Seamless Connectivity Techniques in Vehicular Ad-hoc Networks

In this chapter we describe the traditional techniques used for seamless connectivity in heterogeneous wireless network environments, and in particular adopt them in VANETs, where V2V and V2I represent the main communication protocols. Section 2 deals with the basic features of Vertical Handover (VHO) in the general context of a hybrid wireless network environment, and it discusses how decision metrics can affect handover performance (i.e. number of handover occurrences, and throughput). Instead, Section 3 briefly introduces two proposed techniques achieving seamless connectivity in VANETs. The first technique is a vertical handover mechanism applied to V2I-only communication environments; it is presented in Section 4 via an analytical model, and main simulated results are shown. The second approach is described in Section 5. It addresses a hybrid vehicular communication protocol (i.e. called as Vehicle-to-X) performing handover between V2V and V2I communications, and vice versa.

Satellite QoS Architecture in the SATIP6 Project

This paper deals with QoS provision for broadband access via TCP/IP over DVB satellites. Namely, work carried out by the University of Rome “La Sapienza” in the IST project SATIP6 with specific reference to the traffic control and access control is presented and discussed. The traffic control part in the SATIP6 architecture aims at guaranteeing delay and bandwidth requirements to IP flows and users on the basis of the bandwidth allocated to DVB classes by means of the access control function. The access control part aims at requesting the proper amount of capacity to the satellite network on the basis of measures taken on the traffic offered to the satellite system. In particular, this paper discusses the two components of the satellite QoS architecture and how to coordinate their operation in a single efficient algorithm

Network monitoring and performance evaluation in a 3.5G network

Monitoring network performance and status is a fundamental task for network operators as it directly impacts the quality of the offered services and hence user satisfaction. For this purpose a consolidated approach, which is largely adopted by network operators, is based on the so-called KPIs (key performance indicators). In this paper, we propose and discuss a set of KPIs to monitor network performance of the new HSDPA enhanced UNITS infrastructure. KPI statistics are collected and analysed from the novel HSDPA network of H3G, one of the major Italian mobile network operators. (c) 2007 Elsevier B.V. All rights reserved

Efficient transport of IP flows over IEEE802.11 wireless mesh networks

Wireless Mesh Networks (WMNs) based on the IEEE802.11 standards can be used as convenient replacements of wireline networks in the context of home networking to provide users with a variety of services inside the home context for their low cost and easiness of deployment. However, in order to effectively support multimedia as well as ordinary traffic through a WMN infrastructure, traffic control is generally needed as wireless communications, especially in mesh network configurations, can be affected by significant congestion and channel impairments problems. In this work we are focusing on performance assessment and enhancement in IEEE802.11 WMNs. Experimental results are presented using simulation models of IEEE802.11b technology obtained through the open source INET framework of OMNET++ simulator

Support for Multicast-Aware QoS in NGNs: the DAIDALOS Approach

Spreading of traditional and novel broadcast applications in the Internet, such as messaging and video conferencing has, in the last few years, considerably increased the interest in support for broadcast applications within research community. In general broadcast poses several challenges at network and application/session levels ranging from efficient use of bandwidth, reliability of content delivery to security and authentication, spontaneous activation of multiparty sessions, and flexible support for renegotiation of session parameters. In addition, when considering the Internet, support for broadcast has to be engineered so as to assure full integration of broadcast technology in a heterogeneous infrastructure and high-scalability with respect to the number of potential users of a multicast session. State-ofthe-art of broadcast technology comprises a vast number of proposed protocols, algorithms and network technologies with native-support for broadcast. This paper presents the approach followed by the DAIDALOS project, sponsored by the EU within the Sixth framework Research Programme, for multicast-aware QoS in a heterogeneous end-to-end TCP/IP infrastructure

Vertical handover among broadcast networks

In this article we propose strategies for optimization of vertical handover among broadcast networks. The specific technologies of DVB-H and UMTS/MBMS are taken into account for the modelling of technological parameters including energy consumption and frame loss. Energy consumption is important in a mobile context in order to maximize the possible service duration while frame loss must be considered in order to provide services with an acceptable quality of experience. The proposed strategies are based on two different functions: a ratio between the energy consumption and the frame loss along and a linear objective function. The two function are compared with functions based on only one parameter and against the theoretic frame loss and energy consumption. The paper gives numerical results obtained through simulations in different mobility conditions in order to assess the performance of the proposed functions in terms of frame loss and energy consumption as well as in frequency of vertical handovers. © 2009 IEEE