A Novel Multi-user Detection Approach on Fluctuations of Autocorrelation Estimators in Non-Cooperative Communication

Document Type : Original Article


Faculty of Engineering Modern Technologies, Amol University of Special Modern Technologies, Amol, Iran


Recently, blind multi-user detection has become an important topic in code division multiple access (CDMA) systems. Direct-Sequence Spread Spectrum (DSSS) signals are well-known due to their low probability of detection, and secure communication. In this article, the problem of blind multi-user detection is studied in variable processing gain direct-sequence code division multiple access (VPG DS-CDMA). The method based on the fluctuations of autocorrelation estimators,which previously described in a single and multi-user context, is extended to an asynchronous variable processing gain (VPG) DS/CDMA systems without restrictions on the processing gains in multi-path channel condition. According to the proposed algorithm, not only the presence of the common peaks in the second-order statistic of the received signal is proved, but the relationship between these peaks and the spreading code length is also derived. The simulation results show that the proposed algorithm even in the presence a very low signal-to-noise ratio (SNR) is completely efficient in signal detection. It is remarkable that  the minimum description length (MDL) method is used to determine the number of users.


1. Tabatabaee, S.A., Towliat, M. and Khodadad, F.S., "Joint
equalization-despreading method for oqam-cdma systems",
Signal Processing,  Vol. 146, (2018), 92-98. 
2. Khodadad, F.S., Ganji, F. and Aref, M.R., "A practical approach
for coherent signal surveillance and blind parameter assessment 
in asynchoronous ds-cdma systems in multipath channel", in 
2010 18th Iranian Conference on Electrical Engineering, IEEE.,
(2010), 305-310. 
3. Khodadad, F.S., Ganji, F., Safaei, A. and Khodadad, F.S., "A
robust pn length estimation in down link low-snr ds-cdma
multipath channels", in 2010 The 12th International Conference
on Advanced Communication Technology (ICACT), IEEE. Vol.
2, (2010), 951-955. 
4. Honig, M., Madhow, U. and Verdu, S., "Blind adaptive
multiuser detection", IEEE Transactions on Information
Theory,  Vol. 41, No. 4, (1995), 944-960. 
5. Chih-Lin, I. and Gitlin, R.D., "Multi-code cdma wireless
personal communications networks", in Proceedings IEEE
International Conference on Communications ICC'95, IEEE.
Vol. 2, (1995), 1060-1064. 
6. Sosnin, S.D., Xiong, G., Chatterjee, D. and Kwak, Y., "Nonorthogonal
multiple access with low code rate spreading and 
short sequence based spreading", in 2017 IEEE 86th Vehicular
Technology Conference (VTC-Fall), IEEE., (2017), 1-5. 
7. Qiang, F., Zhao, Z., Gu, X. and Jiang, X., "Blind estimation of
long and short pseudo-random codes in multi-rate lsc-ds-cdma
signals", International Journal of Circuits, Systems and Signal
Processing,  Vol. 13, (2018), 259-265. 
8. Liang, J.-H., Wang, X., Wang, F.-H. and Huang, Z.-T., "Blind
spreading sequence estimation algorithm for long-code ds-cdma
signals in asynchronous multi-user systems", IET Signal
Processing,  Vol. 11, No. 6, (2017), 704-710. 
9. Nzoza, C.N., Gautier, R. and Burel, G., "Blind synchronization
and sequences identification in cdma transmissions", in IEEE
MILCOM 2004. Military Communications Conference, 2004.,
IEEE. Vol. 3, (2004), 1384-1390. 
10. Nzéza, C.N., Gautier, R. and Burel, G., "Parallel blind multiuser
synchronization and sequences estimation in multirate cdma
transmissions", in 2006 Fortieth Asilomar Conference on
Signals, Systems and Computers, IEEE., (2006), 2157-2161. 
11. Nzéza, C.N., Gautier, R. and Burel, G., "Blind multiuser
identification in multirate cdma transmissions: A new
approach", in 2006 Fortieth Asilomar Conference on Signals,
Systems and Computers, IEEE. (2006), 2162-2166. 
12. Gu, X., Zhao, Z. and Shen, L., "Blind estimation of pseudorandom
codes in periodic long code direct sequence spread
spectrum signals", IET Communications,  Vol. 10, No. 11,
(2016), 1273-1281. 
13. Mirzadeh Sarcheshmeh, H., Khaleghi Bizaki, H. and Alizadeh,
S., "Pn sequence blind estimation in multiuser ds‐cdma systems
with multipath channels based on successive subspace scheme",
International Journal of Communication Systems,  Vol. 31,
No. 12, (2018), e3591. 
14. Burel, G. and Bouder, C., "Blind estimation of the pseudorandom
MILCOM 2000 Proceedings. 21st Century Military
Communications. Architectures and Technologies for
Information Superiority (Cat. No. 00CH37155), IEEE. Vol. 2,
(2000), 967-970. 
15. Bouder, C., Azou, S. and Burel, G., "Performance analysis of a
spreading sequence estimator for spread spectrum
transmissions", Journal of the Franklin Institute,  Vol. 341,
No. 7, (2004), 595-614. 
16. Haddadi, F., Malek-Mohammadi, M., Nayebi, M.M. and Aref,
M.R., "Statistical performance analysis of mdl source
enumeration in array processing", IEEE Transactions on Signal
Processing,  Vol. 58, No. 1, (2009), 452-457.