<p>Wireless communication is of great importance for safety and entertainment purposes in vehicular networks. Vehicles on roads are required to share sensor data, road traffic information or digital maps with other vehicles on the road. To be able to do this, vehicles require to either communicate directly with each other or to be connected to a wireless communication-based access points on the road side. These wireless access points support short to medium range wireless communication through the protocol 802.11p. 802.11p is designed specifically for vehicular communication and it is an amended form of the widely used 802.11 protocol suit for wireless local area networks (WLAN). Vehicles are able to be associated with these wireless access points for exchange of information. While vehicles move along the road infrastructure, they change their point of attachment from one wireless access point to another wireless access point. During this process, connectivity to the access point breaks down until the vehicle is connected to a new access point in its area. This disconnection causes an interruption in the data flow. This interruption increases when vehicle requires a new IP address, i.e. when the vehicle is going to attach to an access point which is part of another network. In this thesis report, we give an overview of standard handover methods and their enhancements and propose a fast handover scheme for layer 3 of the communication stack. Based on the assumption that vehicles know their route in advance, we enhance the handover process and improve seamless connectivity. We also discuss different issues which are the cause of delay and how they can be overcome in our proposed solution.</p>

Wireless communication is of great importance for safety and entertainment purposes in vehicular networks. Vehicles on roads are required to share sensor data, road traffic information or digital maps with other vehicles on the road. To be able to do this, vehicles require to either communicate directly with each other or to be connected to a wireless communication-based access points on the road side. These wireless access points support short to medium range wireless communication through the protocol 802.11p. 802.11p is designed specifically for vehicular communication and it is an amended form of the widely used 802.11 protocol suit for wireless local area networks (WLAN). Vehicles are able to be associated with these wireless access points for exchange of information. While vehicles move along the road infrastructure, they change their point of attachment from one wireless access point to another wireless access point. During this process, connectivity to the access point breaks down until the vehicle is connected to a new access point in its area. This disconnection causes an interruption in the data flow. This interruption increases when vehicle requires a new IP address, i.e. when the vehicle is going to attach to an access point which is part of another network. In this thesis report, we give an overview of standard handover methods and their enhancements and propose a fast handover scheme for layer 3 of the communication stack. Based on the assumption that vehicles know their route in advance, we enhance the handover process and improve seamless connectivity. We also discuss different issues which are the cause of delay and how they can be overcome in our proposed solution.

Context. In the present network inventive world, there is a quick expansion of switches and protocols, which are used to cope up with the increase in customer requirement in the networking. With increasing demand for higher bandwidths and lower latency and to meet these requirements new network paths are introduced. To reduce network load in present switching network, development of new innovative switching is required. These required results can be achieved by Software Define Network or Traditional layer-3 technologies.Objectives. In this thesis, the end to end (e2e) transmission performance of OpenFlow and Layer-3 switches and their dynamic characteristics are investigated using network simulation.Methods. To replicate real life network topology and evaluate e2e transmission performance, a simulation based test-bed is implemented for both OpenFlow switch and layer-3 switch. The test beds are implemented using Network Simulator-3 (NS3). A two-tire network topology is designed with specified components for performance evaluation.Results. The performance metrics like throughput, average delay, simulation time and Packet Delivery Ratio (PDR) are measured, results are analyzed statistically and are compared. The behavior of network traffic in both the topologies are understood using NS-3 and explained further in the thesis.Conclusions. The analytical and statistical results from simulation show that OpenFlow switching performs relatively better than layer-3 switching.

