Welcome to the CROWD: Design Decisions for Coexisting Radio and Optical Wireless Deployments

Novel systems and solutions are needed to meet the ultra-dense data demand expected in future wireless networks. Heterogeneous integration of radio and OW communications is one solution that promises to add wireless capacity where it is needed most (e.g., indoor environments). These coexisting radio and optical wireless deployments, or CROWD networks, will utilize densely distributed optical small cells to supplement conventional RF small cells. The directionality of the optical small cells allows access points to be located at reasonable distances from the mobile terminals while offering coverage area on the order of 1m2. Accordingly, the OW network allows for ultra-dense cells, high area spectral efficiency, and high aggregate capacity. Additionally, the heterogeneous integration allows the RF small cells to provide coverage and reliability for highly mobile devices. In this work, we motivate the adoption of CROWD networks, review techniques for RF/OW coexistence, and evaluate the impact of dynamic system characteristics. In particular, we show the need for improved statistical modeling of the wireless environment at the spatial resolution of ultra-dense networks. We also highlight the role that intelligent and adaptive CROWD networks will play in accommodating the variations in traffic distribution from dynamic environments and mobile devices.