There is a variety of technologies available on the market, we will try to provide a very brief overview
Just to mention a few: TETRA, DMR, Analog Radio, LTE 4G 5G, P25, PoC, MCx, MC PTT, IoT ...
Typically the industry does talk about two different types of critical communication. On the one hand mission critical communication where life of human beings is at risk and on the other hand business critical communication where an outage of production or the business of the end customer due to other reasons may have to rest in case the communication system is not working.
We tend to put both of these services into the same box, since the basic requirements are similar, namely the system has to operate everywhere with almost 24/7 availability. In detail the systems do offer different designs, different technologies and different features with different levels of services, redundancies and fall-back options.
A growing aspect not only in critical communication is security in form of cyber security. It has not been part of the development when specification of the technologies started, but gets gradually and constantly added. In the course of sustainability, also less technical properties do become new trends for end customers such as production chains and total energy balance during production and operation.
Let us name and describe shortly a subset terms and technologies the market is dealing with in the below section.
This technology goes several decades back, does use different modulation schemes and is designed for voice only communication. It is available in almost every low frequency bands (VHF and UHF). Terminals and infrastructure are almost 100% compatible from different vendors. Gateways to phone systems or dispatching and recording devices are typically available, but most likely proprietary or based on a radio connection. Squelch tones are used to enhance spectral efficiency at least by separating user groups and allowing them to communicate on the same frequency. Frequency has to be licensed and therefore typically does not collide with other radio systems in the neighbourhood.
DMR (digital mobile radio) is a digital enhancement onto the analog system. It uses TDMA and provides therefore two communication resources on one frequency. DMR does exist in three Tier modes. Tier 1 is radio to radio only, while tier 2 is a repeater mode, where the frequency is fixed to a user group. Tier 3 is trunked mode operation, it basically just provides several resource communication slots, which can then be used by a larger number of group or individual calls based on first come first serve and some priority principles. DMR also provides some positioning data and narrowband packet data options.
TETRA (terrestrial trunked radio) is a European ETSI standard, similar to DMR, but a bit more mature and older. TETRA standard is used by plenty of police forces and fire brigades across Europe plus other nations and also found several installations within transportation, industries or utilities. TETRA is holding a large amount of feature sets for voice communication, it also is specified for narrow and wideband data communication. Location data from the terminals can also be transmitted.
LTE / 4G / 5G
Since data amount is constantly increasing 3GPP is dealing for several years with specifying also mission critical communication into the LTE standard. First nations are considering to use LTE instead of or as a supplement to TETRA for the police forces and fire brigades. Main differences are customers have to choose between owning a private network or using the public network. Same goes on the device side. While with the above dedicated PMR systems, users did have a dedicated device, here users may be able to operate with their own smartphone.
4G is basically the LTE rollout. Technically it would be better to take a look at the 3GPP releases since they do describe the full available feature set instead of the marketing terms like 4G which is used for several releases. Currently in these releases still further vital mission critical communication elements are getting implemented or improved.
5G is a new hype word, actually allowing for 10x more throughput, 10x more device density and 10x less latency than 4G. But it does come with by far smaller foot print, since frequency bands are by far higher and some of them do not have to be licensed, which may cause interferences with other 5G networks next door. 5G is finally a network of different networks and can handle a lot of critical data communication.
IoT (Internet of Things)
Actually IoT is not a technology standard, but since it is currently discussed everywhere, we decided to add this section here. Actually the standards being used for IoT are more Zigbee, Bluetooth IoT, NFC, RFID, LoRa and multiple more. IoT can use any technology, which suits the customer needs. This typically goes for a small area where plenty of sensors, valves and engine data is collected and then transferred via a longer distance radio system with large capacity. So again a network of networks and you may guess, where 5G may find its place.
MCx stands for mission critical features specified inside the 3GPP (mobile network standardisation organisation) for the LTE 4G and 5G releases. x hereby is a place holder for Voice, Data, Video, Positioning and other future services. This standard is currently constantly under development and it will depend on customers’ needs, if it is already usable for him. Since this is a very large, hot and complex topic you are very welcome to contact us on this matter, if you need any further information or do have dedicated questions.
PoC does stand for PTT over cellular and is a way how the industry tries to name all voice services over WiFi or LTE from a smartphone, which are not MCx compliant. Since developing the standard took several years, there are plenty proprietary solutions on the market, which work fine. They may suffer from congestions and priorities in the infrastructure, since most of them share the service as a standard user with other smartphones playing games or watching some videos.
There are also several versions of WiFi existing, each with different ways to enlarge coverage and also to ensure quality of service. Main issue with WiFi is unlicensed spectrum, which may cause some trouble if other systems are operating in an area close by. Anyhow WiFi is even used for train communication in Germany and other nations for passenger information as well as passenger entertainment in several cases.
Similar as demands from customers are different, also the varieties of technologies are available all with their ups, but also with their downs. Anyhow very often the customers do mix and match their technologies to a hybrid solution fulfilling their needs.
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