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

On secure communication in integrated internet and heterogeneous multi-hop wireless networks.

Integration of the Internet with a Cellular Network, WMAN, WLAN, and MANET presents an exceptional promise by having co-existence of conventional WWANs/WMANs/WLANs with wireless ad hoc networks to provide ubiquitous communication. We call such integrated networks providing internet accessibility for mobile users as heterogeneous multi-hop wireless networks where the Internet and wireless infrastructure such as WLAN access points (APs) and base stations (BSs) constitute the backbone for various emerging wireless networks (e.g., multi-hop WLAN and ad hoc networks. Earlier approaches for the Internet connectivity either provide only unidirectional connectivity for ad hoc hosts or cause high overhead as well as delay for providing full bi-directional connections. In this dissertation, a new protocol is proposed for integrated Internet and ad hoc networks for supporting bi-directional global connectivity for ad hoc hosts. In order to provide efficient mobility management for mobile users in an integrated network, a mobility management protocol called multi-hop cellular IP (MCIP) has been proposed to provide a micro-mobility management framework for heterogeneous multi-hop network. The micro-mobility is achieved by differentiating the local domain from the global domain. At the same time, the MCIP protocol extends Mobile IP protocol for providing macro-mobility support between local domains either for single hop MSs or multi-hop MSs. In the MCIP protocol, new location and mobility management approaches are developed for tracking mobile stations, paging, and handoff management. This dissertation also provides a security protocol for integrated Internet and MANET to establish distributed trust relationships amongst mobile infrastructures. This protocol protects communication between two mobile stations against the attacks either from the Internet side or from wireless side. Moreover, a secure macro/micro-mobility protocol (SM3P) have been introduced and evaluated for preventing mobility-related attacks either for single-hop MSs or multi-hop MSs. In the proposed SM3P, mobile IP security has been extended for supporting macro-mobility across local domains through the process of multi-hop registration and authentication. In a local domain, a certificate-based authentication achieves the effective routing and micro-mobility protection from a range of potential security threats

Modeling and Performance Evaluation of MANET Handover

A Mobile Ad Hoc Network (MANET) is an unstructured collection of wireless nodes that move arbitrarily and use multi-hop protocols to communicate between each other. There is not a predefined infrastructure in a MANET as there is in other types of wireless networks. Now days, MANET networks integrate with other networks, like the Internet, permitting ad hoc nodes to communicate with hosts placed in any part of the world. But the integration of MANETs with fixed infrastructures must be carefully studied to evaluate how it performs. In such integrated scenario, commonly known as Hybrid Ad Hoc Network, a MANET can be seen as an extension to the existing infrastructure, whose mobile nodes seamlessly communicate with hosts on the fixed network by forwarding packets throughout the gateways found on the edge that join both types of network. Connecting MANETs to the Internet does not come without difficulties. Ad hoc routing protocols work different than the regular routing protocols used on the Internet, and their interoperability becomes an important issue. But when MANETs integrate with the Internet, a more demanding challenge emerges if node mobility is considered. A moving node may lose registration with its current gateway, and may then need to register to a different gateway (a handover) to continue communicating. During a handover, any ongoing communication will be interrupted affecting network performance. In order to improve this performance, an IP mobility management protocol must be used. The main objective of this research is to develop a model that may be used to evaluate the performance of MANET handovers under different scenarios. Different issues about MANET integration with the Internet are considered: the IP mobility protocol implemented, the external route computation procedure, the type of ad hoc routing protocol used, and the gateway discovery approach used. For this evaluation, a mobile node in a MANET holding a communication with a correspondent node in the Internet roams to a different sub-network, having to change its registration to a different gateway. The different scenarios considered to evaluate the handover performance include the use of different types of MANET protocols, the use of different gateway discovery approaches, and the use of different versions of the Mobile IP protocol. During the research a review was made of the functioning conditions for the proposed scenario. Then, a handover model was proposed, which was used to develop some metrics that were later used to evaluate the MANET handover performance. This metrics are the broken communication time, the probability of handover failure, and the average communication interruption time. In all the results found, we could confirm that the proactive discovery approach has a better handover performance than the reactive discovery approach, which permit us to conclude that regardless the MANET routing protocol, and the Mobile IP version, the proactive agent discovery approach should be used in highly mobile scenarios, preferable, with the reactive routing protocol

