Models and Protocols for Resource Optimization in Wireless Mesh Networks

Wireless mesh networks are built on a mix of fixed and mobile nodes interconnected via wireless links to form a multihop ad hoc network. An emerging application area for wireless mesh networks is their evolution into a converged infrastructure used to share and extend, to mobile users, the wireless Internet connectivity of sparsely deployed fixed lines with heterogeneous capacity, ranging from ISP-owned broadband links to subscriber owned low-speed connections. In this thesis we address different key research issues for this networking scenario. First, we propose an analytical predictive tool, developing a queuing network model capable of predicting the network capacity and we use it in a load aware routing protocol in order to provide, to the end users, a quality of service based on the throughput. We then extend the queuing network model and introduce a multi-class queuing network model to predict analytically the average end-to-end packet delay of the traffic flows among the mobile end users and the Internet. The analytical models are validated against simulation. Second, we propose an address auto-configuration solution to extend the coverage of a wireless mesh network by interconnecting it to a mobile ad hoc network in a transparent way for the infrastructure network (i.e., the legacy Internet interconnected to the wireless mesh network). Third, we implement two real testbed prototypes of the proposed solutions as a proof-of-concept, both for the load aware routing protocol and the auto-configuration protocol. Finally we discuss the issues related to the adoption of ad hoc networking technologies to address the fragility of our communication infrastructure and to build the next generation of dependable, secure and rapidly deployable communications infrastructures

A ‘criminal personas’ approach to countering criminal creativity

This paper describes a pilot study of a ‘criminal personas’ approach to countering criminal creativity. The value of the personas approach has been assessed by comparing the identification of criminal opportunity, through ‘traditional’ brainstorming and then through ‘criminal personas’ brainstorming The method involved brainstorm sessions with Computer Forensics Practitioners and with Product Designers, where they were required to generate criminal scenarios, select the most serious criminal opportunities, and propose means of countering them. The findings indicated that there was merit in further research in the development and application of the ‘criminal personas’ approach. The generation of criminal opportunity ideas and proposal of counter criminal solutions were both greater when the brainstorm approach involved the group responding through their given criminal personas

DEPLOYMENT OF NATIVE IP MULTICAST ROUTING SERVICES ON THE ITALIAN ACADEMIC AND RESEARCH NETWORK

In 1993 the GARR (Italian Academic and Research Network) was connected to MBONE (worldwide IP multicast enabled network backbone). Since then, and especially in the last few years, this network has been used to test and develop new IP multicast routing protocols and applications. However it was a tunnel-based solution, not suitable for taking advantage of the new potential of IP multicast nor for use by a large community. This paper describes the work done for a migration to a native IP multicast routing deployment, highlighting the solutions adopted when dealing with the implementation problems and the complex wide area network management. The aim of this work is also to ensure a native IP multicast connection with the other Research Networks and the rest of Internet

Rete GARR-B: Piano di routing IP multicast

The IP multicast was introduced in the GARR network (Italian Network for University and Scientific Community) in 1993 with the connection to Mbone (worldwide virtual multicast network). Since then the Italian Mbone developed constantly allowing the test of protocols and applications. Nevertheless the original Mbone structure is not suitable for an efficient utilization of multicast potentialities and advantages, preventing from exploiting all the services on a large scale; moreover it doesn\u27t allow an interconnection with those ISP which are enabling multicast in their networks but with different technical solutions. This document, after a description of the limits of the present Mbone on GARR, proposes the steps for an updating plane: - IP multicast implementation on the production routers of the backbone, using the PIM-SM protocol; - choice and configuration of the Rendez-Vous Points; - definition of IP multicast boundary routers; - bandwidth limitation; - inter-domain routing (MSDP and MBGP); - international multicast connections. The document deals with some of IP multicast management tools, as well.L\u27introduzione del multicast IP sulla rete GARR (Rete per l\u27Universit? e la Ricerca Scientifica Italiana) risale al 1993 con la prima connessione a Mbone (rete virtuale multicast mondiale). Da allora c\u27e\u27 stato un costante sviluppo sulla Mbone italiana che ha reso possibile la sperimentazione di protocolli e applicativi. Tuttavia la struttura originaria di Mbone non consente un utilizzo efficace delle potenzialita\u27 e dei vantaggi del multicast, precludendo la possibilita\u27 di sfruttarne appieno i servizi su larga scala; cosi\u27 come non consente l\u27interconnessione con quegli ISP che stanno gia\u27 abilitando le loro reti al multicast con soluzioni tecniche diverse. Questo documento, dopo una descrizione dei limiti dell\u27attuale Mbone sul GARR, ne propone le fasi necessarie per un piano di aggiornamento: - implementazione di IP multicast sulla dorsale sui router di produzione con protocollo PIM-SM; - scelta e configurazione dei Rendez-Vous Point; - definizione delle frontiere amministrative (boundary router); - limitazioni di banda; - inter-domain routing (MSDP e MBGP); - connessioni multicast internazionali. Il documento contiene anche un accenno ad alcuni degli strumenti utilizzabili per la gestione dell?IP multicast

Load-aware routing in mesh networks: Models, algorithms and experimentation

In this paper we consider wireless mesh networks (WMNs) used to share the Internet connectivity of sparsely deployed fixed lines with heterogeneous capacity, ranging from ISP-owned high-speed links to subscriber-owned low-speed connections. If traffic is routed in the mesh without considering the load distribution and the bandwidth of Internet connections, some gateways may rapidly get overloaded because they are selected by too many mesh nodes. This may cause a significant reduction of the overall network capacity. To address this issue, in this paper we first develop a queuing network model that predicts the residual capacity of network paths, and identifies network bottlenecks. By taking advantage of this model, we design a novel Load-Aware Route Selection algorithm, named LARS, which improves the network capacity by allocating network paths to upstream Internet flows so as to ensure a more balanced utilization of wireless network resources and gateways? Internet connections. Using simulations and a prototype implementation, we show that the LARS scheme significantly outperforms the shortest-path first routing protocol using a contention-aware routing metric, providing up to 240% throughput improvement in some network scenarios

The observation of silicon nanocrystals in siloxene

This article discusses the observation of silicon nanocrystals in siloxene using high resolution transmission electron microscopy

Homicide detectives' intuition

Little is known about the decision-making processes of homicide detectives; this study is a first step towards understanding the inferential processes they engage in during the initial stages of an investigation. A card sorting exercise consisting of 20 crime scene photographs showing homicide victims in situ was designed to examine how detectives categorise and conceptualise homicide crime scenes. Forty homicide detectives were asked to 'think aloud' whilst categorising the crime scenes. Qualitative content analysis of the 'think aloud' accounts revealed detectives' intuitive ability to automatically make detailed inferences regarding the circumstances surrounding each homicide on the basis of available crime scene information (victim's sex, location, and method of death). A cycle of cognition was evident whereby detectives drew upon the contextual information available to generate hypotheses regarding homicide type (domestic, male brawl, and crime-related) and derive inferences about victim-offender relationship, offender behaviour, motive, and whether the offence was spontaneous or planned. The detectives made 594 inferences of which 67% (N=398) were accurate. The sorting exercise proved to be ecologically valid, with detectives reporting that they assessed and interpreted the homicide crime scenes, as they would in an actual investigation. The implications for police training and 'offender profiling' research are discussed. © 2013 John Wiley & Sons, Ltd