The performance of the two-cell random access algorithm which is stable with a relatively high throughput of 0.429 and good delay performance is studied in a mobile environment in the presence of capture, Rayleigh fad...
详细信息
The performance of the two-cell random access algorithm which is stable with a relatively high throughput of 0.429 and good delay performance is studied in a mobile environment in the presence of capture, Rayleigh fading, shadowing and path loss. Three distinct antenna diversity plans, two-fold, maximum selection and ideal selection diversity are employed to improve the performance of the two-cell algorithm. Maximum throughputs and optimal window sizes of the two-cell random access algorithm for the capture model and the diversity schemes are analytically computed. The delay performance of the proposed algorithm is evaluated through simulations and compared to that of slotted ALOHA under various mobile scenarios.
We propose an adaptive random access algorithm for mobile environments with capture. The algorithm has a dynamic window size which is updated according to the traffic intensity. The packet arrival rate is tracked by e...
详细信息
We propose an adaptive random access algorithm for mobile environments with capture. The algorithm has a dynamic window size which is updated according to the traffic intensity. The packet arrival rate is tracked by employing sequential detection procedures. Simulations indicate that changing the window size adaptively reduces the average delay under heavy load conditions.
In this research, we propose a new iterative shape from texture (SFT) algorithm which extracts accurate surface depth information of a curved object covered with fairly homogeneous texture directly. The shape informat...
详细信息
In this research, we propose a new iterative shape from texture (SFT) algorithm which extracts accurate surface depth information of a curved object covered with fairly homogeneous texture directly. The shape information can be inferred from the rate of texture distortion depicted in an image, and therefore the modeling of the projection and surface geometry as well as the estimation of local texture variation are crucial in obtaining accurate surface shape of an object. By introducing semi-perspective projection camera model and a parametric surface model, we establish a new SFT problem formulation called the textural irradiance equation which relates the local texture density called textural intensity to finite surface parameters. Moreover, by adopting an adaptive multiscale filtering scheme for local texture density estimation, in which the scale or frequency band of a local edge filter is chosen adaptively according to the local shape information, we greatly enhance the accuracy of the estimation of the projected local texture densities, and the final reconstructed shape. We demonstrate the performance of the proposed algorithm by the test with several synthetic and real texture images.
We consider a distributed system where sensors make location parameter estimates using their observations. A central processor collects the local estimates and declares a final estimate based on them. We present a sim...
详细信息
We consider a distributed system where sensors make location parameter estimates using their observations. A central processor collects the local estimates and declares a final estimate based on them. We present a simple study of the convergence properties of three structures where empirical mean and M-estimates are used in various combinations. It is shown that when occasional outliers exist, decentralized estimators that provide robustness at stages where data corruption occurs perform superiorly. (C) 1997 Elsevier Science B.V.
In the frequency estimation of sinusoidal signals observed in impulsive noise environments, techniques based on Gaussian noise assumption are unsuccessful. One possible way to find better estimates is to model the noi...
详细信息
In the frequency estimation of sinusoidal signals observed in impulsive noise environments, techniques based on Gaussian noise assumption are unsuccessful. One possible way to find better estimates is to model the noise as an alpha-stable process and to use the fractional lower order statistics of the data to estimate the signal parameters. Noise and signal subspace methods, namely the MUSIC and principal component-Bartlett methods, are applied to fractional lower order statistics of sinusoids embedded in alpha-stable noise. The simulation results show that techniques based on lower order statistics are superior to their second order statistics-based counterparts, especially when the noise exhibits a strong impulsive attitude.
This paper is concerned with reducing the rank of the adaptive weight vector in radar array signalprocessing. The motivation for reducing the rank is that modern space-time processing requires many more weights than ...
详细信息
This paper is concerned with reducing the rank of the adaptive weight vector in radar array signalprocessing. The motivation for reducing the rank is that modern space-time processing requires many more weights than can be supported on airborne and space-segment platforms. The loss incurred in partially adaptive radar processing is that the steady-state Wiener solution of the lower rank weight vector may not perform as well as the full rank solution. Hence, this paper examines the Wiener solution of partially adaptive radar arrays and compares the performance of principal component techniques with the cross-spectral technique.
Due to the feedback characteristics of Hopfield networks, the solutions often get stuck at local minima where the objective functions have surrounding barriers. The theory and procedure of hardware annealing, which ca...
详细信息
Due to the feedback characteristics of Hopfield networks, the solutions often get stuck at local minima where the objective functions have surrounding barriers. The theory and procedure of hardware annealing, which can retrieve the optimal solution in parallel, have been developed. In hardware annealing, voltage gains of output neurons in asynchronous VLSI neural chips are increased from an initial low value to a final high value in a continuous fashion. Hardware annealing can be applied to pure analog and mixed analog-digital neurocomputing systems. It achieves a speed-up factor of more than 10000 times over simulated annealing on a SUN-3/60 workstation.< >
暂无评论