  Starting from the Shannon channel capacity, we propose an IR-UWB channel
capacity based on the delay spread for multipath time variant channels. This
IR-UWB channel capacity is obtained from the no ISI (Inter Symbol Interference)
assumption and for binary modulations. The impact of the kind of implementation
is considered on the IR-UWB channel capacity. This study is lead for mixed and
mostly digital implementation. The key parameters and theirs impacts on the
channel capacity are exposed in each case: the data converters for mostly
digital implementations and the pulse generator capabilities for mixed
implementations. Finally, these two implementations are compared from a data
rate point of view. Their behaviors regarding an increase of the operating
frequency are also studied.
