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Abstract-In this paper, Cramer-Rao lower bounds are derived 4for joint estimation of respiration and heartbeat rates via impulse radio ultra-wideband signals. Generic models are employed for I ____ displacement functions due to respiration and heartbeat, and the -T bounds are obtained for the cases of known and unknown channel Fig. 1 Transimitted signal structure for joint estimation of respiration and coefficients. In addition, a two-step suboptimal estimator is pro-heartbeat parameters. posed, which is based on joint time-delay estimation followed by a least-squares approach. It is shown that the proposed estimator is respiratory detection of hidden humans using UWB signals asymptotically optimal under mild conditions. Simulation studies are performed to evaluate the lower bounds and performance of is implemented. A mathematical framework for estimation of the proposed estimator for realistic system parameters.vital signal parameters is established in [4], which employs Index Terms-Ultra-wideband (UWB), impulse radio (IR), the Fourier transform and motions filters for estimation of Cramer-Rao lower bound (CRLB), least-squares (LS) estimation. respiration and heartbeat rates.In Consider a sequence of pulse bursts as shown in Figure 1, advantages such as high penetration capability which fa-which is mathematically expressed as cilitates through-the-wall applications, and low transmission are investigated. The channel characteristics for the signals k=O refilectilng fromn a humanar chest are studied in [6], which also where N is the number of bursts, Ts is the burst period, and preselnts an algorithmL for respiration rate estimnatioln. Inr [8], w(t) is a burst of pulses, which consists of Alt pulses and is t) The authors are with the Department of Electrical and Electronics 1Since reflections from a heart are much weaker than those from a human Engineering, BilLkent University, BilLkent, Ankara TR-06800, Turkey, emlail: chest, the respiration rate estimation problem can omlit the signalLs reflecting {gezici oarikan} @eehbilkent.edu.tr from the heart; hence, it can he studied in the framework proposed in [7].

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Abstract. Printing color images on color printers and displaying them on computer monitors requires a significant reduction of physically distinct colors, which causes degradation in image quality. An efficient method to improve the display quality of a quantized image is error diffusion, which works by distributing the previous quantization errors to neighboring pixels, exploiting the eye's averaging of colors in the neighborhood of the point of interest. This creates the illusion of more colors. A new error diffusion method is presented in which the adaptive recursive leastsquares (RLS) algorithm is used. This algorithm provides local optimization of the error diffusion filter along with smoothing of the filter coefficients in a neighborhood. To improve the performance, a diagonal scan is used in processing the image. © 2000 Society of Photo-Optical Instrumentation Engineers. [S0091-3286(00)