WiFO: Hybrid WiFi-FSO Network for WLAN Femtocells

无线技术已经改变了人类生活的方方面面，从家庭生活和社会交往到开展业务的方式，甚至是科学研究。 随着无线设备数量的增长，这些设备最终将争夺同一个有限的资源：射频（RF）频谱。自由空间光（FSO）技术的最新进展为增加无线容量提供了一种补充方法。然而，这种高数据速率目前仅通过点对点传输可实现，并且没有与现有WiFi系统很好地集成。这个缺点严重限制了自由空间光无线设备的移动性。 本研究开发了一种混合室内WiFi-FSO（WiFO）网络，该网络可以在现有WiFi网络的基础上提供数量级的带宽改善，同时支持无缝移动性。 WiFO部署的普及将使带宽密集型应用在现有WiFi网络失效的机场航站楼、教室、会议中心等拥挤区域成为可能。WiFO使用垂直腔面发射激光器（VCSEL）来创建一个约1.5平方米的不可见光锥，其中每个VCSEL可以以Gbps的速度接收数据。为了解决小面积影响的问题，该项目创建了一个混合系统，可以在安装在天花板上的VCSEL发射器阵列和现有的WiFi系统之间切换。 为此，研究人员研究了新的WiFO架构和移动协议，使无线设备能够同时在WiFi、FSO或两种模式下无缝运行，以显着增加系统带宽，同时保持高移动性。 他们的项目开发了最先进的电路和算法，用于联合优化WiFi和FSO信道上的数据同步传输。 这些算法将利用编码、调制和流量控制方面的最新进展。 为了进行真实的世界验证，研究人员实施并部署了一个WiFO系统，在此基础上，将学习实际问题和经验教训，并将其传递给其他研究人员。

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.