Background to the development of the DMR Interoperability Process
The Digital Mobile Radio (DMR) Association developed the DMR Interoperability (IOP) Process in order to ensure users and equipment suppliers would benefit from a truly open multi-vendor market for DMR equipment. A healthy, competitive, open, multi-vendor market brings proven benefits to users such as choice of equipment, choice of supplier, continuous development of new products with increased functionality and improved price performance. For manufacturers, it provides a growing market and eliminates different and incompatible implementations of the DMR standard. The Interoperability process provides a formal and consistent test mechanism that enables competing manufacturers to test that their products are compatible. One of the purposes of the DMR IOP Process is to encourage competition. It creates a market of multiple and mutually compatible products. It enables customers to have the ability to select the most appropriate products for their needs and to be confident that these products are compatible with each other. Users can be sure that products awarded a DMR Interoperability (IOP) Certificate have been rigorously tested and the functions listed in the certificate are interoperable. This allows users who select equipment from a number of suppliers to reduce the amount of system integration and testing that they need to undertake and gives them confidence that should they incorporate a second supplier in future that existing equipment will not become obsolete.
The DMR Interoperability Process is managed by the Technical Working Group (TWG) of the DMR Association. The DMR Association TWG has established lists of mandatory and optional interoperability features for conventional (Tier II) and trunked (Tier III) DMR based on the published DMR standard. In order to be certified as interoperable with a second manufacturer for a particular tier, a DMR equipment manufacturer must be interoperable with that manufacturer for the mandatory features. In addition the two manufacturers can opt to seek interoperability certification for some or all optional features by testing the equipment against each other for those features using the defined test process. The DMR Association TWG has documented laboratory quality standards and procedures that need to be adhered to by any laboratory wishing to run a test session. Before setting up a test session manufacturers must declare that their laboratory meets the quality criteria set out by the TWG. For both mandatory and optional features, the DMR Association TWG has specified test procedures which determine how each test is to be run to demonstrate interoperability. In addition there are detailed test report forms that need to be completed. At the time tests are run the test process requires that air interface messages are captured and stored. At the time of testing there is a visual inspection of the air interface logs to ensure that there is nothing in them which contradicts the results of the tests. If both manufacturers involved in a test agree that interoperability has been demonstrated by the testing, the test reports and log files are sent to the DMR Association Technical Working Group. Results are then presented to a meeting of the full Technical Working Group for confirmation.
Diagram 1: DMR Interoperability Process
Through this process users can be assured:
- that both vendors agree interoperability;
- there is detailed documented evidence of this at both the functional level and from the air interface record;
- the tests have been set up so that they can be reproduced if required and will be identical between test sessions;
- that the tests have taken place in a laboratory that has been set up to industry accepted quality standards;
- the test results have been peer reviewed by technically skilled representatives of manufacturers in the industry.
Testing may be carried out in a multi-vendor or bilateral vendor environment and tests the interaction between products from two or more different manufacturers. Test sessions and the whole certification process are funded by the participating manufacturers.
DMR Interoperability Certificates
The results presented in the DMR Interoperability Certificates are derived from evaluating the results of functional testing and from signalling information from the over the air interface logs between live equipment. This analysis ensures interoperability between manufacturers’ products is subject to a high level of checking. Certificates are hardware platform specific and software release specific. However, products not directly used in a test session but which belong to the same model class, (meaning equipment that manufacturers have determined, through engineering analysis or internal functional testing, to be functionally equivalent to the products tested) may be declared interoperable by manufacturers. DMR Interoperability Certificates and summary test reports are published on the DMR Association web site. The goal is that certificates are published within 2 months after a test session is completed. The certificates detail which features have been tested, whether interoperability has been achieved and any other relevant details.
The DMR Association declares that the IOP validation process has been carried out with the best possible endeavor in order to ensure the most reliable results. Nevertheless, the DMR Association takes no responsibility for, and shall have no liability as a result of damages, losses, or injuries of any kind that may be caused by non-conformance* of products that are awarded a DMR Interoperability Certificate. Individual manufacturers are responsible for ensuring that the behavior of any equipment for which conformance is claimed is identical to that of the equipment that passed the DMR Association interoperability certification process.
*to the functions listed in the certificates