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Private Mobile Radio must evolve
Private Mobile Radio networks (PMR) have existed for several years. Today, 4G makes it possible to rethink PMR to offer more flexibility and features.
In this article, we focus on what PMR is, what it’s used for, and how digital communications are opening new opportunities.
PMR in a nutshell
Private Mobile Radio (PMR) is widely used within the business community to provide communications outside the normal telephone networks. It serves a specific number of users and is normally owned and operated by the same organization as its users. PMR was developed for business users who need to keep in contact over relatively short distances with a central base station. This base station is also called a dispatcher.
PMR systems generally provide facilities for closed user groups, group call and push-to-talk. Their particularity is to have call set-up times which are generally short compared to cellular systems. Many PMR systems allow Direct Mode Operation (DMO): this means terminals can communicate with one another directly, even outside the coverage area of the network.
Limited to a known number of users, the available bandwidth, latency and reliability of the PMR are not affected by users numbers fluctuations. In addition, as any private network, it is easier to reinforce the security of a PMR thus protecting its users from hacking and confidentiality breaches.
3 typical use cases: mission-critical, business–critical activities, and daily operations
Traditionally, there were 2 main cases for using PMR:
- Mission-critical activities, such as emergency services: in this case, voice is the main usage. Lack of, or delay in, communication can seriously affect the ability to protect populations or other assets. Such activities require an immediate call set-up and a 100% availability of voice bandwidth.
- Business-critical activities: here we can think of the management of a very large event, airport ground handling operations or operations of a production line. In this case, voice is the main usage but data communications between machines may also be required. A communication incident can have a major impact on both revenues and the safety of people and goods. For such activities, call set-up time may take slightly longer but availability of voice and data, even with small bandwidth, must be very close to 100%.
- Daily operations: PMR is perfect for employees that are on the go and need to stay in touch with other mobile employees or with a home office. Organizations such as taxi firms and utility workers used these systems as they enabled them to maintain constant contact with their office.
2 networks: TETRA and GSM
2 networks have competed over time to serve PMR needs: TETRA and GSM
TETRA, one of the first digital standards to be launched, is still widely deployed, especially for the emergency services and PMR over GSM networks is gaining momentum, with the features and possibilities offered by 3G and 4G. TETRA can boast a few advantages over GSM:
- TETRA enables instant and easy one-to-many calls which is critical for emergency situations
- It uses very low frequencies (380-430MHz vs 800/900MHz). Its coverage is therefore wider than GSM.
- In the absence of a network, mobile radios can switch to ‘direct mode’ to communicate (in walkie-talkie mode)
Digital communications are opening new opportunities
With many forms of radio communications migrating to digital technology, there was a similar need to undertake the same migration for business radio / PMR. There were many reasons for the move to digital technology:
- Improved spectral efficiency:
- Improved data transmission performance
- Increased flexibility and improved features
- Improved voice quality
- Improved range
In view of the advantages of digital formats, there is a steady migration to digital PMR technologies. However the change is not as fast as in other areas because of the investment required. It seems indeed irrelevant for companies for whom the analogue systems work well to change. Therefore, a 4G-based PMR offered by operators would encourage those companies to take that move. We believe this to be particularly true in the industry sector.
Read our article on why operators should propose 4G-based PMR to serve Industry 4.0
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