To fix this, simply deactivate the PDP context on the modem using one
of the following commands:
AT#SGACT=1,0 // TC4EU, TC4NAG: AT&T FW image
AT#SGACT=3,0 // TC4NAG: Verizon FW image
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