
NSF Org: |
CNS Division Of Computer and Network Systems |
Recipient: |
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Initial Amendment Date: | July 15, 2016 |
Latest Amendment Date: | July 15, 2016 |
Award Number: | 1618646 |
Award Instrument: | Standard Grant |
Program Manager: |
Alexander Sprintson
CNS Division Of Computer and Network Systems CSE Directorate for Computer and Information Science and Engineering |
Start Date: | October 1, 2016 |
End Date: | September 30, 2019 (Estimated) |
Total Intended Award Amount: | $98,335.00 |
Total Awarded Amount to Date: | $98,335.00 |
Funds Obligated to Date: |
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History of Investigator: |
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Recipient Sponsored Research Office: |
1000 OLIN WAY NEEDHAM MA US 02492-1200 (781)292-2426 |
Sponsor Congressional District: |
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Primary Place of Performance: |
MA US 02492-1245 |
Primary Place of
Performance Congressional District: |
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Unique Entity Identifier (UEI): |
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Parent UEI: |
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NSF Program(s): | Networking Technology and Syst |
Primary Program Source: |
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Program Reference Code(s): |
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Program Element Code(s): |
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Award Agency Code: | 4900 |
Fund Agency Code: | 4900 |
Assistance Listing Number(s): | 47.070 |
ABSTRACT
The explosion in demand for wireless communications has resulted in the crowding of the electromagnetic spectrum. To service the exponentially increasing demand forecast for the near future, new technologies and frequency bands need to be considered. One such technology is Visible-Light-Communications (VLC), where light-emitting diode (LED) based lighting systems can be used to transmit data while also providing illumination. The visible-light spectrum provides a very large bandwidth of electromagnetic spectrum that has the potential to help alleviate the spectral crunch. This proposed effort addresses the challenge of tightly integrating VLC communications with Radio-Frequency (RF) communications, where the RF channel is used only when a VLC link cannot be established, and for upstream data transmissions between users and access points since the upstream link poses a number of challenges for VLC including significant glare that would result from high-powered lights on mobile devices, and high power consumption. The PI proposes to develop practical, efficient protocols and algorithms for hybrid VLC-RF communications systems. The PI works in an undergraduate-only institution and will work with undergraduate students in this project. Additionally, the PI plans to work with a youth teacher program to educate middle- and high-school aged children on the fundamentals of digital communications, using VLC as an example technology. Successful completion of this project will be a major step towards making VLC-RF systems practical which will help service the increased demand for wireless data communications in the future, and help train the next generation of engineers.
The PI proposes to design, develop, and implement in hardware, hybrid RF-VLC systems with integrated Medium-Access Control (MAC), which also provide illumination. The proposed program will involve 1) designing, simulating and implementing a VLC-RF MAC protocol; 2) developing and integrating into the system, physical layer algorithms that exploit channel information that can realistically be obtained through MAC protocol interactions; and 3) optimizing the MAC protocol for Room-Division Multiplexing (RDM). The fact that the proposed systems will have integrated MACs, enables practical VLC-RF systems for which physical layer implementation is decoupled from higher layers, which is an important principle of modular communications system designs. Optimizing the system for RDM can potentially increase data rates significantly due to the higher spectral re-use on the VLC enabled downlink of the hybrid system. Successful completion of this project will help make VLC a practical and modular communications system, which can lead to improved internet access, particularly in dense urban environments.
PUBLICATIONS PRODUCED AS A RESULT OF THIS RESEARCH
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PROJECT OUTCOMES REPORT
Disclaimer
This Project Outcomes Report for the General Public is displayed verbatim as submitted by the Principal Investigator (PI) for this award. Any opinions, findings, and conclusions or recommendations expressed in this Report are those of the PI and do not necessarily reflect the views of the National Science Foundation; NSF has not approved or endorsed its content.
Visible-light communications (VLC) is a promising method to help alleviate the spectral crunch that is predicted for the near future with the exponential growth in demand for wireless communications services. The visible-light spectrum offers a very large range of frequencies that are unregulated. Visible-light is also very directional in its propagation and does not penetrate opaque objects. Hence, many non-interfering VLC networks can be located in a small area, providing high aggregate data rates for many users. In VLC systems, luminaires comprising Light-Emmitting Diodes (LEDs) are proposed to be used for both illumination as well as transmitting data by rapidly modulating light levels at rates imperceptible to users. Therefore, lighting systems can double up as internet access points (Aps). One challenge with VLC systems is that in networks with mobile users, the reverse link from the user device to the AP cannot use VLC due to glare and high power consumption. Non-visible light communications in adjacent frequencies such as infra-red could potentially cause an eye-safety hazard, and still draw significant amounts of power. Additionally, VLC systems in both directions (AP to user device, and vice versa) can easily be impaired by blocking, such as a users hand covering the light detector on their laptop computer. For these reasons, hybrid VLC and radio frequency (RF) systems have been proposed in the literature. These systems often use VLC for the transmission from the AP to a user device, and RF for data transmission from user devices to the AP. Additionally, the RF channel also serves as a backup for the VLC channel if the VLC channel is blocked.
In this project, we designed and constructed a hybrid VLC-RF system which is highly integrated, in the sense that all the processing for the RF and VLC systems are performed on the same device. This high-level of integration results in lower latency (delay between when a transmission is initiated to when it is received) for communications. This system was implemented on an open-source hardware platform with no custom components, including a commercially available luminaire, making it possible for other researchers to use this as a reference design for constructing similar systems for other research projects. All our designs are provided on a website with results of tests provided in accompanying publications. We have developed several novel practical approaches for mitigating signal impairments caused by the lighting systems. These include practical non-linear digital pre-compensation techniques which pre-compensates for the effect of the LED lighting systems, and a new approach for using red-gree-blue (RGB) LED systems in a popularly used modulation technique. We also developed a new medium-access-control (MAC) protocol which controls the behavior of the hybrid VLC-RF system so that it is compatible with independent, commercial wi-fi systems, and can efficiently share the RF medium with wi-fi systems. This latter feature is critical given how ubiquitous wi-fi systems are, and any practical VLC-RF system must be able to coexist with legacy wi-fi systems. Much of the work on this project has been carried out by undergraduate students with six undergraduate students being co-authors on papers related to this project. The outcomes of this project have the potential to help alleviate the impending spectral crunch and improve internet access in crowded environments such as classrooms, office spaces, airports etc., which can have a large impact in society broadly.
Last Modified: 04/21/2020
Modified by: Siddhartan Govindasamy
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