Build you LoRaWAN Gateway with LTE-M backhaul

Build your own LoRaWAN gateway using a Raspberry Pi, RAK Wireless concentrator hat and connect it to LTE-M to offload the LoRaWAN data using a SIMCom cellular modem and Monogoto SIM. The gateway firmware can be built and managed with Balena.

Prerequisites

This story is a follow-up of the the Hackster projectDeploy a Basics Station TTS LoRa Gateway with balena. It assumes you already have a LoRaWAN gateway up and running with Basics Station firmware, connected to The Things Network.

Why LTE-M?

LTE-M, also known as LTE Cat-M1 or eMTC is a low power, wide area network (LPWAN) technology, optimized for low-cost and long-range applications which don't require large bandwidth. LTE-M usually support up to 375kbps data throughput, which is perfect when used to offload LoRaWAN gateway traffic.

Before purchasing a LTE-M modem, make sure to validate that your country has an active LTE-M network running. Have a look at the GSMA coverage map to get an overview of all available networks.

Getting Started

To start off, add the miniPCIe LTE-M modem to the USB dongle. In this example, the SIM7000E is used, alternatives are the SIM7000G or SIM7070G.

Add the Monogoto SIM with global connectivity to the USB dongle and connect an antenna to the USB dongle using the uFL connector.

Connect the LTE modem to the Raspberry Pi using the USB port.

Using Monogoto

Monogoto is a global cellular network provider. Monogoto SIMs can be used to connect with 500+ mobile operators globally.

You can request a free SIM here.

Monogoto SIM come without a PIN and are already activated. To start using the SIM, you only need to set the APN to: data.mono.

Management and monitoring of the SIM can be done via the Monogoto Console, access is provided together with the SIM.

Setting up Balena

Log in to your Balena account and select the LoRaWAN gateway you want to add cellular connectivity to.

Configure the balena Network ManagerStart a Terminal session by clicking select a target - HostOS - >_ Start Terminal Session

Open the folder system-connections:

cd /etc/NetworkManager/system-connections

Create a new file called monogoto by entering the command:

vi monogoto

Press i to edit the file you just created and paste the following content:

[connection]
id=monogoto
type=gsm
autoconnect=true

[gsm]
apn=data.mono

[serial]
baud=115200

[ipv4]
method=auto
route-metric=200

[ipv6]
addr-gen-mode=stable-privacy
method=auto

The text you just pasted contains Monogoto's APN: data.mono

ℹ️️ With route-metric you can define the priority of the technology. A lower metric means a higher priority. If you leave out this line, the RPI will first try to connect using Wifi or wired ethernet, before connecting to cellular.

Save the file by pressing esc, followed by :wq and press enter to write and close the file.

Minimize the terminal, and click Reboot

After a reboot, you should see 2 local IP addresses. One is your local network, one is from Monogoto.

ℹ️️ Important note. It may take several minutes before the cellular module selects a network and a cell tower to connect with. Be patient.

Validate cellular Connection

To find more details about the cellular connection and to validate its priority relative to other connection types, enter:

ip route

This should return something like:

default via 10.136.XX.XX dev wwp1s0u1u1i5  metric 200 
default via 192.168.2.254 dev wlan0  metric 600

wwp1s0u1u1i5 indicates the cellular connection type (this may have a different name in your case), wlan0 indicates a WiFi connection. Lower metrics have higher priority, meaning that in my case the Raspberry Pi first tries to connect over cellular before looking for WiFi.

Test the cellular connection by sending a ping:Replace wwp1s0u1u1i8 with the name of your connection type

ping -I wwp1s0u1u1i8 8.8.8.8

ℹ️️ End the ping session through Control+C

Example response:

PING 8.8.8.8 (8.8.8.8): 56 data bytes
64 bytes from 8.8.8.8: seq=0 ttl=49 time=114.677 ms
64 bytes from 8.8.8.8: seq=1 ttl=49 time=140.060 ms
64 bytes from 8.8.8.8: seq=2 ttl=49 time=94.791 ms
64 bytes from 8.8.8.8: seq=3 ttl=49 time=134.552 ms

Read the connection types and their state

nmcli c

Example response:

NAME                UUID                                  TYPE      DEVICE      
monogoto            d17d0bc1-2f13-39ac-8b72-b81f69d2d045  gsm       cdc-wdm0    
balena-wifi-01      983466c0-806d-361b-9535-e4b548cf0d62  wifi      wlan0       
supervisor0         fc05861a-f6ab-4582-908b-4fbfed47f66a  bridge    supervisor

Active connections are indicated in green. Non-active connections are shown in yellow.

Finally, check the status of the cellular connection

Enter the command:

mmcli -m 0

Expected response:

  Status  |                   lock: sim-pin2          
          |         unlock retries: sim-pin (3), sim-puk (10), sim-pin2 (3), sim-puk2 (10)
          |                  state: connected
          |            power state: on     
          |            access tech: lte     
          |         signal quality: 71% (cached)
----------------------------------
  3GPP     |                  imei: XXXXXXXXXXXXXX
           |           operator id: 20404
           |         operator name: vodafone NL
           |          registration: roaming
  ----------------------------------
  3GPP EPS |   ue mode of operation: csps-2
           |   initial bearer path: /org/freedesktop/ModemManager1/Bearer/0
           |    initial bearer apn: data.mono
           |initial bearer ip type: ipv4
  ----------------------------------

Deploy your gateway in the wild

Congratulations on adding LTE-M to your gateway! 🎉

Next up, install your gateway in a remote location and behold, the gateway still runs like a charm!