On the Performance of TETRA DMO Short Data Service in Railway VANETs

Abstract

In this paper we present the results of an empirical study investigating the performance of TETRA (TErrestrial Trunked RAdio) in a Vehicular Ad-hoc Network (VANET) for safety related railway traffic applications. The Short Data Service (SDS) of TETRA in the Direct Mode Operation (DMO) allows an infrastructure-less exchange of traffic relevant information between vehicles in range of the communication. The propagation channel in case of such a direct (base station free) communication between railway vehicles underlies specific effects, which are not equivalent to other well known terrestrial mobile scenarios. We will present measurements covering urban, suburban and rural environments along a regional railway network in the south of Bavaria. Beside different operational conditions such as front, rear, and flank approaches of trains, we investigated several topological scenarios on both, single and double track sections along the line. We will also discuss the observed characteristic changes in narrow band signal attenuation and Doppler spectra for passages through forests, hilly areas, stations and a tunnel. We determined statistics for the transmission delay of messages and the message erasure rates for single and multi user access on a single common carrier for different transmission intervals. Finally, the quality of service for the envisaged safety applications is assessed.

Reasoning Functional Requirements for Virtually Coupled Train Sets: Communication

“…The Terrestrial Trunked Radio, or TETRA, is a European standard for radio communication and is used for emergency services, public safety networks, train radios and the military. It can be used for T2T communication without network coverage in the direct-mode operation (DMO) [7]. TETRA is especially interesting because of its reliability at high relative speeds and good performance in strong multipath environment.…”

Performance Analysis of ITS-G5 for Dynamic Train Coupling Application

“…Despite this, requirements of time-critical safety applications are not met in general. [5] and low latency (µs to some ms [6]) data transmission for real-time applications such as longitudinal distance control for train platooning. In general the reliability of this kind of transmission increases with reduced distance between mobile users.…”

“…An existing decentralized mobile communication system that has been assessed in [6] for T2T communication is TETRA in Direct Mode Operation (DMO) [5]. With TETRA in 400 MHz UHF band, a relatively large communication range is achievable even for non-LOS.…”

Prevention of Metro Rail Accidents and Incidents in Stations Using RFID Technology

“…Fortunately, locomotives of metro trains have electric motors, so it is possible to control the rotational speed of the electric motor using a control circuit equipped with a processor [21]. The processor must decide on the received data from the environment and set the rotational speed of the electric motor based on that.…”

“…Pseudocode of the algorithm for slowing down the train speed and stopping it based on observed conditions. Formulas for determining the suitability of train speed, rotational speed of the right wheel or the left wheel, and the rotational speed of the electric motor on the slope that are used in the Is_Suitable() procedure are based on the train weight, distance to the barrier or station, route slope, and the route curve as well as the power of the motor and its current rotational speed [30,31]. Calculation of these formulas needs technical knowledge in the field of mechanics which is out of scope of this paper with an IT view to the problem.…”