Radio over Fiber Downlink Design for Spatial Modulation and Multi-Set Space-Time Shift-Keying

Spatial modulation (SM) and multi-set space-time shift-keying (MS-STSK) are capable of striking a flexible design trade-off between the multiplexing and diversity gains attained. These techniques can also be combined with beamfoming for the sake of supporting reliable millimeter-wave (mmWave) communications. In this treatise, we propose an analogue radio-over-fiber (RoF) downlink network relying on SM and MS-STSK combined with beamforming and up-conversion to mmWave carrier frequencies, whilst using all-optical processing. In the proposed analogue RoF (A-RoF) system, most of the digital processing of the baseband SM and MS-STSK is carried out by the central unit and the implicitly carried bits of SM/MS-STSK, such as the antenna index selection and dispersion matrix selection bits, are recovered by the remote radio head of our A-RoF network for creating a multi-functional multiple-input multiple-output arrangement. As detailed by Hanzo et al., the classic modulated bits are conveyed by the radio signal, without requiring any additional analogue-to-digital conversion and digital-to-analogue conversion before transmission from the antennas. Moreover, A-RoF-aided techniques are invoked for achieving optical processing-aided beamforming and optical up-conversion to an mmWave carrier frequency. Thus, we invoke A-RoF techniques for the generation of our SM/MS-STSK signal with the aid of optically up-converted millimetre-wave beamforming without using any electronic oscillators, mixers, or phase shifters. Furthermore, our A-RoF-aided system's bit error ratio performance is similar to the conventional all-electronic SM/MS-STSK scheme.