Some networks, like the Internet, cannot support multicasting — limiting the ability to provide wide area simultaneous coverage. Radio conferencing for the Internet or "simulated multicasting" overcomes this issue without having to completely change existing radio infrastructure. Radio conferencing enables a small number of radios to be linked together over the Internet. Once in operation, audio received will be transmitted to the other radios.
Backup paths are often required to improve reliability and extend interoperability options. A common tool used is satellite phones. This is a common back up for public safety and emergency service organizations, as the reliance on ground-based infrastructure is sometimes limited. This is especially important when catering for natural disasters like hurricanes or earthquakes, where repeater sites may be damaged or mobile command vehicles cannot be deployed to the devastated area. Using VoIP/SIP gateways, interoperability between satellite and IP can easily be created. This improves communications availability and connectivity as demonstrated in Diagram 4 on Page 73.
Some repeater sites are only accessible via small bandwidth connections. Some satellite service providers charge on a cost-per-byte basis. To cater to this limited bandwidth access, and to reduce operating costs, high data compression techniques are utilized. With this high compression it is important to retain reliable signalling to allow connection between radio and remote command center or phone users. It is also important when selecting radio equipment infrastructure that the critical signalling tones are converted to data prior to transmission over the IP environment. Otherwise it will be lost at the highest compression levels. It is paramount that the right interoperable product is selected to take advantage of these traditional costly infrastructures.
Available VoIP/SIP gateways can be retrofitted to existing networks. This means existing systems can be significantly upgraded without high capital expenditure.
Reduced running costs through IP-based solutions can offset capital expenditure. This means the return on investment can be enjoyed over a shorter period of time. System architecture can also be simplified, which improves reliability and reduces costs. IP offers high levels of scalability and flexibility. Backup operations, off-site control rooms, or backup communication paths can be easily incorporated at any stage.
System managers, consultants and radio engineers now have the tools to significantly improve their communication networks. Taking a fresh look at the new opportunities manufacturers now provide will redefine our understanding of interoperability — and open the door to a wealth of innovative applications.
Alan Parker is the chief operations officer of Omnitronics. He can be reached at firstname.lastname@example.org.