91 (References) LTE Modems

With​ ​ the​ ​ addition​ ​ of​ ​ LTE​ ​ wireless​ ​ connectivity,​ ​ the​ ​ Intel​ ​ Aero​ ​ platform​ ​ enables​ ​ a ​ ​ broader​ ​ range of​ ​ use​ ​ cases.​ ​ ​ Your​ ​ drone​ ​ can​ ​ now​ ​ be​ ​ controlled​ ​ remotely​ ​ anywhere​ ​ there​ ​ is​ ​ a ​ ​ cellular​ ​ signal. And​ ​ data​ ​ can​ ​ be​ ​ transmitted​ ​ over​ ​ the​ ​ LTE​ ​ wireless​ ​ link​ ​ to​ ​ provide​ ​ continuous​ ​ connectivity.

With​ ​ the​ ​ v1.5.1​ ​ software​ ​ update,​ ​ the​ ​ Intel​ ​ Aero​ ​ Compute​ ​ Board​ ​ (part​ ​ of​ ​ the​ ​ Intel​ ​ Aero​ ​ Ready​ ​ to Fly​ ​ Drone)​ ​ enables​ ​ users​ ​ to​ ​ install​ ​ LTE​ ​ modem​ ​ devices​ ​ into​ ​ the​ ​ M.2​ ​ interface​ ​ and​ ​ configure their​ ​ drone​ ​ for​ ​ communications​ ​ over​ ​ LTE.

Starting​ ​ with​ ​ version​ ​ 1.5.1,​ ​ LTE​ ​ modem​ ​ capabilities​ ​ are​ ​ enabled​ ​ via​ ​ the​ ​ M.2​ ​ connector​ ​ located on​ ​ the​ ​ top-side​ ​ of​ ​ the​ ​ Intel​ ®​ ​ ​ Aero​ ​ Compute​ ​ Board.​ ​ ​ The​ ​ v1.5.1​ ​ release​ ​ requires​ ​ updates​ ​ to​ ​ both the​ ​ BIOS​ ​ and​ ​ BSP.​ ​ ​ The​ ​ updated​ ​ BSP​ ​ contains​ ​ new​ ​ modem​ ​ management​ ​ software​ ​ and​ ​ the updated​ ​ BIOS​ ​ enables​ ​ the​ ​ M.2​ ​ connector.

We​ ​ recommend​ ​ using​ ​ LTE​ ​ modems​ ​ based​ ​ on​ ​ Intel’s​ ​ XMM​ ​ 7160​ ​ chipset.​ ​ ​ Products​ ​ include​ ​ the Telit​ ​ LN930​ ​ and​ ​ Sierra​ ​ Wireless​ ​ AirPrime*​ ​ EM7345​ ​ which​ ​ are​ ​ certified​ ​ for​ ​ use​ ​ across​ ​ the globe.​ ​ ​ Please ​ ​ refer ​ ​ to ​ ​ the ​ ​ modem ​ ​ manufacturer’s ​ ​ product ​ ​ literature ​ ​ for ​ ​ specific ​ ​ capabilities

NOTE:​​ ​ It​ ​ is​ ​ the​ ​ pilot’s​ ​ responsibility​ ​ to​ ​ obtain​ ​ the​ ​ necessary​ ​ permits​ ​ from​ ​ both​ ​ the​ ​ government regulatory​ ​ agencies​ ​ as​ ​ well​ ​ as​ ​ the​ ​ cellular​ ​ service​ ​ providers.

Installation

Installation Overview

1. Purchase all necessary items listed in the next section "Detailed Hardware Installation"
2. Repurpose the original WiFi antennas for use with the LTE modem
   a. If Wifi is needed, follow Instructables for adding an extended-range WiFi solution
3. Insert the LTE modem into the M.2 connector
4. Secure the LTE modem using the 2mm hex nut
5. Insert the SIM card into the SIM card tray and slide it into the SIM slot slowly
6. Download and install v1.5.1 software update
   a. Update the BIOS
   b. Update the BSP
7. Configure Modem Manager to establish connectivity

Detailed Hardware Installation

To preform the LTE modem hardware installation, you will need to purchase the four items shown in Figure 1:

• LTE modem module
• Nano SIM card
• Tray to hold the nano SIM card
• 2mm hex nut

Links to online retailers where these items can be purchased are found at the end of these instructions.

