SPARCS (Simple-structure and high-Performance ATC by Radio Communication System) is a train control system based on radio technology independently developed by Nippon Signal Co., Ltd. The system allows movement blocking operation and single line bidirectional operation suitable for high density carrier transportation which is required in urban traffic lines. SPARCS provides the core ATP (Automatic Train Protection) functions of CBTC (Communication Based Train Control) systems and ground-train bidirectional data communication control functions. The stability of the wireless communication function is the most important to operate CBTC system stably. SPARCS possesses some characteristics necessary for radio communication of the train control system. They are the stability, robustness and the secrecy. SPARCS was installed in Beijing subway line No.15 and the signal system is operating for stability since December, 2011. This paper describes the technical features of the SPARCS radio communication network. Also it shows an overview of the signaling system of the Beijing subway line No.15.