Analysis of multi-lead QT dispersion by means of an algorithm implemented on Labview

QT dispersion measurement is significant in diagnostic ECG, and several methods are proposed in the literature to implement QT measurement. This study consists of two parts: The first part was the development of an algorithm to measure both QT interval and QT dispersion. To check the reliability of the algorithm, 25 single channel ECGs were recorded and their QT intervals were computed. On two subjects, three and four lead ECG data were recorded respectively and their QT dispersions were statistically analyzed. Another part of this study dealt with the effect of the electric dipole of the heart on QT dispersion. It was found that the mean and the standard deviation of the resulting QT dispersions were significantly smaller than those found in previous studies. In near and far field analysis, subjecting the data to a student\u27s T test revealed that both near and far field QT dispersion data were drawn from the same population

Ultra Wideband Impulse Radio Systems with Multiple Pulse Types

In an ultra wideband (UWB) impulse radio (IR) system, a number of pulses, each transmitted in an interval called a "frame", is employed to represent one information symbol. Conventionally, a single type of UWB pulse is used in all frames of all users. In this paper, IR systems with multiple types of UWB pulses are considered, where different types of pulses can be used in different frames by different users. Both stored-reference (SR) and transmitted-reference (TR) systems are considered. First, the spectral properties of a multi-pulse IR system with polarity randomization is investigated. It is shown that the average power spectral density is the average of the spectral contents of different pulse shapes. Then, approximate closed-form expressions for the bit error probability of a multi-pulse SR-IR system are derived for RAKE receivers in asynchronous multiuser environments. The effects of both inter-frame interference (IFI) and multiple-access interference (MAI) are analyzed. The theoretical and simulation results indicate that SR-IR systems that are more robust against IFI and MAI than a "conventional" SR-IR system can be designed with multiple types of ultra-wideband pulses. Finally, extensions to multi-pulse TR-IR systems are briefly described.Comment: To appear in the IEEE Journal on Selected Areas in Communications - Special Issue on Ultrawideband Wireless Communications: Theory and Application

The Cramer-Rao bounds of hybrid TOA/RSS and TDOA/RSS location estimation schemes

In short range communications, the use of RSS measurements in conjunction with TOA or TDOA leads to enhanced estimation accuracy with respect to the case where only TOA or TDOA are used. In this article, we derive the Cramer-Rao Bound (CRB) for location estimation accuracy of two different hybrid schemes: TOA/RSS and TDOA/RSS. For short ranges, the hybrid schemes offer improved accuracy, particularly in the proximity of the reference devices

Optimum Power Compensation for Error Propagation In Relay-Assisted Wireless Networks

It is known that relay assisted wireless transmission in a triplet, which consists of a source node, intermediate relay node and a destination node results in less power consumption than direct transmission between the source and destination pair. However, extra power compensation is needed for error propagation in the relay-assisted scenario to provision the same end-to-end bit error rate (BER) constraint as the direct transmission. This key point is neglected in the literature. In this paper, we first quantify the impact of power compensation on power savings due to relaying for M-ary QAM modulation schemes, and compare power savings performances of simple relaying and regenerative repeating at the intermediate node. Second, we present upper and lower bounds for the power savings under consideration of lognormal shadowing

A Rayleigh Quotient-Based Recursive Total-Least-Squares Online Maximum Capacity Estimation for Lithium-Ion Batteries

The maximum capacity, the amount of maximal electric charge that a battery can store, not only indicates the state of health, but also is required in numerous methods for state-of-charge estimation. This paper proposes an alternative approach to perform online estimation of the maximum capacity by solving the recursive total-least-squares (RTLS) problem.Different from prior art, the proposed approach poses and solves the RTLS as a Rayleigh quotient optimization problem. The Rayleigh quotient-based approach can be readily generalized to other parameter estimation problems including impedance estimation. Compared with other capacity estimation methods, the proposed algorithm enjoys the advantages of existing RTLS-based algorithms for instance, low computation, simple implementation, and high accuracy, and thus is suitable for use in real-time embedded battery management systems. The proposed method is compared with existing methods via simulations and experiments