Figure 1. Required Hardware

The LTE modem will be installed into the M.2 connector which is located on the top side of the Aero Compute Board, adjacent to the 80 pin I/O Expansion Connector. Use the 2mm hex nut to secure the LTE modem module to the mounting post near the heat sink.

Figure 2. Insert modem into M.2 and secure it with the 2mm hex nut

Connecting the Antennas

When installing the LTE modem, two antennas are required for proper operation. Both the Intel Aero Ready to Fly Drone and the Intel Compute Board are shipped with two WiFi antenna. These two antennas appear as "wings" attached to the sides of the plastic enclosure. The WiFi antennas will be re-purposed for use with the LTE modem.

Figure 4. Image showing location of the wings

if WiFi communication is not needed, then carefully disconnect the antennas micro SMA connectors from the WiFi module on the bottom of the Aero Compute Board and connect them to the two micro SMA connectors on the LTE modem. These are very small connectors. The antennas will "pop" off. Be gentle and careful when removing them. After connecting them to the LTE modem, verify a good connection is made by rotating the antenna on the micro SMA connector to verify that it can rotate freely. If the antenna does not rotate freely, then the antenna is not properly seated on the micro SMA connector.

Figure 5. Image on the left shows the removal of the antenna from the WiFi module underneath the Aero Compute Board. Then on the right they are attached to the modem.

If both WiFi and LTE modem functions are required, we recommend replacing the Intel Aero Ready to Fly Drone's WiFi antennas by following our "Instructable" which will extend the range of the drone's WiFi radio. This will allow you to then use the original WiFi antennas for the LTE modem as described above.

Installing the nano SIM card

The​ ​ SIM​ ​ card​ ​ slot​ ​ is​ ​ located​ ​ on​ ​ the​ ​ bottom​ ​ side​ ​ of​ ​ the​ ​ Compute​ ​ Board​ ​ underneath​ ​ the​ ​ 80​ ​ pin​ ​ I/O Expansion​ ​ Connector.​ ​ You​ ​ will​ ​ notice​ ​ that​ ​ when​ ​ the​ ​ SIM​ ​ card​ ​ is​ ​ inserted,​ ​ the​ ​ SIM​ ​ tray​ ​ sticks​ ​ out more​ ​ than​ ​ allowed​ ​ by​ ​ the​ ​ enclosure​ ​ which​ ​ prevents​ ​ the​ ​ Compute​ ​ Board​ ​ from​ ​ being​ ​ fully​ ​ seated. To​ ​ accommodate​ ​ the​ ​ SIM​ ​ tray,​ ​ the​ ​ opening​ ​ for​ ​ the​ ​ SIM​ ​ card​ ​ must​ ​ be​ ​ widened.​ ​ ​ This​ ​ requires​ ​ a modification​ ​ to​ ​ the​ ​ bottom​ ​ half​ ​ of​ ​ the​ ​ plastic​ ​ enclosure.

Using​ ​ a ​ ​ tool​ ​ of​ ​ your​ ​ choice​ ​ (X-Acto​ ​ knife​ ​ works​ ​ well),​ ​ make​ ​ an​ ​ opening​ ​ in​ ​ the​ ​ plastic​ ​ enclosure for​ ​ the​ ​ SIM​ ​ tray​ ​ that​ ​ is​ ​ approximately​ ​ 16mm​ ​ x ​​ 5mm.​ ​ This​ ​ will​ ​ allow​ ​ enough​ ​ room​ ​ for​ ​ the​ ​ SIM​ ​ tray to​ ​ sit​ ​ comfortably​ ​ within​ ​ the​ ​ enclosure​ ​ and​ ​ also​ ​ allow easy​ ​ access​ ​ for extracting the SIM​ ​ card.