Internet connectivity for mobile Ad Hoc networks

Ad hoc networking allows portable devices to establish communication independent of a central infrastructure. However, the fact that there is no central infrastructure and that the devices can move randomly gives rise to various kind of problems, such as routing and security. In this thesis the problem of routing is considered. There are several ad hoc routing protocols, such as AODV, DSR, OLSR and ZRP, that propose solutions for routing within a mobile ad hoc network. However, since there is an interest in communication between not only mobile devices in an ad hoc network, but also between a mobile device in an ad hoc network and a fixed device in a fixed network (e.g. the Internet), the ad hoc routing protocols need to be modified. In this thesis the ad hoc routing protocol AODV is used and modified to examine the interconnection between a mobile adhoc network and the Internet. For this purpose Network Simulator 2, ns2, has been used. Moreover, three proposed approaches for gateway discovery are implemented and investigated. The goal of the thesis project is twofold: • To modify the source code of AODV in accordance with the Internet draft\Global connectivity for IPv6 Mobile Ad Hoc Networks " which presents a solution where AODV is used to provide Internet access to mobile nodes. • To implement and compare di®erent approaches for gateway discovery. In this thesis, three di®erent type of gateway discovery have been taken: • The proactive gateway discovery is initiated by the gateway itself. The gateway periodically broadcasts a gateway advertisement message which is transmitted after expiration of the gateways timer. The time between two consecutive advertisements must be chosen with care so that the network is not °ooded unnecessarily. All mobile devices residing in the gateways transmission range receive the advertisement and update information about gateway. After receiving advertisement, a mobile device just forward it broadcast it again. This process goes on within entire MANET. • In reactive gateway discovery a mobile device of MANET connects by gateway only when it is needed. For that the mobile device broadcasts request message to the ALL MANET GW MULTICAST address (the IP address for the group of all gateways in a mobile ad hoc network). Thus, only the gateways are addressed by this message and only they process it. Intermediate mobile nodes that receive the message just forward it by broadcasting it again up to gateway. • To minimize the disadvantages of proactive and reactive gateway discovery, the two approaches can be combined. This results is a hybrid gateway discovery. For mobile devices in a certain range around a gateway, proactive gateway discovery is used. Mobile devices residing outside this range use reactive gateway discovery to obtain information about the gateway. In comparing theses di®erent gateway discovery, three matrices are used. These are packet delivery ratio,average end-to-end delay and overhead. In case of proactive gateway discovery and hybrid gateway discovery, value of packet delivery ratio is larger than reactive gateway discovery. In case of proactive gateway discovery and hybrid gateway discovery, value of end to end delay is less than reactive gateway discovery. The overhead of proactive gateway discovery is greater than other two gateway discovery As for the average end-to-end delay, the proactive and hybrid methods perform slightly better than the reactive method. Concerning the routing overhead, when the advertisement interval is short the reactive method generates much less overhead than the proactive method, which in turn generates much less overhead than the hybrid method

Wireless Multi Hop Access Networks and Protocols

As more and more applications and services in our society now depend on the Internet, it is important that dynamically deployed wireless multi hop networks are able to gain access to the Internet and other infrastructure networks and services. This thesis proposes and evaluates solutions for providing multi hop Internet Access. It investigates how ad hoc networks can be combined with wireless and mesh networks in order to create wireless multi hop access networks. When several access points to the Internet are available, and the mobile node roams to a new access point, the node has to make a decision when and how to change its point of attachment. The thesis describes how to consider the rapid fluctuations of the wireless medium, how to handle the fact that other nodes on the path to the access point are also mobile which results in frequent link and route breaks, and the impact the change of attachment has on already existing connections. Medium access and routing protocols have been developed that consider both the long term and the short term variations of a mobile wireless network. The long term variations consider the fact that as nodes are mobile, links will frequently break and new links appear and thus the network topology map is constantly redrawn. The short term variations consider the rapid fluctuations of the wireless channel caused by mobility and multi path propagation deviations. In order to achieve diversity forwarding, protocols are presented which consider the network topology and the state of the wireless channel when decisions about forwarding need to be made. The medium access protocols are able to perform multi dimensional fast link adaptation on a per packet level with forwarding considerations. This i ncludes power, rate, code and channel adaptation. This will enable the type of performance improvements that are of significant importance for the success of multi hop wireless networks

Mobile-IP ad-hoc network MPLS-based with QoS support.

The support for Quality of Service (QoS) is the main focus of this thesis. Major issues and challenges for Mobile-IP Ad-Hoc Networks (MANETs) to support QoS in a multi-layer manner are considered discussed and investigated through simulation setups. Different parameters contributing to the subjective measures of QoS have been considered and consequently, appropriate testbeds were formed to measure these parameters and compare them to other schemes to check for superiority. These parameters are: Maximum Round-Trip Delay (MRTD), Minimum Bandwidth Guaranteed (MBG), Bit Error Rate (BER), Packet Loss Ratio (PER), End-To-End Delay (ETED), and Packet Drop Ratio (PDR) to name a few. For network simulations, NS-II (Network Simulator Version II) and OPNET simulation software systems were used.Dept. of Electrical and Computer Engineering. Paper copy at Leddy Library: Theses & Major Papers - Basement, West Bldg. / Call Number: Thesis2005 .A355. Source: Masters Abstracts International, Volume: 44-03, page: 1444. Thesis (M.Sc.)--University of Windsor (Canada), 2005

