Investigation of data dissemination techniques for opportunistic networks

An opportunistic network is an infrastructure-less peer to peer network, created between devices that are mobile and wireless enabled. The links between devices are dynamic and often short-lived. Therefore, disseminating data from a source to recipients with a quality of service guarantee and efficiency is a very challenging problem. Furthermore, the interactions between devices are based on opportunity and are dependent on the devices mobility, which have extreme diverse patterns. The aim of this thesis is to investigate dissemination of data in opportunistic networks. In particular two conflicting objectives are studied: minimising the overhead costs and maximising the information coverage over time. We also take into account the effects of mobility. Extensive computer simulation is developed to explore models for information dissemination and mobility. On top of existing mobility models (i.e. Random Walk, Random, Waypoint and Gauss Markov) a hybrid model is derived from the Random Waypoint and Gauss Markov mobility models. The effect on mobility model on dissemination performance is found to be highly significant. This is based on sensitivity analysis on mobility and node density. We first consider different baseline push techniques for data dissemination. We propose four different push techniques, namely Pure Push, Greedy, L-Push and Spray and Relay to analyse the impact of different push techniques to the information dissemination performances. The results present different trade-offs between objectives. As a strategy to manage overheads, we consider controlling to which nodes information is pushed to by establishing a social network between devices. A logical social network can be built between mobile devices if they repeatedly see each other, and can be defined in different ways. This is important because it shows how content may potentially flow to devices. We explore the effects of mobility for different definitions of the social network. This shows how different local criteria for defining links in a social network lead to different social structures. Finally we consider the effect of combining the social structure and intelligent push techniques to further improve the data dissemination performance in opportunistic networks. We discover that prioritising pushing over a social network is able to minimise the overhead costs but it introduces a dissemination delay.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Investigation of data dissemination techniques for opportunistic networks

An opportunistic network is an infrastructure-less peer to peer network, created between devices that are mobile and wireless enabled. The links between devices are dynamic and often short-lived. Therefore, disseminating data from a source to recipients with a quality of service guarantee and efficiency is a very challenging problem. Furthermore, the interactions between devices are based on opportunity and are dependent on the devices mobility, which have extreme diverse patterns. The aim of this thesis is to investigate dissemination of data in opportunistic networks. In particular two conflicting objectives are studied: minimising the overhead costs and maximising the information coverage over time. We also take into account the effects of mobility. Extensive computer simulation is developed to explore models for information dissemination and mobility. On top of existing mobility models (i.e. Random Walk, Random, Waypoint and Gauss Markov) a hybrid model is derived from the Random Waypoint and Gauss Markov mobility models. The effect on mobility model on dissemination performance is found to be highly significant. This is based on sensitivity analysis on mobility and node density. We first consider different baseline push techniques for data dissemination. We propose four different push techniques, namely Pure Push, Greedy, L-Push and Spray and Relay to analyse the impact of different push techniques to the information dissemination performances. The results present different trade-offs between objectives. As a strategy to manage overheads, we consider controlling to which nodes information is pushed to by establishing a social network between devices. A logical social network can be built between mobile devices if they repeatedly see each other, and can be defined in different ways. This is important because it shows how content may potentially flow to devices. We explore the effects of mobility for different definitions of the social network. This shows how different local criteria for defining links in a social network lead to different social structures. Finally we consider the effect of combining the social structure and intelligent push techniques to further improve the data dissemination performance in opportunistic networks. We discover that prioritising pushing over a social network is able to minimise the overhead costs but it introduces a dissemination delay.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Investigation of data dissemination techniques for opportunistic networks

