First arrival detection for positioning in mobile channels

Vidal, Josep

doi:10.1109/pimrc.2002.1045437

Cited by 16 publications

(10 citation statements)

References 5 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…These two tasks pose several problems in the presence of mobile wireless channels, due to the various adverse effects of the channel, such as the multipath propagation, the possibility of having the line-of-sight (LOS) component obstructed by closely spaced non-line-of-sight (NLOS) components, or even the absence of LOS, and the high level of noise (especially in indoor scenarios). Moreover, the fading statistics of the channel and the possible variations of the oscillator clock limit the coherent integration length at the receiver (i.e., the receiver filters which are used to smooth the various estimates of channel parameters cannot have the bandwidth smaller than the maximum Doppler spread of the channel without introducing significant errors in the estimation process) [7][8][9][10][11]. The Doppler shift induced by the satellite movement is also prone to deteriorate the receiver performance, unless correctly estimated and removed.…”

Section: Background and Motivationmentioning

confidence: 99%

“…One particular situation in multipath propagation is the situation when LOS component is overlapping with one or several closely spaced NLOS components [7,[9][10][11][12][13][14][15][16], making the delay estimation process more difficult. This closely 2 EURASIP Journal on Applied Signal Processing spaced path scenario is likely to be encountered in indoor positioning applications or in outdoor urban environments, and will be the main focus of our paper.…”

Section: Background and Motivationmentioning

confidence: 99%

See 1 more Smart Citation

Feedforward Delay Estimators in Adverse Multipath Propagation for Galileo and Modernized GPS Signals

Lohan

Lakhzouri

Renfors

2006

EURASIP J. Adv. Signal Process.

View full text Add to dashboard Cite

The estimation with high accuracy of the line-of-sight delay is a prerequisite for all global navigation satellite systems. The delay locked loops and their enhanced variants are the structures of choice for the commercial GNSS receivers, but their performance in severe multipath scenarios is still rather limited. The new satellite positioning system proposals specify higher code-epoch lengths compared to the traditional GPS signal and the use of a new modulation, the binary offset carrier (BOC) modulation, which triggers new challenges in the delay tracking stage. We propose and analyze here the use of feedforward delay estimation techniques in order to improve the accuracy of the delay estimation in severe multipath scenarios. First, we give an extensive review of feedforward delay estimation techniques for CDMA signals in fading channels, by taking into account the impact of BOC modulation. Second, we extend the techniques previously proposed by the authors in the context of wideband CDMA delay estimation (e.g., Teager-Kaiser and the projection onto convex sets) to the BOC-modulated signals. These techniques are presented as possible alternatives to the feedback tracking loops. A particular attention is on the scenarios with closely spaced paths. We also discuss how these feedforward techniques can be implemented via DSPs.

show abstract

Section: Background and Motivationmentioning

confidence: 99%

Section: Background and Motivationmentioning

confidence: 99%

Feedforward Delay Estimators in Adverse Multipath Propagation for Galileo and Modernized GPS Signals

Lohan

Lakhzouri

Renfors

2006

EURASIP J. Adv. Signal Process.

View full text Add to dashboard Cite

show abstract

“…These two tasks pose several problems in the presence of mobile wireless channels, due to the various adverse effects of the channel, such as the multipath propagation, the possibility of having the line-of-sight (LOS) component obstructed by closely spaced nonline-of-sight (NLOS) components, or even the absence of LOS, and the high level of noise (especially in indoor scenarios). Moreover, the fading statistics of the channel and the possible variations of the oscillator clock limit the coherent integration time at the receiver (i.e., the receiver filters which are used to smooth the various estimates of channel parameters cannot have the bandwidth smaller than the maximum Doppler spread of the channel without introducing significant errors in the estimation process) [7][8][9][10][11]. The Doppler shift induced by the satellite is also prone to deteriorate the receiver performance, unless correctly estimated and removed.…”

Section: Introductionmentioning

confidence: 99%

“…One particular situation in multipath propagation is the situation when LOS component is overlapping with one or several closely spaced NLOS components [7,[9][10][11][12][13][14][15][16] making the delay estimation process more difficult. This closely spaced path scenario is most likely to be encountered in indoor positioning applications or in outdoor urban environments, and is the main focus of our paper.…”

Section: Introductionmentioning

confidence: 99%

Code Tracking Algorithms for Mitigating Multipath Effects in Fading Channels for Satellite-Based Positioning

Bhuiyan

Lohan

Renfors

2007

EURASIP J. Adv. Signal Process.

