Principle, technology and challenge of radio over fiber (RoF) based broadband access for metro and intercity trains

In this article the author presents the RoF technology based broadband access network architecture for the metro and intercity trains, analyzes the relating issues in realizing the network, and addresses challenges towards the direction. The author first identifies insufficiency of the present wireless communication infrastructure, reviews the RoF technology and its characteristics, presents the network architecture meeting the performance and reliability, describes multi-diversities mechanisms for the two-channel transmission, discusses the RoF system structures and their realization, and finally analyzes the issues of the MMW propagation.