A mobile ad hoc network is a collection of wireless mobile devices which dynamically form a temporary network, without using any existing network infrastructure or centralised administration. Each node in the network effectively becomes a router, and forwards packets towards the packet’s destination node. Ad hoc networks are characterized by frequently changing network topology, multi-hop wireless connections and the need for dynamic, efficient routing protocols. <p.This work considers the routing problem in a network of uniquely addressable sensors. These networks are encountered in many industrial applications, where the aim is to relay information from a collection of data gathering devices deployed over an area to central points. The routing problem in such networks are characterised by: <ul> <li>The overarching requirement for low power consumption, as battery powered sensors may be required to operate for years without battery replacement;</li> <li>An emphasis on reliable communication as opposed to real-time communication, it is more important for packets to arrive reliably than to arrive quickly; and</li> <li>Very scarce processing and memory resources, as these sensors are often implemented on small low-power microprocessors.</li> </ul> This work provides overviews of routing protocols in ad hoc networks, swarm intelligence, and swarm intelligence applied to ad hoc routing. Various mechanisms that are commonly encountered in ad hoc routing are experimentally evaluated under situations as close to real-life as possible. Where possible, enhancements to the mechanisms are suggested and evaluated. Finally, a routing protocol suitable for such low-power sensor networks is defined and benchmarked in various scenarios against the Ad hoc On-Demand Distance Vector (AODV) algorithm. / Dissertation (MSc)--University of Pretoria, 2005. / Computer Science / Unrestricted

With the fast development of 5G networks and the advancement in networking technologies, more and more new technologies such as internet of vehicles (IoV) is catching our eyes. With technologies of artificial intelligence and automatic control, IoV is transformed into an intelligent transportation system (ITS). The object of this thesis is to analyze the connectivity probability issues in vehicle ad hoc networks (VANETs), which is a subset of ITS. This will be achieved by a platoon-based two dimensional model. In order to make the results more accurate and more close to real scenario, different situations will be analyzed separately, and different types of platoon will be included. In addition, other system parameters are also discussed and stimulated. The results show that many parameters like the increases of traffic density, ratio of platoon, and lane numbers will improve connectivity probability. No-leader based platoons are easier to connect to the base stations compared to leader based platoons.

This master's thesis (further only MT) deal with problems of scale-free topology networks with a view to technology MANET (Mobile Ad hoc network) or more precisely Motorola MESH. Further studies routing technique and quality of services (QoS) in these networks. Theoretic part of MT in introduction shortly characterizes properties and kind of Ad hoc networks, next part is dedicated to technology Motorola MESH and shows practical usage of this technology. Analysis of problems quality of services and optimalization QoS in MANET is content third parts of MT. Fourth part specifies division of routing protocols, analysis of routing in MANET and characteristics routing protocols OLSR, AODV, DSR and TORA. In practical fifth part of MT are in introduction simulated simple MANET and mesh networks and further is created model of MANET network, into the model are implemented accessible routing protocols in simulation program OPNET Modeler and on the basis of simulation these protocols or more precisely output statisticians of simulation are protocols compared from several aspects and suitability for transmission of multimedia data (voice, video).

Contemporary studies of Intelligent Transportation Systems (ITS) use simulations of vehicular and communications traffic, due to the ethical and practical infeasibility of conducting experiments on real transportation networks. Different simulators have been developed for modeling real-time vehicular mobility and inter-vehicular communication under varying traffic and roadway conditions. While most model the effect of mobility on communications, only a few simulate the impact of inter-vehicular communication on vehicular mobility. None, moreover, are implemented as parallel or distributed frameworks: an essential requirement for the study of ITS applications in large-scale urban environments. As a starting point for developing such a framework, one contemporary simulator, VNetInetSim, was tested to determine its behavior under large loads. Testing determined that VNetInetSim's memory usage and execution time increase exponentially in the number of simulated vehicles while remaining relatively constant under increased communication traffic.

On the battlefield, having accurate positions of allied troops is crucial for making effective decisions. However, obtaining this information can be challenging, particularly outside of one's own battalion network. This research focuses on developing and evaluating methods for disseminating digital geographic position data between different interconnected radio networks in a military context. The radio networks in question are ad hoc networks that use a Wide Band Waveform (WBWF) as their communication waveform. The objective is to transfer position data between networks without overloading them. The networks have a limited bandwidth and it's shared among all nodes belonging to the network. A node is a unit with a radio at hand that can communicate with other similar configured radios. To allow networks to communicate with each other, some nodes, called gateway nodes, are geared with a second radio. The second radio is used to communicate with other nearby battalions. Protocols and algorithms can use these gateway nodes to transfer data between different networks. The research evaluates two methods, one is based on Simplified Multicast Forwarding (SMF) combined with Optimized Link State Routing (OLSR) and the other is a self-developed algorithm called Gateway Node Election (GNE) algorithm. The GNE algorithm gives control to the gateway nodes, allowing for more selective transmission of position data between different networks. To evaluate the performance of methods this thesis uses a simulation tool called Aquarius to measure the performance of the methods in various scenarios, including bandwidth usage and message age. The result shows that the GNE algorithm, compared to SMF, uses less network bandwidth and it's a more robust solution since it gives redundancy by transmitting packets again if they weren't received. The findings of this research will contribute to improving the dissemination of critical information among different radio networks in a military context.

