Open Access

Physical Layer Built-In Security Analysis and Enhancement Algorithms for CDMA Systems

EURASIP Journal on Wireless Communications and Networking20072007:083589

DOI: 10.1155/2007/83589

Received: 18 July 2006

Accepted: 20 January 2007

Published: 19 March 2007

Abstract

Historically developed for secure communication and military use, CDMA has been identified as a major modulation and multiple-access technique for 3G systems and beyond. In addition to the wide bandwidth and low power-spectrum density which make CDMA signals robust to narrowband jamming and easy to be concealed within the noise floor, the physical layer built-in information privacy of CDMA system is provided by pseudorandom scrambling. In this paper, first, security weakness of the operational and proposed CDMA airlink interfaces is analyzed. Second, based on the advanced encryption standard (AES), we propose to enhance the physical layer built-in security of CDMA systems through secure scrambling. Performance analysis demonstrates that while providing significantly improved information privacy, CDMA systems with secure scrambling have comparable computational complexity and overall system performance with that of conventionally scrambled systems. Moreover, it is shown that by scrambling the training sequence and the message sequence separately with two independent scrambling sequences, both information privacy and system performance can be further improved. The proposed scheme can readily be applied to 3G systems and beyond.

[1234567891011121314]

Authors’ Affiliations

(1)
Department of Electrical and Computer Engineering, Michigan State University

References

  1. Nichols R, Lekkas P: Wireless Security: Models, Threats, and Solutions, McGraw-Hill Telecom Professional Series. McGraw-Hill, New York, NY, USA; 2002.Google Scholar
  2. IEEE : IEEE Standard for Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) Specifications. 1999.Google Scholar
  3. Massey J: Shift-register synthesis and BCH decoding. IEEE Transactions on Information Theory 1969,15(1):122-127. 10.1109/TIT.1969.1054260MathSciNetView ArticleMATHGoogle Scholar
  4. Bhashyam S, Aazhang B: Multiuser channel estimation and tracking for long-code CDMA systems. IEEE Transactions on Communications 2002,50(7):1081-1090. 10.1109/TCOMM.2002.800808View ArticleGoogle Scholar
  5. Escudero CJ, Mitra U, Slock DTM: A Toeplitz displacement method for blind multipath estimation for long code DS/CDMA signals. IEEE Transactions on Signal Processing 2001,49(3):654-655. 10.1109/78.905897View ArticleGoogle Scholar
  6. Weiss AJ, Friedlander B: Channel estimation for DS-CDMA downlink with aperiodic spreading codes. IEEE Transactions on Communications 1999,47(10):1561-1569. 10.1109/26.795824View ArticleGoogle Scholar
  7. National Bureau of Standards : FIPS Publication 197: Advanced Encryption Standard (AES). 2001.http://csrc.nist.gov/publications/fips/fips197/fips-197.pdfGoogle Scholar
  8. TIA/EIA/IS-95-B : Mobile Station-Base Station Compatibility Standard for Dual-Mode Wideband Spread Spectrum Cellular System. 1998.
  9. Garg VK: IS-95 CDMA and cdma 2000: Cellular/PCS Systems Implementation. Pearson Education, Upper Saddle River, NJ, USA; 1999.Google Scholar
  10. National Bureau of Standards : FIPS Publication 81: DES Modes of Operation. 1980.http://www.itl.nist.gov/fipspubs/fip81.htmGoogle Scholar
  11. Electronic Frontier Foundation (EFF) : EFF DES Cracker Project. http://www.eff.org/Privacy/Crypto/Crypto_misc/DESCracker/
  12. Parkvall S: Variability of user performance in cellular DS-CDMA-long versus short spreading sequences. IEEE Transactions on Communications 2000,48(7):1178-1187. 10.1109/26.855525View ArticleGoogle Scholar
  13. Rappaport TS: Wireless Communications: Principles and Practices. 2nd edition. Prentice-Hall, Upper Saddle River, NJ, USA; 2002.Google Scholar
  14. Proakis J: Digital Communications. 4th edition. McGraw-Hill, New York, NY, USA; 2000.Google Scholar

Copyright

© Tongtong Li et al. 2007

This article is published under license to BioMed Central Ltd. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.