The most interesting part of
WCDMA is the receiver.
One of the major troubles all
communication systems must deal with is the multipath.
Since WCDMA uses spread
spectrum it can actually use the multipath in order to improve the receiving
performance. This receiver is called the Rake Receiver.
Since each user’s signal is
coded and modulated by a specific PN-code sequence, we can look at the delayed
data as data arriving from different channels.
Thus, if we assume, for
example, that the data passes through three different paths, then we could put
three different correlators, which correlate the data with the PN sequence.
Now we got three separate
paths of the same data, but in different delays.
We can “move” all these
delayed paths and sum it up together.
The signal is received and
its SNR is greatly increased.