Integrating mobile ad hoc network into mobile IPv6 network

In the future more and more devices connected to the Internet will be wireless. Wireless networks can be classified into two types of networks: network with infrastructure (i.e. networks with base stations, gateway and routing support), which is called Mobile IP, and network without infrastructure which is called ad hoc networks. Mobile IP tries to solve the problem of how a mobile node may roam from its network to foreign network and still maintain connectivity to the Internet. Ad hoc network tries to solve the problem if the infrastructure is not available or inconvenient for its use such as in rural environments. Integrating ad hoc into Mobile IP provide new feature for Mobile ad hoc network such as Internet connectivity, streamline communication with another network. This paper presents the development of a test bed for integrating Mobile Ad hoc NETwork (MANET) into Mobile IPv6

A Taxonomy of Self-configuring Service Discovery Systems

We analyze the fundamental concepts and issues in service discovery. This analysis places service discovery in the context of distributed systems by describing service discovery as a third generation naming system. We also describe the essential architectures and the functionalities in service discovery. We then proceed to show how service discovery fits into a system, by characterizing operational aspects. Subsequently, we describe how existing state of the art performs service discovery, in relation to the operational aspects and functionalities, and identify areas for improvement

Supporting service discovery, querying and interaction in ubiquitous computing environments.

In this paper, we contend that ubiquitous computing environments will be highly heterogeneous, service rich domains. Moreover, future applications will consequently be required to interact with multiple, specialised service location and interaction protocols simultaneously. We argue that existing service discovery techniques do not provide sufficient support to address the challenges of building applications targeted to these emerging environments. This paper makes a number of contributions. Firstly, using a set of short ubiquitous computing scenarios we identify several key limitations of existing service discovery approaches that reduce their ability to support ubiquitous computing applications. Secondly, we present a detailed analysis of requirements for providing effective support in this domain. Thirdly, we provide the design of a simple extensible meta-service discovery architecture that uses database techniques to unify service discovery protocols and addresses several of our key requirements. Lastly, we examine the lessons learnt through the development of a prototype implementation of our architecture

Game theory for dynamic spectrum sharing cognitive radio

This thesis was submitted for the degree of Doctor of Philosophy and was awarded by Brunel University on 21 June 2010.‘Game Theory’ is the formal study of conflict and cooperation. The theory is based on a set of tools that have been developed in order to assist with the modelling and analysis of individual, independent decision makers. These actions potentially affect any decisions, which are made by other competitors. Therefore, it is well suited and capable of addressing the various issues linked to wireless communications. This work presents a Green Game-Based Hybrid Vertical Handover Model. The model is used for heterogeneous wireless networks, which combines both dynamic (Received Signal Strength and Node Mobility) and static (Cost, Power Consumption and Bandwidth) factors. These factors control the handover decision process; whereby the mechanism successfully eliminates any unnecessary handovers, reduces delay and overall number of handovers to 50% less and 70% less dropped packets and saves 50% more energy in comparison to other mechanisms. A novel Game-Based Multi-Interface Fast-Handover MIPv6 protocol is introduced in this thesis as an extension to the Multi-Interface Fast-handover MIPv6 protocol. The protocol works when the mobile node has more than one wireless interface. The protocol controls the handover decision process by deciding whether a handover is necessary and helps the node to choose the right access point at the right time. In addition, the protocol switches the mobile nodes interfaces ‘ON’ and ‘OFF’ when needed to control the mobile node’s energy consumption and eliminate power lost of adding another interface. The protocol successfully reduces the number of handovers to 70%, 90% less dropped packets, 40% more received packets and acknowledgments and 85% less end-to-end delay in comparison to other Protocols. Furthermore, the thesis adapts a novel combination of both game and auction theory in dynamic resource allocation and price-power-based routing in wireless Ad-Hoc networks. Under auction schemes, destinations nodes bid the information data to access to the data stored in the server node. The server will allocate the data to the winner who values it most. Once the data has been allocated to the winner, another mechanism for dynamic routing is adopted. The routing mechanism is based on the source-destination cooperation, power consumption and source-compensation to the intermediate nodes. The mechanism dramatically increases the seller’s revenue to 50% more when compared to random allocation scheme and briefly evaluates the reliability of predefined route with respect to data prices, source and destination cooperation for different network settings. Last but not least, this thesis adjusts an adaptive competitive second-price pay-to-bid sealed auction game and a reputation-based game. This solves the fairness problems associated with spectrum sharing amongst one primary user and a large number of secondary users in a cognitive radio environment. The proposed games create a competition between the bidders and offers better revenue to the players in terms of fairness to more than 60% in certain scenarios. The proposed game could reach the maximum total profit for both primary and secondary users with better fairness; this is illustrated through numerical results