Novel Orthogonal Codes for Spectrally-Encoded CDMA Systems in Fading Channels

Orthogonal spreading codes play an essential role in code-division multiple-access (CDMA) systems by eliminating multiple-access interference (MAI). In this paper, a novel orthogonal spreading code has been proposed for spectrally-encoded (SE) CDMA, a.k.a., spread-time (ST) CDMA with arbitrary pulse shape. It has been shown that it is possible to retain the orthogonality of the code in the presence of tail truncation by time windowing and in a general multipath fading channel in which users experience different frequency selectivity just by modifying the user codewords. Simulation results show that the proposed codes can achieve single user performance when the code length is twice the number of users.

[1]  Mahrokh G. Shayesteh,et al.  Spread-time CDMA resistance in fading channels , 2001, 12th IEEE International Symposium on Personal, Indoor and Mobile Radio Communications. PIMRC 2001. Proceedings (Cat. No.01TH8598).

[2]  Fred W. Glover,et al.  A new modeling and solution approach for the number partitioning problem , 2005, Adv. Decis. Sci..

[3]  J.E. Mazo,et al.  Digital communications , 1985, Proceedings of the IEEE.

[4]  Liru Lu,et al.  Performance of a Complete Complementary Code-Based Spread-Time CDMA System in a Fading Channel , 2008, IEEE Transactions on Vehicular Technology.

[5]  Masoumeh Nasiri-Kenari,et al.  Spread-time CDMA performance with and without windowing , 2002, The 13th IEEE International Symposium on Personal, Indoor and Mobile Radio Communications.

[6]  Laurence B. Milstein,et al.  Spectral-encoded UWB communication systems: real-time implementation and interference suppression , 2005, IEEE Transactions on Communications.

[7]  Jawad A. Salehi,et al.  UWB spectrally-encoded spread-time CDMA in the presence of multiple gaussian interferences: RAKE receiver and three-level codes , 2008, IEEE Transactions on Communications.

[8]  Mahrokh G. Shayesteh,et al.  Multiple-Access Performance Analysis of Combined Time-Hopping and Spread-Time CDMA System in the Presence of Narrowband Interference , 2009, IEEE Transactions on Vehicular Technology.

[9]  Jawad A. Salehi,et al.  Novel probabilistic bounds on power level profile of spectrally-encoded spread-time CDMA signals , 2009, IEEE Transactions on Wireless Communications.

[10]  J.A. Salehi,et al.  Spread-time/time-hopping UWB CDMA communication , 2004, IEEE International Symposium on Communications and Information Technology, 2004. ISCIT 2004..

[11]  Andrew M. Weiner,et al.  Coherent ultrashort light pulse code-division multiple access communication systems , 1990 .

[12]  Pedro M. Crespo,et al.  Spread-time code-division multiple access , 1995, IEEE Trans. Commun..

[13]  Amir R. Forouzan,et al.  Orthogonal Code Design for Spectrally Encoded CDMA Systems , 2007, IEEE GLOBECOM 2007 - IEEE Global Telecommunications Conference.