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Über dieses Buch

The book systematically introduces the visible light communication (VLC) technology in detail. Basic concepts and how to realize the system are both illustrated, including the transmitter, channel, and the receiver. In addition, a good many experimental results are presented to help readers further understand the VLC technologies. The upper-layer protocols of visible light communication system and the technology trends are also discussed. This book can be a good reference work for researchers, engineers, and graduate students in the fields of communications, LED, and optics.

Inhaltsverzeichnis

Frontmatter

Chapter 1. Outline

Abstract
The emergence of “smart home” and the rapid spread of intelligent devices have made revolutionary changes to the category of the mobile digital terminal, which brings about a big test to the traditional access of network technology. The dilemmas of the “last mile” from optical fibers to home relate to the limited spectrum of resources regarding the wireless access network, the immaturity of ROF technologies, and electromagnetic radiation, which all restrict the bottleneck breakthrough.
Nan Chi

Chapter 2. The Transmitter of the Visible Light Communication System

Abstract
In recent years, semiconductor lighting technology, also known as green lighting, has been developed rapidly. The light-emitting diode (LED) is one of the most promising solid green light sources of the twenty-first century.
Nan Chi

Chapter 3. Models of the Visible Light Channel

Abstract
For the indoor wireless communication based on white light LED as the new communication system, the establishment of the channel model has not been determined. The measurement and establishment of it are still in its exploratory stages. This chapter makes a preliminary modeling analysis of the visible light channel. The present research on visible light communication systems is mostly based on white LEDs. Thus, first we make a modeling analysis of the generic LED frequency response model, and then secondly, we introduce the physical characteristics and modulation bandwidth of several LEDs, which are commonly used in experiments.
Nan Chi

Chapter 4. Visible Light Communication Receiving Technology

Abstract
In the VLC receiving system, photodetectors play a major role. They are a kind of device that transforms optical radiation signals (light energy) into electrical signals (electrical energy).
Nan Chi

Chapter 5. The Modulation Technologies of Visible Light Communication

Abstract
In visible light communication systems, the LED’s modulation bandwidth is quite limited. The 3-dB modulation bandwidth of the current commercially available LEDs is only few MHz. In order to improve the VLC system’s transmission data rate, apart from the LED structure and the drive circuit design, selecting the appropriate modulation format is one of the most important ways to expand the modulation bandwidth. OOK modulation and PPM/PMW modulation have an advantage regarding the system complexity; however, DMT modulation, OFDM modulation, and CAP modulation have better spectral efficiency and can overcome multipath effects. This chapter will introduce various modulation format principles and their implementations, advantages and disadvantages in visible light communication systems.
Nan Chi

Chapter 6. Visible Light Communication Pre-equalization Technology

Abstract
In the visible light communication system, the serious unevenness of the channel to the realization of high-speed data transmission has brought great obstacles, although the use of OFDM and other high-order modulation technology to a certain extent optimize system performance, but make the system capacity to further enhance. Transmitter also need to use a variety of pre-equalization technologies, the frequency response to the LED to compensate, thereby improving the system’s modulation bandwidth.
Nan Chi

Chapter 7. Visible Light Communication Post-equalization Technology

Abstract
Equalization can be divided into two categories: frequency domain equalization and time domain equalization. The so-called frequency domain equalization corrects the system’s frequency characteristics, so that the total characteristics, including the baseband system equalizer, satisfy the undistorted transmission conditions. The so-called time domain equalization directly corrects distorted waveforms to satisfy the requirements of no inter-symbol interference criterion in the time domain, with parameters generated by the equalizer.
Nan Chi

Chapter 8. High-Speed VLC Communication System Experiments

Abstract
Speed is an important indicator of a communication system, and providing high-speed wireless access is also a significant advantage of visible light communication. At present, the transmission rate of Wi-fi is about 100 Mbit/s, and the power line communication is basically at this rate and even lower. Compared with traditional wireless access technology, visible light communication can realize more high-speed wireless access due to its potentially huge bandwidth.
Nan Chi

Chapter 9. Visible Light Communication Technology Development Trend

Abstract
LEDs offer many advantages including threshold-less operation, high fabrication yield, high energy efficiency, fast response and reduced complexity of driver, reducing the requirement for threshold feedback control significantly, thus reducing the overall cost, form factor, and power consumption of transmitters.
Nan Chi
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