331 research outputs found
RATE COMPATIBLE PUNCTURED TURBO-CODED HYBRID ARQ FOR OFDM SYSTEM
Now a dayâs orthogonal frequency division multiplexing (OFDM) is under intense research for broadband wireless transmission because of its robustness against multipath fading. A major concern in data communication such as OFDM is to control transmission errors caused by the channel noise so that error free data can be delivered to the user. Rate compatible punctured turbo (RCPT) coded hybrid ARQ (RCPT HARQ) has been found to give improved throughput performance in a OFDM system. However the extent to which the RCPT HARQ improves the throughput performance of the OFDM system has not been fully understood. HARQ has been suggested as a means of providing high data rate and high throughput communication in next generation systems through diversity combining transmit attempts at the receiver. The combination of RCPT HARQ with OFDM provides significant bandwidth at close to capacity rates of channel. In this paper, we evaluate by computer simulations the throughput performance of RCPT code HARQ for OFDM system as compared to that of conventional OFDM
Models of Control Channels in the LTE System
DizertaÄnĂ prĂĄce se zabĂœvĂĄ zpracovĂĄnĂm signĂĄlu fyzickĂœch ĆĂdicĂch kanĂĄlĆŻ systĂ©mu LTE a vyĆĄetĆovĂĄnĂm bitovĂ© chybovosti pĆi pĆenosu ĆĂdicĂ informace z vysĂlaÄe do pĆijĂmaÄe v zĂĄvislosti na podmĂnkĂĄch pĆĂjmu. PrĂĄce je rozdÄlena do dvou hlavnĂch ÄĂĄstĂ. PrvnĂ ÄĂĄst prĂĄce je zamÄĆena na simulaci pĆenosu ĆĂdicĂ informace LTE v zĂĄkladnĂm pĂĄsmu. Jsou zde prezentovĂĄny vytvoĆenĂ© simulĂĄtory ĆĂdicĂch kanĂĄlĆŻ ve smÄru uplink i downlink. Simulace jsou provedeny pro vĆĄechny druhy nastavenĂ systĂ©mu a zĂĄkladnĂ modely pĆenosovĂ©ho prostĆedĂ. Jsou zde popsĂĄny vĂœsledky vlivu pouĆŸitĂ MIMO technologiĂ na kvalitu pĆĂjmu ĆĂdicĂ informace pĆedevĆĄĂm v ĂșnikovĂœch kanĂĄlech. DruhĂĄ ÄĂĄst prĂĄce je zamÄĆena na moĆŸnost nasazenĂ systĂ©mu LTE ve sdĂlenĂ©m pĂĄsmu ISM (2.4 GHz). Jsou zde pĆedstaveny zĂĄkladnĂ koncepce pouĆŸitĂ, na jejichĆŸ zĂĄkladÄ je vytvoĆen scĂ©nĂĄĆ simulacĂ. Kapitola dĂĄle popisuje tvorbu simulĂĄtoru koexistence LTE a systĂ©mu Wi-Fi v pĆenesenĂ©m pĂĄsmu ISM 2.4GHz. Jsou zde uvedeny vĂœsledky simulacĂ koexistence LTE a ruĆĄivĂ©ho systĂ©mu Wi-Fi provedenĂœch dle vytvoĆenĂ©ho scĂ©nĂĄĆe. VĂœsledky simulacĂ koexistence LTE a Wi-Fi jsou ovÄĆeny mÄĆenĂm v laboratornĂch podmĂnkĂĄch. Toto porovnĂĄnĂ je dĆŻleĆŸitĂ© z hlediska optimalizace simulĂĄtoru koexistence. Dle vĂœsledkĆŻ obou typĆŻ simulacĂ a mÄĆenĂ jsou stanovena provoznĂ doporuÄenĂ, kterĂĄ majĂ pĆispÄt k bezpeÄnĂ©mu a spolehlivĂ©mu vysĂlĂĄnĂ a pĆĂjmu ĆĂdicĂch informacĂ LTE i pĆi nepĆĂznivĂœch podmĂnkĂĄch pĆĂjmu.The doctoral thesis is focused on a signal processing in the LTE physical control channels and performance analysis of control information transmission according to receiving conditions. The thesis is divided into two parts. The first part deals with simulation of the transmission of control information in baseband. The created simulators for uplink and downlink are presented. The simulations are performed for all possible system settings and various channel models. The MIMO influence on a quality of control information reception under fading channels is also presented. The second part of the thesis is focused on LTE utilization in shared channel ISM (2.4 GHz). The basic LTE application concept for ISM band is presented. This concept is fundamental to created simulation scenario. The chapter also presents the LTE and Wi-Fi coexistence simulator in 2.4 GHz ISM passband. The coexistence simulation are presented according to simulation scenario and the results are shown. The simulated coexistence analysis results are verified in laboratory environment. The comparison of the simulated and the measured coexistence analysis results is crucial for further optimization of the coexistence simulator. Recommendations for optimal and reliable operation of LTE are specified according to the simulated and the measured results. Recommendations should be useful to the reliable transmission of LTE control information in bad receiving conditions.
Radio Communications
In the last decades the restless evolution of information and communication technologies (ICT) brought to a deep transformation of our habits. The growth of the Internet and the advances in hardware and software implementations modiïŹed our way to communicate and to share information. In this book, an overview of the major issues faced today by researchers in the ïŹeld of radio communications is given through 35 high quality chapters written by specialists working in universities and research centers all over the world. Various aspects will be deeply discussed: channel modeling, beamforming, multiple antennas, cooperative networks, opportunistic scheduling, advanced admission control, handover management, systems performance assessment, routing issues in mobility conditions, localization, web security. Advanced techniques for the radio resource management will be discussed both in single and multiple radio technologies; either in infrastructure, mesh or ad hoc networks
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