This paper presents an architecture for a table-lookup (TLU) engine that allows the real-time operation of complicated TLU for telecommunications, such as the longest prefix match (LPM) and the long-bit match in packet classification. The engine consists of many CAM (Content Addressable Memory) chips, which are classified into several groups. When actual TLU is performed, the entries in each CAM group are searched simultaneously, and the best entry candidate in each group is selected by an intra-group arbiter. The final output, the entry desired, is decided by an inter group arbiter that selects one group. This hierarchical structure of arbitration is the key to the scalability of the engine. To accelerate the operation speed of the engine, we introduce a novel mechanism called "hit-flag look-ahead" that sends a hit-flag signal from each matched CAM chip to the inter group arbiter before each intra group arbiter calculates the best CAM output in the group. We show that a TLU engine based on the above architecture achieves significantly fast performance compared to engines based on conventional techniques, especially in the case of a large number of entries with long-bit matching. Furthermore, our architecture can realize an 33.3 Mlps (lookups per second) within a 128 bit 300,000-entry table at wire speed.

In this paper we propose two diagnosis methods for crosstalk-induced pulse faults in sequential circuits using crosstalk fault simulation. These methods compare observed responses and simulated values at primary outputs to identify a set of suspected faults that are consistent with the observed responses. The first method is a restart-based method which determines the suspected fault list by using the knowledge about the first and last failures of the test sequence. The advantage of the restart-based method over a method using full simulation is its reduction of the number of simulated faults in a process of diagnosing faults. The second method is a resumption-based method which uses stored state information. The advantage of the resumption-based method over the restart-based method is its reduction of the CPU time for diagnosing the faults. The effectiveness of the proposed methods is evaluated by experiments conducted on ISCAS '89 benchmark circuits. From the experimental results we show that the number of suspected faults obtained by our methods is sufficiently small, and the resumption-based method is substantially faster than the restart-based method.

This paper presents a practical fault model for delay testing, called a multiple-threshold gate-delay fault model, to obtain high quality tests that guarantee the detection of delay faults for various extra-delays. Fault efficiencies for multiple thresholds of the extra-delay are introduced as a coverage metric that describes the quality of tests. Our approach guarantees that each gate-delay fault is tested on the path that is almost the longest one passing through the faulty line by using two-pattern tests with pattern-independent timing. We present the procedures of the path selection, fault simulation, and the test generation, where the path-status graph technique is used as not to rely on the enumeration of paths. Experimental results for benchmark circuits demonstrate that the proposed metric gives useful information that transition fault efficiency cannot, and that the proposed test generation can achieve high fault efficiencies for multiple-threshold gate-delay faults.

In this paper we present the analog architecture and the implementation of an on-chip learning Multi Layer Perceptron network. The learning algorithm is based on Back Propagation but it exhibits increased capabilities due to local learning rate management. A prototype chip (SLANP, Self-Learning Neural Processor) has been designed and fabricated in a CMOS 0.7 µm minimum channel length technology. We report the experimental results that confirm the functionality of the chip and the soundness of the approach. The SLANP performance compare favourably with those reported in the literature.

This paper investigates the behavior of one-dimensional discrete-time binary cellular neural networks with both the A- and B-templates and gives the necessary and sufficient conditions for the above network to be stable for unspecified fixed boundaries.

A quasi-synchronous (QS) Multi-Carrier time division duplex DS-CDMA is studied for reverse link on multipath indoor environment. Quasi-synchronous DS-CDMA drastically reduces the effect of multiple access interference with several interesting features of time division duplex (TDD) mode for mobile communications. In this paper, we use the time division duplex transmission mode and each user appropriately adjusts its transmission time, through feed back control from the base station, so its signal can arrive at the base station synchronously with the other mobile stations. This paper evaluates the performance of a quasi-synchronous multi-carrier TDD DS-CDMA for reverse link on multipath indoor environment. The performance results are shown with different quasi-synchronous accuracy and power control error values. Orthogonal codes are used for spreading the signals in QS transmission. On the other hand, random codes are used for an asynchronous transmission. From the results, when the performance of asynchronous system is assumed to be a reference, we can see that the constraint of quasi-synchronous accuracy equals 2.3 chips of multi-carrier system at spreading factor 32.

Uniform color spaces are very important in color engineering, image source coding and multimedia information processing. In spite of many efforts have been paid on the subject, however, construction of an exact uniform color space seems difficult until now. Existing approaches mainly used local and heuristic approximations. Moreover, there seemed also certain confusion in definitions of the uniform spaces. In this paper we discuss the issue from a point of view of global Riemannian geometry. The equivalence between global and local definitions of uniform space are shown. Then both an exact and a simplified algorithm are presented to uniformize either a part or the totality of a color space. These algorithms can be expected to find applications in optimal quantization of color information.

A DS-CDMA mobile communication system accommodating multi-class users is considered. The number of supportable users depends on the distributions of data rate and required communication quality among users. Simple expressions for the reverse link capacity with transmit power control, antenna diversity, and rake combining, are derived for a single-cell system and a multi-cell system.

The Belousov-Zhabotinsky (BZ) reaction provides us important clues in controlling 2D phase-lagged stable synchronous patterns in an excitable medium. Because of the difficulty in computing reaction-diffusion systems in large systems using conventional digital processors, we here propose a cellular-automaton (CA) circuit that emulates the BZ reaction. In the circuit, a two-dimensional array of parallel processing cells is responsible for fast emulation, and its operation rate is independent of the system size. The operations of the proposed CA circuit were demonstrated by using a simulation program with integrated circuit emphasis (SPICE).

