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Roaming in LoRaWAN networks - How does it work?

LoRaWAN is one of the most popular IoT connectivity technologies that operates on an unlicensed sub-GHz spectrum. It is widely popular for its long-range and low-power use cases.


One of the features of LoRaWAN networks is their capability for inter-op. Similar to how your cell phone can work in another country if your network operator has an agreement with one of the local operators, all LoRaWAN devices can technically go to another location where you don't have your own gateways and still work.


What is LoRaWAN Roaming?

It is the process in which your LoRaWAN end device can communicate with its home network server even when moved out of range of your network. It can be different cities of different countries.


Every LoRaWAN device usually has its own home network server; whenever the device roams, it enters another network's premises. It is called a visited network server. If the visited network server and your home network server have an agreement beforehand, the visited network server will transmit the data coming from your LoRaWAN end device.


This can usually happen in one of two ways for LoRaWAN devices.

  1. Passive Roaming

  2. Handover Roaming

1. Passive Roaming

In Passive Roaming, the visited network server will not process any packets received from the end device and forwards everything it receives. In passive roaming, there are two types

  1. Stateless Roaming (default / traditional)

  2. Stateful Roaming (Introduced in 1.1 spec)

1.1 Stateless Roaming

This is the default type of roaming used in most of the LoRaWAN devices running on spec 1.0.x

In this type of roaming, the visited network servers forward all packets without verifying whether the home network server approves the device to join or not.


1.2 Stateful Roaming

This is introduced as part of the LoRaWAN 1.1 spec, and in this type, the home network server must validate all packets from the end device, and the connection between the device and the home network server is stateful. This may add additional network overhead as the home network server has to maintain sessions for devices across the world. This is not yet actively used but is an option.


2. Handover Roaming

This type of roaming is similar to our mobile phones, where the end device connects to the visited network server and managing the device is the responsibility of the visited network server.


What is LoRaWAN Roaming Hub?

As LoRaWAN passive roaming is the most popular choice of roaming, it can become extremely complicated as every network has to have an agreement with every other network to support a wide variety of networks and it becomes extremely complicated.


To simplify this, the concept of LoRaWAN Roaming Hub is introduced. This concept is similar to internet exchanges that connect a large group of networks. A LoRaWAN Roaming Hub acts as an exchange that transfers data between networks. Network providers can access all the other networks supported by a Roaming Hub with just one agreement.


What are the downsides of LoRaWAN Roaming in its current state?

While connecting to your device wherever it is sounds awesome, it comes at a cost. LoRaWAN is usually preferred when you want operational costs for hardware and software with nothing added on top like network fees, but with Roaming, you have to pay for other network providers forwarding your device data. Multiple gateways may receive packets from one device due to the nature of LoRaWAN networks, so you may have to pay for the packet multiple times.


LoRaWAN roaming is not widely supported everywhere in the world, and at the time of writing AWS IoT Core for LoRaWAN supports roaming with EveryNet in the USA and UK. You can learn more about it here: https://docs.aws.amazon.com/iot/latest/developerguide/connect-iot-lorawan-roaming-works.html


If you want to learn more about the downsides of LoRaWAN roaming, here is a slightly older article by Johan Stokking, CTO and Co-Founder of The Things Industries.


If you want to discuss your application and see if LoRaWAN is right for your use case or whether you may need NB-IoT based global sims, our experts are one step away to discuss and find a solution for your application. Please contact us or email us on info@ellenex.com

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