In all situations the whole frequency-spectrum is used. Privacy due to unknown random codes. This means that it is hardly possible to detect the message of an other user. Applying spread spectrum implies the reduction of multi-path effects. Random access possibilities.
Users can start their transmission at any arbitrary time.
Good anti-jam performance. Because of the difficulty to jam or detect spread spectrum signals, the first applications were in the military field. However nowadays spread spectrum systems are gaining popularity also in commercial applications. The processing gain determines the number of users that can be allowed in a system, the amount of multi-path effect reduction, the difficulty to jam or detect a signal etc. For spread spectrum systems it is advantageous to have a processing gain as high as possible.