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Characterizing Interference and Coverage in Downlink Li-Fi Optical Attocell Networks

May 9 @ 2:00 pm - 3:00 pm

Date: 9th May, 2018

Time: 2:00p.m.

Venue: ESB244

Speaker: AtchutanandaSurampudi (EE16S003)

Guide: Dr. Ganti Radhakrishna


GTC Members:

Dr. Srikrishna B (Chairperson)

Dr. Uday Khankhoje (M)

Dr. Siva Ram Murty(M) (CSE)


The internet has transformed our world, our healthcare, our education, our economy, our democracy and our opportunities. But not for everyone. Astonishingly, 60% of the world’s population don’t have access to the internet. The digital divide is the gap between those who have access to the internet and those who don’t. This gap is widening in terms of education, health, genuine democracy and income. Trying to bridge this gap, scientists have worked on a new way to transmit data wirelessly. This technology uses something that’s around us all the time. It’s light, and it’s popularly known as Light Fidelity (Li-Fi). Li-Fi is one of the key emerging technologies which promises huge bandwidths and data rates. In Li-Fi, the data is modulated on optical intensities and transmitted and detected using off-the-shelf light-emitting-diodes (LED) and photodiodes (PD) respectively. This form of wireless communication has the advantage of using the existing lighting infrastructure we have in our homes. A network of such LED access points illuminates a given region in the form of attocells. Akin to wireless networks, co-channel interference or simply interference is a major impediment in Li-Fi attocell networks. Also, when in such networks, the field-of-view (FOV) of a receiver is limited, the network interference distribution gets affected significantly. So, for a given network scenario, interference characterization, and hence probability of coverage is critical for good system design. The traditional methods for characterizing probability of coverage and interference in wireless networks do not apply here because of two main reasons. Firstly, the optical wireless channel is essentially quasi-static and the time varying fading over such channels is absent. Secondly, Li-Fi LEDs will always be arranged in a regular lattice and hence the approximation to a Poisson point process becomes invalid. So, currently, there are no good closed-form approximations to interference in Li-Fi attocell networks, that can be used for the analysis of signal-to-interference-plus-noise-ratio (or coverage), particularly for the case of receivers with limited FOVs. So, using a technique from Fourier analysis, we provide a very close approximation to interference in one and two dimension Li-Fi attocell networks. This is for any given finite ratio between the height of installation h to the inter- LED separation a. We validate the interference approximation by providing theoretical error bounds using asymptotics and by performing numerical simulations. We show that our method of approximation can be extended to characterize interference in limited FOV scenarios as well. Further, we derive a closed form expression for the probability of coverage in such a network using the earlier derived expression for interference and analyze the same when the LEDs are scheduled in time.

All are cordially invited.


May 9
2:00 pm - 3:00 pm
Event Category:


ESB – 244
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