LED replacing fluorescent and incandescent lamps for lighting has become an obvious trend. The feature that LED can be used for both illumination and communications makes visible-light communication (VLC) become a hot point in recent years. With the rapid popularization of computers and smart devices, the bandwidth and coverage of access networks need further improvement. VLC technology is a promising communication technology for high speed data transmission to break through the bottlenecks. A main challenge of this technology is the limited modulation bandwidth of white LED. Researchers have proposed a variety of techniques, such as equalization technology, blue filtering, high-order modulation formats, discrete multi-tone (DMT) modulation, wavelength division multiplexing (WDM) technology, and multiple-input multiple-output (MIMO) technology, to extend bandwidth and increase transmission speed. The principles and performances of those techniques are analyzed and discussed to provide a reference for future researches.