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Signal Processing and Communication Systems (ICSPCS), 2010 4th International Conference on

Date 13-15 Dec. 2010

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Displaying Results 1 - 25 of 140
  • [Copyright notice]

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  • [Front cover]

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  • Contents

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  • AE chair

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  • Organizing Committee

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  • Advisory committee

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  • Technical program committee

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  • List of reviewers

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  • AH Program

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  • Towards a low-complexity dynamic decode-and-forward relaying protocol

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    We first provide an overview of the dynamic decode-and-forward (DDF) relaying protocol, which is a recently proposed technique for cooperative wireless communications. DDF is based on the idea that each relay in the system should listen to the transmission from other active nodes till it receives enough information to decode, and retransmit only then. It has been proven to outperform any amplify and forward (AF) protocol in terms of diversity-multiplexing gain tradeoff (DMT). However, this protocol is quite complex and providing a simple implementation for the case of multiple relays is still an open problem. We then discuss our recently proposed technique to implement DDF with distributed rotations. In addition to being one of the first implementations of the DDF protocol proposed for any number of relays, this technique allows to exploit cooperative diversity without inducing the high decoding complexity of a space-time code. The analysis of outage probabilities for different number of relays and rotations shows that the performance of this technique is close to optimal. Moreover, a lower-bound on the DMT is provided in the case of a single relay and two rotations. This lower-bound reaches the optimal DDF's DMT when the frame-length grows to infinity, which shows that even a small number of rotations is enough to obtain good performance. View full abstract»

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  • 2D Mobile-to-Mobile wireless channel model

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (213 KB) |  | HTML iconHTML  

    A novel 2D Mobile-to-Mobile physical model is developed in this paper by considering the underlying physics of free space propagation. When compared to existing statistical channel models, the development and application of our new model is better in terms of complexity as it requires less parameters. In addition, the proposed new model is flexible in applying to any scattering environment whereas the design of the existing models could not easily be extended for any scattering environment. View full abstract»

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  • Using in-air Acoustic Vector Sensors for tracking moving speakers

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (210 KB) |  | HTML iconHTML  

    This paper investigates the use of an Acoustic Vector Sensor (AVS) for tracking a moving speaker in real time through estimation of the Direction of Arrival (DOA). This estimation is obtained using the MUltiple SIgnal Classification (MUSIC) algorithm applied on a time-frame basis. The performance of the AVS is compared with a SoundField Microphone which has similar polar responses to the AVS using time-frames ranging from 20 ms to 1 s. Results show that for 20 ms frames, the AVS is capable of estimating the DOA for both mono-tone and speech signals, which are both stationary and moving, with an accuracy of approximately 1.60 and less than 50 in azimuth, for stationary and moving speech sources, respectively. The results also show that the DOA estimates using the SoundField microphone are significantly less accurate than those obtained from the AVS. Furthermore, the results suggest that for estimating the DOA for speech sources, a Voice Activity Detector (VAD) is critical to ensure accurate azimuth estimation. View full abstract»

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  • Internal structure identification of random process using principal component analysis

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (168 KB) |  | HTML iconHTML  

    Principal component analysis (PCA) is known to be a powerful linear technique for data set dimensionality reduction. This paper focuses on revealing the essence of PCA to interpret the data, which is to identify the internal structure of the random process from a large experimental data set. We give an explanation of the PCA procedure performed on a generated data set to demonstrate the exact meaning of the dimensionality reduction. Especially, a method is proposed to precisely determine the number of significant principal components for a random process. Then, the internal structure of the random process can be modeled by analyzing the relation between the PCA results and the original data set. This is vital in the efficient random process modeling, which is finally applied to an application in HRTF Modeling. View full abstract»

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  • Time-frequency domain fundamental frequency estimation and localization of quasiperiodic, pulsatic signal in a correlated mixture

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (401 KB) |  | HTML iconHTML  

    We propose a method for estimating the fundamental frequency and localizing a pulsatic, quasiperiodic signal in a correlated mixture. The spectra of the correlated signal is obtained by using the short-time Fourier transform (STFT). For a quasiperiodic, pulsatic signal, the frequency signal variation over the frame index is itself quasiperiodic and pulsatic. In a mixture, the overlap of the spectra of the second signal can erase this quasiperiodic and pulsatic property for a subset of frequency indices. Applying singular value decomposition (SVD) with different frame lengths to these frequency index signals, we can determine the length for which the sum of the ratio of the first over the second singular values is maximum. From this frame length, the fundamental frequency can be calculated. To localize the pulsatic signal, we apply the inverse STFT to the frequency bins where the ratio of singular values are large to obtain a time domain signal. This time domain signal gives an approximation to the position of the pulsatic signal in the mixture. View full abstract»

