63 research outputs found
Analysis and Simulation of the Signals Transmission in the DVB-H/SH Standards
Tato disertaÄnĂ prĂĄce se zabĂœvĂĄ analĂœzou, simulacĂ a mÄĆenĂm zpracovĂĄnĂ a pĆenosu signĂĄlĆŻ digitĂĄlnĂ televize pro pĆĂjem mobilnĂho TV vysĂlĂĄnĂ ve standardech DVB-H a DVB-SH. Tyto standardy vychĂĄzejĂ z pĆedpokladu, ĆŸe pĆĂjem signĂĄlu je charakterizovĂĄn modely pĆenosovĂœch kanĂĄlĆŻ s vĂcecestnĂœm ĆĄĂĆenĂm. Tyto, tzv. ĂșnikovĂ© kanĂĄly, jsou charakterizovĂĄny hlavnÄ zpoĆŸdÄnĂm a ziskem jednotlivĂœch cest. V zĂĄvislosti na dalĆĄĂch parametrech (rychlost pĆijĂmaÄe, DopplerovskĂ© spektrum), je moĆŸnĂ© rozdÄlit ĂșnikovĂ© kanĂĄly do tĆech hlavnĂch skupin: mobilnĂ, pĆenosnĂ© a fixnĂ. DĂĄ se pĆedpoklĂĄdat, ĆŸe v rĆŻznĂœch modelech kanĂĄlĆŻ bude pĆenĂĄĆĄenĂœ signĂĄl rĆŻznÄ ovlivnÄn. Proto je potĆebnĂ© najĂt optimĂĄlnĂ parametry systĂ©mĆŻ (DVB-H/SH) pro kvalitnĂ pĆĂjem vysĂlanĂœch sluĆŸeb mobilnĂ televize, coĆŸ je hlavnĂm cĂlem tĂ©to disertaÄnĂ prĂĄci. Pro tento ĂșÄel byly vytvoĆeny dvÄ vhodnĂ© aplikace (jedna pro DVB-H a jedna pro DVB-SH) s GUI v prostĆedĂ MATLAB, kterĂ© umoĆŸĆujĂ simulovat a analyzovat mĂru zkreslenĂ signĂĄlu v pĆĂpadÄ mobilnĂch, pĆenosnĂœch a fixnĂch scĂ©nĂĄĆĆŻ pĆenosu. NavĂc, tyto aplikace obsahujĂ i druhĂœ samostatnĂœ simulĂĄtor pro nastavenĂ a modifikaci parametrĆŻ jednotlivĂœch pĆenosovĂœch cest. DĂky tomu je moĆŸnĂ© zhodnotit vliv parametrĆŻ celĂ©ho systĂ©mu a kanĂĄlovĂœch modelĆŻ na dosaĆŸenou chybovost (BER a MER) a kvalitu pĆenosu. Ve vĆĄech pĆenosovĂœch scĂ©nĂĄĆĂch (v zĂĄvislosti na pomÄru C/N) byly zĂskanĂ©, vyhodnocenĂ© a diskutovanĂ© zkreslenĂ signĂĄlĆŻ. NavĂc, u standardu DVB-H, vĆĄechny zĂskanĂ© vĂœsledky ze simulacĂ byly ovÄĆeny mÄĆenĂm. RozdĂly mezi dosaĆŸenĂœmi vĂœsledky (simulace a mÄĆenĂ) byly rovnÄĆŸ podrobeny diskuzi. Tuto disertaÄnĂ prĂĄci je moĆŸnĂ© rozdÄlit do ÄtyĆ hlavnĂch ÄĂĄstĂ. PrvnĂ ÄĂĄst disertaÄnĂ prĂĄce se zabĂœvĂĄ reĆĄerĆĄĂ souÄasnĂ©ho vĂœvoje v oblasti digitĂĄlnĂho televiznĂho vysĂlĂĄnĂ na mobilnĂ terminĂĄly ve standardech DVB-H/SH. Na konci tĂ©to ÄĂĄsti jsou jasnÄ popsĂĄny cĂle tĂ©to disertaÄnĂ prĂĄce. DruhĂĄ ÄĂĄst prĂĄce je zamÄĆenĂĄ na struÄnĂœ popis blokovĂ©ho diagramu vysĂlaÄĆŻ v obou standardech DVB-H/SH. DĂĄle jsou struÄnÄ popsĂĄny modely pĆenosovĂœch kanĂĄlĆŻ, kterĂ© se pouĆŸĂvajĂ pro modelovĂĄnĂ pĆenosu signĂĄlu. StruÄnĂœ popis vytvoĆenĂœch aplikacĂ, i s vĂœvojovĂœm diagramem, kterĂ© jsou vhodnĂ© pro simulaci a analĂœzu pĆenosu v DVB-H/SH, jsou popsĂĄny v tĆetĂ ÄĂĄsti prĂĄce. ÄtvrtĂĄ a nejdelĆĄĂ ÄĂĄst tĂ©to disertaÄnĂ prĂĄce se zabĂœvĂĄ vyhodnocenĂm zĂskanĂœch vĂœsledkĆŻ ze simulacĂ a mÄĆenĂ.This dissertation thesis deals with the analysis, simulation and measurement of the signal processing and transmission in DVB-H and DVB-SH standards. These standards are based on the assumption that signal reception is characterized by the transmission channels with echoes. These, so called fading channels, are mainly characterized by the path delays and path losses. Depending on the other, additional features (speed of the receiver, Doppler spectrum, etc.), it can be possible divided these channels onto three main groups: mobile, portable and fixed. Of course, signal transmission in different transmission channel models are affected differently. Therefore, it is needed found the optimal system parameters in both, DVB-H and DVB-SH standards, for the quality reception of the broadcasted mobile TV services, which is the main goal of this thesis. For this purpose, two appropriate applications (one for DVB-H and one for DVB-SH) with GUI were created in MATLAB, which enable simulated and analyzed the signal distortions in mobile, portable and fixed transmission scenarios. Moreover, these applications also contain a second application with GUI for the easy set and modification of the parameters of the used channel models. Therefore, it is possible to evaluate the effect of parameters of whole system and channel models on the achieved error rate (BER and MER) and quality of the transmission. In all mentioned transmission scenarios, the signal distortions (depending on the Carrier-to-Noise ratio) were obtained, evaluated and discussed in this dissertation thesis. Furthermore, in case of DVB-H, all obtained results from the simulations, were verified by the measuring. Differences between the obtained results (simulation and measuring) are also discussed. This dissertation thesis can be divided into four main parts. The first part of this dissertation thesis, after the short introduction, deals with present state-of-the-art and literature survey in mobile broadcast DVB-H/SH standards. At the end of this part are clearly outlined the main aims of this dissertation thesis. Second part is focused on the brief description of the functional block diagram of transmitters in both, DVB-H/SH standards. Furthermore, there are briefly described the transmission fading channel models, which are commonly used for the modeling of the signal transmission. The brief description of program applications with flowcharts, appropriate for the simulation of the transmission in the DVB-H/SH standards, are presented and described in the third part of this thesis. Finally, the fourth and longest part of this thesis is focused on the evaluation and comparison of obtained results from the simulations and measurements.