Wireless mobile internet market is still an unprecedented, uncaptured territory for cellular service providers. The shortage and high cost of downlink data bandwidth in a cellular network has remained a huge factor for the slow growth of data services in mobile devices. Although there has been a significant evolution in telephony infrastructures in form of 3G and 4G systems, the potential of high speed ad hoc network for sharing cellular spectrum have not been realized to its full potential. Like (e.g. Verizon) users can share voice minutes with friends, there is a potential for sharing the unutilized cellular bandwidth among friends to increase net data speed. In a scenario like a football stadium where people visit in groups, although a lone phone cannot stream a high quality replay video, unused cellular bandwidth of proximate friend’s devices can automatically be used in real time to view the replays. An available secondary ad hoc network such as Wi-Fi or Bluetooth in phone can be used for sharing this cellular bandwidth. Thus, we propose BuddyShare, a novel social-based automatic bandwidth sharing overlay platform on short range ad hoc devices to increase net data speed. The motivation stems from the fact that the location of mobile users tends to be clustered to form “people hotspots” such as conferences, stadiums, stations, buses and trains. For example, in a scenario like a football stadium where people visit in groups, although a lone phone cannot stream a high quality replay video, unused cellular bandwidth of proximate friends’ devices can automatically be used in real time to view the replays. Our work creates an overlay on horizontal ad hoc network to enable users to form a group among socially trusted members who can collaboratively share their data connections. Social trust is automatically derived from social relationships obtained by mining mobile-phone behavior pattern. This work aims to improve the overall utilization of the data connection, and increase the data rate of individual users without compromising their privacy and unauthenticated usage. The user privacy is preserved by using the bandwidth resources of only socially trusted member of the user, which also guarantees against unauthenticated exploitation of expensive bandwidth. Our proposed work promises to deliver win-win situation to users, content providers and service providers. The advantages of users are: 1) Increased data rate for the same cost.2) Secure and trusted overlay based communication for sharing resources. The advantages for the service providers are manifold: 1) Customer increase: More customers will avail the data plan due to social influence. 2) Customer retention: [18] Customers part of the social-cum-adhoc network are least likely to leave the network.3) Group subscription: Service provider can get bulk subscriptions as collaborative groups increase data rate. In this work, we address some key technical issues of developing a socially aware overlay collaborating medium. Some of the addressed functionalities associated with the overlay formations are group discovery, creation, management and actual data distribution. This proposal also accounts the computation of social trustworthiness by using standard social networking analytics. We also account the several key technical challenges associated with management of overlay on mobile nodes and trust computation using abstract social network. In order to verify the usefulness of BuddyShare, we collected realistic datasets from various sources (questionnaires, mobile device logs, social networking portal) and conducted analyses and simulations on it. The analyses concluded that sample users from the dataset shared sufficient social trustworthiness. The real events from the datasets were captured in the simulations. These simulations showed that, by using Bluetooth as a horizontal ad hoc medium, an user can scale his data speed three times on average for sufficient duration per day. This thesis achieves the following objectives: 1) It presents a comprehensive design for an overlaid social based internet sharing platform called BuddyShare. 2) It presents a social analysis to validate the concept of social trust among users. 3) It delivers a flexible simulation platform to realistically simulate mobile phones with dual interfaces. 4) It presents the results of simulations of real events captured from the device logs of sample users. These results conclude the usefulness of BuddyShare work.

As the need to remain connected increases, more and more people are turning to wireless mesh networks because they reduce the need for network infrastructure. Unfortunately, TCP does not perform well in such networks. HxH, an alternate protocol, has shown great promise in simulations, but since it relies on exploiting passive feedback, real measurements are needed to determine how effective the protocol really is. This thesis uses a measurement study on a wireless mesh network to characterize the performance of the HxH protocol in real-world networks. Several aspects of the HxH protocol do in fact perform well on real networks, but the high rate of packet loss renders other aspects of the protocol ineffective.

Mobile Ad hoc NETworks (MANETs) have attracted great research interest in recent years. Among many issues, lack of motivation for participating nodes to collaborate forms a major obstacle to the adoption of MANETs. Many contemporary collaboration enforcement techniques employ reputation mechanisms for nodes to avoid and penalize malicious participants. Reputation information is propagated among participants and updated based on complicated trust relationships to thwart false accusation of benign nodes. The aforementioned strategy suffers from low scalability and is likely to be exploited by adversaries. To address these problems, we first propose a finite state model. With this technique, no reputation information is propagated in the network and malicious nodes cannot cause false penalty to benign hosts. Misbehaving node detection is performed on-demand; and malicious node punishment and avoidance are accomplished by only maintaining reputation information within neighboring nodes. This scheme, however, requires that each node equip with a tamper-proof hardware. In the second technique, no such restriction applies. Participating nodes classify their one-hop neighbors through direct observation and misbehaving nodes are penalized within their localities. Data packets are dynamically rerouted to circumvent selfish nodes. In both schemes, overall network performance is greatly enhanced. Our approach significantly simplifies the collaboration enforcement process, incurs low overhead, and is robust against various malicious behaviors. Simulation results based on different system configurations indicate that the proposed technique can significantly improve network performance with very low communication cost.

No description available.

No description available.