Optimized Analog Multi-Band Carrierless Amplitude and Phase Modulation for Visible Light Communication-Based Internet of Things Systems

Abstract

This paper presents a multi-user Visible Light Communication (VLC)-based Internet of Things (IoT) system using multi band-Carrierless Amplitude and Phase (m-CAP) modulation for IoT applications. The proposed system uses a digital m-CAP modulator embedded in a ceiling LED light fixture and analog receivers, aiming at low-cost, low-power, and small-sized IoT devices. The performance was evaluated in terms of the filtering stage design and the usage of guard bands. Different pairs of emitter and receiver filters were considered. While Bessel and Butterworth analog filters were tested in the analog receiver, the digital m-CAP modulator pulse shaping filter considered raised cosine filters, as well as digital matched filters for the analog Bessel and Butterworth filters. Regarding the guard bands, two approaches were considered: either by using the raised cosine roll-off factor (bandwidth compression) or by suppressing the even bands. The Bit Error Rate (BER) performance was obtained by simulation. The usage of the Bessel filter in the receiver, along with a digital matched filter, proved to be the best solution, achieving a BER lower than 10−3 for an Eb/No of 6 dB, using a third-order filter. Furthermore, guard bands should be used in order to mitigate inter-band interference in order to have improved performance when multiple users intend to simultaneously communicate.

Application of Internet of Things and Data Optimization in the Design of Smart Medical Park

“…After the sensor technology obtains this information, it converts them into corresponding output signals, so that people can better control them. e environment in which one lives and works can eventually make the park intelligent [25]. e unified security identity authentication system is mainly responsible for the user's permission to log in to the application platform of the park according to the user information and provides a unified authentication platform for the park [26,27].…”

Carrier synchronisation in multiband carrierless amplitude and phase modulation for visible light communication‐based IoT systems

“…Costas-loop is a synchronisation loop commonly used for suppressed carrier modulations [21]. This paper presents the use of a Costas-loop to recover the central frequency of a m-CAP band, thus the need for mitigating both frequency and phase offsets in a VLC-based IoT system which uses multiple analogue Rxs [20,22]. While synchronisation circuits should be built with low hardware resources to cope with the IoT requirements, a tradeoff between complexity and performance must be considered.…”

Editorial to the Special Issue on “Visible Light Communications, Networking, and Sensing”

“…The next papers are devoted to modulation formats. L. Rodrigues et al [5], in the paper on "Optimized Analog Multi-Band Carrierless Amplitude and Phase Modulation for Visible Light Communication-Based Internet of Things Systems", develop a VLCbased IoT system architecture based on mCAP modulation, with the emitter implemented in the digital domain, while the demodulation in the receiver is accomplished in the analog domain. The authors focus especially on the filtering aspects, and the usage of guard bands parameters is evaluated.…”