第四章 Visible Light Communications.docx

第四章 Visible Light CommunicationsVLCusing LEDs for both illumination and data communications照明和通信the increasing popularity of solid-state lighting固体照明longer lifetime of high-brightness LEDs 寿命high bandwidth/data rate带宽data security数据安全no health hazards健康low power consumption功耗interesting applicationshome networkinghigh-speed data communication via lighting infrastructures in officescar-to-car communicationhigh-speed communication inaeroplane cabinsin-trains data communicationtraffic lights management and communications…Solid-state lighting(SSL)generated through solid-state electroluminescence电致发光relatively short history1990s: the introduction of high-brightness LEDs for the purpose of general illuminationLED’s luminous efficacy 0.1lm/W 230 lm/W, lifetime 100,000 horganic LED (OLED): A new type source as an alternative solution for large area lighting and communicationsSSL will be an imperative technology for significant energy savings and consequently a much greener worldAdvantages of LEDsA longer life expectancyA higher tolerance to humidityAre mercury freeA smaller and compact sizeA much higher energy conversion efficiency (white LEDs 200 lm/W ~425 lm/W Incandescent: 52lm/W; fluorescent: 90lm/W)Minimum heat generation characteristics compared to all other lighting sourcesLower power consumptionMost importantly, fast switchingLED ApplicationsEnvironment protectionKyoto Protocol : CO2 emission regulationRoHS : Hg-free bulbEnergy savingElectricity in Korea20% for Lighting : 55.6 TWh50% saving by LED : 27.8TWhEnergy Saving Effect:3 Nuclear Stations (1GW/day)；2 B$/yeaHistorical development of VLC2003first VLC started at Nakagawa Laboratory in Keio University, Japan2004Demonstration of LED light systems for high-speed transmission of data to hand-held and vehicle-borne computing devices; Japan2005Land trials of VLC communications to transmit information to mobile phones, with throughput estimated at 10 kbps and several Mbps using fluorescent light and an LED; Japan2007