Beam control for indoor FSO and dynamic dual-use VLC lighting systems

Abstract

Practical VLC (Visible Light Communication) systems are expected to leverage the lighting infrastructure in order to deliver data to devices in a lighting field. These devices can be static or quasistatic (e.g., laptops or IoT devices); however, it is becoming clear that the preponderance of wireless data consumption is dominated by handheld mobile devices which will exhibit varying physical orientations and 3D dynamics. Because free-space optical and visible light communications are primarily line of sight, transmitter radiation patterns and receiver field of view are very important for predicting the data performance. Given dynamic emission characteristics, there is an opportunity to adapt to the receiver. The caveat of dynamic VLC systems is that the quality and distribution of the resulting illumination must be considered as part of the dual goal of providing high quality lighting. In this paper we investigate the impact of device orientation and mobility on static and then dynamic lighting emission under a multi-cell lighting model. From a source standpoint we consider the performance of beam control through angular control and beam focus for one or more sources in a lighting array. Analysis and simulation demonstrate that dynamic beam and luminaire control can increase the AP coverage range by 12.8X under a 1.67 m ceiling height. Furthermore, the use of multiple sources tracking device orientation and position can mitigate off-angle performance degradation by increasing redundancy in the number of available connections. Our proposed techniques, when applied in concert, successfully mitigate common concerns about the viability of VLC and indoor FSO (Free Space Optical Communication) methods related to signal occlusion and device dynamics.

Slow Beam Steering and NOMA for Indoor Multi-User Visible Light Communications

“…Likewise, the location and the orientation of the k-th user are r k = [x k , y k , z k ] T , and n k = [n x(k) , n y(k) , n z(k) ] T , respectively. Then, the vector 6 from the AP to k-th user is…”

“…VLC networks can provide highly accurate localization information [4], [5], and this location information can be used to steer the light beam towards user location by manipulating the orientation of the light source to further enhance the communications performance. It has been shown in the literature that using a steerable directional beam maximizes both the overall signal strength and the coverage area [6]. In [7], tracking users by steering LEDs is shown to provide a higher signal to interference plus noise ratio (SINR) in the VLC cell borders, which provides smoother handovers between adjacent VLC access points (APs).…”

Interference in multi-user optical wireless communications systems

“…This class consists of the techniques that allow an AP or set of APs to distribute defined resources across a set of users. It is divided into two further categories: [18,73,74] Differential detection (DD) [75] Spatial light modulators (SLM) [67] Orthogonal multiplexing (WDM) [53][54][55] AP placement and configuration [43][44][45][46] Beam control and steering [32,[47][48][49][50][51][52]68] Multiple access techniques (TDMA, OFDMA, CDMA) [19][20][21] Precoding (ZF, MMSE) for MU-MISO NOMA [29][30][31][33][34][35][36][37][38][39][40][41][42] [ [22][23][24][25][26][27][28] MA-SP MA-PHY spatial diversity multiple access -Spatial diversity. This class encompasses both of the PHY and SP cases and is concerned with receiving data by many spatially unique channels or multiple PDs then performing signal processing to have them de-correlated.…”

“…Beam and FOV control can also be used to address dynamic user behaviour. Examples include aforementioned work [52] and references [32,48,49] which can be considered dynamic as they adapt to system changes to fulfill the user requirements. In [52], the receiver adapts to changes in the user location, orientation and velocity by evaluating the best (transmitter-FOV) pair per receiver dynamic change to allow it to receive the best SNR.…”

Investigation of Outage Probability and AP Placement for Mobile Users in Indoor VLC System Design

“…Visible Light Communications (VLC) is one of the possible cooperative networking technologies to help offload some of the traffic from the crowded Radio Frequency (RF) spectrum. One of the many advantages of VLC systems is that it does not interfere with RF signals and can help in achieving higher aggregate rates if deployed properly [2], [3]. It is also desirable as it can be piggybacked on lighting infrastructure (power distribution, packaging, and light engine).…”