Chapter 9 - Spread Spectrum 9e
- 1. Spread Spectrum CEN 220/CIS 192 Advanced Data Communications and Networking Data and Computer Communications, W. Stallings 9/E, Chapter 9
- 2. 2 Spread Spectrum “All creative people want to do the unexpected.” —Ecstasy and Me: My Life as a Woman, Hedy Lamarr
- 5. 5 General Model of Spread Spectrum System
- 6. 6 Spread Spectrum Advantages Immunity from noise and multipath distortion Can hide / encrypt signals Several users can share same higher bandwidth with little interference CDM/CDMA Mobile telephones
- 7. 7 Frequency Hopping Spread Spectrum (FHSS)
- 9. 9 FHSS (Transmitter) Frequency Hopping Spread Spectrum (FHSS)
- 10. 10 FHSS (Receiver) Frequency Hopping Spread Spectrum (FHSS)
- 11. 11 Slow and Fast FHSS Commonly use multiple fsk (mfsk) Have frequency shifted every tc seconds Duration of signal element is ts seconds Slow fhss has tc ts Fast fhss has tc < ts FHSS quite resistant to noise or jamming with fast FHSS giving better performance
- 14. 14 Direct Sequence Spread Spectrum (DSSS) Each bit is represented by multiple bits using a spreading code This spreads signal across a wider frequency band Has performance similar to FHSS
- 15. 15 Direct Sequence Spread Spectrum Example
- 16. 16 Direct Sequence Spread Spectrum System
- 17. 17 DSSS Example Using BPSK
- 19. 19 Code Division Multiple Access (CDMA)
- 20. 20 CDMA Example
- 21. 21 CDMA Example
- 22. 22 CDMA for DSSS
- 23. 23 Summary Concept of spread spectrum FHSS FHSS using MFSK DSSS DSSS using BPSK Code Division Multiple Access CDMA for Direct Sequence Spread Spectrum