Index modulation for next generation wireless communications.

Doctoral Degree. University of KwaZulu-Natal, Durban.A multicarrier index modulation technique in the form of quadrature spatial modulation (QSM) orthogonal frequency division multiplexing (QSM-OFDM) is proposed, in which transmit antenna indices are employed to transmit additional bits. Monte Carlo simulation results demonstrates a 5 dB gain in signal-to-noise ratio (SNR) over other OFDM schemes. Furthermore, an analysis of the receiver computational complexity is presented. A low-complexity near-ML detector for space-time block coded (STBC) spatial modulation (STBC-SM) with cyclic structure (STBC-CSM), which demonstrate near-ML error performance and yields significant reduction in computational complexity is proposed. In addition, the union-bound theoretical framework to quantify the average bit-error probability (ABEP) of STBC-CSM is formulated and validates the Monte Carlo simulation results. The application of media-based modulation (MBM), to STBC-SM and STBC-CSM employing radio frequency (RF) mirrors, in the form of MBSTBC-SM and MBSTBC-CSM is proposed to improve the error performance. Numerical results of the proposed schemes demonstrate significant improvement in error performance when compared with STBC-CSM and STBC-SM. In addition, the analytical framework of the union-bound on the ABEP of MBSTBC-SM and MBSTBC-CSM for the ML detector is formulated and agrees well with Monte Carlo simulations. Furthermore, a low-complexity near-ML detector for MBSTBC-SM and MBSTBC-CSM is proposed, and achieves a near-ML error performance. Monte Carlo simulation results demonstrate a trade-off between the error performance and the resolution of the detector that is employed. Finally, the application of MBM, an index modulated system to spatial modulation, in the form of spatial MBM (SMBM) is investigated. SMBM employs RF mirrors located around the transmit antenna units to create distinct channel paths to the receiver. This thesis presents an easy to evaluate theoretical bound for the error performance of SMBM, which is validated by Monte Carlo simulation results. Lastly, two low-complexity suboptimal mirror activation pattern (MAP) optimization techniques are proposed, which improve the error performance of SMBM significantly

Capacity and Error Performance Verification of Multi-Antenna Schemes in Radio-over-Fiber Distributed Antenna System

A radio-over-fiber distributed antenna system permits larger physical separation between antennas in a wireless system’s infrastructure; this investigation verifies that improved performance – lower error rates and higher capacities – can thus be achieved. In this paper, specific single-input multiple-output (SIMO), multiple-input single-output (MISO) and multiple-input multiple-output (MIMO) algorithms are compared in an experimental radio over fiber system, using user-defined processing functions for the signals. It is shown that significantly reduced symbol error rate (SER) and modestly increased capacity is achieved for a wireless 1x2 SIMO uplink using the maximal ratio combining (MRC) processing algorithm and 2x1 MISO downlink using the Alamouti space time block coding (STBC) scheme. Further, SER is reduced for a downlink 2x2 wireless MIMO using the zero-forcing algorithm while, most importantly, greatly increased capacity is achieved through the spatial multiplexing gain