Soft-output detection for transit antenna index modulation-based schemes.
A. A. Tijani · ResearchSpace (University of KwaZulu-Natal) · 2016
The use of multiple-input multiple-output (MIMO) techniques in wireless communication systems has led to substantial improvements in spectral efficiency and reliability.However, challenges such as inter-antenna synchronization, inter-channel interference, and computational/hardware complexity remains.In recent times, innovative MIMO systems based on transmit antenna index modulation, such as spatial modulation (SM), quadrature SM (QSM), space shift keying (SSK) and Bi-SSK, have been proposed.These schemes address the abovementioned challenges of MIMO; hence, rendering them as promising schemes for integration into the next generation of wireless communication systems.In this dissertation, the error performances of these transmit antenna index modulationbased schemes are firstly investigated.It is evident that the schemes are able to achieve a good combination of high spectral efficiencies/improved reliability and relatively low hardware complexities.In practice, channel coding would be employed with the above mentioned transmit antenna index modulation-based schemes.However, the available detectors for SSK/Bi-SSK and QSM are hard-decision and will not exploit the coding gains achievable with softdecision detection combined with soft-input channel decoding.On this note, in this dissertation, soft-output maximum-likelihood detectors (SOMLD) for the above schemes are formulated.Monte Carlo simulation results demonstrate the substantial improvements in error performance that can be achieved in comparison to the conventional hard-decision ML detector (HDMLD).viii For example, at a BER of 10 -6 , coded SOMLD for 6 bits/s/Hz SSK system achieves an SNR gain of 4.3 dB over the coded HDMLD.At the same BER and spectral efficiency, the coded Bi-SSK-SOMLD system performs better than its coded HDMLD counterpart by 4.2 dB SNR gain.For coded QSM system, the receiver with SOMLD achieve 5.1 dB gains over HDMLD, at 6 b/s/Hz spectral efficiency and a BER of 10 -6 .It was clear that further improvements in error performance are observed in coded SOMLD systems over uncoded conventional HDMLD systems.Finally, the SOMLD is shown to impose no additional computational complexity at the receiver; and without channel coding, the proposed detector yields identical error performance as the HDMLD.ix Acknowledgements ٲ ﳊﻣﺪ ﻟﻟﻪ ٲ رب ﻟﻌﻠﻣﱭ .The biggest thanks goes to ﷲ (Allah) for seeing me through the years of pursuing the degree of Master of Science in Engineering (MSc.Eng).Many thanks to my amiable supervisor, Dr. Narushan Pillay, from whom I have learnt a lot in the field of Electronic Engineering.He also taught me how best to prepare technical reports.I appreciate his patience in dealing with me and the time spent in going through this dissertation over and over again to make sure it is error-free.