Thursday, April 16, 2015
Various possible applications of wireless optical communication has slowly emerge
Optics in the semiconductor, electronics, using a wide range of ICT industries, such as optoelectronic semiconductors can be used as LED lights, lighting; Opto Semiconductors CCD, CMOS image sensors do digital cameras, digital surveillance, micro-electromechanical systems do DMD projector; Phototransistor, couplers for automatic control.
Or optical storage, such as Blu-ray Disc BD-chip; or optical communication, such as FTTH FTTH broadband, and optical communications is actually divided into wired and wireless, wireline, such as fiber to the House, that xPON various passive optical network; or large enterprise IT room, storage area network SAN within the data centers used; consumer electronics field, as in the past Sony MD with optical S / PDIF audio transmission line; or in the professional video editing regard, Apple Mac optical version Thunderbolt (referred TBT) transmission line.
Cable transmission of light has been used a lot, but rarely use wireless transmission, especially in the field of consumer end, almost all stay in the IR infrared remote control stage, and then the last few years people began to advocate the visible wireless communications VLC, estimated future a few years there will be a new development.
Why wireless optical communications to start showing off? Because the existing Wi-Fi in 2.4GHz spectrum resources have been squeezed almost to the limit, you want a faster rate, almost all to consider the 5GHz band, IEEE 802.11ac is the case, LTE-U is true, but not the global access 5GHz The band, some countries can not be used, or only partially used, conditional use (not for outdoor use, or may not exceed the number of transmit power).
In addition to 2.4GHz, another global access is available band 60GHz, but because the band is too high, the relevant design are highly difficult, is still developing. Plus LED popularity, people began to consider the use of wireless communication to accelerate the transmission of light in the region.
About this, the most representative of the technology for Li-Fi, has demonstrated over the 2014 CES, the fastest way transmission 150Mbps, two-way down to 110Mbps, in fact only a single antenna 11n Wi-Fi is almost, but the future There greatly enhance the potential of up to 1Gbps, 10Gbps than standard lights and colors currently available to improve the rate of increase, and the other is a channel such as a red LED, green LED is also a channel and so on.
Two other advantages of wireless optical communications, one from electromagnetic interference, although the current flight regulations allow passengers to use electronic products, and medical equipment in hospitals is important to use the room on the plane, are buried in the walls of the copper network in order to avoid interference from mobile phones, but there is still cause interference, in these sensitive sites use optical wireless communication, you can avoid interference.
Another is the power, the drive to pass the signal LED light off, more power than the RF radio frequency signal transmission mode, the handheld device battery power cable, optical wireless transmission would be more favorable. But optical wireless communication has its drawbacks, such as once shading can not receive, such as people walking, can not communicate through the wall, unless the wall can light.
Li-Fi direct vision combined with daylight plate LED bulbs, we can provide in-room wireless Internet HotSpot hot spots, while the phone more than a LED flash and CMOS camera lens, equivalent to already have the ability to close out of one, the future of inter-phone can easily pass information.
In addition to Li-Fi, the Japanese also developed indoor positioning IPS (Indoor Positioning System) with lighting, similar to Bluetooth Low Energy's Beacon indoor location, so you can be more energy-efficient.