Spreading Factor (SF) or Processing Gain

Spreading factor (SF) is the ratio of chip rate to bit rate OR the ratio of the chips to baseband information rate. As after spreading, A single bit of the user data is called chip.

Spreading factor is the concept of CDMA used in UMTS. Spreading factors vary from 4 to 512 in FDD UMTS.

Spreading factor in dB indicates the processing gain as in a spread spectrum system, the processing gain is the ratio of the spread (or RF) bandwidth to the unspread (or baseband) bandwidth. It is the ratio of the signal-to-noise ratio (SNR) of a processed signal to the SNR of the unprocessed signal. The lower the spreading factor, the higher the data rate.