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Improved QC-STBC OFDM system using null interfeence eliminationAnoh, Kelvin O.O., Abd-Alhameed, Raed, Dama, Yousef A.S., Jones, Steven M.R., Ghazaany, Tahereh S., Rodriguez, Jonathan, Voudouris, Konstantinos N. January 2013 (has links)
Yes / The quasi-orthogonal space time block coding (QO-STBC) over orthogonal frequency division multiplexing (OFDM) is investigated. Traditionally, QO-STBC does not achieve full diversity since the detection matrix of QO-STBC scheme is not a diagonal matrix. In STBC, the decoding matrix is a diagonal matrix which enables linear decoding whereas the decoding matrix in traditional QO-STBC does not enable linear decoding. In this paper it is shown that there are some interfering terms in terms of non-diagonal elements that result from the decoding process which limit the linear decoding. As a result, interference from the application of the QO-STBC decoding matrix depletes the performance of the scheme such that full diversity is not attained. A method of eliminating this interference in QO-STBC is investigated by nulling the interfering terms towards full diversity for an OFDM system. It was found that the interference reduction technique permits circa 2dB BER performance gain in QO-STBC. The theoretical and simulation results are presented, for both traditional QO-STBC and interference-free QO-STBC applying OFDM
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A Multi-Antenna Design Scheme based on Hadamard Matrices for Wireless CommunicationsAnoh, Kelvin O.O., Chukwu, M.C., Dama, Yousef A.S., Abd-Alhameed, Raed, Ochonogor, O., Jones, Steven M.R. 27 August 2014 (has links)
Yes / A quasi-orthogonal space time block coding (QO-STBC) scheme that exploits Hadamard matrix
properties is studied and evaluated. At first, an analytical solution is derived as an extension of
some earlier proposed QO-STBC scheme based on Hadamard matrices, called diagonalized
Hadamard space-time block coding (DHSBTC). It explores the ability of Hadamard matrices
that can translate into amplitude gains for a multi-antenna system, such as the QO-STBC
system, to eliminate some off-diagonal (interference) terms that limit the system performance
towards full diversity. This property is used in diagonalizing the decoding matrix of the QOSTBC
system without such interfering elements. Results obtained quite agree with the analytical
solution and also reflect the full diversity advantage of the proposed QO-STBC system design
scheme. Secondly, the study is extended over an interference-free QO-STBC multi-antenna
scheme, which does not include the interfering terms in the decoding matrix. Then, following
the Hadamard matrix property advantages, the gain obtained (for example, in 4x1 QO-STBC
scheme) in this study showed 4-times louder amplitude (gain) than the interference-free QOSTBC
and much louder than earlier DHSTBC for which the new approach is compared with.
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