1,720,962 research outputs found
Multi-user OFDM employing genetic algorithm aided minimum bit error rate multi-user detection
No full textLDPC and Turbo Coding Assisted Space-Time Block Coded OFDM for H.26L
No full textIn this contribution we propose an LDPC assisted Space-Time Block Coded OFDM transceiver designed for wireless video telephony and characterise its performance when communicating over the UTRA wideband vehicular fading channels. Low Density Parity Check (LDPC) and turbo channel coding schemes are invoked. By concatenating a space-time block coded OFDM scheme with powerful channel codes, the performance of the system can be substantially enhanced. The LDPC codec outperformed the turbo codec in terms of both the achievable video and transmission frame error rate performance
Minimum bit error rate multiuser detection in multiple antenna added OFDM
No full textIn this contribution, we propose a Minimum Bit Error Rate (MBER) multiuser detector for Space Division Multiple Access (SDMA) aided Orthogonal Frequency Division Multiplexing (OFDM) systems. It is shown that the MBER detector outperforms the Minimum Mean Squared Error (MMSE) detector, since the MBER detector directly minimizes the BER, while MMSE detector minimizes the mean-squared error (MSE), which does not guarantee achieving the minimum BER. When supporting two users, the proposed MBER scheme substantially outperforms the classic MMSE arrangement in the investigated propagation scenario
Minimum Bit Error Rate Multiuser Detection in Multiple Antenna Aided OFDM
No full textIn this contribution, we propose a Minimum Bit Error Rate (MBER) multiuser detector for Space Division Multiple Access (SDMA) aided Orthogonal Frequency Division Multiplexing (OFDM) systems. It is shown that the MBER detector outperforms the Minimum Mean Squared Error (MMSE) detector, since the MBER detector directly minimizes the BER, while MMSE detector minimize the mean-squared error (MSE), which does not guarantee achieving the minimum BER. When supporting two users, the proposed MBER scheme substantially outperforms the classic MMSE arrangement in the investigated propagation scenario
LDPC and Turbo Coding Assisted Space-Time Block Coded OFDM
No full textSpace-time block coded OFDM is capable of achieving substantial diversity gains, while supporting high bit-rates in wireless communications. By concatenating a space-time block coded OFDM scheme with powerful channel codes, the performance of the system can be further enhanced. In this contribution both Low-Density Parity-Check (LDPC) coding and turbo coding assisted space-time block coded OFDM is investigated. The achievable performance is studied as a function of the number of iterations, coding delay, code rate and decoding complexity
Genetic Algorithm Assisted Minimum Bit Error Rate Multiuser Detection in Multiple Antenna Aided OFDM
No full textThe family of minimum bit error rate (MBER) multiuser detectors (MUD) is capable of outperforming the classic minimum mean-squared-error (MMSE)MUDin term of the achievable bit-error rate (BER) owing to directly minimising the BER cost function. In this paper, we will invoke genetic algorithms (GA) for finding the optimum weight vectors of the MBERMUDin the context of multipleantenna aided multi-user OFDM
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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