Figure 6. Image on the left shows how the SIM tray interferes with the plastic enclosure. Image on the right shows the SIM tray fits within the plastic enclosure after modifications.

Software Configuration

Install Necessary Software

Follow these instructions for downloading and installing the software update. Both the BSP and BIOS must be updated to at least the following versions

• BSP v1.5.1
• BIOS v01.00.13

Note that the Aero Ready to Fly Drone will also require the flight controller firmware to be updated as well. Review the Aero software release notes for details.

Verify Hardware is Recognized

After​ ​ updating,​ ​ open​ ​ up​ ​ a ​ ​ SSH​ ​ terminal​ ​ by​ ​ connecting​ ​ to​ ​ Aero's WiFi​ ​ Access​ ​ Point​ ​ (refer​ ​ to​ ​ this wiki​ ).​ ​ ​ Modem​ ​ Manager​ ​ (replaces​ ​ Connection​ ​ Manager​ ​ on​ ​ previous​ ​ Aero BSP​ ​ releases)​ ​ should automatically​ ​ detect​ ​ the​ ​ installed​ ​ LTE​ ​ modem​ ​ and​ ​ enumerate​ ​ it​ ​ as​ ​ Modem​ ​ 0.​ ​ Query​ ​ the​ ​ modem info​ ​ below.

# mmcli -m 0

If​ ​ the​ ​ LTE​ ​ modem​ ​ is​ ​ not​ ​ detected,​ ​ please​ ​ double​ ​ check​ ​ that​ ​ the​ ​ modem​ ​ is​ ​ seated​ ​ securely​ ​ and the​ ​ SIM​ ​ card​ ​ is​ ​ properly​ ​ inserted.​ ​ Take​ ​ precautions​ ​ as​ ​ the​ ​ SIM​ ​ card​ ​ can​ ​ potentially​ ​ slide​ ​ out​ ​ due to​ ​ airframe​ ​ vibrations​ ​ while​ ​ in​ ​ flight.

This is a good point to verify that the SIM card is properly recognized and is not locked. This can be found in the Status section reported above. If the SIM card is locked, contact your carrier for unlock instructions.

lock: `none`
state: `registered`

An​ ​ APN​ ​ must​ ​ be​ ​ set​ ​ to​ ​ correctly​ ​ to​ ​ access​ ​ the​ ​ public​ ​ internet.​ ​ Below​ ​ are​ ​ a ​ ​ few​ ​ carriers​ ​ in​ ​ the​ ​ U.S. and​ ​ their​ ​ corresponding​ ​ APN.

• AT&T - "phone"
• Verizon - "vzwinternet"
• Tmobile - "fast.t-mobile.com"
• Sprint - "cinet.spcs"

APN name can be updated using the command below.

# nmcli con modify modem gsm.apn <name> 

Verify Connectivity

Reboot the system so that the configuration will take effect. With the previous "mmcli -m 0" command, find the bearer number from the output. Execute the following to show the details of the IP addresses.

# mmcli -b <bearer number>

Below you can see the device "cdc-wdm0" with connection name "modem" is in the connected state.

# nmcli device

Verify internet connectivity by pinging your favorite website.

# ping www.intel.com

QGroundControl over LTE

By​ ​ default,​ ​ QGC​ ​ communicates​ ​ directly​ ​ with​ ​ Aero​ ​ when​ ​ connected​ ​ to​ ​ Aero's WiFi ​ Access​ ​ Point. However,​ ​ when​ ​ the​ ​ drone​ ​ is​ ​ on​ ​ LTE,​ ​ a ​ ​ direct​ ​ connection​ ​ is​ ​ non-trivial​ ​ as​ ​ both​ ​ the​ ​ drone​ ​ and​ ​ PC can​ ​ be​ ​ behind​ ​ multiple​ ​ layers​ ​ of​ ​ NATs/firewall.

