Wireless communication technologies, pros and cons overview
Technologies
WiFi and Bluetooth are two widely accepted technologies. WiFi is more suitable for the transfer of longer messages over a greater distance. WiFi requires a little more power and is therefore particularly suitable for fixed local networks. Bluetooth, in contrast, is suitable for exchanging information over shorter distances between more mobile equipment. Bluetooth also requires the necessary power, making both technologies suitable for sending and receiving messages in hard-to-reach places.
Other technologies are more geared to long-term unmanned use. EnOcean can work without a battery. Dash 7, a fairly new technology, does not continuously transmit signals but does so periodically.
These alternative technologies are somewhat slower. Furthermore, they have been assigned different frequency ranges worldwide, often differing per region. In some cases, they also have to share that frequency range with other technologies, which increases the risk of communication failure. This is unacceptable for certain applications.
There are other technologies suitable for transmission over long distances, such as LoRa/LoRaWAN and SigFox. The speed and energy consumption of these technologies vary considerably, but they can cover several kilometres. This makes them suitable for monitoring slower processes in, for example, the (waste) water world or tank parks.
Various technologies are also available for short distances. The most important are NFC (often used in consumer applications: e.g. bank cards, access security, OV-chip card) and RFID (mainly used in industry, logistics and professional services).
Whatever technology is used: because they communicate wirelessly in an open environment, all systems must have a built-in security layer that encrypts the data. The technology is after all sensitive to eavesdropping, interference and manipulation.
Protocols
You cannot communicate successfully with only a wireless (or wired) connection. Agreements must also be made with regard to data transfer, sender, receiver, control bits, etc. These are the protocols. A number of protocols are available for the communication layer, the most important of which are TCP and UDP. The internet makes most use of TCP, which is reliable and has a built-in check whether a message has arrived. UDP does not have this, but is much faster and is therefore mainly used for telephony and video.
A messaging layer runs on top of the communication layer. This can be HTTP, HTTPS, REST or MQTT (above TCP) or CoAP (above UDP). REST runs above HTTP and HTTPS for network devices, while IoTivity is a protocol above UDP that recognises connected devices. Most protocols also regulate the end-to-end encryption of messages (REST only guarantees encryption when running on HTTPS).
Thanks to the Industrial Internet of Things, equipment with (embedded) controllers can be connected to each other, allowing the equipment to make use of specific services on the Internet (e.g. remote read outs, diagnosis and configuration). Different topologies are possible which can also be combined.