Hybrid Visible-Light and Radio-Frequency Communications with Integrated Medium-Access Control

Principal Investigator: Siddhartan Govindasamy

National Science Foundation: CNS 1618646

Project Synopsis

With global wireless data traffic set to increase significantly in the near future, the electromagnetic spectrum has become crowded, making it necessary to explore frequency ranges previously unused for data communications. The visible-light spectrum is one such band of frequencies that has been proposed for data communications. The visible-light channel is attractive for data communications for a number of reasons including the availability of low-cost Light-Emitting-Diode (LED) lighting which can be modulated at high frequencies, the availability of a wide range of previously unutilized frequencies, and the possibility of high spectral reuse since visible light does not penetrate walls as illustrated in the figure, leading to the possibility of room division multiplexing (RDM). Visible-Light Communications (VLC) poses a number of challenges such as the requirement of a near line-of-sight (LOS) between a transmitter-receiver pair for high rate communications, and the impracticality of implementing a visible light transmitter on mobile devices as it will be undesirable for users to have bright lights on their mobile devices. Hybrid VLC and Radio Frequency (RF) systems can overcome these limitations as the RF link can be used on the uplink channel from a mobile device to an access point, and on the downlink channel when the VLC channel cannot support a high-rate link.

Existing research on practical hybrid VLC-RF systems, has primarily focused on independent Medium-Access Control (MAC) for the VLC and RF channels. Integration of the RF and VLC sub-systems happens at the network layer. In such systems Internet-Protocol (IP) packets are routed through either the VLC or RF subsystems depending on the capabilities of different devices. In this work, we propose to design, develop, and implement in hardware, hybrid RF VLC systems with integrated MAC, which are compatible with existing 802.11 WiFi devices, and provide illumination.

Students

Taejin Kim (graduate student, Carnegie-Mellon University)

JeeHyun Kim

Ariana Olson (Google Inc.)

Pravallika Dhulipalla (Olin College student)

Minju Kang (Olin College student)

Nathaniel Tan (Olin College student)

Lisa Hachmann (Starry Communications)

Collaborators

Michael Rahaim, University of Massachusetts, Boston.

Publications and reports

Undergraduate students listed in bold.

“An approach for Tomlinson-Harashima Precoding in Visible-Light-Communications Systems”, by JeeHyun Kim, Ariana Olson, Siddhartan Govindasamy and Michael B. Rahaim. International Conference on Computer, Information and Telecommunications Systems. 2018.

“An Integrated Visible-Light and Radio Frequency Communications System”, by P. Dhulipalla, M. Kang, T. Kim, N. Tan, S. Govindasamy and M. Rahaim. In review

“Technical Report: Approaches for shared use of base-band hardware in OFDM-based hybrid VLC-RF Systems with multicolored LEDs”. by P. Dhulipalla, M. Kang, T. Kim, and S. Govindasamy. CODE

Educational activities

Four undergraduate students who worked on this project and have graduated, three others are currently students at Olin College.