TY - JOUR
T1 - Blind code-timing estimation for CDMA systems with bandlimited chip waveforms in multipath fading channels
AU - Li, Hongbin
AU - Wang, Rensheng
AU - Amleh, Khaled
PY - 2006/1
Y1 - 2006/1
N2 - In this paper, we present a blind code-timing estimator for asynchronous code-division multiple-access (CDMA) systems that use bandlimited chip waveforms. The proposed estimator first converts the received signal to the frequency domain, followed by a frequency deconvolution to remove the convolving chip waveform, and then calculates the code-timing estimate from the output of a narrowband filter with a sweeping center frequency, which is designed to suppress the overall interference in the frequency domain. The proposed estimator is near-far resistant, and can deal with time- and frequency-selective channel fading. It uses only the spreading code of the desired user, and can be adaptively implemented for both code acquisition and tracking. We also derive an unconditional Cramér - Rao bound (CRB) that is not conditioned on the fading coefficients or the information symbols. It is a more suitable lower bound than a conditional CRB for blind code-timing estimators which do not assume knowledge of the channel or information symbols. We present numerical examples to evaluate and compare the proposed and several other code-timing estimators for bandlimited CDMA systems.
AB - In this paper, we present a blind code-timing estimator for asynchronous code-division multiple-access (CDMA) systems that use bandlimited chip waveforms. The proposed estimator first converts the received signal to the frequency domain, followed by a frequency deconvolution to remove the convolving chip waveform, and then calculates the code-timing estimate from the output of a narrowband filter with a sweeping center frequency, which is designed to suppress the overall interference in the frequency domain. The proposed estimator is near-far resistant, and can deal with time- and frequency-selective channel fading. It uses only the spreading code of the desired user, and can be adaptively implemented for both code acquisition and tracking. We also derive an unconditional Cramér - Rao bound (CRB) that is not conditioned on the fading coefficients or the information symbols. It is a more suitable lower bound than a conditional CRB for blind code-timing estimators which do not assume knowledge of the channel or information symbols. We present numerical examples to evaluate and compare the proposed and several other code-timing estimators for bandlimited CDMA systems.
KW - Code-division multiple access (CDMA)
KW - Code-timing estimation
KW - Cramér - Rao bound (CRB)
KW - Interference suppression
KW - Time-varying multipath fading
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U2 - 10.1109/TCOMM.2005.861653
DO - 10.1109/TCOMM.2005.861653
M3 - Article
AN - SCOPUS:31344466166
SN - 0090-6778
VL - 54
SP - 141
EP - 149
JO - IEEE Transactions on Communications
JF - IEEE Transactions on Communications
IS - 1
ER -