A cost effective multi services converged access scheme for urban rail transit based on radio-over-fiber technique

Safety critical data communication in data communication sub-system (DCS) for urban rail transit operation is always separated from non safety critical services, and always requires redundancy and fall-safe design which is not conform to the “cost effective” concept in network construction. Actually, redundant dedicated fiber optic network applied in rail transit operation system can provide huge amount of bandwidth resources for data communication not only just for safety critical use, for non safety critical services related data communication can also be transmitted through fiber in different frequency band channel apart from it, and radio-over-fiber (RoF) technique can just help to realize the multi services broadband data exchanging between trains and central operation control/management room, and to be transmitted separately in a single fiber optic network and on some level save the construction cost against the redundancy design background. Till now, most research on RoF applied rail transit communication system only focuses on its wireless part including signal modulation, protocol standard and networking parameter setting, however, the system design and performance analysis of its fiber access part still has rarely been discussed yet. In this paper, a cost effective multi services converged access scheme including non safety critical as well as safety critical data communication for urban rail transit based on RoF technique has been designed in detail, and via simulation analysis, the proposed scheme has been demonstrated to not only satisfy the fall-safe principle, but have a steady data communication performance for safety critical services as well.