The thesis deals with MANET networks and it focuses on the routing process. Most attention is paid to the routing protocols AODV and OLSR. These protocols are described in the detail. The aim of the thesis is to create a simulation model of MANET network in OPNET Modeler environment. In this model the AODV protocol is configured. In order to achieve improved characteristics of the network traffic the routing protocol parameters are optimized. Furthermore the process model of AODV protocol in this environment is studied and extended by a new type of message, which allows a transfer of current transmission speed of MANET station network interface. Current transmission rate of stations is retrieved from the statistics. Every station periodically sends a message to neighboring nodes. The node stores the information into the file when a new message arrives.

This diploma thesis deals with modeling wireless transmission in simulation environment OPNET Modeler. In theoretical part, there is described the very substance of spreading the signal via electromagnetic wave including impact of the surroundings that affects the spreading. These impacts have an influence on described selected parameters of wireless transmission of the signal characterizing its quality. Furthermore, there is described the OPNET Modeler setting, which allows designing the wireless transmission and by means of simulation verifies its functionality and acquires it is parameters. The transmission of the signal from transmitter to receiver itself is divided to individual steps, which are described in detail considering the implementation in aforementioned environment. In practical part, there is configured the basic model of wireless network and also executed series of simulations with different variants of commonly adjustable basic parameters of the transmission, as signal modulation, antenna types and network topology. Additionally, attention is turned to the stages of transmission itself, philosophy of their cooperation based on sharing the information via data units called TDA and their implementation in source code of the C++ language called transmission models. Based on these foundations is beyond beforehand defined created new user TDA and by means of simulation verified its correct implementation within packet switching. Values of the selected including user TDA are written in the window of simulation console with the help of the C++ language. Acquired results of the simulations are analyzed and documented in the conclusion. Source codes are available in the diploma thesis appendix.

The theoretical part of Master's thesis has been dealing with issues of MANET networks, issues of providing quality of services in MANET networks and analysis of various implementations of quality of services in these networks. At the start of the practical part of this thesis was described modified OLSR process model with support of quality of services. In simulation program OPNET Modeler was designed a topology of MANET network, firstly was run a simulation of this network without any support of quality of services and then was run a simulation with support of quality of services. The results of these simulations were analyzed, compared and graphically interpreted. In the next part of this thesis was designed a real MANET network with OLSR support. OLSR network communication was captured with the use of Wireshark. In the last part of this thesis was firstly described a meaning and functions of plugins in OLSR implementation and then was developed a plugin which is responsible for sending messages which contain a state of the links between nodes of MANET networks.

The main topic of this master´s thesis is a practical simulation of wireless mobile networks. For this purpose, the model simulating urban enviroment in which mobile nodes move according to desgined trajectories was created. The parameters of transmitted signal and impact of obstacles in the way of propagation were examined by the simulation. Number of obstacles and type of material of given obstacle was taken into consideration.

This thesis consists of theoretical and practical parts. The theoretical part contains an analysis of the problems of wireless networkssolutions individual standards and methodologies to ensure quality of service. In the practical part using the OPNET Modeler, a number of different simulation models and their evaluation. It is a model of individual standards, support mobility and interference effects on quality of service.

The doctoral thesis is focused on a research in the area of the quality-of-service support technologies in data networks. The current modern communication networks cannot operate correctly without an effective tool allowing differentiated treatment for various network traffic classes. Looking at the current trends in this area it turns out that the technology of Differentiated services is currently the most widely used mechanism for QoS assurance in data networks. The major part of this doctoral thesis concerns the design of a novel QoS system which offers a solution for one of the main problems of DiffServ technology. This disadvantage lies in the missing cooperation between the end station and edge node of the DiffServ domain. To overcome this limitation the system proposed introduces an improvement which enables the user application to actively participate in the resource reservation process by direct configuration of the DSCP value in the IP header of its own packets. This functionality is based on the identification of DiffServ configuration parameters available in the edge router. To retrieve the information required from network component the well-known SNMP protocol has been chosen, which has direct access to the components’s configuration stored in the MIB database. On the basis of this theoretical proposal several simulation scenarios have been created and analysed. The results show that the system designed presents an efficient solution for the mentioned problem of DiffServ. They also give good assumptions for the successful implementation of this system into a real environment.