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  • Towards three-dimensional fusion of infrared guidance measurements for biopsy procedures: Some preliminary results and design considerations

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (382 KB) |  | HTML iconHTML  

    A system comprising of a digital infrared sensitive camera and high intensity infrared illuminator was used to track infrared reflective tape on a coaxial biopsy needle. Data was sent in real-time to a computer where needle position with respect to the desired path was displayed in 2D, enabling instant corrections in needle trajectory by the operator. In this preliminary study, two operators each performed 30 simulated computed tomography (CT) guided biopsies of targets within a phantom. The operators alternated between freehand and infrared guided techniques with the axial angular error statistically compared. The mean axial angular error significantly decreased for both operators for the infrared guidance technique compared to the freehand method. The operators found the 2D simulation and training system easy to learn and intuitive to use despite no prior training on the device. In this paper we also look at further developing the 2D system (used in the simulated CT biopsy trials) into a 3D needle tracking system. We consider what is involved in its integration into a volume rendering simulation and training module, which would allow real-time needle placement in any plane on simulated patient anatomy. The proposed simulation and training module would further help improve the operator's spatial reference, improve accuracy, increase confidence, decrease radiation exposure to the patient and help reduce the time it takes to perform a biopsy. View full abstract»

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  • Ultra-wideband technology-based ranging platform with real-time signal processing

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (275 KB) |  | HTML iconHTML  

    The ultra-wideband (UWB) technology is recognized as an ideal candidate to provide accurate localization in challenging indoor environments where other technologies, e.g. WiFi or ZigBee cannot yield good accuracy due to their signal bandwidth limitation. The energy detection receiver is currently one of the most promising low complexity non-coherent architectures that neither requires high sampling rates nor information about the channel. Despite a vast body of research on UWB ranging and localization, relatively little knowledge is available regarding practical implementations of the proposed ideas. Although there are some testbeds already proposed and built, most of them imply a sort of correlation and require very high sampling rates (in the order of several GS/s) which are still difficult to realize in hardware. Moreover, the majority of the platforms does not support visualization of results in real-time. In this paper, a UWB-based ranging platform with real-time signal processing is presented. It is based on the time-of-arrival (ToA) technique and relatively simple to implement non-coherent energy detection (ED) receiver architecture. Our first measurement results indicate that it is possible to achieve ranging accuracy of 1-3 cm with the sampling rate of 1 GS/s and with max. 3 bits of the A/D resolution. View full abstract»

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  • A new approach to design a WLAN-based positioning system

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (216 KB) |  | HTML iconHTML  

    In recent years, as the deployment of Wireless Local Area Networks (WLAN) in dense-urban areas is growing rapidly, it can be a perfect supplement for providing location information of users in indoor environments where other positioning techniques such as GPS, are not much effective. However, most systems only focus on the network deployment for positioning but overlook that the original purpose of these WLAN infrastructures is providing the required connectivity. Furthermore, there is a lack of good analytical models that can be used as a framework for designing and deploying the positioning systems. In this paper, we propose an effective approach where WLAN planning and positioning error reduction are modeled as an optimization problem and tackled together during the WLAN planning process. A Mono-objective algorithm and a multi-objective algorithm both based on Variable Neighborhood Search (VNS) are implemented respectively and the simulations demonstrate that these two algorithms are highly efficient for designing the indoor positioning system. View full abstract»

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  • Analysis of RSS improved RFID estimation

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (163 KB) |  | HTML iconHTML  

    Signal strength (SS) based tag estimation significantly improves the accuracy and speed of RFID tag interrogation. In, SS estimation was applied to a Manchester based RFID system and a formula for the lower bound on number of tags was derived. This paper analytically extends this analysis to a comprehensive list of encoding formats including all those used in commercially available tags. The developed formulas are shown to be based on properties of the line encoding. Our analysis shows that Manchester is the most appropriate encoding scheme for the signal strength estimation method. View full abstract»

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  • Degree of Inconsistency: Iterative localization with error control

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (130 KB) |  | HTML iconHTML  

    A novel iterative localization algorithm based on Particle Filter with error control is proposed in this paper. First, each node's location is estimated by a cloud of particles and their weights. Second, Degree of Inconsistency(DoI) is proposed to detect the nodes with high error. DoI makes full use of the fact that node density is high and they are randomly and uniformly distributed. The nodes with large error could be gradually identified by DoI and their estimated locations are then updated wisely to get higher accuracy. The proposed algorithm only needs local information and it is implemented in a distributive way. Simulation results show that the proposed error control strategy can solve error propagation problem successfully and provide relative high accuracy, especially in network with high ranging error and low beacon density. View full abstract»

