Design and Analysis of a Visible-Light-Communication Enhanced WiFi System

Abstract

Visible light communication (VLC) has wide unlicensed bandwidth, enables communication in radiofrequency-sensitive environments, realizes energy-efficient data transmission, and has the potential to boost the capacity of wireless access networks through spatial reuse. On the other hand, WiFi provides more coverage than VLC and does not suffer from the likelihood of blockage due to the line-of-sight requirement of VLC. In order to take the advantages of both WiFi and VLC, we propose and implement two heterogeneous systems with Internet access. One is the hybrid WiFi-VLC system, utilizing a unidirectional VLC channel as the downlink and reserving the WiFi backchannel as the uplink. The asymmetric solution resolves the optical uplink challenges and benefits from the full-duplex communication based on VLC. To further enhance the robustness and increase throughput, the other system is presented, in which we aggregate WiFi and VLC in parallel by leveraging the bonding technique in the Linux operating system. We also theoretically prove the superiority of the aggregated system in terms of average system delay. Online experiment results reveal that the hybrid system outperforms the conventional WiFi for crowded environments in terms of throughput and Web page loading time, and also demonstrate the further improved performance of the aggregated system when considering the blocking duration and the distance between the access point and the user device.

A Hybrid RF-VLC System for Energy Efficient Wireless Access

“…The increase in power consumption is mainly due to the switching loss in the driver circuitry at high speeds (AC current). Such behavior is observed in our experimental results [30], [31], [40] and the results in [41].…”

“…Therefore, a constant level of background noise can be assumed. Our experimental results [31] validated this behavior even in outdoor settings. The AC signal bandwidth can be divided into several channels and two AC signals from different APs operating on the same channel will interfere with each other.…”

“…The background noise consists of the thermal noise and the shot noise. If the modulation bandwidth is large (above 50 MHz) and the optical power level is low (below 20 W) as is the case with most VLC APs and the VLC front-ends utilized in our research [31], the thermal noise would dominate the shot noise [43]- [45]. With fixed gain of the receiver, the thermal noise does not depend on the AC and DC signals while the shot noise does.…”

Experimental Demonstration of Staggered CAP Modulation for Low Bandwidth Red-Emitting Polymer-LED Based Visible Light Communications

“…Typically in modern wireless access network technologies, data rates are lower for the uplink and hence, a reduced transmit power level is allocated [12]. In general, VLC systems have usually been contextualised as a unidirectional broadcasting technology to date, with alternative technologies such as radio frequency (RF) being used for the uplink [13,14]. Due to the relaxed requirement for high data rates, it is envisaged that individually addressable pixels embedded into PLED display technologies can effectively be utilised as the uplink in future VLC networks whilst displaying an image.…”

Design and Implementation of Client Side at Application Layer of Internet of Things

“…WIFI signals in 2.4GHz frequency band are slightly affected by wall obstructions. [6] WIFI transmission rate is continuously improving as technology evolves. In China, the WIFI technology adopted by telecom operators for constructing wireless cities has upgraded to 802.11n and the highest rate has risen from 11Mbps of 802.11g standard to above 50Mbps.…”