Dsss – Direct sequence spread spectrum
DSSS – Direct Sequence Spread Spectrum is a spread spectrum technology in which original data is expand using PN code randomly to reduce noise and this also provide high security to data as is scrambled data.
Spread spectrum technology
spread spectrum technology used in CDMA and Cdma is a scheme in which multiple users are assigned radio resources using the direct sequence – spread spectrum (dsss) techniques.
Although all users are transmitting in the same rf band, all users are separated from each other via the use of orthogonal codes (walsh code).
Each user has full time use of the entire spectral allocations.
Each user’s signal energy is spread over the entire bandwidth and coded so as to appear like broadband noise to every other user.
Frequency hopping spread spectrum
Frequency hopping spread spectrum is a method of transmitting radio signals by fast switching of a carrier between a plurality of frequency channels using a known pseudo-random sequence of the transmitter and the receiver.
Spread spectrum – Benefit
- Low Noise main benefit as all user using same carrier / frequency
- High security as PN code (pseudo random noise spreading code) only known by BTS (Base Transceiver Station) and Mobile
- Low Power requirement
- High coverage as not dependant on level (receive power)
Spread spectrum radio
spread spectrum techniques are methods used In telecom and radio communication by which a signal generated at a particular bandwidth is intentionally spread in the frequency domain, resulting in a signal having a larger bandwidth.