Understanding AIS – the DMR Application Interface Specification

Digital Mobile Radio (DMR) is an open digital mobile radio standard defined in the European Telecommunications Standards Institute (ETSI) Standard and used in radio products around the world. DMR, along with P25, Tetra and NXDN are the main competitor technologies in achieving 6.25 kHz equivalent bandwidth.

The DMR Association has approved a protocol for use by dispatch consoles in either Tier II (conventional) or Tier III (Trunking) systems. This protocol is known as “AIS” – Application Interface Specification – and provides a baseline for a console to interface with a DMR radio system.

One of the advantages of the AIS protocol for DMR is that it enables dispatch consoles to connect to an Ethernet port on Base Stations or Repeaters and communicate using IP. This method greatly simplifies installation and provides significant cost savings. In addition, an IP connection enables the console to be physically separated from the DMR system but connected using standard IT equipment.

Since an AIS interface connects directly into infrastructure, it can’t be compared to a wireless connection, also called a control station or donor radio. For example, connecting into four talk groups or channels using gateway connections to four control stations could include the expense of four gateways, four radios, four power supplies, four antennas, etc. The AIS interface to infrastructure is a single cable regardless of the number of radio channels.

Compared to a wireless interface, AIS has significant advantages. Spectrum utilization is excellent as a wide area radio system only needs to consume channels in the geographic area of the subscriber radios, not the donor radios. The wireline interface provides flexibility for managing large numbers of talk groups as opposed to attempting to allocate subsets of talk groups to different donor radios. AIS reduces the chance that a console operator will miss a call or an emergency indication versus the donor radio approach.

Catalyst, as a member of the DMR association, assisted with the standards process. The AIS solution offers high-level functionality and enhanced features to DMR users of various manufacturers’ radio systems that comply with the standard.

Catalyst’s IP|AIS Gateway software solution supports digital audio and user control to the Tier III DMR radio system through a single Ethernet interface. Sophisticated dispatch user control and communication is realized through an intuitive Windows based graphical user interface. Catalyst’s consoles provide dispatch for DMR Tier III systems and supports features like Unit ID with alias translation, Texting, Emergency Signaling, Group Calling, Emergency Group Calls, custom graphics for each talk group, roaming for dispatchers, and instant playback. Catalyst’s IntelliLink solution with AIS allows wireline interoperability with the DMR system and wireline or wireless interfaces to other radio systems such as Project 25, LTR, SmartNet, EDACS, and more depending on the technology.

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