In this paper, a novel ultrawideband system for multiuser data communications is proposed. In this system multiple users are allowed to transmit on-off keying modulated signals in the same time intervals and exploiting the same frequency subband. Time/frequency overlapped data frames sent by distinct users include low data rate training sequences characterized by different repetition periods. This transmission strategy, known as rate division multiple access in the technical literature, allows to ease two fundamental tasks at the receive side, namely joint channel estimation and timing synchronization. Channel estimates are exploited by a multiuser detector based on a zero forcing equalizer. Numerical results evidence that the proposed solution yields good error performance at the price of a limited complexity.