Green-Inspired Hybrid FSO/RF Wireless Backhauling and Basic Access Signalling for Next Generation Metrozones

Abstract—With the adoption of the fourth generation (4G) technologies, the green Metrozones concept presents a viable approach to address the non-negligible presence of power-hungry base transceiver stations (BTSs), and the mushrooming of metro access points (M-APs); and their contributions to the world’s carbon footprint. This paper proposes a new hybrid-BTS (H-BTS) system architecture for the green Metrozones. The hybrid free-space optical and radio frequency (FSO/RF) system is integrated at the macro-cellular tier, to enable high-capacity, power-efficient wireless backhauling. A resource prioritization mechanism is designed, to maintain good control and optimal on-demand resource allocation. Next, a basic access signalling (BAS) scheme is introduced, to necessitate the discovery, registration and monitoring of active M-APs. The proposed BAS scheme enables the sleep-wake-on-demand (SWoD) mechanism and the cooperative inter-cell support. Furthermore, preliminary feasibility studies are carried out to examine the time-varying characteristics of the BTS daily traffic profile, and the performance of the proposed hybrid FSO/RF systems under different weather conditions. Keywords-Free-space optical (FSO) communications; 60 GHz radio frequency (RF) links; hybrid FSO/RF systems; wireless backhauling; basic access signalling; Metrozones I