AbstractA cost-effective spectrum sliced wavelength division multiplexing radio over free space (SS-WDM RoFSO) full duplex communication system architecture has been proposed and analyzed. For the downlink, a 10 Gbits/s high spectrally efficient and amplitude maintaining modified duobinary return to zero (MDRZ) modulated the filtered slices from the light source. The free space optical (FSO) channel was modeled by the well-known Gamma-Gamma model and was further subjected to moderate rain attenuation conditions. Four FSO transceivers were used to mitigate against laser beam scintillation, geometrical losses and rain attenuation. For uplink, a reflective semiconductor optical amplifier (RSOA) was used both as a modulator and an amplifier. Its amplitude squeezing effect was used to erase the information in the MDRZ modulated downstream seeding wavelength for uplink transmission of 10 Gbits/s NRZ OOK signals. At a bit error rate (BER) of $1.262 imes 10^{-9}$, our proposed architecture revealed that 10 Gbits/s symmetric SS-WDM RoFSO can achieve 4.167 km of free space transmission. Power penalty of approximately 0.2 and 3 dB was achieved for downstream and upstream, respectively, which assures the feasibility of the proposed architecture. Such a system is meant to co-exist with the forthcoming fifth generation long-term evolution urban systems.