Wireless technology for communication and localization in train applications are widely used. Ultra wide band appears as a very suitable technology for this kind of application, due to its large bandwidth, also to its good resistance to the interference and to multipath. In this paper, a new system dedicated to railway transport, based on UWB technology is presented. The originality of this study is combination of the two main functionalities, localization and communication providing a high data rate. The sensor, in order to detect the position of vehicles, uses a matched digital correlation receiver. To allow a multi user access and to combine the two functionalities, two original multiplexing techniques called SSS2 (Sequential Spreading Spectrum technique) and CPM (Code Position Modulation) are performed, in addition to other parameters like used waveform and orthogonal codes.