Re: spreading factor
Each user has its own spreading code. The identical code is used in both
transformations on each end of the radio channel, spreading the original signal
to produce a wideband signal, and despreading the wideband signal back
to the original narrowband signal . The ratio between the
transmission bandwidth and the original bandwidth is called the processing
gain (also known as the spreading factor). Note that this ratio simply means
how many chips are used to spread one data symbol. In the UTRAN, the
spreading-factor values can be between 4 and 512 (however, in the TDD
mode also SF=1 is allowed). The lower the spreading factor, the more payload
data a signal can convey on the radio interface.
Spreading Factor = chip rate/bit rate