Performance analysis and enhancement schemes for spatial modulation.
Multiple-input multiple-output (MIMO) technology has emerged as a popular technique for enhancing the reliability and capacity of wireless communication systems. In this dissertation, we analyze the spatial modulation (SM) MIMO technique and investigate possible extensions to this scheme. To date, there has been no literature reporting on the theoretical performance of M-ary quadrature amplitude modulation (M-QAM) SM with maximum likelihood (ML) based detection. The first objective of this dissertation is to present an asymptotic bound to quantify the average bit error rate (BER) of M-QAM SM with ML detection over independent and identically distributed (i.i.d) Rayleigh flat fading channels. The analytical frameworks are validated by Monte Carlo simulation results, which show the derived bounds to be tight for high signal-to-noise ratio (SNR) values. The ML based SM detector is optimal, since it offers the best detection performance. However, this technique is not practical due to its high computational complexity. The second objective of this dissertation is to introduce a novel SM detection scheme, termed multiple-stage (MS) detection. Performance and complexity comparisons with existing SM detectors show two main benefits of MS detection: near optimal BER performance and up to a 35% reduction in receiver complexity as compared to the ML based detector. Conventional SM schemes are unable to exploit the transmit diversity gains provided by the MIMO channel. The third objective of this dissertation is to propose Alamouti coded spatial modulation (ACSM), a novel SM based scheme with transmit diversity. The ACSM technique combines SM with Alamouti space-time block coding (STBC), thereby improving the diversity aspect and overall system performance of conventional SM. A closed form expression for the average BER of real constellation ACSM over i.i.d Rayleigh flat fading channels is derived and Monte Carlo simulations are used to verify the accuracy of this analytical expression. The BER performance of ACSM is compared to that of SM and Alamouti STBC. Simulation results show that the new scheme outperforms SM and Alamouti STBC by approximately 5.5 dB and 1.5 dB respectively, albeit at the cost of increased receiver complexity.