Michelle Wetterwald

ITETRIS: a modular simulation platform for the large scale evaluation of cooperative ITS applications

Cooperative ITS systems are expected to improve road traffic safety and efficiency, and provide infotainment services on the move, through the dynamic exchange of messages between vehicles, and between vehicles and infrastructure nodes. The complexity of cooperative ITS systems and the interrelation between its components requires their extensive testing before deployment. The lack of simulation platforms capable to test, with high modelling accuracy, cooperative ITS systems and applications in large scale scenarios triggered the implementation of the EU-funded iTETRIS simulation platform. iTETRIS is a unique open source simulation platform characterized by a modular architecture that allows integrating two widely adopted traffic and wireless simulators, while supporting the implementation of cooperative ITS applications in a language-agnostic fashion. This paper presents in detail the iTETRIS simulation platform, and describes its architecture, standard compliant implementation, operation and new functionalities. Finally, the paper demonstrates iTETRIS large scale cooperative ITS evaluation capabilities through the implementation and evaluation of cooperative traffic congestion detection and bus lane management applications. The detailed description and implemented examples provide valuable information on how to use and exploit iTETRIS simulation potential.

Architectures for cognitive radio testbeds and demonstrators — An overview

Wireless communication standards are developed at an ever-increasing rate of pace, and significant amounts of effort is put into research for new communication methods and concepts. On the physical layer, such topics include MIMO, cooperative communication, and error control coding, whereas research on the medium access layer includes link control, network topology, and cognitive radio. At the same time, implementations are moving from traditional fixed hardware architectures towards software, allowing more efficient development. Today, field-programmable gate arrays (FPGAs) and regular desktop computers are fast enough to handle complete baseband processing chains, and there are several platforms, both open-source and commercial, providing such solutions. The aims of this paper is to give an overview of five of the available platforms and their characteristics, and compare the features and performance measures of the different systems.

The 'pure-IP' Moby Dick 4G architecture

Network operators, service providers and customers are players who have different interests and raise different requirements on the functionality of future mobile communication networks. However, some new capabilities, such as mobility, security, ubiquity and quality are spelled out by all, which means that there exist some fundamental mechanisms which are in fact needed in every network. This paper concentrates on critical elements of the network infrastructure which need to be deployed in 4G networks before services can be offered. In the paper we discuss these elements, and show how they can be combined to satisfy versatile service requirements. Furthermore, the paper shows how to combine these mechanisms of three traditionally quite separate architectures-for Authentication, Authorisation, Accounting and Charging (AAAC), for Mobility (Mobile IP with Fast Handover), and Quality-of-Service (QoS). A technology-independent paging concept is also integrated in this system. The resulting integrated system architecture is general and can be deployed in heterogeneous environments. Our implementation has recently been completed, validated and verified with applications such as data transfer, voice-over-IP, video streaming and real time concurrent gaming. This prototypical implementation incorporates TD-CDMA, 802.11 WLANs and Ethernet, and treats all transmission technologies as physical and data-link layers, while higher-level functions are supported in a uniform way with an all-IPv6-based signalling.

Integration of Broadcast Technologies with Heterogeneous Networks - An IEEE 802.21 Centric Approach

In order to integrate broadcast communication technologies like DVB-H and MBMS in a heterogeneous system, different mechanisms have to be developed, both on the mobile user terminal and on the network infrastructure. This paper presents the framework developed in the Daidalos-II (FP6) project for supporting broadcast integration with heterogeneous wireless networks with a focus on the development of a hybrid terminal.

IPv6 Soft Handover Applied to Network Mobility over Heterogeneous Access Networks

Toward seamless inter-networking between cellular networks and Wireless LAN, one of the major challenges is seamless vertical handover between different access technologies. Even in heterogeneous access networks which provide combined radio coverage, users may still suffer from packet losses due to bad radio conditions during the handover. Eurecom IPv6 soft handover can reduce packet losses even in the case of vertical handover. Considering that Network Mobility (NEMO) has an advantage of hiding mobility functions from users involved, Eurecom IPv6 soft handover and NEMO are expected to provide a good combination. This paper proposes IPv6 soft handover extension for NEMO over heterogeneous access networks to achieve better performance for UDP and TCP traffic. The proposed method called NEMO-SHO uses two different interfaces simultaneously during vertical handovers, and provides good Quality of Service for the users regardless of the radio coverage quality. Using 3G and IEEE802.11b interfaces, our experiments show that NEMO- SHO can achieve better performances for UDP traffic and constant-bit-rate TCP traffic than Make-Before-Break handovers in lossy radio conditions. We find that in case of TCP traffic the performance gain of NEMO-SHO is more affected by the difference of bandwidth and transmission delay between the two links due to the larger amount of outstanding TCP segments.

