DMR Trunked System (Tier III)

DMR Trunked System (Tier III)

Multiple ECOS-D radios are typically connected via an IP core network, forming a trunked mobile radio network pursuant to DMR Standard ETSI TS 102 361-4. The trunked mobile radio network can only be set up at a single location (so-called single site Tier III using LAN technology) or across several sites (so-called multi-site Tier III using MAN/WAN technology).


The key benefits of a digital DMR private trunked mobile radio network are:

  • Dynamic assignment of the communication channel significantly increases the availability of the radio service in comparison with a conventional private radio network


  • Priority usage with four prioritization levels, e.g. for an emergency call function
  • Two communication channels are available for each radio channel


Frequency range


2m and 70cm


Operating mode

The trunked mobile radio network can be configured either as a simulcast (master/slave principle) system or as a cellular network (individual Radio GateWay stations (RGW)). When configured as a simulcast network, six communication channels are available with the three radio channels in the overall radio network shown in the example above, while the example of a cellular trunked mobile radio network shown below provides four times as many communication channels – making 12 in total – that can be used simultaneously. In both operating modes one communication channel is used as an organisational channel for controlling the trunked radio network.



Over the whole area of coverage the following services can be used, provided the appropriate terminal devices are available:

  • Digital voice services, i.e. via DMR (individual call, group call, all call, emergency call) with preemption and prioritization
  • Digital data services vis SDS (short data messages) or IP

By adding further infrastructure components, dispatcher services and telephone call services to simple wired terminal devices or to existing extension telephones can be realized.



Irrespective of the operating mode, the coverage of the trunked mobile radio network can be extended (i.e. through the addition of a further location) or its capacity can be expanded (i.e. by a further radio channel).