Single ODSB Radio-Over-Fiber Signal Supports STBC at Each RAP

We propose and mathematically characterize a novel radio-over-fiber (ROF) downlink, where a radio access point (RAP) benefits from the transmit diversity gain of space–time block coding (STBC). Significantly, this transmit diversity is achieved using a single optical modulator in the base station (BS). In the proposed architecture, each RAP is fed with a single optical double-sideband signal, where each sideband transmits one of the two STBC-encoded signals. This optical signal is generated in the BS by performing the simultaneous optical upconversion of the baseband STBC signals using a single Mach–Zehnder modulator. The proposed optical backhaul is designed and simulated to impose negligible degradation to that imposed by the dominant wireless link, thereby enabling a designer to exploit the advantages offered by a wireless link having a diversity gain.