Smart Lighting and Internet Access as a Green Service

Abdallah Khreishah
ECE Department, NJIT


According to Cisco Visual Networking Index, most of the Internet access traffic will happen indoor at fixed locations (about 80% indoor and 20% outdoor). This amount is expected to increase as 54% of the cellular traffic is expected to be offloaded to WiFi by 2019. Based on this projected functionality of the future Internet, the two major types of traffic that the future Internet access networks should support are mobile traffic and small devices Internet of Things (IoT) traffic. The mobile traffic includes traffic for laptops, smart phones, and tablets. The IoT small devices include devices that perform sensing and control for our daily life operation, such as home appliances. It is expected that the traffic generated by more than 95% of the devices connected to the Internet in 2019 will fall under one of the above two types of traffic. This projected functionality of the Internet puts more pressure on the access points’ traffic and the energy consumed by the access points. Note that even though the power consumption of a single access point is small, the aggregate power consumption of all of these devices is very large as there are more than half billion wireless routers in the world. In this talk, we present our design of visible-light enhanced WiFi system. We first discuss the design and analysis of the hybrid system to enhance the throughput and delay of the system. After that we present the utilization of the system to minimize the power consumption of wireless indoor access networks. Our system utilizes both the traditional RF access methods as well as the emerging technology of Visible-light communication (VLC). VLC facilitates the great advantage of being able to jointly perform illumination and communications, and little extra power beyond illumination is required to empower communications, thus rendering wireless access with almost zero power consumption. On the other hand, when illumination is not required from the light source, the energy consumed by VLC could be more than that consumed by the RF. By capitalizing on the above properties, the proposed hybrid RF-VLC system is more energy efficient and more adaptive to the illumination conditions than the individual VLC or RF systems. To demonstrate the viability of the proposed system, we first formulate the problem of minimizing the energy consumption of the hybrid RF-VLC system while satisfying the users’ requests and maintaining acceptable level of illumination, which is shown to be NP-complete. To facilitate real-time communications, we develop a randomized online algorithm for the problem that achieves a competitive ratio of $\log(N )\log(M )$ with probability of success $(1-\frac{1}{N})$, where $N$ is the number of users and $M$ is the number of VLC and RF access points. We also show that the best online algorithm to solve this problem can achieve a competitive ratio of $\log(M)$. Simulation results performed with parameters representing measurements from real RF and VLC hotspots show that the hybrid system can achieve up to 75% energy reduction compared to the individual VLC and RF systems.