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Communication channel

About: Communication channel is a research topic. Over the lifetime, 137411 publications have been published within this topic receiving 1715077 citations. The topic is also known as: communication channel & communications channel.


Papers
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Proceedings ArticleDOI
01 Dec 2014
TL;DR: A novel scheme for device-free PAssive Detection of moving humans with dynamic Speed (PADS), where both amplitude and phase information of CSI are extracted and shaped into sensitive metrics for target detection; and CSI across multi-antennas in MIMO systems are further exploited to improve the detection accuracy and robustness.
Abstract: Device-free passive detection is an emerging technology to detect whether there exists any moving entities in the area of interests without attaching any device to them. It is an essential primitive for a broad range of applications including intrusion detection for safety precautions, patient monitoring in hospitals, child and elder care at home, etc. Despite of the prevalent signal feature Received Signal Strength (RSS), most robust and reliable solutions resort to finer-grained channel descriptor at physical layer, e.g., the Channel State Information (CSI) in the 802.11n standard. Among a large body of emerging techniques, however, few of them have explored full potentials of CSI for human detection. Moreover, space diversity supported by nowadays popular multi-antenna systems are not investigated to the comparable extent as frequency diversity. In this paper, we propose a novel scheme for device-free PAssive Detection of moving humans with dynamic Speed (PADS). Both amplitude and phase information of CSI are extracted and shaped into sensitive metrics for target detection; and CSI across multi-antennas in MIMO systems are further exploited to improve the detection accuracy and robustness. We prototype PADS on commercial WiFi devices and experiment results in different scenarios demonstrate that PADS achieves great performance improvement in spite of dynamic human movements.

226 citations

Proceedings ArticleDOI
19 Mar 2008
TL;DR: This paper proposes sparse channel estimation methods based on convex/linear programming and derived by adapting recent advances from the theory of compressed sensing, revealing significant advantages of the proposed methods over the conventional channel estimation schemes.
Abstract: Reliable wireless communications often requires accurate knowledge of the underlying multipath channel. This typically involves probing of the channel with a known training waveform and linear processing of the input probe and channel output to estimate the impulse response. Many real-world channels of practical interest tend to exhibit impulse responses characterized by a relatively small number of nonzero channel coefficients. Conventional linear channel estimation strategies, such as the least squares, are ill-suited to fully exploiting the inherent low-dimensionality of these sparse channels. In contrast, this paper proposes sparse channel estimation methods based on convex/linear programming. Quantitative error bounds for the proposed schemes are derived by adapting recent advances from the theory of compressed sensing. The bounds come within a logarithmic factor of the performance of an ideal channel estimator and reveal significant advantages of the proposed methods over the conventional channel estimation schemes.

225 citations

Patent
22 Nov 1994
TL;DR: In this article, a receiver for pseudorandom noise (PRN) encoded signals consisting of a sampling circuit, multiple carrier and code synchronizing circuits, and multiple digital correlators is presented.
Abstract: A receiver for pseudorandom noise (PRN) encoded signals consisting of a sampling circuit, multiple carrier and code synchronizing circuits, and multiple digital correlators. The sampling circuit provides digital samples of a received composite signal to each of the several receiver channel circuits. The synchronizing circuits are preferably non-coherent, in the sense that they track any phase shifts in the received signal and adjust the frequency and phase of a locally generated carrier reference signal accordingly, even in the presence of Doppler or ionospheric distortion. The multiple correlators in each channel correlate the digital samples with locally generated PRN codes having multiple offsets, to produce a plurality of correlation signals. The plurality of correlation signals are fed to a parameter estimator, from which the delay and phase parameters of the direct path signal, as well as any multipath signals, may be estimated, and from which a range measurement may be corrected.

225 citations

Journal ArticleDOI
TL;DR: It is demonstrated that time-varying effects on wireless channels result in wireless traces which exhibit non-stationary behavior over small window sizes, and an algorithm is presented that extracts stationary components from a collected trace in order to provide analytical channel models that more accurately represent characteristics such as burstiness, statistical distribution of errors, and packet loss processes.
Abstract: Techniques for modeling and simulating channel conditions play an essential role in understanding network protocol and application behavior. In [11], we demonstrated that inaccurate modeling using a traditional analytical model yielded suboptimal error control protocol parameters choices. In this paper, we demonstrate that time-varying effects on wireless channels result in wireless traces which exhibit non-stationary behavior over small window sizes. We then present an algorithm that extracts stationary components from a collected trace in order to provide analytical channel models that, relative to traditional approaches, more accurately represent characteristics such as burstiness, statistical distribution of errors, and packet loss processes. Our algorithm also generates artificial traces with the same statistical characteristics as actual collected network traces. For validation, we develop a channel model for the circuit-switched data service in GSM and show that it: (1) more closely approximates GSM channel characteristics than traditional Markov models and (2) generates artificial traces that closely match collected traces' statistics. Using these traces in a simulator environment enables future protocol and application testing under different controlled and repeatable conditions.

225 citations

Journal ArticleDOI
TL;DR: A new and simple analytical framework is presented to model dual-polarized Rayleigh and Ricean fading channels for arbitrary array sizes and investigates the multiplexing advantage of dual- polarized transmissions through the evaluation of the ergodic mutual information.
Abstract: In this paper, we address the potential benefits of dual-polarized arrays in multi-antenna wireless systems. After an extensive literature overview of experimental data, we present a new and simple analytical framework to model dual-polarized Rayleigh and Ricean fading channels for arbitrary array sizes. The model relies on a limited number of physical parameters, such as the channel spatial correlations, the channel co-polar and the cross-polar ratios and the antenna cross-polar discrimination. Then, we investigate the multiplexing advantage of dual-polarized transmissions through the evaluation of the ergodic mutual information, for both TITO and MIMO systems. Finally, the performance of two space-time coding schemes (Alamouti OSTBC and uncoded spatial multiplexing) is evaluated via a detailed analysis of the pairwise error probability.

224 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
202270
20214,425
20206,535
20197,160
20187,052
20176,315