Short Data Service Research Articles

A TETRA-Based System for Remote Health Monitoring of First Responders: Peak AoI Assessment in Direct and Trunked Mode

In this article, we study peak age of information (PAoI) performance of a novel Internet of Things (IoT) solution for remote health monitoring of first responders over terrestrial trunked radio (TETRA) links. The solution features a set of sensors embedded in a smart garment that periodically records and sends physiological parameters of first responders to a remote agent. The received data are analyzed by the remote agent, which feeds back notifications and warnings to the first responders in the form of electrotactile stimuli. The communication in the system is performed over the TETRA short data service (SDS), which is the default option for the development of third-party applications and which has rather limited capabilities. The choice of PAoI as the parameter of interest is motivated by its suitability to measure data freshness in IoT applications with periodic monitoring. We derive closed-form expressions of PAoI for different packet-management schemes allowed by the TETRA standard and verify the analytical results through extensive simulations under varying message generation rates. Our results provide important insights on the expected PAoI performance, which can be used for the system design guidelines. To the best of our knowledge, this is the first work that analyzes AoI performance of the TETRA networks.

Sensor Networks for Monitoring Metro-de-Medellín System Infrastructure

Structural health monitoring systems rely on electronic instrumentation and telemetry for improving maintenance tasks, preventing catastrophic failures and following the behavior of critical variables for infrastructure works such as tunnels, highways, bridges and buildings. A proposal for the development of sensor networks for monitoring Metro-de-Medellín system infrastructure is presented. The adopted approach is based on the deployment of generic sensing units that can operate either individually or by constituting wireless personal area networks un-der the MiWi P2P protocol from Microchip. Different transceivers can be added to monitoring units that can act as gateways in order to allow collected data reach other networks, ranging from local area to metropolitan area coverage. Several sensors, digital and analog, can be attached to the generic units depending on the particular requirements of specific situations and monitoring locations. The results obtained from performed tests and the options considered for graphical user interfaces are also presented.Keywords: MiWi Protocol, Structural Health Monitoring, Short Data Service, Terrestrial Trunked Radio, Wireless Sensor Networks.

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

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.

On the Performance of TETRA Short Data Service-Transport Layer

This paper presents the results of an extensive measurement survey on the performance of Short Data Service Transport Layer (SDS-TL) of Terrestrial Trunked Radio (TETRA) cellular networks. We developed a novel software measurement platform that runs over the TETRA Peripheral Equipment Interface (PEI), generates SDS-TL traffic, performs measurements, and presents statistics of QoS metrics. The measurement platform was utilized in two measurement campaigns: in the first one, two terminals were co-located in the same TETRA cell, and in the second campaign the terminals were positioned in different cells. Measurements were taken for SDS-TL sizes varying from 10 to 190 bytes (excluding the TL header) with an increment of 5 bytes. For each SDS-TL size, 1,500 messages were exchanged through the measurement platform between the TETRA mobile terminals. We repeated all measurements for three intertransmission intervals, namely 2, 1.5, and 1 s, corresponding to measurement durations-for each set of 1,500 SDS-TL- of ? 3,000, 2,250 and 1,500 s, respectively. Hence, 166,500 SDS-TL messages were exchanged between two terminals for each measurement campaign. Results obtained include the end-to-end transmission delay (mean and standard deviation) and the percentage of lost SDS-TL versus the message size for the three intertransmission intervals. The effects of inadequate radio capacity as well as gaps in the radiocoverage can be easily identified through the measurement platform, and we analyze such representative cases.

Research on End-to-End Encryption of TETRA

The Terrestrial Trunked Radio ( TETRA) system uses end-to-end encryption in addition to the air interface encryption to provide enhanced security. The TETRA system uses a synchronization technique known as frame stealing to provide synchronization of end-to-end encrypted data. However, the frame stealing process degrades the quality of video. This paper proposes an end-to-end encryption system with the frame stealing technique for voice and frame insertion for video. A block cipher in the output feedback mode is used to implement the end-to-end key stream generator. Moreover. In the Short Data Service ( SDS) message encryption, a block cipher in the Cipher Block Chaining ( CBC) mode is used to calculate the cryptographically secure checksum, which is sufficient to certify the integrity.