What is the importance of signal bandwidth in radar systems for velocity and localization estimation

So I know about the basics of doppler shift which relates the velocity of a moving object with the frequency carrier shift seen at the reciever. But, I don't understand the importance of the transmitted signal bandwidth to the process? I can use the same the same carrier frequency but with different BW... Any clarification please? Thanks

Bandwidth affects the "gate/cell width" of your measurements. If you think about an LFM waveform reflecting back off an object and going through a matched filter to determine the range, a signal with a very low bandwidth is going to have a more ambiguous return time (range) than a more aggressive chirp. The rough calculation for the smallest range resolution for a certain bandwidth is $$\frac{c}{2B}$$.