For decades, land mobile radio (aka two-way radio) has been the mainstay of mobile critical communications. Used by millions worldwide in countless different conditions, constantly tested and refined, it has been the yardstick of success for critical communications, particularly in Public Safety. However, with broadband technologies such as WiFi, cellular and others becoming more and more prevalent, does LMR still hold its ground? In this lesson of the Tait Radio Academy, we take a closer look at the pros and cons of LMR.
Land Mobile Radio: Focus on Voice Communications and Coverage
From the start, LMR was geared towards voice communications. As a result, it has all the voice services that critical communications users expect including individual, group, and broadcast calls, emergency calls, various types of call prioritization, call pre-emption, simplex and so forth.
To make a call, a user presses a push to talk (PTT) button, speaks, and then releases the button to put the radio into receive mode. This type of operation is considered essential for critical communications. In dangerous or high-pressure situations, you don’t have time to look down at your phone, unlock it, find the right app, look up the right contact, and then make the call. You want to be connected as quickly and simply as possible.
Pros: Robust, Reliable and Interoperable
Modern LMR technologies such as DMR, P25, TETRA, and NXDN are all open standard and, being digital, can operate over standard IP networks. It also enables LMR to carry a certain amount of data in addition to voice.
LMR communications have an outstanding reputation for reliability based on the ruggedness of LMR equipment and on the numerous failsafe options built into LMR radios and networks.
And through its close association with public safety, a lot of security options have been developed for LMR systems, including military grade encryption of all voice and data transmissions. This way, public safety organizations can rest easy knowing their comms are secure.
Cons: High Power Usage, Spectrum Scarcity and Limited Bandwidth
LMR’s excellent coverage also has a cost: high-power mobile radios need lots of power and consequently are fitted with big batteries. That is why 5W police portables with an 11 hour 5/5/90 duty cycle look as big as they do. It takes more battery power to go broadcast far distances for longer periods of time.
LMR is also an inefficient user of scarce radio spectrum, so professional organizations sometimes struggle to find available frequencies. One consequence is that spectrum authorities have reduced LMR bandwidth in order to squeeze more users into limited spectrum. As a result, data transmission has suffered.
LMR can only offer low capacity data in its limited bandwidth, which is okay for short text-oriented data services but rules out high bandwidth data applications such as streaming video. It comes as no surprise, then, that LMR users have looked for another bearer to access broadband data.
For more on LMR, make sure you check out our Basic Radio Awareness course.
Tait Radio Academy
Want to know more? For the full lesson, head over to the How to Choose the Right Communication Bearers course on the Tait Radio Academy, where you can learn about the pros and cons of not only LMR, but also WiFi, Satellite, and LTE.
The Tait Radio Academy is a free training resource, providing foundational education on a wide range of critical communications topics. From basic radio awareness to Industrial Control Systems, there is a range of material for people in both technical and non-technical roles.
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