The signal bandwidth for the W-CDMA system is set at 5 MHz. This high bandwidth allows the received signal to be split into distinct multipaths with high resolution.
so, for example, if you have 5Mhz BW and your sample rate is 10Msps then, you can resolve multipaths delayed 100ns (1/sample rate). So you can take the benefits of a great number of multipaths (using the RAKE receiver) than a system with minor bandwidth.
Resolution depends on the chip rate. In WCDMA the chip rate is Rc=3.84 Mcps. hence, the chip duration is 1/Rc=0.26 usec. Hence, the receiver can resolve (i.e, distinguish) any two paths with relative delay > 0.26 usec. This is done using the code matched filter.
The bandwidth depends on the pulse shaping filter used. The root raised cosine filter used in WCDMA gives a 5 MHz bandwidth.