# Utilization of an OLED-Based VLC System in Office, Corridor, and Semi-Open Corridor Environments
## 1 Introduction  
Visible light communications (VLC) with its huge available bandwidth [1] and its dual functionality, i.e., illumination and safe and low-cost communications [2], has a great potential for different high data rate fixed and mobile applications [3]. The VLC technology has many advantages include inherent security, energy efficiency, healthy for human, and unregulated bandwidth [4, 5]. These features make it attractive for numerous applications in different fields including indoor networking [6], vehicular communication [7], medical applications [8], Internet access for vehicles and in airplane cabins [9], and positioning systems [10]. At the receiver (Rx) side, a single photodetector (PD) is usually used, which converts the incident optical power to the electrical power. To enhance the performance, the single PD can be replaced by an angle diversity Rx, which contains multiple PDs oriented in different directions as reported in [11]. For further improvement, the field of view angles of these PDs can be optimized to increase the received signal-to-noise-ratio (SNR) as reported in [12; 13]. Optical cameras have been recently introduced to capture data [14; 15], resulting in interesting VLC systems applications. It is also possible to utilize the organic PDs with more synthetic flexibility [16], however the limited spectral responsivity range is the drawback. VLC relies on the use of light-emitting diodes (LEDs), organic LEDs (OLEDs) as well as white laser diodes (LDs) as the light source [17]. Owing to OLEDs attractive advantages, including transparent displays, rich color, low power consumption and large active areas [18; 19], there has been a growing interest in using OLEDs for soft lighting and display applications in public places [20]. The main differences between OLEDs and the LEDs are (i) the modulation bandwidth of OLEDs, which increases linearly with the drive current, is lower than silicone LEDs (i.e., kHz compared to MHz); and (ii) OLEDs have wider radiation patterns compared with non-organic LEDs, which influences the optical path loss (OPL). This work emphasizes on utilizing OLEDs for VLC systems, where is the potential of flexible light sources could be used in office and public indoor environments. Numerous efforts have been made in modeling VLC channel in order to determine the channel impulse response (CIR) and its characteristics in terms of the average OPL and the root-mean-square (RMS) delay spread. The achievable SNR for a given transmit power can be calculated by OPL obtained from CIR [21]. In addition, the RMS delay spread provides a good estimate of how susceptible the channel is to inter-symbol interference (ISI), thus leading to transmission data rate \(R_{b}\) restriction [18; 21]. That is why quantifying channel characteristics is vital; hence, a number of studies have been done so far. For instance, in [22], the CIR of an empty room was evaluated using Monte Carlo (MC) ray tracing at the visible wavelength range where the surface materials reflectance were not wavelength-dependent. However, in [23] the VLC channel was investigated including wavelength-dependent reflectance of materials. In [24], the modified MC ray tracing approach was used for analyzing the CIR as a function of the wavelength using a simplified matrix model. In [25], a three-dimensional (3D) model based on MC algorithm using a CAD software was presented for the VLC system. A simulation of VLC channel by the use of OpticStudio(r) simulator produced by Zemax [26] was reported in [27; 28], which was endorsed by the IEEE 802.15.7r1 Task Group. In addition, the use of OpticStudio(r) for validation of the channel modelling was reported in [29]. Recently, utilizing OLEDs in VLC systems has captured attention. In [30], it is claimed that the use of curved OLED in VLC system for an empty room offers lower RMS delay spread and the average OPL values of 8.8% and 3 dB, respectively compared with Lambertian source. The impact of reflections using flat and half-circular OLEDs in a furnished office was investigated [31].