Doubly Orthogonal Wavelet Packets for Multi-Users Indoor Visible Light Communication Systems

Abstract

Visible Light Communication (VLC) is a data communication technology that modulates the intensity of the light to transmit the information mostly by means of Light Emitting Diodes (LEDs). The data rate is mainly throttled by the limited bandwidth of the LEDs. To combat, Multi-carrier Code Division Multiple Access (MC-CDMA) is a favorable technique for achieving higher data rates along with reduced Inter-Symbol Interference (ISI) and easy access to multi-users at the cost of slightly reduced compromised spectral efficiency and Multiple Access Interference (MAI). In this article, a multi-user VLC system is designed using a Discrete Wavelet Transform (DWT) that eradicates the use of cyclic prefix due to the good orthogonality and time-frequency localization properties of wavelets. Moreover, the design also comprises suitable signature codes, which are generated by employing double orthogonality depending upon Walsh codes and Wavelet Packets. The proposed multi-user system is simulated in MATLAB software and its overall performance is assessed using line-of-sight (LoS) and non-line-of-sight (NLoS) configurations. Furthermore, two sub-optimum multi-users detection schemes such as zero forcing (ZF) and minimum-mean-square-error (MMSE) are also used at the receiver. The simulated results illustrate that the doubly orthogonal signature waveform-based DWT-MC-CDMA with MMSE detection scheme outperforms the Walsh code-based multi-user system. Keywords: visible light communication (VLC); LED; photo-diode (PD); line-of-sight (LoS); non-line-of-sight (NLoS); multi-carrier code division multiple access (MC-CDMA); discrete wavelet transform (DWT); doubly orthogonal wavelet packets (DOWP); multiple access interference (MAI); minimum-mean-square-error (MMSE) IntroductionWith unprecedented demand for high-speed multi-media mobile services, optimization of wireless communication systems has become critical. Due to the limited range of frequencies, radio-frequency (RF) technology is unable to fulfill the needs for the current demands of mobile users [1]. As we are advancing towards 5G, the necessity for the evolution in broadband communication technologies has grown to its peak. The 5G communication networks have already defined performance requirements in which high-speed data delivery (expected to be 10 Gbps) and low latency (less than 1 ms) are the key performance parameters [2]. Visible Light Communication (VLC) is a completely new paradigm that is going to revolutionize the next generation of wireless communication by making use of a visible

Physical deployment of enhanced visible light communication system using forward error correction codes

“…The output of the modulator after electrical to optical transformation moves through the LOS and NLOS VLC channels. The LOS and NLOS channel employed in the existing work is borrowed from our earlier work …”

“…The LOS and NLOS channel employed in the existing work is borrowed from our earlier work. 17,18 The receiver is equipped with PDs and a matched filter. PDs transform the collected optical signals into analog electrical signals while the matched filter tries to wipe out the deleterious effects of the VLC channel.…”

Optimization of Bit Allocation for Spatial Multiplexing in MIMO VLC System with Smartphones

“…Accordingly, the overall system design is inexpensive compared to radio frequency (RF) systems. In [ 6 ], some advantages of VLC include unregulated and license-free bandwidth, frequency reuse in adjacent rooms, security as light signals are undetectable behind walls, fewer health issues, and functionality in such environments where traditional RF systems are limited or forbidden.…”

Hybrid Adaptive Bias OFDM-Based IM/DD Visible Light Communication System

“…With the rapid increase in wireless mobile devices, the continuous increase of wireless data traffic has brought challenges to the continuous reduction of radio frequency (RF) spectrum, which has also driven the demand for alternative technologies [1,2]. In order to solve the contradiction between the explosive growth of data and the consumption of spectrum resources, visible light communication (VLC) has become the development direction of the next generation communication network with its huge spectrum resources, high security, low cost, and so on [3][4][5]. The orthogonal frequency division multiplexing (OFDM) technology has the advantages of high spectrum utilization and strong ability of resisting inter-symbol interference (ISI) [6,7].…”