Coordinated Multipoint Transmissions in Millimeter-Wave Radio-Over-Fiber Systems

We propose a coordinated multipoint transmission method in millimeter-wave small cells enabled by a centralized radio-over-fiber architecture. By using coordinated transmissions, we improve infrastructure utilization and reception quality, increase the chance of line-of-sight links, and reduce inter-cell interference. With radio-over-fiber, we release coordination overhead and provide joint processing, resource sharing, precise synchronizations, and channel orthogonality based on which coordination multipoint transmissions are achieved. We theoretically derive gains in a 2 x 1 transmission model with space-frequency block coding. A real-time end-to-end experiment reveals extended transmission distance, robust stability, improved power performance, and enlarged field of view. The significance of centralization is experimentally analyzed in terms of impacts from asynchronizations.