  The frequency selectivity of wireless communication channels can be
characterized by the delay spread Ds of the channel impulse response. If the
delay spread is small compared to the bandwidth W of the input signal, that is,
Ds*W approximately equal to 1, the channel appears to be flat fading. For Ds*W
>> 1, the channel appears to be frequency selective, which is usually the case
for wideband signals. In the first case, small scale synchronization with a
precision much higher than the sampling time T = 1/W is crucial. In this paper,
it is shown by analytical means that this is different in the wideband regime.
Here synchronization with a precision of T is sufficient and small scale
synchronization cannot further increase the captured energy at the receiver.
Simulation results show that this effect already occurs for W > 50MHz for the
IEEE 802.15.4a channel model.
