29 January 2018 Indoor communications networks realized through hybrid free-space optical and Wi-Fi links
Author Affiliations +
Recently, free-space optical (FSO) networks have been investigated as a potential replacement for traditional WiFi networks due to their large bandwidth potentials. However, FSO networks often suffer from a lack of mobility. We present a hybrid free-space optical and radio frequency (RF) system that we have named WiFO, which seamlessly integrates free-space optical links with pre-existing WiFi networks. The free-space optical link in this system utilizes infrared LEDs operating at a wavelength of 850nm and is capable of transmitting 50Mbps over a three-meter distance. In this hybrid system, optical transmitters are embedded periodically throughout the ceiling of a workspace. Each transmitter directs an optical signal downward in a diffuse light cone, establishing a line of sight optical link. Line of sight communications links have an intrinsic physical layer of security due to the fact that a user must be directly in the path of transmission to access the link; however, this feature also poses a challenge for mobility. In our system, if the free-space optical link is interrupted, a control algorithm redirects traffic over a pre-existing WiFi link ensuring uninterrupted transmissions. After data packets are received, acknowledgments are sent back to a central access point via a WiFi link. As the demand for wireless bandwidth continues to increase exponentially, utilizing the unregulated bandwidth contained within optical spectrum will become necessary. Our fully functional hybrid free-space optical and WiFi prototype system takes full advantage of the untapped bandwidth potential in the optical spectrum, while also maintaining the mobility inherent in WiFi networks.
Conference Presentation
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Spencer Liverman, Spencer Liverman, Qiwei Wang, Qiwei Wang, Yu-Chung Chu, Yu-Chung Chu, Anindita Borah, Anindita Borah, Songtao Wang, Songtao Wang, Arun Natarajan, Arun Natarajan, Thinh Nguyen, Thinh Nguyen, Alan X. Wang, Alan X. Wang, "Indoor communications networks realized through hybrid free-space optical and Wi-Fi links", Proc. SPIE 10559, Broadband Access Communication Technologies XII, 105590H (29 January 2018); doi: 10.1117/12.2292292; https://doi.org/10.1117/12.2292292


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