Short-range IoT communication protocols
Short-range channels allow a device to transmit data up to several hundred meters. Transmission can occur directly via the internet or via a gateway. This kind of IoT communication protocol is often found in plants and home automation installations.
LAN Local Area Network
WiFi
One of these IoT communication protocols is Wi-Fi, which connects devices directly to the local network (LAN). If the local network has internet access, it’s possible to connect devices directly to the cloud.
The main disadvantage of Wi-Fi in the IoT context is energy consumption. Although there are techniques to mitigate its consumption, it remains more energy-intensive than all the other alternatives.
However, it enables excellent performance in terms of high-speed. This presents many advantages:
- Beyond Wi-Fi’s intrinsic security, high-speed allows the use of the TLS protocol, offering optimal security.
- There are no application constraints.
- Real-time data transmission.
Additionally, Wi-Fi can only be used over short distances. It’s often necessary to deploy several access points in an industrial environment to cover the entire surface. And this requires a substantial initial investment.
PAN Personal Area Network
Other short-range IoT communication protocols most suitable for IoT are PAN: Personal Area Network. These primarily include Bluetooth and ZigBee.
Bluetooth Low Energy (BLE)
Bluetooth exists in several variations. Beyond the classic version found in many everyday objects (keyboards, mice, headphones, speakers, car stereos, etc.), there is a version more suited to IoT: Bluetooth Low Energy (BLE).
BLE is a point-to-point protocol, well-supported on tablets and smartphones, which also works on all desktop operating systems. Most of the time, it is used to connect to a device from a smartphone.
A common example is BLE connection from the technician’s smartphone to configure the Wi-Fi access point to be used or to retrieve data if it has no network coverage.
A notable advantage of BLE over classic Bluetooth is that it is not necessary to go through an OS menu to connect to the device. This can be done directly through the smartphone application, allowing for automatic connection.
The energy consumption of BLE is lower than that of classic Bluetooth but still much higher than ZigBee, another PAN alternative.
BLE can send frames of 20 to 255 bytes, so it is not well suited for large data streams. There are many adjustment variables to adjust the data rate, so it is complicated to announce a maximum theoretical data rate because it would probably not be representative of your situation.
Bluetooth Mesh
There is also another version: Bluetooth Mesh. This version allows for interconnecting BLE devices in a mesh network, instead of adopting the star network model of classic BLE. Thus, devices can spread over a much larger area because they are no longer all dependent on a central device. Additionally, the mesh network provides robustness as in the event of a node failure, other nodes are still present to transmit information, limiting data loss. The Mesh theoretically supports up to 32,000 devices on the same network, but practical constraints limit their number to a few hundred.
Bluetooth Mesh requires an encrypted connection, providing a minimum security guarantee.
Note that the Bluetooth Mesh specification was adopted in 2017. This technology is therefore newer than its alternatives, so it has fewer resources.
Zigbee
Like Bluetooth Mesh, ZigBee is a wireless channel for setting up mesh networks. Its very low power consumption makes it particularly suitable for IoT.
It supports up to 65,000 devices on the same network.
Messages are also encrypted on a ZigBee network, via AES 128.
Long-range IoT communication protocols
Long-range IoT communication protocols allow the device to transmit data directly to the cloud or via a gateway without the constraint of geographic proximity to the network.
Cellular networks
Cellular networks have historically served in mobile telephony. However, they now represent reliable communication channel for use in IoT.
These networks are all of the same family and, beyond technical considerations, share many characteristics. They all require passing through an established telecom infrastructure, relying on a third-party provider. This involves providing a SIM card to all connected devices, as well as paying a subscription per device. Choosing one of these networks therefore requires studying prices, but also checking the network coverage provided by the operator. This can quickly become complex when the project is international, and the devices need to operate in different countries.
Considering that operators have a limited number of frequencies, it is also important to check beforehand that there is no risk of frequencies being recycled in favor of a new generation of network.
The first cellular network to be adopted in this context is GSM, a second-generation (2G) network. GSM is an extremely widespread standard, benefiting from excellent network coverage even in less developed countries. However, some operators are starting to discontinue GSM support to reclaim frequencies in favor of newer standards (4G and 5G). Although coverage remains significant, it is important to take this aspect into consideration. 3G faces the same problem, with a longer-term deadline than 2G.
Currently, the two most widely used cellular standards in the context of IoT are LTE-M and NB-IoT.
LTE-M
LTE-M is an evolution of the LTE network (4G). This standard supports high speeds: up to 7Mbits/s uplink and 4Mbits/s downlink for LTE-M Cat-M2 version. It also offers low latency, on the order of tens of milliseconds, which allows for real-time scenarios. LTE-M supports “cell handover,” allowing it to change antennas without losing connection. Thus, it supports mobility scenarios such as real-time vehicle tracking.
LTE-M also includes features to reduce modem usage to preserve battery life (PSM and eDRX). This makes the use of this network realistic in IoT projects. However, this implies greatly limiting network performance and making the device unreachable from the cloud during sleep periods.
LTE-M is supported by 4G and 5G networks.
NB-IoT
NB-IoT is an alternative to LTE-M. Its main advantage lies in its better network coverage because the standard is supported by the GSM (2G) network in addition to 4G and 5G networks. Many countries offer NB-IoT coverage but not LTE-M.
However, this standard offers lower performance than LTE-M. Its maximum theoretical uplink speed is 159kbit/s, and 127kbit/s in downlink speed (in NB2 version). Latency ranges from 1 to 10 seconds, invalidating real-time options. NB-IoT is designed for fixed devices, so it does not support cell handover.
LoRaWAN
LoRaWAN is a radio communication protocol falling into the category of LPWAN (Low Power Wide Area Network). Its main difference from cellular networks is that it uses public radio frequencies, allowing the creation of private networks.
Each LoRaWAN-equipped device communicates with a gateway. The gateway is equipped with an internet connection and transmits data to the cloud. It is possible to install your own gateways to set up a network independent of any access provider.
Take the example of a company manufacturing sensors for farmers: their sensors can be placed in fields spanning several kilometers. A field can be equipped with dozens or even hundreds of devices. In this configuration, providing each device with an LTE-M subscription will increase recurring costs. An alternative solution would be to place a LoRaWAN gateway in the middle of the field, equip all devices with LoRaWAN antennas, and delegate to the gateway the responsibility of transmitting information to the cloud.
Setting up a private network is not mandatory with LoRaWAN. Many providers have established public networks allowing LoRaWAN devices to connect to an existing infrastructure. The providers then route the data to your cloud. This solution involves adopting a model similar to cellular networks, and therefore paying a recurring cost per device.
LoRaWAN has good coverage, many countries have infrastructures. However, it is still necessary to verify that the regions targeted by your IoT project do have IoT coverage.
Regarding technical characteristics:
- Energy consumption is very low. LoRaWAN was designed to serve autonomous battery-powered sensors, making it one of the ideal solutions in this case.
- Messages are encrypted in AES 128 between devices and gateways.
- LoRaWAN is limited in data rate: up to 27kbits/sec.
- This protocol is bidirectional: it is possible to contact devices from the cloud.
Satellite connection
The last IoT communication protocol is satellite connection. This protocol is not widely used in IoT because the cost of subscriptions is often prohibitive. However, satellite communication has the major advantage of offering unparalleled coverage. For example, the provider Iridium highlights a network of 66 low-orbit satellites allowing it to cover the entire Earth’s surface.
This solution is therefore indicated when connectivity is required continuously for devices, and other IoT communication protocols do not offer sufficient coverage. For example, a solution for tracking container ships could use satellite connection to ensure connectivity even when the ship is in the middle of the ocean.
