Wireless technologies have changed every aspect of human life from family life and social interaction to ways of conducting business, and even doing science. As the number of wireless devices grows, these devices will ultimately compete for the same limited resource: radio frequency (RF) spectrum. Recent advances in free space optical (FSO) technology promise a complementary approach to increase wireless capacity. However, such high data rates are currently achievable only with point-to-point transmissions and are not well integrated with existing WiFi systems. This drawback severely limits the mobility of the free space optical wireless devices. This research develops a hybrid indoor WiFi-FSO (WiFO) network that can provide orders of magnitude improvement in bandwidth over the existing WiFi networks while supporting seamless mobility. The proliferation of WiFO deployments will make bandwidth-intensive applications possible in crowded areas such as airport terminals, classrooms, conference centers where the existing WiFi network fails.
WiFO uses Vertical-Cavity Surface-Emiting Laser (VCSELs) to create an invisible cone of light about 1.5 meter squares in which the data can be received at Gbps per VCSELs. To work around the issue of a small area of effect, the project creates a hybrid system that can switch between an array of VCSEL transmitters installed on a ceiling, and the existing WiFi system. To that end, the researchers study novel WiFO architecture and mobility protocols that allow wireless devices to seamlessly operate in WiFi, FSO, or both modes simultaneously, in order to significantly increase the system bandwidth while maintaining high mobility. They project develops state-of-the-art circuits and algorithms for jointly optimizing simultaneous transmission of data over the WiFi and FSO channels. The algorithms will take advantage of the latest advances in coding, modulation, and flow control. For real world validation, the researchers implement and deploy a WiFO system based on which, practical issues and lessons will be learnt and passed on to other researchers.
