Three fast search routines to be used in the encoding phase of vector quantization (VQ) image compression systems are presented. These routines, which are based on geometric considerations, provide the same results as an exhaustive (or full) search. Examples show that the proposed algorithms need only 3-20% of the number of mathematical operations required by a full search and fewer than 50% of the operations required by recently proposed alternatives.

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s-The psychophysical properties of a multiple-channel neuralcounting model are investigated. Each channel represents. a peripheral afferent fiber (or a group of such fibers) and consists of a cascade of signal-processing transformations, each of which has a physiological correlate in the auditory system. The acoustic signal (which may be a pure tone or Gaussian noise) is passed by our mathematical construct through the following series of transformations: an outer-and middle-ear transmission function, an inner-ear multiple-pole linear-filter tuning mechanism, a nonlinear receptor saturation function, and a refractoriness-modified Poisson transduction mechanism (which leads to a sub-Poisson neural spike count). Spontaneous neural activity is independently incorporated into each channel by means of an additive refractoriness-modified Poisson process. A union process at a more distal center in the nervous system is generated by a parallel collection of such channels with a density (in frequency) determined by the cochlear mapping function. The statistics of the union count (in a fixed time) are then processed at a decision center in a manner that depends on the psychophysical paradigm under consideration. This random count number is assumed to contain all of the information for the examples we consider. Our model has been used to calculate psychophysical functions for the following paradigms: pure-tone loudness estimation, pure-tone and variable-bandwidth noise intensity discrimination, and variable-bandwidth noise loudness summation. The theoretical results, which are determined in large part by spread of excitation, are in good agreement with human psychophysical data, provided that the parameters of the theoretical model are appropriately chosen. It has been found that a suitable choice of parameters is both physiologically sensible and self-consistent. As a further indication of the consistency of the model, the same general parametric dependencies as neurophysiological isointensity contours for peripheral afferent fibers in the squirrel monkey are exhibited by the single-channel theoretical count mean, which is calculated as a function Manuscript .of stimulus level and frequency. The single-channel count mean-to-variance ratio is in accord with laboratory data. Finally, the roles of the various components comprising our theoretical system are discussed, and our model is compared with related constructs.

Abstract-One of the major challenges in supporting multimedia services over Internet protocol (IP)-based code-division multiple-access (CDMA) wireless networks is the quality-of-service (QoS) provisioning with efficient resource utilization. Compared with the circuit-switched voice service in the second-generation CDMA systems (i.e., IS-95), heterogeneous multimedia applications in future IP-based CDMA networks require more complex QoS provisioning and more sophisticated management of the scarce radio resources. This paper provides an overview of the CDMA-related QoS provisioning techniques in the avenues of packet scheduling, power allocation, and network coordination, summarizes state-of-the-art research results, and identifies further research issues.Index Terms-Code-division multiple-access (CDMA), intercell coordination, multimedia services, packet scheduling, power allocation, quality-of-service (QoS), soft handoff.

In this paper, we propose intelligent call admission control for wideband code-division multiple-access (CDMA) cellular systems to support differentiated quality-of-service (QoS) requirements, guarantee the forced termination probability of handoffs, and maximize the spectrum utilization. The intelligent call admission controller (ICAC) contains a fuzzy call admission processor to make admission decision for a call request by considering QoS measures such as the forced termination (drop call) probability of handoff, the outage probability of all service types, the predicted next-step existing-call interference, the link gain, and the estimated equivalent interference of the call request. The pipeline recurrent neural network (PRNN) is used to accurately predict the next-step existing-call interference, and the fuzzy logic theory is applied to estimate the new/handoff call interference based on knowledge of effective bandwidth method. Simulation results indicate that ICAC achieves system capacity higher than conventional CAC schemes by an amount of more than 10% in both low and high moving speed cases. Moreover, ICAC can cope with the unpredictable statistical fluctuation of wireless multimedia traffic; it always fulfill QoS requirements for all service types and keep the forced termination probability satisfied, while the CAC of multimedia calls (MCAC) and SIR-based CAC with intercell interference prediction (PSIR-CAC) fail to adapt to the variation of traffic conditions. Index Terms-Call admission control, equivalent interference, fuzzy logic, handoff, neural network.