Seamless 25 GHz Transmission of LTE 4/16/64-QAM Signals over Hybrid SMF/FSO and Wireless Link

We propose and experimentally demonstrate a photonics-assisted converged radio-over-fiber (RoF), radio-over-free-space optics (RoFSO) and millimeter-wave (MMW) wireless transmission system for use in broadband wireless access (BWA) networks. The focus is at the emerging frequency band of 25 GHz, as recommended for fifth-generation networks. As a proof-of-concept demonstration, all-optical up-converted long-term evolution test models with 4-, 16-and 64-quadrature amplitude modulation (QAM) are transmitted and evaluated over the proposed hybrid link under weak-to-strong atmospheric turbulence regimes. Link performance shows that, the error vector magnitudes are below the 3GPP standard for 4-, 16-and 64-QAM. We also show that, for all QAM signals under turbulence conditions, the bit error rate performance is below the forward error correction limit of {10^{-3}}. Simulation analysis is also performed for the 10 Gb/s hybrid systems under turbulence for an extended FSO link up to 500 m to emulate a practical outdoor environment. Furthermore, we analytically estimate the attainable MMW wireless range for different rain rates in Prague, Czech Republic. The obtained experimental and simulation results confirm the feasibility and potential of the proposed hybrid system for next-generation last mile BWA networks.