QoE-aware traffic management for mobile video delivery

Video delivery has become a major challenge for mobile networks. The increasing spread of smartphones, along with the expanding availability of LTE coverage, has contributed to an extensively growing mobile video demand, bringing large volumes of video traffic and far exceeding the capacity of mobile networks. As a result, wireless access congestion is becoming more frequent, degrading the Quality of Experience (QoE) for mobile video consumers. In this paper, we present a novel QoE-aware traffic management scheme and architecture for scalable video delivery. Thereby, Scalable Video Coding (SVC) is able to organize video data into layers of different importance, thus facilitating the rate adaptation of video streams. The proposed cross-layer architecture is implemented and the optimization is validated in a real-time streaming prototype and testbed. Results demonstrate the benefit of applying QoE-awareness and cross-layer optimization in congestion scenarios. The perceived video quality is improved considerably for all users in the cell, under both light and heavy congestion.

An all-IP software radio architecture under RTLinux

This paper presents an overview of software radio architectures for testing quality-of-service (QoS) aware IP data services over a typical third-generation radio interface. The testbed is implemented using a hard real-time micro-kernel known as RTLinux, running beneath the Linux operating system, for providing real-time end-to-end functionality. The testbed runs on a variety of Intel Pentium-based computing platforms including laptops and high-end servers. Layers 1 and 2 are compliant with the 3GPP specifications forTdd operation and layer 3 provides a direct interconnection with an IPv6 core network. The intent is to study the impact of an ip core network and QoS constraints on the physical and link layers as well as the co-design of physical layer configurations and IP layer networking.RésuméCet article présente un aperçu des architectures radio logicielles destinées aux tests de la qualité de service (Quality of Service: QoS) pour des services IP de transmission de données à travers des interfaces radio 3e génération. Le banc d’essai est réalisé en utilisant un micro-noyau temps réel comme RTLinux, qui tourne sous un système d’exploitation Linux, assurant ainsi des fonctionnalités temps réel de bout en bout. Le banc d’essai consiste en une plateforme comprenant des PC portables et des serveurs à base de processeurs Intel Pentium. Les couches 1 et 2 sont totalement compatibles avec les spécifications de la norme 3GPP pour le modeTdd. Quant à la couche 3, elle est conçue pour offrir une interconnexion directe avec des réseaux IPv6. Notre objectif étant d’étudier, aussi bien, l’impact des architectures ip et des contraintes de la qualité de service sur les couches physique et de liaison, que la conception conjointe des configurations de la couche physique et de la couche IP.

Multicast and Virtual Road Side Units for Multi Technology Alert Messages Dissemination

This paper presents a method to disseminate alert messages in the context of new emerging communication standards, such as LTE and Wave. The applications involving the broadcast of periodic messages, can be described using the MBMS (Multicast/Broadcast Multimedia Service). Public Safety alert systems perform one important task in the context of Public Safety Networks (PSNs). The method proposed here is responsible for delivering alert messages to the greatest number of people in a specified area. To accomplish this task a new method, Virtual Road Side Unit (vRSU) is proposed to help the authorities to reach isolated people. The system works even if the deployed structure is severed damaged, i.e. most part of the regular Road Side Units (RSU) are out of order. In our method nodes work cooperatively to propagate the message to other nodes, when re-propagating messages nodes, vRSUs, behave as regular RSUs. KeywordsPublic Safety; multicast; alert; LTE; data

Wireless access mechanisms and architecture definition in the MEDIEVAL project

Wireless network access and the exchange of multimedia flows over the Internet are becoming more and more pervasive in the everyday life. However, simple technological advances in terms of improved network capacity cannot satisfy the increasing demand of such services, since a paradigm shift from the current Internet architecture is required. The EU FP7 MEDIEVAL project tackles this issue by addressing novel architectural frameworks and viable strategies to efficiently deliver video services in a wireless Internet context. This paper reviews the currently ongoing activities of the project for what concerns wireless access, in particular the identification of useful techniques for the considered access technologies (WLAN and LTE-A) and the general definition of architectural schemes to efficiently support video flows.

Wireless access architectures for video applications: the approach proposed in the MEDIEVAL project

Video transmission is expected to be the next big thing in personal communication systems. While text messaging applications have already experienced an explosive growth, the exchange of multimedia content is still lacking architectural solutions which enable it to become the next killer application. The EU project MEDIEVAL (MultimEDia transport for mobIlE Video AppLications) [1] aims at filling this gap. In this paper we describe the approaches envisioned by the project for what concerns the data link layer, with special emphasis on wireless access and its related cross-layer issues. After presenting some general project aspects, we will review the state of the art and enumerate several open issues, concerning the identification of the most suitable radio technologies for video support, as well as their integration and required enhancements to enable efficient video transport.