What effect is there on signal by spreading and dispreading?

Spreading will increase the bandwidth of a as signal. A signal of 10 Kb/s will become 40 Kb/s after spreading and will become 10 Kb/s after despreading. The processing gain term expresses the gain achieved by spreading a narrow band signal over a wideband spectrum.

This gain is the ratio between the spreading chip rate and the actual service bit rate measured at the RLC level.