When building an IoT network of connected devices there are two common approaches – a per sensor model or a gateway model. There are benefits to both options, but your decision will largely centre on the type of network you are building. Here we’ll look at how the architecture differs, what the security benefits are, and the typical use cases of each.
Individual model: sensors operate independently
With an individual or per sensor model, the architecture is simple in that each sensor or device connects directly to the network, using NB-IoT, LTE Cat-M or 4G/5G. The devices operate and communicate independently with the network, which means scaling up the network is relatively straightforward – you simply add a new sensor or device. With this type of setup, costs are essentially on a per-sensor basis, in that every sensor will need its own cellular module and SIM card.
Because each sensor or device operates independently, they are managed and secured individually too. The benefit here is that there are less opportunities for a single point of failure. On the flip side, managing each individual sensor or device can increase the complexity, and it’s important to note that each sensor’s security will need to be managed separately.
All data from the sensors or devices is encrypted and typically authentication is SIM based. Of course, the devices will also be operating in licensed spectrum bands, which reduces the risk of unauthorised access, however, you may be reliant on the network carrier to solve any coverage or connectivity issues.
An individual or per sensor model is designed for wide area coverage, making it suitable for remote or dispersed sensors, including vehicle tracking and telemetry, like our work with AJT Transport Consultancy, which can reliably access the tachograph data from its fleet of drivers using our SIMs. Another client, Retail Services, uses a per-sensor architecture to connect its footfall counters and digital signage solutions, and WatchTower Security uses it to connect its network of security cameras all over the country.
Gateway model: multiple sensors one gateway
With a gateway architecture, multiple sensors or devices connect to a central gateway, which then communicates via the cellular network, or back over a fixed network, if one is available.
The initial setup is more complex than the per-sensor model as a gateway and local network will need to be put in place, however, you will have more control over coverage, and won’t be reliant on a network carrier; to enhance coverage, you can use repeaters or simply add another gateway. You will need to be strategic when choosing gateway locations – in large locations like a warehouse or a campus environment, there is the possibility of coverage blackspots. Map out your environment and ensure there are sufficient gateways in optimal locations to provide complete coverage.
While sensors are generally low-power, gateways will typically need a mains power supply. The cost of a gateway can be significant, but that initial outlay is shared among multiple sensors, and these particular sensors won’t require the individual cellular modules that the per-sensor model requires (each will have some other form of radio module instead – LoRa or Bluetooth for example).
Network management is more complex because you will be managing multiple sensors, and it’s important to note that the end user will generally be responsible for troubleshooting any sensor or gateway issues.
If you plan on scaling your network, you will need to future proof your gateway and ensure it can handle an increased load. You can do this from the outset, choosing a gateway that is capable of facilitating extra load. In general, gateways can handle higher data rates and they will be able to aggregate data from multiple sensors.
When it comes to security, a gateway can implement strong encryption and authentication mechanisms to secure data from multiple sensors before transmitting it to the network. Your sensors will be communicating with the gateway over a local network, which can be secured using various protocols and encryption methods. However, you will be responsible for ensuring the security of your gateway.
Unlike the per-sensor option, there is only one point of entry to the cellular or backhaul network – the gateway. This means you can manage the security of all sensors or devices centrally, which makes it somewhat less complex. On the other hand, the gateway is your critical point of failure. If it is compromised, this can have a knock on effect on all connected devices or sensors. This means that the initial security setup, and ongoing monitoring of the gateway, is vital to the overall security of your network.
A gateway model is best suited for localised sensor networks. It works well in a campus, factory or warehouse environment. Some clients use this model to establish smart factories, or implement smart building management systems. It can also be used in large environments like university campuses, airports or ports.
Choosing the right model for your IoT network will largely depend on what you are using your connected devices for, and where you are using them. As you can see, the use cases are specific to particular environments – either widely dispersed or contained in one area.
If you are setting up a new IoT network and would like to chat through your options, call Damian on +353 (0)44 967 5000 or email info@thinglabs.ie.