This report aims to compare different layer 2 tunneling protocols in order to determine what advantages and disadvantages each protocol comes with. Since wireless communication is becoming more used demand for these protocols has risen. The main goal is to help industries, like Hardware Meets Software (HMS), choose the most suitable layer 2 tunneling protocol and give a detailed view of each protocol. To compare the protocols, information about various protocols was gathered as well as other studies done on layer 2 tunneling protocols. A decision was then made on the protocols to focus on, Layer 2 Tunneling Protocol (L2TP), Internet Protocol Security (IPsec), Virtual eXtensible Local-Area Network protocol (VXLAN), Generic Routing Encapsulation protocol (GRE), and Network Virtualization using Generic Routing Encapsulation protocol (NVGRE). Furthermore, tests were done on non-tunneling, L2TP together with IPsec and VXLAN, using two laptops, two gateways as well as a shark trap together with Wireshark to record the traffic. These tests were recorded and documented. The results of the tests were used to calculate the protocol’s latency, throughput and jitter. The background research together with the tests concluded in specific protocol characteristics, with different use cases for each protocol. The tests show that non-tunneling was the fastest communication. The L2TP together with the IPsec had better latency and jitter while VXLAN had better throughput. Using other studies together with our tests, different advantages and disadvantages with each protocol was discussed and it was concluded that deeper research would be needed toconclude which protocol best suits HMS, but that L2TP with IPsec outperformed VXLAN on 2 of the 3 main factors. Finally, the methodology is discussed with the factors of reliability, accuracy, and limitation.

Handoff is a call handling mechanism that is invoked when a mobile node moves from one cell to another. Such movement may lead to degradation in performance for wireless networks as a result of packet losses. A promising technique proposed in this thesis is to apply multicasting techniques aided by mobility prediction in order to improve handoff performance. In this thesis, we present a method that uses a Grey model for mobility prediction and a fuzzy logic controller that has been fine-tuned using evolutionary algorithms in order to improve prediction accuracy. We also compare the self-tuning algorithm with two evolutionary algorithms in terms of accuracy and their convergence times. Our proposed method takes into account signal strengths from the base stations and predicts the signal strength of the next candidate base station in order to provide improved handover performance. The primary decision for mobility prediction is the accurate prediction of signal strengths obtained from the base stations and remove any unwanted errors in the prediction using suitable optimisation techniques. Furthermore, the model includes the procedures of fine-tuning the predicted data using fuzzy parameters. We also propose suitable multicasting algorithms to minimise the reservation of overall network resource requirements during handoff with the mobility prediction information. To be able to efficiently solve the problem, the situation is modelled using a multicast tree that is defined to maintain connectivity with the mobile node, whilst ensuring bandwidth guarantees and a minimum hop-count. In this approach, we have tried to solve the problem by balancing two objectives through putting a weight on each of two costs. We provide a detailed description of an algorithm to implement join and prune mechanisms, which will help to build an optimal multicast tree with QoS requirements during handoff as well as incorporating dynamic changes in the positions of mobile nodes. An analysis of how mobility prediction helps in the selection of potential Access Routers (AR) with QoS requirements - which affects the multicast group size and bandwidth cost of the multicast tree -- is presented. The proposed technique tries to minimise the number of multicast tree join and prune operations. Our results show that the expected size of the multicast group increases linearly with an increase in the number of selected destination AR's for multicast during handoff. We observe that the expected number of joins and prunes from the multicast tree increases with group size. A special simulation model was developed to demonstrate both homogeneous and heterogeneous handoff which is an emerging requirement for fourth generation mobile networks. The model incorporates our mobility prediction model for heterogeneous handoff between the Wireless LAN and a cellular network. The results presented in this thesis for mobility prediction, multicasting techniques and heterogeneous handoff include proposed algorithms and models which aid in the understanding, analysing and reducing of overheads during handoff.

his thesis describes Perceptual Audio Coding of MPEG1 Layer 3 format (ISO/IEC 11172-3), principles and algorithms of psychoacoustic model. MATLAB application for modeling of Psychoacoustic model 2 of this audio format is developed.

This thesis deals with the issue of the creation of a programme that would simulate the distortion that appears during the process of lossy audio coding. As the environment for the creation, the MATLAB programming language has been chosen. An encoder, which changes the subjective signal quality according to customer preferences for the bitrate, has been created as a practical part of this thesis. Its function is based on a dynamic bit allocation technique and includes an optional window switching algorithm. The theoretical background for the creation of the programme consists of an explanation of the main principles of lossy coding with emphasis on MPEG1 layer 3 operating principles. The practical chapter describes how the created programme and its parts work, and it includes results of the run quality testing. The testing was conducted using the objective assessment method PEMO-Q, and consisted of comparing the objective quality of the programme’s outputs to the quality of samples on which a regular MP3 encoder with identical settings was used.