The Background
The BOS nationwide TETRA public safety radio network in Germany has much higher levels of resilience built-in compared with public commercial networks. But even the most robust TETRA network can suffer outages in the event of major natural disasters and other extraordinary events.
Unfortunately, it is exactly these kinds of major incidents when radio communications are most urgently needed to manage the response of the emergency services and other rescue organisations. But if part of the radio network is out of action, this not only makes effective coordination and stable communication between emergency response teams more difficult, it can even make it impossible.
A good example of this kind of major incident is the flood disaster that occurred in the Ahr Valley in 2021. The enormous masses of water released by the flash flood caused extensive damage, which led to the failure of the BOS TETRA network in the area. As a result, there was a complete breakdown of the radio network, for which there was no quick repair or temporary alternative communication solution.
The Challenge
In the Ahr Valley floods, the radio infrastructure, which was thought to be safe, completely collapsed and neither the local base stations nor the radio devices could be used for a long period of time. As the rescue effort was severely hampered by the lack of critical communications, this had a devastating effect on people, animals and nature.
The situation was further complicated by the fact that in Germany, the TETRA public safety network cannot be used by non-authorised personnel for legal reasons. Moreover, in the case of possible failures of this network, there are no technical or regulatory provisions in place to add or connect new radio units.
What was needed to overcome these technical and legal challenges, and to avoid a similar communications blackout like the one in 2021, was a mobile and flexible communications solution that could be set up quickly and used in any disaster or emergency. The solution had to be highly robust with fail-safe technical back-up solutions built-in to ensure continuous and reliable communications for the emergency services and any other relevant users.
The Solution
The company OffgridLinx, a Hytera reseller, has been working on just such a mobile critical communications solution over the past one and half years. It has developed a stand-alone, portable base station which can be set up in two to three hours. Its diesel generator and state-of-the-art lithium battery backup power system means it can operate entirely self-sufficiently for a period of up to 72 hours.
The central system component of this in-house development is the HR1065 Repeater from Hytera. The repeater is supplemented by four Hytera HM785 Mobile Radios, which enable flexible connections to existing networks using back-to-back, direct-mode operation.
This set-up enabled OffgridLinx to create an XPT-capable trunking system. Hytera XPT (extended pseudo trunking) enables more users onto a DMR Tier II conventional network sharing existing spectrum resources, but without the need for a control channel as required on a full Tier III trunking network.
Coverage can be extended by integrating additional transmission sites into the network via a satellite connection using the Hytera IP Multi-Site Connect solution, which links two or more DMR Tier II conventional sites together. The radios used for the project included the new H-series, such as the HP685 and HP785, as well as the BP565.
OffgridLinx carried out an extensive evaluation of its new base station from 26 to 29 May 2023 in cooperation with the local emergency services in Niederkassel, Germany, such as the DRK Ortsverein Niederkassel e.V., the local fire brigade as well as public security services and the local police.
As part of this evaluation, the participants tested the new system in the context of a simulated major event. All the communications made by the emergency service teams were handled via the Hytera radios using four HM785 Mobile Radio Devices being used as base stations.
The new radio system was intensively tested over a period of four days with a daily usage time of 9 to 15 hours. Despite the fact that most of the emergency forces had little experience with the Hytera equipment, there were no failures, and they were able to fully operate the devices after only a short time.
The Benefits
The ease of use of the equipment is an important consideration, since in emergency situations responders do not have time for complex briefings and must react quickly in order to work efficiently. The emergency forces were particularly impressed by the sound quality of the Hytera radios and rated them as "significantly better" compared with other radios they have used in the past.
By creating the basic mobile base station solution with various add-on possibilities, OffgridLinx has succeeded in developing a flexible communications solution for emergency situations, and one that is available at short notice and fast to deploy. The solution ensures reliable and, above all, fail-safe communications, especially in the event of power failures.
As a result of this success, OffgridLinx is now manufacturing a second, identical version. Both systems will then be stationed at its premises in Troisdorf and can be called upon at any time for emergency operations or also be rented for private events.
