Interference Characterization in Downlink Li-Fi Optical Attocell Networks

Abstract

Wireless access to data using visible light, popularly known as light-fidelity (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 light-emitting-diodes (LED) and photodiodes respectively. 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 photodiode is limited, the network interference distribution gets affected significantly. So, for any given network scenario, interference characterization is critical for good system design. 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 limited FOVs. In this paper, using a technique from Fourier analysis, we provide a very close approximation to interference in one and two dimension Li-Fi attocell networks for any given finite inter-LED separation. 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.

A Review on LiFi Network Research: Open Issues, Applications and Future Directions

“…Therefore, this section aims to elaborate and discuss the components and architecture of LiFi. A standard LiFi operating system involves propagation in one path, such as DL [89,158,159] or UL [34,155] or where both of them are BID [78,103,160]. Power and data may be supplied to each light fixture through various approaches, including Power Over Ethernet (PoE) and Power Line Connectivity (PLC) [14].…”

Analyzing Optical TDMA to Mitigate Interference in Downlink LiFi Optical Attocell Networks

“…• Since the LiFi LEDs are centrally monitored, the TDMA is implemented over the LEDs to mitigate interference over a two dimensional LiFi attocell network. • Using the results in [1] over M-PAM modulated signals, an exact expression (10) is derived an for the goodput G of the TDMA system, where G is defined as the product of the rate and the probability of correctness of reception. • The existence of an optimum TDMA parameter K is shown, at which G is maximized.…”

“…Infinite two dimension plane Figure 1. This figure, taken from [1], shows the infinite two dimensional model. There are infinite number of LEDs (circular dots) indexed as (i, j) ∈ S and arranged symmetrically at regular intervals of a as a uniform square grid, all over the plane, installed at a height h. The rectangular dotted regions on ground depict the attocells corresponding to each (i, j) th LED above.…”

“…Co-channel interference or simply interference in such networks significantly affects the SINR and hence limits the data rate. Tractable closed form expressions characterizing this interference have been provided in [1] over the attocell geometries. While various multiple access schemes have been used to mitigate interference in conventional wireless networks, the time division multiple access (TDMA) over the LiFi LEDs will be suitable to analyze and implement since the attocell networks are always centrally monitored over a deterministic lattice.…”

Optimal frequency reuse scheme based on cuckoo search algorithm in Li‐Fi fifth‐generation bidirectional communication

“…Increased data rate and bandwidth are achieved by Li‐Fi while transferring the data through visible light. The photodiodes and light‐emitting diodes (LEDs) are utilised for signal transmission and reception with data modulation over optical intensities [4]. Separate colour beams are utilised for uplink and downlink data transmission.…”