In this paper we present a flexible multiple input multiple output (MIMO) measurement system for communication signals in the 2.4 GHz band. We present some measurements of the digital to digital transmission channel w...
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In this paper we present a flexible multiple input multiple output (MIMO) measurement system for communication signals in the 2.4 GHz band. We present some measurements of the digital to digital transmission channel which includes all impairments of the hardware realization. Using this system we perform a multi-layer transmission of communication signals. At the receiver side we use blind source separation (BSS) techniques as front-endprocessing to avoid estimation and synchronization problems. In order to improve the estimation of the channel and the symbol detection, we propose an iterative approach, which uses the knowledge of the finite symbol alphabet but does not need additional training data.
With the rising number of modulation types used in multiuser communication systems, we need to find efficient methods to discriminate them. Indeed, modulation recognition has become important in wireless communication...
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With the rising number of modulation types used in multiuser communication systems, we need to find efficient methods to discriminate them. Indeed, modulation recognition has become important in wireless communications for both civilian and military applications. Traditionally, to classify modulation types, most studies assume abundant a priori knowledge about modulated signals such as binary data rate, baud rate or carrier frequency. However, new transmission receiver systems need to classify automatically digital modulations without specific information. In the course of making decision on modulation type, these parameters may have to be estimated in order to perform efficient demodulation. This paper proposes a new way of estimating baud rate of digital modulated signals. This approach is based on abrupt changes detection in time-frequency plane and on abrupt change periodicity analysis using Kalman filtering.
A method is presented that uses an approximate nearest neighbor method for determining correspondences within the iterative closest point algorithm. The method is based upon the k-d tree. The standard k-d tree uses a ...
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A method is presented that uses an approximate nearest neighbor method for determining correspondences within the iterative closest point algorithm. The method is based upon the k-d tree. The standard k-d tree uses a tentative backtracking search to identify nearest neighbors. In contrast, the approximate k-d tree (Ak-d tree) applies a depth-first nontentative search to the k-d tree structure. This search improves runtime efficiency, with the tradeoff of reducing the accuracy of the determined correspondences. This approximate search is applied to early iterations of the iterative closest point algorithm, transitioning to the standard k-d tree for the final iterations after the change in the mean square error of the correspondences becomes sufficiently small. The method benefits both from the improved time performance of the approximate search in early iterations as well as the full accuracy of the complete search in later iterations. Experimental results indicate that the time efficiency of Ak-d tree is superior to the k-d tree and Elias for moderately large point sets. The change in the shape of the minimum potential well space is subtle, and the convergence properties are often identical. In those cases where the global minimum was not achieved, the difference in final mse was very small. In one trial, Ak-d tree converged faster to a better minimum with a smaller mse, which indicates that the use of approximate methods may be beneficial in the presence of outliers.
Video transmission over unreliable networks such as Internet or wireless networks suffers from various kinds of adverse conditions such as bandwidth fluctuation, burst-error contamination, packet loss, and excessive p...
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Video transmission over unreliable networks such as Internet or wireless networks suffers from various kinds of adverse conditions such as bandwidth fluctuation, burst-error contamination, packet loss, and excessive packet delay due to network congestion. By taking advantage of multiple logical channels provided by digital networks, a multiple description video coding scheme is proposed to accommodate varying network environments and to meet quality of service requirements. The embedding bit-stream is obtained by exploiting the 3-d SPIHT algorithm. The coding efficiency of the proposed codec is optimized by removing spatio-temporal redundancy from video signals and constructing a more compact hierarchical zero-tree for 3-d SPIHT algorithm. The error resilience in spatio-temporal domain is utilized to conceal the distortion due to packet lost or erroneous transmission. Through the just-noticeable distortion (JNd) profiles estimating, the spatio-temporal redundancy inherent in YCbCr components of video signal is evaluated and the threshold of significance signal can be evaluated. The simulation results show that the visual quality can be maintained in transmitting video sequences at low bit rate (200 kbps) over the channel of high data loss rate (50%).
A generic framework based on services for 3d information visualization is presented. The framework can support a wide range of applications and offers the flexibility to be tailored to specific application needs by co...
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ISBN:
(纸本)0769515223
A generic framework based on services for 3d information visualization is presented. The framework can support a wide range of applications and offers the flexibility to be tailored to specific application needs by configuration. The design and implementation details are discussed as well as a concrete application based on this framework.
This paper describes a technique for building a 3d volumetric model of an unknown surrounding based on data acquired by the IR Range Finder located on board of a mobile robot. The paper presents all the steps needed f...
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ISBN:
(纸本)0769515223
This paper describes a technique for building a 3d volumetric model of an unknown surrounding based on data acquired by the IR Range Finder located on board of a mobile robot. The paper presents all the steps needed for the description of the environment, including measurement data acquisition, samples processing and3d surface-model reconstruction.
In this paper, a system for the visualization and entry of 3d stratigraphic layers into a new Geographic Information System (GIS) based on the varying and sometimes incomplete records of the field archaeologist is pre...
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ISBN:
(纸本)0769515223
In this paper, a system for the visualization and entry of 3d stratigraphic layers into a new Geographic Information System (GIS) based on the varying and sometimes incomplete records of the field archaeologist is presented This paper presents a computer-based system that allows for incomplete and ambiguous data, indicating problems associated with this entry and shows how inaccuracies are represented so that later misinterpretation is avoided.
In this paper, we describe 3WPS, a framework to builddistributed systems that are able to monitor and interact with a process via a 3d interface that is accessible via the World Wide Web. 3WPS is easily configurable,...
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ISBN:
(纸本)0769515223
In this paper, we describe 3WPS, a framework to builddistributed systems that are able to monitor and interact with a process via a 3d interface that is accessible via the World Wide Web. 3WPS is easily configurable, easily adaptable to different processes with high reuse of its software components and its distributed architect re leverages on off-the-shelf components of the infrastructure such as Java applets and VRML browsers.
A "Collaboratory" is a lightweight application component allowing project teams to collaborate and share data and insight while distributed over a network, using intuitive visual navigation techniques. The i...
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ISBN:
(纸本)0769515215;0769515223
A "Collaboratory" is a lightweight application component allowing project teams to collaborate and share data and insight while distributed over a network, using intuitive visual navigation techniques. The innovation can be summarised as the integration of network technology used in collaborative games with 3ddata navigation technique based on a low-level, fine-grained, customisable "atomic" visualization component infrastructure. In this paper we have focused on 3d medical imaging tools describing a Collaboratory implementation of a "Volume Viewer". This paper is also a blueprint to inform researchers and software engineers about the possibility to extend existing visualisation applications to support collaboration, e.g. making it easier to "collaboratize" visualization applications based on Microsoft's directX class library.
3d medical images represent tremendous amounts of data. Grid technologies offer large anddistributed computing power suited to medical images analysis. However interactive programs with user supervision are made diff...
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ISBN:
(纸本)0769515215;0769515223
3d medical images represent tremendous amounts of data. Grid technologies offer large anddistributed computing power suited to medical images analysis. However interactive programs with user supervision are made difficult on a grid architecture due to the remote program execution. In this paper we propose a new framework for interactive execution of remote applications dealing with large 3d medical data sets. Our solution is both efficient and easy to use from the user point of view.
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