We propose an Orthogonal code-divisionmultiplexing and Time-hopping multiple access (OCDMTHMA) transmission scheme for Ultra-wide bandwidth(UWB) communications in a multi-user and multipath environment. The design achieves high data throughput dueto the use of the orthogonal code division multiplexingtransmission technology for individual users. The databits from each user are mapped by using the serial-paralleltransform, and then are summed and transmitted simultaneously after being modulated by their correspondingorthogonal code sequences. At the receiving side, we employ a Rake-receiver to combat multipath fading. The Biterror-rate (BER) performance in the presence of Multipleaccess interference (MAI) is analyzed for multipath channels.