<p>Nowadays a lot of research efforts focus on Mobile Ad-hoc NETworks (MANETs). A MANET is a collection of mobile autonomous nodes, which can move arbitrary, leading to a constantly changing network topology. However, today most of the information is still stored on wired servers. A wired network has a hierarchical topology, while in a MANET the topology is usually flat to allow for nodes to easily change there position in the network. Due to the different topological natures of these systems, interconnectivity is not trivial.</p><p>To further complicate the situation the Transmission Control Protocol (TCP) is designed for wired networks, in a MANET with different link and route characteristics, as multihop and frequent packet losses, the performance of current TCP proposals drop considerably.</p><p>The purpose of this report is to give an overview of the current MANET – Internet connectivity situation and to evaluate TCP performance in a hybrid MANET where mobile nodes connect to a wired network through a gateway.</p><p>The report is divided into two parts. The first theoretical part will evaluate the different routing and mobility problems that occur in a realistic scenario with multiple gateways. Main problems that will be discussed are: path selection, gateway discovery, handover between gateways and address configuration in current solutions.</p><p>In the last part, a simulation-based evaluation will be made on a simplified scenario where one gateway is linking the two different networks. The simulation will be conducted with ns-2.28, which is extended with support for Uppsala University version of Ad-hoc On-demand Distance Vector (AODVUU) as routing and gateway discovery protocol and TCP AP (Adaptive Pacing) as transport protocol. In the performance evaluation, AODVUU and Destination-Sequenced Distance-Vector Routing (DSDV) combined with TCP Newreno, TCP Vegas and TCP AP will be used. The simulation based evaluation concluded that the best performance was achieved with TCP Vegas in conjunction with AODVUU.</p>

Nowadays a lot of research efforts focus on Mobile Ad-hoc NETworks (MANETs). A MANET is a collection of mobile autonomous nodes, which can move arbitrary, leading to a constantly changing network topology. However, today most of the information is still stored on wired servers. A wired network has a hierarchical topology, while in a MANET the topology is usually flat to allow for nodes to easily change there position in the network. Due to the different topological natures of these systems, interconnectivity is not trivial. To further complicate the situation the Transmission Control Protocol (TCP) is designed for wired networks, in a MANET with different link and route characteristics, as multihop and frequent packet losses, the performance of current TCP proposals drop considerably. The purpose of this report is to give an overview of the current MANET – Internet connectivity situation and to evaluate TCP performance in a hybrid MANET where mobile nodes connect to a wired network through a gateway. The report is divided into two parts. The first theoretical part will evaluate the different routing and mobility problems that occur in a realistic scenario with multiple gateways. Main problems that will be discussed are: path selection, gateway discovery, handover between gateways and address configuration in current solutions. In the last part, a simulation-based evaluation will be made on a simplified scenario where one gateway is linking the two different networks. The simulation will be conducted with ns-2.28, which is extended with support for Uppsala University version of Ad-hoc On-demand Distance Vector (AODVUU) as routing and gateway discovery protocol and TCP AP (Adaptive Pacing) as transport protocol. In the performance evaluation, AODVUU and Destination-Sequenced Distance-Vector Routing (DSDV) combined with TCP Newreno, TCP Vegas and TCP AP will be used. The simulation based evaluation concluded that the best performance was achieved with TCP Vegas in conjunction with AODVUU.

The purpose of this thesis is to analyze a non-intrusive connectivity visualization method for OLSR-based MANET topology in different mobility models. The visualization relies on the local topology databases (neighborhood database and topology database) available in OLSR nodes in the network. Two different views are considered in this method: central view and nodal view. In the central view, the network topology is viewed from a control center which has access to the databases of all nodes, while on the other hand, the nodal visualization provides a picture of the network topology from individual nodes point of view. In this thesis, the full view of the network has been compared to the nodal view to calculate the error rate for topology discovery, based on the total numbers of active and undiscovered links. The main contribution of this thesis is to analyze and improve the accuracy of coarse localization techniques under different mobility models, using the Force-directed algorithm to calculate the approximate location of the nodes. The localization information was gathered from layer-3 connectivity, utilizing anchor nodes that are equipped with GPS and other non-GPS nodes instead of using traditional methods that include received signal strength, time of arrival and angle of arrival. The approximate location information of the nodes derived from this technique has been compared with original node location in order to determine the accuracy of this technique. To improve the accuracy, several mobility prediction filters such as moving average filter, Kalman filter and low pass filter have been applied to the approximate location data. The simulation is done to calculate the error between the original location data and the coarse approximations, and the results shows that Moving Average provides the best results. / UOIT

