Abstract

Hybrid light fidelity (Li-Fi) and wireless fidelity (Wi-Fi) networks are an emerging technology for future indoor wireless communications. This hybrid network combines the high-speed data transmission offered by visible light communication and the ubiquitous coverage of radio-frequency techniques. While a hybrid network can improve the system throughput and users' experience, it also challenges the process of access point selection (APS) due to the mixture of heterogeneous access points. In this paper, the differences between homogeneous and heterogeneous networks regarding APS are discussed, and a two-stage APS method is proposed for hybrid Li-Fi/Wi-Fi networks. In the first stage, a fuzzy logic system is developed to determine the users that should be connected to Wi-Fi. In the second stage, the remaining users are assigned in the environment of a homogeneous Li-Fi network. Compared with the optimisation method, the proposed method achieves a close-to-optimal throughput at significantly reduced complexity. Simulation results also show that our method greatly improves the system throughput over the conventional methods, such as the signal strength strategy and load balancing, at slightly increased complexity.

Highlights

  • Mobile communication has been technically challenged by exponentially increasing demands for data traffic

  • In light fidelity (Li-Fi), light-emitting diode (LED) lamps act as access points (APs), and light is used as a medium to carry information bits via intensity modulation and direct detection (IM/DD)

  • The access point selection (APS) for a hybrid Li-Fi and wireless fidelity (Wi-Fi) network is formulated as a two-stage problem: i) determine the users that need to be served by Wi-Fi; and ii) conduct APS for the remaining users as if they are in a stand-alone Li-Fi network

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Summary

INTRODUCTION

Mobile communication has been technically challenged by exponentially increasing demands for data traffic. With the aim of maximising the overall throughput, [12] reported a centralised optimisation method, which requires extensive computational complexity Those methods were developed from the APS solutions in a homogeneous network, and they fail to exploit the distinguishing characteristics between Li-Fi and Wi-Fi. In general, a hybrid Li-Fi and Wi-Fi network challenges the APS in two aspects: i) a Wi-Fi AP dominantly attracts the users close to it, leading to an inefficient use of nearby Li-Fi APs; and ii) a Wi-Fi AP has a larger coverage area but less capacity than a Li-Fi AP, and is more susceptible to overload.

Wi-Fi Channel Model
CONVENTIONAL ACCESS POINT SELECTION METHODS
Signal Strength Strategy
Load Balancing
Optimisation Method
PROPOSED ACCESS POINT SELECTION METHOD
Proposed APS Method
OPTIMALITY AND COMPLEXITY OF THE PROPOSED METHOD
Optimality
Complexity
SIMULATION RESULTS
Performance Comparison
Effects of the Number of Wi-Fi channels
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