The strengths of mobile radio

When Cyclone Larry ripped through the northern Queensland coast last year, crops were left ravaged, homes destroyed and local infrastructure severely damaged.

As a result of the 300 km/h winds, phone lines were cut and residents were forced to forgo electricity. Weeks after the disaster, many in the town of Innisfail near Cairns were still without water, electricity and telephones.

For these kinds of scenarios, private radio networks are designed to continue operating for days or weeks without power so that they can be used by responding personnel.

These systems are not only crucial for critical infrastructure communications, they also protect the lives of field crews doing hazardous work.

The scenario after many other natural disasters, such as hurricane Katrina in the US, has been the same: private radio networks come through when they are needed most. So why are some users switching to commercial, cellular networks — saying they are the future of mobile communications?

The decision to move from a private to public network is not always based on the comparison of hard facts. Often within the traditional PMR market, the benefits of a private network are overshadowed by the aggressive marketing tactics of the network providers.

Private radio networks may have higher initial costs, but long-term cost of ownership will be less — since no monthly fees or call charges are involved.

Network availability and reliability are both within the control of the organisation. Private networks can be tailored to the needs of a specific organisation, project or event and essentially means not relying on the variable performance of cellular networks during times of crisis.

In contrast, those willing to sign up to a cellular mobile network will be at the mercy of a third-party operator. Such networks are not focused towards a specific user or industry, but offer broad options that service the majority of users, rather than meeting the specific requirements of individual organisations.

Organisations that cover varied terrain or remote areas are some that notice major benefits in a private network. Despite improvements in cellular coverage, private networks can be tailored to reach areas where cellular does not.

For a data application which can wait until it's within range of the cellular network, this may be acceptable. But for voice confirmation before working on a power line, immediate interaction is the necessity.

Operations in remote areas or even beyond the highways most travelled will require more reliability to ensure the safety of its workers.

Two-way radios such as the TM8200 series have built-in safety features, such as 'lone worker', which means the radio will automatically signal for help in the event of an emergency.

Much has been made of the introduction of push-to-talk (PTT) functionality on the cellular network and how it will herald the demise of the two-way radio. A number of cellular operators, keen to emulate the success of US operator Nextel, have begun to launch PTT services and many more are expected to follow suit. A string of leading manufacturers has already developed PTT-enabled handsets.

For those organisations where time is critical to the success of a project or task, herein lies the difference. Public safety staff, for example, require rapid call set-up times, which is often about one second on a PMR network. Technology restraints, however, mean that call set-up times over cellular networks are significantly longer.