An opportunistic network is an infrastructure-less peer to peer network, created between devices that are mobile and wireless enabled. The links between devices are dynamic and often short-lived. Therefore, disseminating data from a source to recipients with a quality of service guarantee and efficiency is a very challenging problem. Furthermore, the interactions between devices are based on opportunity and are dependent on the devices mobility, which have extreme diverse patterns. The aim of this thesis is to investigate dissemination of data in opportunistic networks. In particular two conflicting objectives are studied: minimising the overhead costs and maximising the information coverage over time. We also take into account the effects of mobility. Extensive computer simulation is developed to explore models for information dissemination and mobility. On top of existing mobility models (i.e. Random Walk, Random, Waypoint and Gauss Markov) a hybrid model is derived from the Random Waypoint and Gauss Markov mobility models. The effect on mobility model on dissemination performance is found to be highly significant. This is based on sensitivity analysis on mobility and node density. We first consider different baseline push techniques for data dissemination. We propose four different push techniques, namely Pure Push, Greedy, L-Push and Spray and Relay to analyse the impact of different push techniques to the information dissemination performances. The results present different trade-offs between objectives. As a strategy to manage overheads, we consider controlling to which nodes information is pushed to by establishing a social network between devices. A logical social network can be built between mobile devices if they repeatedly see each other, and can be defined in different ways. This is important because it shows how content may potentially flow to devices. We explore the effects of mobility for different definitions of the social network. This shows how different local criteria for defining links in a social network lead to different social structures. Finally we consider the effect of combining the social structure and intelligent push techniques to further improve the data dissemination performance in opportunistic networks. We discover that prioritising pushing over a social network is able to minimise the overhead costs but it introduces a dissemination delay

Mobile Computing in Digital Ecosystems: Design Issues and Challenges

In this paper we argue that the set of wireless, mobile devices (e.g., portable telephones, tablet PCs, GPS navigators, media players) commonly used by human users enables the construction of what we term a digital ecosystem, i.e., an ecosystem constructed out of so-called digital organisms (see below), that can foster the development of novel distributed services. In this context, a human user equipped with his/her own mobile devices, can be though of as a digital organism (DO), a subsystem characterized by a set of peculiar features and resources it can offer to the rest of the ecosystem for use from its peer DOs. The internal organization of the DO must address issues of management of its own resources, including power consumption. Inside the DO and among DOs, peer-to-peer interaction mechanisms can be conveniently deployed to favor resource sharing and data dissemination. Throughout this paper, we show that most of the solutions and technologies needed to construct a digital ecosystem are already available. What is still missing is a framework (i.e., mechanisms, protocols, services) that can support effectively the integration and cooperation of these technologies. In addition, in the following we show that that framework can be implemented as a middleware subsystem that enables novel and ubiquitous forms of computation and communication. Finally, in order to illustrate the effectiveness of our approach, we introduce some experimental results we have obtained from preliminary implementations of (parts of) that subsystem.Comment: Proceedings of the 7th International wireless Communications and Mobile Computing conference (IWCMC-2011), Emergency Management: Communication and Computing Platforms Worksho

Delay Tolerant Networking over the Metropolitan Public Transportation

We discuss MDTN: a delay tolerant application platform built on top of the Public Transportation System (PTS) and able to provide service access while exploiting opportunistic connectivity. Our solution adopts a carrier-based approach where buses act as data collectors for user requests requiring Internet access. Simulations based on real maps and PTS routes with state-of-the-art routing protocols demonstrate that MDTN represents a viable solution for elastic nonreal-time service delivery. Nevertheless, performance indexes of the considered routing policies show that there is no golden rule for optimal performance and a tailored routing strategy is required for each specific case

Requirement analysis for building practical accident warning systems based on vehicular ad-hoc networks

An Accident Warning System (AWS) is a safety application that provides collision avoidance notifications for next generation vehicles whilst Vehicular Ad-hoc Networks (VANETs) provide the communication functionality to exchange these notifi- cations. Despite much previous research, there is little agreement on the requirements for accident warning systems. In order to build a practical warning system, it is important to ascertain the system requirements, information to be exchanged, and protocols needed for communication between vehicles. This paper presents a practical model of an accident warning system by stipulating the requirements in a realistic manner and thoroughly reviewing previous proposals with a view to identify gaps in this area

On the Dynamics of Human Proximity for Data Diffusion in Ad-Hoc Networks

We report on a data-driven investigation aimed at understanding the dynamics of message spreading in a real-world dynamical network of human proximity. We use data collected by means of a proximity-sensing network of wearable sensors that we deployed at three different social gatherings, simultaneously involving several hundred individuals. We simulate a message spreading process over the recorded proximity network, focusing on both the topological and the temporal properties. We show that by using an appropriate technique to deal with the temporal heterogeneity of proximity events, a universal statistical pattern emerges for the delivery times of messages, robust across all the data sets. Our results are useful to set constraints for generic processes of data dissemination, as well as to validate established models of human mobility and proximity that are frequently used to simulate realistic behaviors.Comment: A. Panisson et al., On the dynamics of human proximity for data diffusion in ad-hoc networks, Ad Hoc Netw. (2011