There​ ​ are​ ​ several​ ​ ways​ ​ to​ ​ circumvent​ ​ this.​ ​ In​ ​ the​ ​ options​ ​ described​ ​ below,​ ​ a ​ ​ cloud​ ​ server​ ​ is used​ ​ to​ ​ help​ ​ route​ ​ packets​ ​ between​ ​ the​ ​ drone​ ​ and​ ​ PC.​ ​ These​ ​ servers​ ​ are​ ​ inexpensive​ ​ and​ ​ easy to​ ​ set​ ​ up,​ ​ like​ ​ Amazon’s​ ​ AWS​​ ​ and​ ​ Google’s​ ​ Compute​ ​ Engine​.

Option 1: Server running mavlink-router

On​ ​ the​ ​ Intel Aero​ ​ Ready to Fly Drone (aka Aero RTF),​ ​ mavlink-router​ ​ runs​ ​ locally​ ​ to​ ​ handle​ ​ routing​ ​ packets​ ​ between​ ​ the​ ​ flight controller​ ​ and​ ​ different​ ​ IP​ ​ endpoints.​ ​ But​ ​ we​ ​ can​ ​ also​ ​ deploy​ ​ another​ ​ instance​ ​ of​ ​ mavlink-router in​ ​ the​ ​ cloud​ ​ to​ ​ handle​ ​ routing​ ​ just​ ​ IP​ ​ traffic.​ ​ Both​ ​ the​ ​ drone(s)​ ​ and​ ​ QGC​ ​ are​ ​ then​ ​ connected​ ​ to this​ ​ cloud​ ​ based​ ​ mavlink-router​ ​ and​ ​ communication​ ​ is​ ​ established.​ ​ One​ ​ benefit​ ​ of​ ​ using​ ​ this method​ ​ is​ ​ flight​ ​ logs​ ​ are​ ​ stored​ ​ automatically​ ​ in​ ​ the​ ​ cloud,​ ​ so​ ​ in​ ​ case​ ​ of​ ​ fly-aways​ ​ a ​ ​ copy​ ​ of​ ​ the logs​ ​ can​ ​ be​ ​ retrieved.​ ​ This​ ​ method​ ​ also​ ​ scales​ ​ well​ ​ with​ ​ one-to-many​ ​ use​ ​ cases.

1. Obtain access to a Linux based cloud server and note its external IP
2. Configure the server's firewall to allow TCP traffic on port 5760
3. Access the server through a terminal. Build and deploy mavlink-router
4. On the Aero RTF, edit /etc/mavlink-router/main.conf and append the following line: [TcpEndpoint LTE] Address = XX.XX.XX.XX (replace with server ip) Port = 5760
5. Reboot the drone. Mavlink-router will automatically try to connect to the server
6. In QGC, under the Comm Links tab add an additional TCP connection with the server IP and port number
7. Click connect. You should now be communicating over LTE!

Option 2: Server with SSH tunneling

This​ ​ method​ ​ is​ ​ simpler​ ​ to​ ​ deploy​ ​ and​ ​ requires​ ​ no​ ​ additional​ ​ software​ ​ on​ ​ the​ ​ server.​ ​ The​ ​ server effectively​ ​ acts​ ​ as​ ​ a ​ ​ bridge​ ​ between​ ​ the​ ​ PC​ ​ and​ ​ drone.​ ​ Steps​ ​ below​ ​ assumes​ ​ AWS​ ​ cloud service.

1. Obtain access to a Linux based cloud server and note its external IP
2. Configure the server's firewall to allow TCP traffic on port 5760

On PC execute:

# ​ssh -i .keys/AmazonCloud.pem -L 5760:localhost:5760 -N <AWS User>@<AWS Instance>.compute.amazonaws.com

On Aero RTF execute:

# ssh -i /home/root/.keys/AmazonCloud.pem -R 5760:localhost:5760 -N -f -T <AWS User>@<AWS Instance>.compute.amazonaws.com>/var/log/aero.log 2>&1

Resources

These links are examples of where to purchase the required hardware. Intel does not advocate any specific retailer. Use these links as general reference only.

Item	Link
LTE Modem	Telit LN930 Sierra Wireless AirPrime EM7345
Nano SIM card	Purchase from local wireless carrier
Nano SIM card tray	Link
2mm hex nut	Link

For all issues not addressed in this document, please submit them to the Aero online Community Support Forum