Double spatial media based modulation.
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Date
2019
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Abstract
Multiple-input multiple-out (MIMO) systems have become an increasingly popular technology
in wireless communications due to their high data rates and increased reliability. However,
several drawbacks degrade the performance of MIMO systems. Inter-channel interference, inter-
antenna synchronization, low energy e ciency, and relatively high-complexity receive algorithms
are several of the challenges that MIMO systems face. As such, spatial modulation (SM) was
introduced as a scheme that is capable of exploiting the advantages of MIMO systems, while
simultaneously mitigating its drawbacks. SM provided an excellent method of exploiting spatial diversity, which eventually replaced MIMO systems. However, as the use of SM became
more prominent, its drawbacks became more apparent. The spectral e ciency of SM is limited
by the logarithmic relationship between spectral efficiency and the number of transmit antennas.
Several SM-based transmission schemes, such as quadrature spatial modulation and double
spatial modulation (DSM), were introduced with the prospect of improving the spectral efficiency of SM. These schemes have a single radio frequency (RF) chain; therefore, relatively
low-complexity receive algorithms are employed. Conventional transmission techniques are referred to as source-based modulation (SBM).
Media-based modulation (MBM) is a new attractive transmission scheme that has been recently receiving increased research attention. MBM employs the use of RF mirrors to vastly
improve the error performance and/or spectral efficiency of modulation schemes. It has been
demonstrated that MBM, coupled with SBM techniques, vastly improves the error performance
and can potentially increase the spectral efficiency of these systems.
In this dissertation, DSM is extended to employ MBM, such as to improve error performance.
The proposed transmission scheme is called double spatial media-based modulation (DSMBM).
The theoretical average bit error probability (ABEP) of DSMBM over an independent and
identically distributed Rayleigh frequency-
at fading channel in the presence of additive white Gaussian noise is formulated. The theoretical ABEP of DSMBM is validated by Monte Carlo
simulations, where the error performance matches the theoretical ABEP at high signal-to-noise
ratios (SNRs).
Lastly, coded channels are investigated. Typically soft-output detection coupled with soft-input
channel decoding yields a signicant SNR gain. Motivated by this, this dissertation further
proposes a soft-output maximum-likelihood detector for the DSM and DSMBM schemes.
Description
Masters Degree. University of KwaZulu-Natal, Durban.