In loudspeaker-based 3D audio systems, there are some acoustic crosstalk cancellation methods to enlarge the 'sweet spot' around a fixed listener position. However, these methods have common defect that most of them can be applied only to the specific narrow frequency band. In this letter, we propose the more robust acoustic crosstalk cancellation method so that we can cancel the crosstalk signal in far wider frequency band and enlarge 'sweet spot. ' For this goal, we apply a sum and difference filter to the conventional three loudspeaker-based 3D audio system.

Active integrated antennas are a maturing topic. Many novel configurations have been described and system designers are how investigating how the advantages of compactness and increased functionality can be exploited in applications. In this paper, the various types of integrated antennas are discussed together with possible ways of exploiting the technology. New configurations of direct conversion integrated antennas are then described in detail, which illustrate some of the possibilities inherent in the technology.

This paper proposes a novel packet classification method using ternary content-addressable memory (TCAM), which can store very wide policy rules despite the limited width of TCAM. For IP version 6, policy rules could be 304 bits wide. This method enables us to use commercially available TCAM for packet classification and thus builds an ultra high-speed policy based packet forwarding engine for differentiated services on the Internet.

Vector quantization (VQ) is an attractive image compression technique. VQ utilizes the high correlation between neighboring pixels in a block, but disregards the high correlation between the adjacent blocks. Unlike VQ, side-match VQ (SMVQ) exploits codeword information of two encoded adjacent blocks, the upper and left blocks, to encode the current input vector. However, SMVQ is a fixed bit rate compression technique and doesn't make full use of the edge characteristics to predict the input vector. Classified side-match vector quantization (CSMVQ) is an effective image compression technique with low bit rate and relatively high reconstruction quality. It exploits a block classifier to decide which class the input vector belongs to using the variances of neighboring blocks' codewords. As an alternative, this paper proposes three algorithms using gradient values of neighboring blocks' codewords to predict the input block. The first one employs a basic gradient-based classifier that is similar to CSMVQ. To achieve lower bit rates, the second one exploits a refined two-level classifier structure. To reduce the encoding time further, the last one employs a more efficient classifier, in which adaptive class codebooks are defined within a gradient-ordered master codebook according to various prediction results. Experimental results prove the effectiveness of the proposed algorithms.

This letter proposes recursive space-time TCM with two transmit antennas. A recursive component code is crucial in a serial or parallel concatenation scheme. These codes were obtained through computer search and their performance was simulated and compared with previously known codes.

Using less wavelengths to serve more communication channels is one of the primary goals in the design of WDM networks. By installing wavelength converters at some nodes in a network, the number of wavelengths needed can be reduced. It has been observed that the more converters installed in a network, the less number of wavelengths is needed, given the same network load. In this paper, we study the relationship between the number of converters and the number of wavelengths needed in a system, and propose a suite of theories and results on how to place the minimal number of converters in the system so that the number of wavelengths W is at most a constant α times the maximal link load L (i.e., W α L), where α = 3/2 or 5/3. The results show a significant saving of converters in networks of both special topologies and general topology.

Since the deployment of base stations (BS's) is far from optimum in 3-dimensional (3-D) space, i.e., the vertical baseline is relatively shorter than the planar baseline, the geometric degradation of precision of the altitude estimate is larger than that of the planar location. This paper considers the problem of 3-D range location and attempt to improve the altitude estimate. We first use a volume formula of tetrahedron to transform the range measurements to the volume measurements, then a novel pseudo-linear solution is proposed based on a linear relationship between the rectangular and the volume coordinates. Theory analysis and numerical examples are included to show the improved accuracy of the altitude estimate of mobile location. Finally, an improved estimate of 3-D mobile location is given by solving a set of augmented linear equations.

ZCZ sets are families of sequences, whose periodic auto/cross-correlation functions have zero correlation zone at the both side of the zero-shift. They can provide approximately synchronized CDMA systems without intra-cell interference for cellular mobile communications. This paper presents ternary ZCZ sets achieving a mathematical bound, and investigates the average interference parameters for the sets in order to evaluate inter-cell interference. It is shown that they can provide AS-CDMA systems with efficiency frequency usage.

A novel method for the primitive description of the multiprimitive texture is proposed. This method segments a texture by the watershed algorithm into fragments each of which contains one grain. The similar fragments are grouped by the cluster analysis in the feature space whose basis is the morphological size density. Each primitive is extracted as the grain of the central fragment in each cluster.

The lossy magnetic composite material made from soft magnetic metal powder and rubber is widely used as an EMI countermeasure material, due to its higher magnetic loss than those of spinel ferrites in microwave frequencies. In this paper, we clarify the material characteristics by measuring the relative complex permeability r and relative complex permittivity r of two kinds of composite materials in microwave frequencies. Since the composite materials are anisotropic, both r and r are measured as diagonal tensors by utilizing extended S-parameter method. The results show that the imaginary part of r of flaky-powder composite exceeded the Snoek's limit for the spinel ferrites which has been reported so far. The measured r and r are partially compared with those measured by cavity resonator method, and good agreement is obtained.

In this paper, a high performance 3232-bit multiplier for a DSP core is proposed. The multiplier is composed of a block of Booth Encoder, a block of data compression, and a block of a 64-bit adder. In the block of Booth encoder, a conditional sign decision Booth encoder that reduces the gate delay and power consumption is proposed. In the block of data compression, 4-2 and 9-2 data compressors based on a novel compound logic are used for the efficient compressing of extra sign bit. In the block of 64-bit adder, an adaptive MUX-based conditional select adder with a separated carry generation block is proposed. The proposed 3232-bit multiplier is designed by a full-custom method and there are about 28,000 transistors in an active area of 900 µm 500 µm with 0.25 µm CMOS technology. From the experimental results, the multiplication time of the multiplier is about 3.2 ns at 2.5 V power supply, and it consumes about 50 mW at 100 MHz.