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  • Geolocation of WiMAX subscriber stations based on the timing adjust ranging parameter

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (190 KB) |  | HTML iconHTML  

    This paper examines the geolocation of standard compliant WiMAX subscriber stations based on timing adjust values captured from the air interface during network entry and initial ranging. Field tests were conducted to verify a linear correlation between timing adjust and distance. Repeated observations at fixed distances established the variance within timing adjusts. Results of this field testing were extended to multiple base station networks modeled in computer simulation, ultimately suggesting the possibility for geolocations based on WiMAX initial ranging with ten times greater accuracy then similar methods applied to GSM. View full abstract»

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  • RSS-based distance measurement in Underwater Acoustic Sensor Networks: An application of the Lambert W function

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (127 KB) |  | HTML iconHTML  

    Fast and accurate distance measurement is crucial for target tracking and node localization in Wireless Sensor Networks. For short-range Underwater Acoustic Sensor Networks (UASNs), received signal strength (RSS) can give distance between acoustic devices. An extensive study on the application of the Lambert W function over RSS for distance estimation in short-range UASNs shows that it can be done accurately in as few as 4 iterations. The method is mathematically derived in this paper and the accuracy verified with Matlab simulation. View full abstract»

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  • A cluster based time division multiple access scheme for surveillance networks using directional antennas

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2238 KB) |  | HTML iconHTML  

    Surveillance networks are of importance in tactical and civilian applications. In this work we present a scheduling algorithm for a time division multiplexing based medium access control protocol for such networks, which employ directional antennas. The scheduling algorithm uses the attributes of a multi hop clustering scheme also used to aggregate data from cluster clients to cluster heads. We evaluated the scheme in networks of up to one hundred nodes to assess its scalability. The performance assessment was done using Opnet simulation tool and the results are presented for two variations of the scheduling algorithm. View full abstract»

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  • Blind identification and real-time calibration of memory nonlinearity based on RLS algorithm

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (721 KB) |  | HTML iconHTML  

    Regular broadband software radio receivers could not simultaneously satisfy the requirements for high power efficiency and high dynamic acquiring. This paper develops a real-time digital calibration system based on recursive least square algorithm. A blind identification criterion for the minimizing of the total energy of the nonlinear distortions in the compensated output is designed as the characteristic of the input signal can hardly be obtained by the receiver in advance. The coefficients of the nonlinear model are measured and adaptively updated with the nonstationary input signals. Results on both multi-tone and 16-QAM modulating signals show that with the proposed system, the Spurs-Free-Dynamic-Range (SFDR) of the effective receiver's front-end working in nonlinear region would achieve 20 dB's improvement. View full abstract»

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  • A joint distributed resource management and scheduling scheme for future UWB-based high-rate WPAN

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (209 KB) |  | HTML iconHTML  

    In this paper, we investigate the resource management and scheduling issues for the future UWB-based high-rate WPAN systems. Based on a distributed management architecture, we propose a novel multiple access scheme in the context of multiuser channel and time allocation for the UWB applications. Using a self-learning and managing approach, the distributed resource allocation is based on the exchange of useful information among the existing users to achieve a priority-based scheduling. A service differentiation principle is thus followed to guarantee a high level of QoS support for high-priority applications that have strict requirements. However, with the evidence of the service urgency that gives some type of applications a kind of privileged and high-prioritized medium access, fairness among all the users has to be taken into consideration in order not to decrease significantly the performance of some low-priority applications for the sake of other ones. Simulation results demonstrate the efficiency of the simple scheduling scheme that ensures fairness among the competing users while guaranteeing the QoS support for high-priority users. View full abstract»

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  • A low complexity scheduling for maximizing satisfied users in wireless networks

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (146 KB) |  | HTML iconHTML  

    Traditional scheduling algorithms are focused in maximizing system throughput considering a grade of fairness. However, maximizing the system throughput does not necessarily result in maximizing the number of satisfied users (users with a packet delay below a threshold). More over, the throughput maximization could cause a low grade of fairness. In this paper, we propose a low complexity scheduling algorithm that improves fairness and maximizes the number of satisfied users in the system. The main idea of this algorithm is to find the optimum data transmission rate for each user, based on their statistical channel variations and their required qualities of service (QoS). The algorithm dynamically adapts to the optimum data transmission rate for each user according to their channel variations. We consider a channel gain that reflects the effects of shadowing and multipath fading. The results show that, with this algorithm, the system capacity is increased 10% and the throughput for user in bad channel conditions increased 42% over the Modified Largest Weighted Delay first (M-LWDF) scheduler. View full abstract»

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