Visible Light Communications for Vehicular Communications- ارتباط خودروها از طریق نور مرئی در شبکه حمل و نقل هوشمند
There has been a growing interest in the field of Intelligent Transportation Systems (ITSs) in an effort to improve road safety, traffic flow, and environmental concerns. ITS involves the application of the advanced information processing, control technologies, sensors, and communications in an integrated approach to improve the functioning of the road transportation systems. Considerable efforts have been spent in the last decade by researchers from both academia and industry to enable Cooperative ITS, which is seen as the next generation of ITS and it is enabled by Vehicle-to-Vehicle (V2V) and Vehicle-to-Infrastructure (V2I) communications. Vehicular networking is an essential component of Cooperative ITSs requiring V2V and V2I (V2X) communications to enable vehicles within short range vicinity to communicate with each other and with the roadside units installed along the roads. Current Cooperative ITS research activities and standardization efforts briefly summarized above have mainly assumed the deployment of radio frequency (RF) communication techniques as the wireless connectivity means in vehicular networking. Currently, the impact of current V2V and V2I communications on the amount of RF spectrum usages is low, but this is expected to significantly increase in the near future. Such small RF bands can quickly suffer from interferences when hundreds of vehicles located in the same vicinity try to communicate simultaneously. There are a number of solutions to address this potential bandwidth congestion problem. In this talk the focus will be on visible light communications (VLC) as a complementary and/or an alternative technology to RF based systems. VLC refers to the use of optical radiation at the visible wavelengths to transmit data in an unguided medium. Since the human eye perceives only the average intensity when light is switched on and off fast enough, then it is possible to transmit information data using light emitting diodes (that can be now found in brake lights, turn signals, and headlamps) without a noticeable effect on the light illumination level and the human eyes.