Cdma by svr
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This document summarizes a seminar on CDMA technology presented by Soda Venkata Raveendra. It includes an introduction to CDMA, its history and evolution. It discusses multiple access techniques like FDMA, TDMA and CDMA. It also covers spread spectrum communications, CDMA applications and advantages. The document contains diagrams illustrating CDMA encoding and decoding techniques using pseudorandom noise sequences. It provides examples of how CDMA works and compares it to using the wrong spreading code. Finally, it outlines the evolution of CDMA standards over time.
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Cdma by svr
- 1. WELCOME
- 2. SEMINOR on CDMA TECHNOLOGY by SODA VENKATA RAVEENDRA UNDER UGIDENCE Mr.DEVANANDA.S.N Assoc. professor Dept. of ECE,SRSIT
- 3. CONTENTS INTRODUCTION HISTORY OF CDMA MULTIPLE ACCESS TECHNIQUES SPREAD SPECTRUM COMMUNICATIONS CDMA EVOLUTION APPLICATIONS & ADVANTAGES
- 5. HISTORY OF CDMA THE CELLULAR CHALLENGES COMMERCIAL DEVELOPMENT
- 7. FDMA
- 8. TDMA
- 9. CDMA
- 10. FDMA TDMA CDMA
- 11. Antenna Antenna Radio Channel Source Channel Coding Carrier Carrier Source Channel Decoding Coding （SS） Modulation Demodulation Decoding Transmit Receive DS-PN DS-PN Radio Channel Source Channel Carrier Carrier Source Channel Coding Decoding Decoding Demodulation Modulation Coding （SS） Receive Transmit DS-PN DS-PN A B
- 12. Spread Spectrum S（f） S（f） Signal Signal f0 f f0 f Signal Frequency Before SS Signal Frequency after SS S（f） S（f） Noise Signal Signal Noise f0 f f0 f Signal Frequency Before Decoding Signal Frequency After Decoding Signal Pulse Noise Other Noise
- 13. Generation PN sequence 0 0 1 1 0 1 1 1 1 0 0 0 0 1 0 0 1 1 1 1 1 1 0 0 1 0 1 1 Sequence = 1001011 1001011
- 14. PN SEQUENCE properties oBalancing property(no 1’s one more than o ’s) oRun property(no. of runs=(N+1)/2) oAutocorrelation property(periodic) Sequence = 1001011 1001011 No Runs=4(00,1,0,111) N is length of PN Sequence=2 power m-1 m is no of ff’s used.
- 15. CDMA example Low-Bandwidth Signal: High-Bandwidth Spreading Code: ...repeated...
- 16. CDMA example Low-Bandwidth Signal: High-Bandwidth Spreading Code: Mix is a simple multiply … and transmit.
- 17. CDMA example To Decode / Receive, take the signal:
- 18. CDMA example To Decode / Receive, take the signal: Multiply by the same Spreading Code: … to get ... … which you should recognise as...
- 19. CDMA example To Decode / Receive, take the signal: Multiply by the same Spreading Code: … to get ...
- 20. What if we use the wrong code? Take the same signal: Multiply by the wrong Spreading Code: … you get ... … which clearly hasn't recovered the original signal. Using wrong code is like being off-frequency.
- 21. cdma2000-3x IS-95A cdma2000-1x 1X-EV IS-95B HDR
- 23. •INCRESED VOICE CAPACITY •HIGHER DATA THROUGHPUT •INCREASED BATTERY LIFE •SOFT HAND-OFF •TRANSMIT DIVERSITY •VOICE AND DATA CHANNELS •TRAFFIC CHANNEL •TURBO CODING
- 26. THANKS