View full text Add to dashboard Cite

The ever-increasing public interest in location and positioning services has originated a demand for higher performance global navigation satellite systems (GNSSs). In order to achieve this incremental performance, the estimation of line-of-sight (LOS) delay with high accuracy is a prerequisite for all GNSSs. The delay lock loops (DLLs) and their enhanced variants (i.e., feedback code tracking loops) are the structures of choice for the commercial GNSS receivers, but their performance in severe multipath scenarios is still rather limited. In addition, the new satellite positioning system proposals specify the use of a new modulation, the binary offset carrier (BOC) modulation, which triggers a new challenge in the code tracking stage. Therefore, in order to meet this emerging challenge and to improve the accuracy of the delay estimation in severe multipath scenarios, this paper analyzes feedback as well as feedforward code tracking algorithms and proposes the peak tracking (PT) methods, which are combinations of both feedback and feedforward structures and utilize the inherent advantages of both structures. We propose and analyze here two variants of PT algorithm: PT with second-order differentiation (Diff2), and PT with Teager Kaiser (TK) operator, which will be denoted herein as PT(Diff2) and PT(TK), respectively. In addition to the proposal of the PT methods, the authors propose also an improved early-late-slope (IELS) multipath elimination technique which is shown to provide very good mean-time-to-loselock (MTLL) performance. An implementation of a noncoherent multipath estimating delay locked loop (MEDLL) structure is also presented. We also incorporate here an extensive review of the existing feedback and feedforward delay estimation algorithms for direct sequence code division multiple access (DS-CDMA) signals in satellite fading channels, by taking into account the impact of binary phase shift keying (BPSK) as well as the newly proposed BOC modulation, more specifically, sine-BOC(1,1) (SinBOC(1,1)), selected for Galileo open service (OS) signal. The state-of-art algorithms are compared, via simulations, with the proposed algorithms. The main focus in the performance comparison of the algorithms is on the closely spaced multipath scenario, since this situation is the most challenging for estimating LOS component with high accuracy in positioning applications.

show abstract

“…A generalized ML method is examined in [6]. For conventional CDMA and WCDMA systems, techniques such as the minimum variance method [7] and the binary hypothesis test [8], [9] have been explored. These schemes exhibit various advantages in certain circumstances.…”

Section: Introductionmentioning

confidence: 99%

Mitigation of Sampling-induced Errors in Delay Estimation

Kohno

2005 IEEE International Conference on Ultra-Wideband

View full text Add to dashboard Cite

Delay estimation has been well accepted as an important approach to ranging with a UWB (ultra-wide band) system. Delay estimation errors due to digital sampling can be considerably large at a low sampling frequency. In this paper, we investigate reduction of such errors in both analytical and practical aspects. A delay estimation scheme based on the socalled simplified maximum likelihood formulation is first derived, and is further shown to be optimal in the sense that its error variance converges to the corresponding theoretical lower limit as the sampling frequency is sufficiently high. Next, an iterative scheme for first arrival detection is devised in light of the near-far robustness in multiuser detection. This scheme can effectively cope with a frequent UWB environment where the first arriving signal component may not be dominant among multipath components. Efficient reduction of sampling-induced errors and a low computation complexity are main advantages of the proposed schemes.

show abstract

First arrival detection for positioning in mobile channels

Cited by 16 publications

References 5 publications

Feedforward Delay Estimators in Adverse Multipath Propagation for Galileo and Modernized GPS Signals

Feedforward Delay Estimators in Adverse Multipath Propagation for Galileo and Modernized GPS Signals

Code Tracking Algorithms for Mitigating Multipath Effects in Fading Channels for Satellite-Based Positioning

Mitigation of Sampling-induced Errors in Delay Estimation

Contact Info

Product

Resources

About