The aim of this work is to propose feasible solution for the simulation of the SNMP (Simple Network Management Protocol) protocol in the OPNET Modeler simulation environment. This work describes in detail individual procedures, which were chosen for this simulation . The work also contains an introduction to the OPNET Modeler simulation environment, the SNMP protocol, the DiffServ model and the DiffServ-MIB database. The main part of this work describes the algorithms programmed to model the functions of the SNMP protocol. Source codes of the algorithms programmed are included as well. The work deals especially with the functions for obtaining values from different levels of a multilevel model attributes, packet creation functions with dynamically changing length of user-data field, for the implementation process of a simplified DiffServ MIB database and with the functions for statistic creation.

Subject of this thesis was the issue of effectiveness of wireless networks from the perspective of services. Become acquainted with WiFi network standard IEEE 802.11 with protocols and principles of WiFi networks and services. It should be focused on the quality of service QoS. In teoretical part of this thesis are described problems considering wireless networks, layer model and types of nets used in WiFi. Standard IEEE 802.11 is analysed in details including supplements and used packets. Special attention is paid to the quality of service QoS. Next are discussed the principles and application services as VoIP, videoconferencing, video streaming and others in WiFi network. On the basis of obtained knowledge is designed extensive WiFi network with assured supply of services. For modelling and simulation of wireless network is used software development environment Opnet Modeler. Model of wireless network is used to optimize and analyse this wireless communication network. In thesis are also simulated properties of data which are sensitive to delay. In last part of thesis is created a laboratory work, which contains a submission of task, detailed theory, wiring diagram, instructions for elaboration, guidelines for simulation and example of elaboration of task. Work is about comparison of network with used 802.11b and 802.11e standard, and support of quality of service QoS.

This thesis discusses wireless network standards 802.11a/b/g/n. First part explains basic principles of networks and media access. Next the standard IEEE 802.11, general QoS parameters and their application in wireless networks, according to standard 802.11e are analyzed. Second part of the thesis verifies the acquired knowledge in simulating program Opnet - effects of the delay, jitter and packet loss on VoIP call are tested. In the last part of the thesis a network for video streaming has been designed. The video was streamed in different qualities and the influence of other network traffic (with and without the support of QoS) on the video streaming was tested.

Spurred by change in government regulations and to leverage lower-cost technology and services, many land mobile radio (LMR) operators have begun transitioning from circuit-switched to packet-switched backbone networks to handle their future communication needs. Due to the unique demands of packet-switched backbone networks for LMR, it may not be wise to carry over the previously implemented security methods used with circuit-switch systems or to treat an LMR backbone as a regular packet-switched network. This thesis investigates security in packet-switched LMR backbone networks to identify security issues in packet-switched LMR networks and provide possible solutions for them. Security solutions that are examined include different types of virtual private networks (VPNs), various encryption and keying procedures for safe communication, and logic behind how and where to implement security functions within the network. Specific schemes examined include IP Security (IPSec), OpenVPN, Virtual Tunnel (VTun), and Zebedee. I also present a quantitative analysis of the effects that the solutions have on packet-switched networks, in terms of link utilization, and on voice traffic, in terms of delay and delay jitter. In addition, I evaluate, in general terms, the additional cost or complexity that is introduced by the different security solutions. Simulation with OPNET Modeler was used to evaluate how the various security schemes affect voice communication and network performance as a whole. Since OPNET Modeler does not provide models of security functions, the source code of the transceiver system models was modified to introduce additional overhead that is representative of the various security solutions. Through experimentation, simulation, and analysis of the security schemes considered, it was found that the most effective security scheme overall for a packet-switched LMR backbone network would either be IPSec or OpenVPN implemented at the base stations and end-hosts. Both security schemes provide strong encryption, flexibility, and are actively supported. However, if bandwidth is scarce and flexibility is less important, then a security solution with less overhead, such as VTun, should be considered. Thus, one has to balance performance with security to choose the most effective security solution for a particular application. / Master of Science