P2P search system usually be integrated to many systems in wired network. As the result of technology development, wireless networks are more and more popular. Many system in wired networks are be implemented in wireless network environment, too. In virtue of diverseness between wired and wireless networks, there are some modify for characteristic of wireless network. In this paper, we demonstrate KAdHoc, a peer-to-peer search system for Mobile Ad Hoc Network (MANET).There are problems when P2P systems being used in MANET such as physical locality, power exhaustion and nodes information outdated when nodes move. KAdHoc consider these problems and design a mechanism for P2P search system in MANET. The simulation result show that KAdHoc has fewer lookup time and has high success rate and low total traffic even in High Node density. KAdHoc even has higher success rate in higher node velocity.

Texte remanié de: Dissertation--Stuttgart, 2005. / Bibliogr. p. 327-350.

Zugl.: Berlin, Humboldt-Univ., Magisterarbeit, 2002

The diploma thesis "QoS model for Mobile ad hoc network" focuses on the quality of services in MANET (Mobile Ad-hoc) networks. It describes MANET networks and covers the theoretical analysis of routing protocols with QoS (Quality of Service) support. Furthermore, there is processed the creation process of model MANET networks with the routing protocol DSDV (Destination-Sequenced Distance Vector) in the simulation environment NS-3 (Network Simulator 3) and its extension of QoS support. The used QoS model is subsequently modified to improve core operating parameters. The implementation of QoS parameters as well as the improvement of delay and jitter (the delay between selected packets) is verified by the functional simulation.

ITC/USA 2006 Conference Proceedings / The Forty-Second Annual International Telemetering Conference and Technical Exhibition / October 23-26, 2006 / Town and Country Resort & Convention Center, San Diego, California / Research at Morgan State University shows a means of enabling both a mobile ad-hoc network (MANET) and a cellular network to operate simultaneously in the same spectrum. This enhanced frequency efficiency would facilitate the creation of a hybrid or Mixed Cellular/MANET network (MCMN) in which each of the MCMN sub-networks would have access to the entire allotted spectrum. Interference rejection and excision have been identified as a means of distinguishing between and isolating the two different kinds of signals. This paper shows the promising performance of such techniques within the MCMN environment as a part of the integrated Network Enhanced Telemetry (iNET) project.

The mobile ad hoc network (MANET) has become a popular technology in recent years. Due to most devices are battery powered, energy conservation is a critical issue in the MANET. To save energy and extend battery life, nodes should turn their radios off when they have no packet to send or receive. To achieve this, IEEE 802.11 defined a synchronous power saving mechanism (PSM) based on periodical beacon transmission. It allows devices to turn their radios off when no data has to be sent or received. However, the idle state is long because the device must remain awake during the entire beacon interval even though there is only a small amount of data packets to be sent. Although some PSMs have been proposed, they still suffer from a long idle state. In this paper, we propose a new power saving mechanism by dynamically adjusting the sleeping time based on the network traffic. Simulation results show that the proposed PSM outperforms other PSMs in energy goodput and lifetime.

Recent advances in low-power technologies have resulted in the proliferation of inexpensive handheld mobile computing devices. Soon, just like the Internet empow- ered a whole new world of applications for personal computers, the development and deployment of robust ubiquitous wireless networks will enable many new and exciting futuristic applications. Certain to be an important part of this future is a class of networks known as "mobile ad hoc networks." Mobile ad hoc networks (or simply "ad hoc networks") are local-area networks formed "on the spot" between collocated wireless devices. These devices self-organize by sharing information with their neigh- bors to establish communication pathways whenever and wherever they are. For ad hoc networks to succeed, however, new protocols must be developed that are capable of adapting to their dynamic nature. In this dissertation, we present a number of adaptive protocols that are designed for this purpose. We investigate new link layer mechanisms that dynamically monitor and adapt to changes in link quality, including a protocol that uses common control messages to form a tight feedback control loop for adaptation of the link data rate to best match the channel conditions perceived by the receiver. We also investigate routing protocols that adapt route selection according to network characteristics. In particular, we present two on-demand routing protocols that are designed to take advantage of the presence of multirate links. We then investigate the performance of TCP, showing how communication outages caused by link failures and routing delays can be very detrimental to its performance. In response, we present a solution to this problem that uses explicit feedback messages from the link layer about link failures to adapt TCP's behavior. Finally, we show how link failures in heterogeneous networks containing links with widely varying bandwidth and delay can cause repeated "modal" changes in capacity that TCP is slow to detect. We then present a modifed version of TCP that is capable of more rapidly detecting and adapting to these changes.