An ultra-wideband (“UWB”) communication system comprising a transmitter and a receiver. In one embodiment, the symbol mapper circuit in the transmitter is adapted, in a first mode, to develop symbols having the number of pulses as currently defined in the 4z Standard; and, in a second mode, to develop symbols having fewer pulses than as currently defined in the 4z Standard. In an optional third mode, each data bit is mapped to a single pulse.