The DMR Association developed the DMR Interoperability (IOP) Process so that users and equipment suppliers may benefit from an open multi-vendor market for DMR equipment. In principle, a competitive, open, multi-vendor market brings benefits to users giving them a choice of equipment and suppliers, ongoing development of new products with increased functionality and improved price performance.
The Interoperability process (IOP) is a formal test mechanism allowing manufacturers to test that their products are compatible. Unlike TETRA and other industry standards, interoperability testing is carried out by the manufacturers themselves with a representative of the DMRA present.
By comparison, TETRA interoperability testing is managed by a notified body and there are over 100 mandatory features and thousands of test cases. TETRA IOP also covers interoperability between terminals whereas the DMRA IOP only covers the air interface between terminal and base station.
The IOP only covers the RF air interface and not inperoperability between infrastructure components (e.g. dispatch consoles and repeaters - see DMR AIS).
Products that are awarded a DMR IOP Certificate have been tested, and the functions listed in the certificate have been confirmed to be interoperable. This provides certainty that where a second supplier is added later that existing equipment will not become obsolete.
The DMR IOP is managed by the Technical Working Group (TWG) of the DMR Association. The TWG maintains lists of mandatory and optional interoperability features for conventional (Tier II) and trunked (Tier III) DMR systems, based on the published DMR standards. To be certified as interoperable with a second manufacturer for a particular tier, an equipment manufacturer must be interoperable, for that manufacturer, for the mandatory features. Additionally manufacturers can seek IOP certification for optional features by using the defined test process.
During the test process air interface messages is to be captured and stored, as part of the test process. There is also a visual inspection of the air interface logs to confirm there is no conflict with the test results. If both manufacturers agree that interoperability has been demonstrated the test reports and log files are sent to the TWG which presents them to a full TWG meeting for confirmation.
Mandatory and Optional Features
In order to be interoperable, the participating terminal and infrastructure vendors must show that the equipment under test support the mandatory features. It is not necessary to test or pass the optional features in order to claim interoperability. There is no IOP for DMR Tier 1.
List of Mandatory DMR Tier 2 IOP Features
- Group Call
- Individual Call (PATCS)
- Individual Call (OACSU)
- All Call (Repeater Mode)
List of Optional DMR Tier 2 IOP Features
- Radio Check (Repeater Mode)
- Call Alert (Repeater Mode)
- Radio Disable/Enable (Repeater Mode)
- Remote Monitor (Repeater Mode)
- Emergency Alarm (Repeater Mode)
- Emergency Call (Repeater Mode)
- Individual Text Message (Repeater Mode)
- Group Text Message (Repeater Mode)
List of Mandatory DMR Tier 3 IOP Features
- Talkgroup Call (Single Site Message Trunking)
- Talkgroup Call (Single Site Transmission Trunking)
- Individual Call OACSU (Single Site)
- Individual Call FOACSU (Single Site)
- Short Data Message (Single Site)
List of Optional DMR Tier 3 IOP Features
- Talkgroup Call (Multi-Site Message Trunking)
- Talkgroup Call (Multi-Site Transmission Trunking)
- Individual Call OACSU (Multi-Site Site)
- Individual Call FOACSU (Multi-Site Site)