Low complexity adaptive code tracking with improved multipath resolution for DS-CDMA communications over fading channels

Schulz-Rittich, P.; Fock, G.; Baltersee, J.; Meyr, H.

doi:10.1109/isssta.2000.878075

Cited by 12 publications

(7 citation statements)

References 6 publications

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“…Our approach based on OU random processes additionally covers the time‐variant statistical properties of the timing error for adaptive DLLs of any order. We are also able to extend the SDE solutions towards low complexity multipath‐resistant adaptive code tracking algorithms . Above all, we get the MTLLs for the respective DLLs as well without the complex singular perturbation method .…”

Section: Introductionmentioning

confidence: 93%

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A novel tracking jitter computation method for delay‐locked loops in spread‐spectrum systems

Groh

Gentner

Selva

2012

Trans. Emerging Tel. Tech.

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In spread‐spectrum navigation systems, the positioning error (or tracking accuracy) is determined from the jitter deviation of delay‐locked loops (DLLs). However, jitter simulations are computationally complex, and conventional analytical methods provide only unsatisfactory and incomplete jitter results. Thus, our contribution presents a novel method for the analytical jitter computation by mapping the stochastic differential equation (SDE) of the DLL onto an Ornstein–Uhlenbeck (OU) SDE. Its solution is the well‐known OU random process, which is a time‐variant Gaussian distribution. The expectation value and the variance of the OU random process yield the jitter deviation. Thus, we derive the analytical time‐variant jitter function with its transient response, which was to date unavailable. Contrary to previous jitter computations based on a loop transfer function, our method covers DLLs of any order. We obtain the loop parameters that minimise the jitter deviation analytically without computationally complex simulations. Above all, our method based on OU random processes enables for the first time an efficient joint analytical mean time to lose lock (MTLL) and jitter computation. Therefore, both computationally complex MTLL and jitter simulations become obsolete for many kinds of DLLs.Copyright © 2012 John Wiley & Sons, Ltd.

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Section: Introductionmentioning

confidence: 93%

“…where we introduce the total loop bandwidth [17] B L D S ı .0/K p P 2 (14) and the bit energy As in Equation (11), we evaluate the time-dependent variance 2 A;" .t A / in Equation (13) for large values of t A , and we obtain the stationary variance…”

Section: Analytical Solution Of the First-order Sde-jitter Rms Value mentioning

confidence: 99%

A novel tracking jitter computation method for delay‐locked loops in spread‐spectrum systems

Groh

Gentner

Selva

2012

Trans. Emerging Tel. Tech.

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“…The first one consists of reconstructing the multipath interference in order to cancel it [6], [7], but the compensation term needs complete channel state information (including path magnitudes) and has to be updated each time the channel changes. The second method consists of minimizing the multipath interference [8], [9]. In [9], the estimation bias due to multipath is cancelled thanks to an adaptive timing error detector, but the estimation variance is not taken into account.…”

Section: Introductionmentioning

confidence: 99%

“…The second method consists of minimizing the multipath interference [8], [9]. In [9], the estimation bias due to multipath is cancelled thanks to an adaptive timing error detector, but the estimation variance is not taken into account. In [8], the new scheme is not robust to channel phase and magnitude variations.…”

Section: Introductionmentioning

confidence: 99%

Synchronization Over Rapidly Time-Varying Multipath Channel for CDMA Downlink RAKE Receivers in Time-Division Mode

Simon

Ros²,

Raoof³

2007

IEEE Trans. Veh. Technol.

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Abstract-In this paper, we consider a time-division codedivision multiple-access (CDMA) system operating in downlink mode in a multiuser multipath channel scenario. In order to implement RAKE reception, the delays, phases, and magnitudes of the different paths need to be estimated and the estimates updated. In the context of burst transmissions, delays do not vary during a burst, and only phases and magnitudes need to be tracked. In this paper, we investigate the issue of phase tracking over rapidly time-varying multipath channels. We propose a new version of the conventional phase loop that mitigates the interpath interference effect. The optimization is based on the concept of prefiltering. The analysis shows improved tracking performance in comparison with the standard phase recovery algorithm.Index Terms-Code-division multiple access (CDMA), downlink, multipath channels, phase estimation.

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“…A similar way of dealing with interference cancellation is also described in [6], which, however, cannot track data modulated signals. The second approach can be classified as interference minimization [15]. Both approaches can be applied to timing tracking, whereas for phasor estimation, only an interference minimization scheme is applicable.…”

Section: Introductionmentioning

confidence: 99%

Channel tracking for RAKE receivers in closely spaced multipath environments

Fock

Baltersee

Schulz-Rittich

et al. 2001

IEEE J. Select. Areas Commun.

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This paper deals with the problem of channel tracking for RAKE receivers in propagation environments characterized by closely spaced multipath components. After outlining why conventional single-path channel tracking algorithms fail in such scenarios, several new estimation algorithms are developed that are tailored to channels with closely spaced multipaths. This is achieved by removing or minimizing self-interference caused by multipath components. Other interfering users are treated as noise. Both timing tracking and phasor tracking and their interaction are covered in this paper. The derived algorithms are benchmarked against perfect channel knowledge on one hand and conventional tracking algorithms on the other hand, both in a UMTS test scenario. In moderate scenarios, the use of these new algorithms leads to performance improvements of up to 2 dB, in terms of signal-to-noise ratio (SNR) at moderate bit error rates, and even manages to track the channel in conditions where conventional tracking algorithms fail completely.

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Low complexity adaptive code tracking with improved multipath resolution for DS-CDMA communications over fading channels

Cited by 12 publications

References 6 publications

A novel tracking jitter computation method for delay‐locked loops in spread‐spectrum systems

A novel tracking jitter computation method for delay‐locked loops in spread‐spectrum systems

Synchronization Over Rapidly Time-Varying Multipath Channel for CDMA Downlink RAKE Receivers in Time-Division Mode

Channel tracking for RAKE receivers in closely spaced multipath environments

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