The document outlines the development of Code Division Multiple Access (CDMA) technologies from 2G to 4G, detailing standards, data rates, and modulation schemes. It highlights the advantages of spread spectrum communications for increasing capacity and reducing interference among users. Future goals include further enhancing data rates and continuing research into non-binary sequences for improved performance.

1. Code Division Multiple Access Prepared by: Christina Chiu Mar 24, 2004

2. Outline Spread Spectrum Communications Multiple Access Technique Direct Sequence DS-CDMA CDMA standards CDMAOne (2G) – IS 95A, (2.5G) IS-95B CDMA 2000 and WCDMA (3G) – IMT2000 4G in the future Conclusions

3. Spread Spectrum Technique Low power spectral density Rejection to jamming signal and interference Pseudorandom sequence Randomness and noise properties Walsh, M-sequence, Gold, Kasami, Z4 Provide signal privacy

4. Direct Sequence Spread Spectrum Spreading Source signal is multiplied by a PN signal Processing Gain: Despreading Spread signal is multiplied by the spreading code

5. System Block Diagram

6. Spreading & Despreading Polar {±1} signal representation

7. Spreading & Despreading

8. CDMA Unique code to differentiate all users Sequence used for spreading have low cross-correlations Allow many users to occupy all the frequency/bandwidth allocations at that same time Processing gain is the system capacity How many users the system can support

9. Demodulation (Correlator)

10. 2G: IS-95A (1995) Known as CDMAOne Chip rate at 1.25Mbps Convolutional codes, Viterbi Decoding Downlink (Base station to mobile): Walsh code 64-bit for channel separation M-sequence 2 15 for cell separation Uplink (Mobile to base station): M-sequence 2 41 for channel and user separation

11. 2G: IS-95A (1995) 8~13 kbps Speech Rate Up to 14.4 kbps Data Rate 1.25 Mbps (chip rate) Channel Bit Rate 600 mW Maximum Tx Power 64 Number of Channel BPSK/QPSK Modulation Scheme 1.25 MHz Channel Separation 824-849 MHz Downlink Frequency 869-894 MHz Uplink Frequency CDMA Multiple Access IS-95, ANSI J-STD-008 Standard

12. 2.5G: IS-95B (1998) Increased data rate for internet applications Up to 115 kbps (8 times that of 2G) Support web browser format language Wireless Application Protocol (WAP)

13. 3G Technology Ability to receive live music, interactive web sessions, voice and data with multimedia features Global Standard IMT-2000 CDMA 2000, proposed by TIA W-CDMA, proposed by ARIB/ETSI Issued by ITU (International Telecommunication Union)

14. 3G Specficiations Excellent voice quality Data rate 144 kbps in high mobility 384 kbps in limited mobility 2 Mbps in door Frequency Band 1885-2025 MHz Convolutional Codes Turbo Codes for high data rates

15. 3G: CDMA2000 (2000) CDMA 1xEV-DO peak data rate 2.4 Mbps supports mp3 transfer and video conferencing CDMA 1xEV-DV Integrated voice and high-speed data multimedia service up to 3.1 Mbps Channel Bandwidth: 1.25, 5, 10, 15 or 20 MHz Chip rate at 3.6864 Mbps Modulation Scheme QPSK in downlink BPSK in uplink

16. 3G: CDMA2000 Spreading Codes Downlink Variable length orthogonal Walsh sequences for channel separation M-sequences 3x2 15 for cell separation (different phase shifts) Uplink Variable length orthogonal Walsh sequences for channel separation M-sequences 2 41 for user separation (different phase shifts)

17. 3G: W-CDMA (2000) Stands for “wideband” CDMA Channel Bandwidth: 5, 10 or 20 MHz Chip rate at 4.096 Mbps Modulation Scheme QPSK in downlink BPSK in uplink

18. 3G: W-CDMA Spreading Codes Downlink Variable length orthogonal sequences for channel separation Gold sequences 2 18 for cell separation Uplink Variable length orthogonal sequences for channel separation Gold sequences 2 41 for user separation

19. 4G Technology (2010) High data rates => 100 Mbps Multimedia data up to ~10 2 Mbps IP-oriented network => Internet MIMO using Multiple Antennas Spreading code Non-binary sequences Multiple Access Technique MC-CDMA

20. MC-CDMA

21. Conclusions CDMA can increase the capacity of mobile system Goals of next generation cellular Further increase data rate Reduce interference among users Future research: Search for good non-binary sequences Ideal 2-level autocorrelation Low cross correlations