Tracking of Fast-Fading Channels in

A new technique for blind tracking of fast-fading channels in long-code code division multiple access (CDMA) is proposed by exploiting multipath diversity. Based on a linear interpolation channel model, the proposed method blindly identi- fies a time-varying channel at arbitrary estimating points within a block up to a scale factor and increases bandwidth efficiency allowing only one pilot symbol within a block, which is much larger than channel coherence time. The proposed method can be implemented using an efficient state-space inversion technique for multiuser cases. The mean square error (MSE) performance of the proposed estimator is compared with the Cramer-Rao bound (CRB) for interpolated channel. Modeling error and bit error rate (BER) are also evaluated using Monte-Carlo simulations and compared with the block fading model and a decision-directed tracking technique.

[1]  N. Johnson,et al.  Methods for Recovering a Random Waveform from a Finite Number of Samples , 1965 .

[2]  Srikrishna Bhashyam,et al.  Multiuser channel estimation and tracking for long-code CDMA systems , 2002, IEEE Trans. Commun..

[3]  Michail K. Tsatsanis,et al.  Blind channel estimation for long code multiuser CDMA systems , 2000, IEEE Trans. Signal Process..

[4]  J. Cavers.  An analysis of pilot symbol assisted modulation for Rayleigh fading channels (mobile radio) , 1991 .

[5]  Fumiyuki Adachi,et al.  Channel estimation using time multiplexed pilot symbols for coherent RAKE combining for DS-CDMA mobile radio , 1997, Proceedings of 8th International Symposium on Personal, Indoor and Mobile Radio Communications - PIMRC '97.

[6]  Thomas W. Parks,et al.  New results in the design of digital interpolators" ieee trans , 1975 .

[7]  Xavier Mestre,et al.  ML approaches to channel estimation for pilot-aided multirate DS/CDMA systems , 2002, IEEE Trans. Signal Process..

[8]  Fuyun Ling.  Optimal reception, performance bound, and cutoff rate analysis of references-assisted coherent CDMA communications with applications , 1999, IEEE Trans. Commun..

[9]  Georgios B. Giannakis,et al.  Subspace methods for blind estimation of time-varying FIR channels , 1997, IEEE Trans. Signal Process..

[10]  Anthony J. Weiss,et al.  Channel estimation for DS-CDMA downlink with aperiodic spreading codes , 1999, IEEE Trans. Commun..

[11]  W. C. Jakes,et al.  Microwave Mobile Communications , 1974 .

[12]  Bengt Lindoff,et al.  Channel estimation for the W-CDMA system, performance and robustness analysis from a terminal perspective , 1999, 1999 IEEE 49th Vehicular Technology Conference (Cat. No.99CH36363).

[13]  Lang Tong,et al.  Blind decorrelating RAKE receivers for long-code WCDMA , 2003, IEEE Trans. Signal Process..

[14]  David Gesbert,et al.  On-line blind multichannel equalization based on mutually referenced filters , 1997, IEEE Trans. Signal Process..

[15]  R. Marks.  Introduction to Shannon Sampling and Interpolation Theory , 1990 .

[16]  Urbashi Mitra,et al.  A Toeplitz displacement method for blind multipath estimation for long code DS/CDMA signals , 2001, IEEE Trans. Signal Process..

[17]  Urbashi Mitra,et al.  Maximum-likelihood-based multipath channel estimation for code-division multiple-access systems , 2001, IEEE Trans. Commun..

[18]  Alfred O. Hero,et al.  Spread spectrum sequence estimation and bit synchronization using an EM-type algorithm , 1995, 1995 International Conference on Acoustics, Speech, and Signal Processing.

[19]  D. Slock,et al.  Cramer-Rao bounds for semi-blind, blind and training sequence based channel estimation , 1997, First IEEE Signal Processing Workshop on Signal Processing Advances in Wireless Communications.