The planning and optimisation of DVB-H radio network
In the DVB-H (Digital Video Broadcasting - Handheld) radio network planning, there are details that lack final consensus in the scientific field. The aim of this doctoral dissertation is to investigate advanced DVB-H radio network planning and optimisation. This dissertation presents the results of measurement techniques, network coverage and quality estimation, technological and economical optimisation, as well as error correction and single frequency network performance. The outcome includes proposed DVB-H radio network planning and optimisation methods that can be applied to the further investigation of detailed parameters in the radio link budget. There are also case studies that show the functionality of the presented methods with typical performance values.
Based on comparative investigations, a process chart was created for DVB-H radio network planning and optimisation. The process blocks can be applied in a typical DVB-H network deployment, for the initial high-level phase as well as in the detailed network planning and optimisation phase. Using this process, the most relevant items were selected for in-depth studies. The investigations are presented in the annexed publications. The reminder was revised by comparative literature studies. The structure of the thesis follows the designed process charts.
The main focus of this dissertation is the development of DVB-H radio network planning methodologies. One of the goals was to investigate the radio interface measurements, their post-processing and analysis. This can provide a guide to the selection of the appropriate values as a function of the radio channel type. An additional goal is the controlled management of over-sized single frequency network areas through the balancing of elevated SFN interference levels and related SFN gains. The development of a radio path loss simulator is the basis for these studies. The case results are presented as a function of the relevant radio parameter values, transmitter power levels and site antenna heights, both in theoretical and realistic network layouts. In addition to these topics, this document also investigates selected electro-magnetic compatibility, human exposure safety zones and radio coverage estimations. Also the balancing of technical radio parameters and network costs in order to complete the planning process steps is covered
Quality-Oriented Mobility Management for Multimedia Content Delivery to Mobile Users
The heterogeneous wireless networking environment determined by the latest developments in wireless access technologies promises a high level of communication resources for mobile
computational devices. Although the communication resources provided, especially referring to bandwidth, enable multimedia streaming to mobile users, maintaining a high user perceived quality is still a challenging task. The main factors which affect quality in multimedia streaming over wireless networks are mainly the error-prone nature of the wireless channels and the user mobility. These factors determine a high level of dynamics of wireless communication resources, namely variations in throughput and packet loss as well as network availability and delays in delivering the data packets. Under these conditions maintaining a high level of quality, as perceived by the user, requires a quality oriented mobility management scheme. Consequently we propose the Smooth Adaptive Soft-Handover Algorithm, a novel quality oriented handover management scheme which unlike other similar solutions, smoothly transfer the data traffic from one network to another using multiple simultaneous connections. To estimate the capacity of each connection the novel Quality of Multimedia Streaming (QMS) metric is proposed. The QMS metric aims at offering maximum flexibility and efficiency allowing the applications to fine tune the behavior of the handover algorithm. The current simulation-based performance evaluation clearly shows the better
performance of the proposed Smooth Adaptive Soft-Handover Algorithm as compared with other handover solutions. The evaluation was performed in various scenarios including
multiple mobile hosts performing handover simultaneously, wireless networks with variable overlapping areas, and various network congestion levels
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