In this paper, we present the first indoor light-based detection and localization system that builds on concepts from radio detection and ranging (radar) making use of the expected growth in the use and adoption of visible light communication (VLC), which can provide the infrastructure for our LiDAL system. Our system enables active detection, counting and localization of people, in addition to being fully compatible with existing VLC systems. In order to detect human (targets), LiDAL uses the visible light spectrum, it sends pulses using a VLC transmitter and analyses the reflected signal collected by a photodetector receiver. Although we examine the use of the visible spectrum here, LiDAL can be used in the infrared spectrum and other parts of the light spectrum. We introduce LiDAL with different transmitter-receiver configurations and optimum detectors considering the fluctuation of the received reflected signal from the target in the presence of Gaussian noise. We design an efficient multiple input multiple output (MIMO) LiDAL system with wide field of view (FOV) single photodetector receiver, and also design a multiple input single output (MISO) LiDAL system with an imaging receiver to eliminate the ambiguity in target detection and localization. We develop models for the human body and its reflections and consider the impact of the colour and texture of the cloth used as well as the impact of target mobility. A number of detection and localization methods are developed for our LiDAL system including cross correaltion and a background subtraction method. These methods are considered to distinguish a mobile target from the ambient reflections due to background obstacles (furniture) in a realistic indoor environment.

This paper presents an indoor visible light communication (VLC) system in conjunction with an imaging receiver with parallel data transmission (spatial multiplexing) to decrease the effects of inter-symbol interference (ISI). To distinguish between light units (transmitters) and to match the light units used to convey the data with the pixels of the imaging receiver, we propose the use of subcarrier multiplexing (SCM) tones. Each light unit transmission is multiplexed with a unique tone. At the receiver, a SCM tone decision system is utilized to measure the power level of each SCM tone and consequently associate each pixel with a light unit. In addition, the level of co-channel interference (CCI) between light units is estimated using the SCM tones. Our proposed system is examined in two indoor environments taking into account reflective components (first and second order reflections). The results show that this system has the potential to achieve an aggregate data rate of 8 Gb/s with a bit error rate (BER) of 10 -6 for each light unit, using simple on-off-keying (OOK).

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In this paper, we propose, design, and evaluate two indoor visible light communication (VLC) systems based on computer generated holograms (CGHs); a simple static CGH-VLC system and an adaptive CGH-VLC system. Each transmitter is followed by the CGH, and this CGH is utilized to direct part of the total power from the best transmitter and focus it to a specific area on the communication floor. This leads to reduction in inter-symbol interference and increasing in the received optical power, which leads to higher data rates with a reliable connection. In the static CG11H-VLC system, the CGH generates 100 beams (all these beams carry same data) from the best transmitter and directs these beams to an area of 2 m × 2 m on the communication floor. In the adaptive CGH-VLC system, the CGH is used to generate eight beams from the best transmitter and steer these beams to the receiver's location. In addition, each one of these eight beams carries a different data stream. Whereas in the first system, a single photodetector is used (added simplicity), an imaging receiver is used in the second one to obtain spatial multiplexing. We consider the lighting constraints where illumination should be at acceptable level and consider diffusing reflections (up to second order) to find the maximum data rate that can be offered by each system. Moreover, due to the fact that each beam in the adaptive CGH-VLC system conveys a different data stream, co-channel interference between beams is taken into account. We evaluate our proposed systems in two different indoor environments: an empty room and a realistic room using simple on-off-keying modulation. The results show that the static CGH-VLC system offers a data rate of 8 Gb/s while the adaptive CGH-VLC system can achieve a data rate of 40 Gb/s. INDEX TERMSComputer generated hologram, static CGH-VLC system, adaptive CGH-VLC system, inter-symbol interference, co-channel interference, on-off-keying.

A system that employs wavelength division multiplexing (WDM) in conjunction with sub-carrier multiplexing (SCM) tones is proposed to realise high data rate multiuser indoor visible light communication (VLC). The SCM tones, which are unmodulated signals, are used to identify each light unit, to find the optimum light unit for each user and to calculate the level of the co-channel interference (CCI). WDM is utilised to attain a high data rate for each user. In this study, multi-colour (four colours) laser diodes are utilised as sources of lighting and data communication. One of the WDM colours is used to convey the SCM tones at the beginning of the connection to set up the connection among receivers and light units (to find the optimum light unit for each user). To evaluate the performance of the VLC system, two types of receivers are proposed: an array of nonimaging receivers and an array of non-imaging angle diversity receivers. In this study, the effects of diffuse reflections, CCI and mobility on the system performance are considered.

The main encounters face visible light communication (VLC) systems to provide high data rates for multiuser scenario are intersymbol interference (ISI) and cochannel interference (CCI). This work proposes delay adaptation technique (DAT) in conjunction with power adaptation technique (PAT) to improve the performance of the multiuser indoor VLC systems. The DAT is used to reduce the ISI while the PAT is utilized to reduce the CCI. To apply the DAT and PAT, each access point (AP) requires to share its information with the controller, which is responsible to manage the connection between user equipment (UEs) and APs. Therefore, each AP is given a control signal (an unmodulated unique tone signal). These control signals are utilized to set‐up the connection between APs and UEs (allocate each UE its best APs, which are APs that offer good connection links). Our proposed system performance is evaluated in a realistic room while considering the effect of diffuse reflections and CCI and using on‐off‐keying modulation. The results reveal that a remarkable improvement in the VLC system's performance with using DAT and PAD compared with the VLC system without using DAT and PAT.

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