Wyniki 1-2 spośród 2 dla zapytania: authorDesc:"Krzysztof K. Cwalina"


  Realization of point to point high-speed data transmission is an object of interest of public institutions and economic entities which aim to implement, e.g. autonomous and independent monitoring systems. Actually, there is a need to send operational data between executive units, e.g., patrol helicopter and command center. To realize these type of radio link, it is not possible to use commercially available high-speed data transmission radio systems, mainly due to safety rules and too low offered bitrate in radio interface over distance of more than 10 km. Potential users expectations of this type of solutions are much higher. Therefore, there is a need to develop a dedicated solution, which has utility features suitable for implementation in security systems, e.g., protection of maritime state border. In this article, the realization of digital radio link designed for high-speed data transmission for coastal environments using USRP (Universal Software Radio Peripheral) devices, was presented. Types of used digital modulations, methods of their implementation and techniques for receiving digital radio signals using non-synchronized devices, were discussed. In addition, measurement studies of designed radio link in laboratory conditions were also commented. 2. DESCRIPTION OF RADIO LINK CONCEPTION Realization of digital radio link for high-speed data transmission was preceded by determination of the most important design assumptions. The key factor, which determines the types of used digital modulations and time and frequency synchronization mechanisms, is target working environment, i.e., area of the Baltic Sea coastal waters. This fact is connected with the need to immunize a realization of radio transmission against multipath propagation phenomenon (approximated by two-path electromagnetic wave propagation model) and Doppler effect (caused by possible high-speed of movement of the mobile unit, e.g., aircraft) [3, 4]. [...]


  Increasing user expectations for maximizing data rates and minimizing delays forced fourth and fifth generation of mobile networks to evolve dynamically. Exchange of the multimedia data, including movies, images and sound, is the main traffic within the network, which forces operators to implement high-speed data transmission systems. Technologies that enable fast highdefinition multimedia broadcasting arouse a lot of interest among special forces, which belong, among others, Polish Maritime Regional Unit of Border Guard. Teleinformatics security systems considered for special applications necessitate the implementation of such a data transmission by dedicated radiocommunication devices, not connected to commercial mobile networks. In this article the development of the high-speed technology demonstrator in software defined radio technology for special applications is presented. The developed system has been characterized, including asymmetric uplink and downlink frame transmission, bandwidth, frequency, modulations, coding, sampling rates that were implemented in technology demonstrator. Presented research work was financed by The National Centre for Research and Development, as a project No DOB-BIO6/09/5/2014 and was carried out in Department of Radiocommunication System and Networks, Gdansk University of Technology. 2. DESCRIPTION OF SYSTEM OPERATION The architecture of the developed system is hierarchical, where mobile stations (MS) communicate and synchronize only with the base station (BS). In Fig. 1. an example implementation of high-speed data transfer system (DTS) for special applications is shown. Fig. 1. An example of system for high-speed data transmission for special services High-definition video transmission from mobile units, such as air units or vessels to the data center (DC) requires the design of a broadband asymmetric radio link in which the amount of uplink (UL) data is significantly higher than i[...]

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