Zhitong Huang

Evolutionary algorithm based uniform received power and illumination rendering for indoor visible light communication

In this paper, an evolutionary algorithm based optimization scheme is proposed to realize uniform received power and illumination distribution on the communication floor for fully diffuse indoor visible light communication. Simulation results show that in three distributed lighting configurations, by dynamically modifying the relative optical intensity of transmitters the dynamic range of the received power, referenced against the peak received power, can be reduced to about 40.0% while the uniformity illuminance ratio can be improved up to about 0.70 with the impact to the root mean square delay spread and bandwidth being negligible. Furthermore, the relationship between the field of view of the receivers and the optimization performance is presented as well.

Independent reflecting element interaction characterization for indoor visible light communication based on new generation lighting

Indoor visible light communication (VLC) based on next generation environmentally friendly lighting is important in energy conservation. However, at present, the efficient characterization of VLC channels, including sophisticated reflection, has not yet been proposed. In this letter, we present a fast and comparably accurate channel characterization algorithm called independent reflecting element interaction characterization (IREIC), which can be used to describe optical power, illuminance, and impulse response.

Game theory-based mode cooperative selection mechanism for device-to-device visible light communication

Various patterns of device-to-device (D2D) communication, from Bluetooth to Wi-Fi Direct, are emerging due to the increasing requirements of information sharing between mobile terminals. This paper presents an innovative pattern named device-to-device visible light communication (D2D-VLC) to alleviate the growing traffic problem. However, the occlusion problem is a difficulty in D2D-VLC. This paper proposes a game theory–based solution in which the best-response dynamics and best-response strategies are used to realize a mode-cooperative selection mechanism. This mechanism uses system capacity as the utility function to optimize system performance and selects the optimal communication mode for each active user from three candidate modes. Moreover, the simulation and experimental results show that the mechanism can attain a significant improvement in terms of effectiveness and energy saving compared with the cases where the users communicate via only the fixed transceivers (light-emitting diode and photo diode) or via only D2D.

Polarity separating optical orthogonal frequency division multiplexing for free-space visible light communications

Abstract. A modulation format, polarity separating optical orthogonal frequency division multiplexing (PSO-OFDM), is proposed to mitigate the light-emitting diode (LED) nonlinearity for visible light communication systems. A polarity separator is used to divide the OFDM signal in time domain x(t) into two parts: x+(t) and x−(t), which will be transmitted parallelly from the different LEDs and overlap linearly in free space to realize PSO-OFDM. The experimental results demonstrate that PSO-OFDM has high spectral efficiency and suffers less nonlinear distortions than other methods. Employing PSO-OFDM, the modulation index and bit error rate performance can be significantly enhanced.

Channel cooperation for anti-occlusion visible light communication systems

The need to exchange data wirelessly has increased as the growth of the number of mobile devices. Visible light communication (VLC) is a promising technology to alleviate the growing traffic problem. However, the occlusion problem is a difficulty in VLC system. In order to solve the problem, an anti-occlusion VLC system has been proposed in this article. In this VLC system, we propose the channel cooperative selection mechanism, which is based on the best-response dynamics and best response strategies of the game theory. This mechanism uses bit error ratio (BER) as the utility function to optimize system performance. In addition, the system provides three candidate communication channels, including direct channel, indirect channel, and mixed channel, to active users who will select the optimal communication channel. Moreover, the anti-occlusion VLC system has many application scenarios, such as the office, which has practical significance. For verifying the validity of the proposed mechanism, we accomplish the simulation results in terms of BER and throughput in different communication cases. It is demonstrated that the proposed channel cooperative selection mechanism in VLC systems offers superior performance in environment of obstructions.

Evolutionary Algorithm Based Power Distribution Optimization for Visible Light Communication

Visible Light Communications (VLC), which is expected to provide wireless communications and illumination facilities together, is earning increasing attention. However, it is hard to obtain satisfyingly uniform signal quality at the receiving terminal even for locations within the same room by Komine et al. in Asia-Pacific conference on communication (APCC 05), IEEE Press, Perth, pp 294–298 (2005). In this letter, an evolutionary algorithm-based optimization scheme is proposed as a candidate approach for VLC to reduce the variability of the received power. The presented results based around the use of a commercially available detector with a FOV = 45o. show that the dynamic range of received power can be reduced to 34% against the peak optical power from 52% while the impact on illuminance function is negligible.

Ubiquitous Hierarchical Generalized-Sensor Network: Architecture and Application

A ubiquitous hierarchical generalized-sensor network (UHGSN) is presented as a typical network model for the future unified communication environment among human society, computer network and the real physical world. Two kinds of novel network elements, the sensor information processing unit and the hierarchical distributed agent server are introduced in this architecture for the effective information communication. The topology and addressing problems of the UHGSN architecture are analyzed in details, and the combined “key word” based characterized searching mechanism is discussed as the basic application in UHGSN, along with the corresponding protocol message definition. Simulation results show the advancements of the presented hierarchical architecture and the job-list based characterized searching mechanism.

Indoor white light wireless data transmission based on new generation environment-friendly solid state lighting

White light emitting diode (LED) is viewed as the new generation green solid state lighting (SSL) source by academia and industry based on its charming advantages, such as high brightness, low cost, steadily improved power efficiency and etc. Visible light communication based on white LED which aims to realize lighting and data transmission simultaneously is attracting more and more attention. In this paper, two indoor VLC design schemes which need less power cost are proposed and corresponding illuminance ability is estimated in a moderate size office. One proves that distributed design scheme can improve the power efficiency (add 300 lx in central area) and related SNR performance is improved as well. And the other illustrates the amount of needed chips can be reduced (from 900 to less than 800) maintaining the similar illuminance level. The performance of systems based on improved modulation schemes in terms of pulse position modulation (PPM), multiple pulse position modulation (MPPM) and overlapping pulse position modulation (OPPM) are tested.

Rigorous modeling for visible light wireless access based on environment friendly illuminance

Visible light wireless access (VLWA) technique based on environment friendly illuminance is in progress. To the best of our knowledge, the efficient modeling of corresponding indoor channel including sophisticated reflection has not been proposed. In this paper, a rigorous and efficient channel modeling scheme, named independent reflection interaction characterization (IRIC), is presented which can be used to account for reflection of any order. And simulation results show that this scheme can characterize the VLWA channel model in less than 10 seconds in a medium-sized room with up to 6 order reflection considered for analyzing received optical power and illuminance function.

Multi-domain Impairment-Aware Routing and Wavelength Assignment algorithm with Wavelength converters in wson

Impairment-Aware Routing and Wavelength Assignment (IA-RWA) is essential for optical network due to accumulated impairments which may degrade signal quality. Wavelength converter can release the wavelength continuity constraint, so considering the presence of wavelength conversion in IA-RWA algorithm can improve the network resource utilization. In this paper we propose a multi-domain IA-RWA algorithm with wavelength conversion. Simulation results show the algorithm can achieve good performance in blocking probability.