The Tetra LTE pilot system allows voice and broadband data services to be used simultaneously in the 400MHz frequency range.
The mobile Tetra LTE (terrestrial trunked radio long-term evolution) system from Airbus Defence and Space, jointly developed with Alcatel-Lucent, has passed further functional tests as a part of the highly mobile cellular networks study, HochZeN (Hochmobile Zellulare Netzwerke), conducted by the German Armed Forces (Bundeswehr).
The prototype of the mobile radio system – the first of its kind worldwide – allows voice and broadband data services to be used in parallel. The results of the second test phase were accepted by the Bundeswehr Technical Centre for Information Technology and Electronics (Wehrtechnische Dienststelle 81, WTD 81) in November.
As part of the tests, up to three radio cells combining both the Tetra and LTE standards passed assessments over several weeks in two of the Bundeswehr’s EAGLE IV armoured vehicles, as well as laboratory tests at the Bundeswehr Technical Centre WTD 81 in Greding, Germany.
The main focus of this phase was on assessing the parallel operation of Tetra voice transmission and LTE broadband data transmission. In addition to networking multiple cells, additional networks and communication solutions were integrated and tested.
For example, as part of more than 90 test cases, the voice connection between HochZeN and Tetrapol radios was assessed. Furthermore, voice communications between HochZeN radios and VHF handhelds and vehicle intercom systems were proven using dedicated gateway solutions in HochZeN mobile cells. Thanks to a voice over IP interface, it was also possible to establish voice and data connections between the HochZeN system and participants using the Bundeswehr’s Mobile Unified Platforms (MUP), which are part of the local deployable subscriber network solutions (TlnNwv).
The tests examined communication links between vehicle and handheld radio devices as well as the connection to both stationary and moving radio cells.
The results attained for radio coverage were above expectations and – thanks to the LTE antenna system in the mobile cells and vehicle radio devices being optimised – even exceeded the ranges and throughput rates achieved in Phase 1 at radio cell edge. In the case of stationary cells, and depending on distance and the height of the antenna, data rates of between 100Kbps and 2Mbps (kilobits resp. megabits per second) and distances of up to 20km were attained when LTE and Tetra were used in parallel.
The mobile Tetra LTE radio system will undergo further tests with the Bundeswehr from next March until the end of 2015. These tests will involve end-users from different branches of the armed forces to assess the system’s behaviour in real-life conditions. Bundeswehr system administrators will receive training over the next few months, so they can operate the radio system autonomously. Airbus Defence and Space will support this field test phase, including by setting up a hotline for technical queries.