Access Frameworks and Application Scenarios for Hybrid VLC and RF Systems: State of the Art, Challenges, and Trends

The further demand for data traffic growth makes the conventional radio frequency (RF) wireless network face ever increasing challenges such as spectrum shortage and access congestion. Visible light communication (VLC) is envisioned as a promising candidate for wireless communication in the future, but it also has limitations like limited coverage and inconvenient uplinks. Naturally, it is a rational strategy to combine VLC and RF systems to form hybrid systems, which can take full advantage of high data rate in VLC and wide coverage in RF. In this article, the current research on hybrid VLC and RF systems is reviewed. First, the structures of hybrid access frameworks are introduced as complementary single-hop networks and heterogeneous multihop networks, while common frameworks in the current literature are summarized. Moreover, the technical characteristics and specific advantages of hybrid VLC and RF systems are discussed in different application scenarios for high data rate, high energy efficiency, and high reliability. Finally, the future trends of hybrid VLC and RF systems are looked forward to in some typical enabling technologies.