In radio surveillance systems we consider the problem of identifying interferers or illegal radios in licensed communication channels. The systems considered are receivers using arrays of antennas for spatial processing. At the output of each antenna, we have a mixture of communication signals. The mixture will depend on the distance of the source radios and the propagation environment. These signals may or may not have the same modulation type. The main four tasks in the radio surveillance system are: Separation of the source signals contained in the data mixture at the array antenna, modulation recognition to identify the illegal radio, direction of arrival estimation to pinpoint the location of the illegal radios, and demodulation to intercept the information contained within the illegal transmission. In this paper we deal with the application of the Fast ICA algorithm to a uniform linear array. Our interest is to separate the independent source signals from the mixture of signals obtained at the sensors. Since the target system operates in the HF domain, where analog modulations dominate, the impinging signals are assumed analog modulated communication signals.

Space-Time Turbo code is an effective method for the enhancement of link capacity and maximizing the link-budget by balancing the coding gain obtained via Turbo codes and the diversity gain obtained through multiple antenna transmission. A study on an antenna selection scheme for Space-Time Turbo code for OFDM systems is presented in this paper. In the proposed method, the systematic bits and the punctured parity bits are sent from the selected antenna for each sub-carrier, while data transmission is suspended from the antenna experiencing poor channel conditions at the receiver. Simulation results show that the proposed method yields a 2.2 dB gain in the required TxEb/N0 relative to the conventional method, and makes the channel estimation accuracy more robust. Moreover, the proposed method reduces transmission power by about 4 dB compared to the conventional method.

Interest in the regulatory issues for Software Defined Radio (SDR) is spreading worldwide since the Federal Communications Commission (FCC) recently recognized SDR and created a new category for SDR authorization. SDR technology will bring enormous benefits to the field of wireless services. However, in order to ensure such benefits, revisions of the radio law and/or related ordinances are required regardless of standardization of the software downloading and other implementation details. In order to define the issues peculiar to SDR and to investigate how conformity evaluation should be conducted for radio equipments whose RF characteristics can be altered by software changes in the field, "Study Group on Software Technology for Radio Equipment" was organized by the Telecom Engineering Center (TELEC) in 2000. This paper summarizes a report of the Study Group that was published in March 2003 including the proposal for "Technical regulation conformity evaluation system," the principal output of the study, which proposes how to prevent unauthorized changes to radio equipment in the field.

We propose a new protocol, Clustered Group Multicast (CGM), for multicasting in ad-hoc mobile networks. In CGM, there is a set of forwarding nodes (called multicast backbone) which are responsible for forwarding multicast datagrams. Unlike the multicasting protocols in wired networks (e.g., Internet) which construct and maintain a shortest path tree for every multicast {source, group} pair, CGM is a mesh-based multicasting protocol in which the connectivity among the nodes in the backbone is of no longer importance. Thus, there is no tree maintenance overhead, but there are more connectivity than trees and yet it can prevent long-term or permanent routing loops from occurring. A key feature of CGM is the use of the advertising agent to reduce advertising traffic to the system. An advertising agent acts as both a server and a client for the purpose of advertising join requests on behalf of its local clients. Because in CGM multicast traffic is only allowed to be delivered over the backbone, CGM restricts the amount of hosts participating in the backbone to decrease the impact of multicast traffic to the system. From the simulation results, the multicast group management traffic and multicast datagram traffic are much less than the other protocols. This is particularly important for wireless networks which lacks bandwidth.

Usually, paintings are more appealing than photographic images. This is because paintings can incorporate styles based on the artist's subjective view of motif. This style can be distinguished by looking at elements such as motif, color, shape deformation and brush texture. In our work, we focus on the effect of "color" element and devise a method for transforming the color of an input photograph according to a reference painting. To do this, we consider basic color category concepts in the color transformation process. We assume that color transformations from one basic color category to another may cause peculiar feelings. Therefore, we restrict each color transformation within the same basic color category. For this, our algorithm first categorizes each pixel color of a photograph into one of eleven basic color categories. Next, for every pixel color of the photograph, the algorithm finds its corresponding color in the same category of a reference painting. Finally, the algorithm substitutes the pixel color with its corresponding color. In this way, we achieve large but natural color transformations of an image.

Computers are increasingly used for implementing control algorithms in safety-critical embedded applications, such as engine control, braking control and flight surface control. Consequently, computer errors can have severe impact on the safety of such systems. Addressing the coupling of control performance with computer related errors, this paper develops a methodology for analyzing the impacts data errors have on control system dependability. The impact of a data error is measured as the resulting control error. We use maximum bounds on this measure as the criterion for control system failure (i.e., if the control error exceeds a certain threshold, the system has failed). In this paper we a) develop suitable models of computer faults for analysis of control level effects and related analysis methods, and b) apply traditional control theory analysis methods for understanding the impacts of data errors on system dependability. An automobile slip-control brake-system is used as an example showing the viability of our approach.

This paper proposes an efficient method for design space exploration of the global optimum configuration for parameterized ASIPs. The method not only guarantees the optimum configuration, but also provides robust speedup for a wide range of processor architectures such as SoC, ASIC as well as ASIP. The optimization procedure within this method takes a two-steps approach. Firstly, design parameters are partitioned into clusters of inter-dependent parameters using parameter dependency information. Secondly, parameters are optimized for each cluster, the results of which are merged for global optimum. In such optimization, inferior configurations are extensively pruned with a detailed optimality mapping between dependent parameters. Experimental results with mediabench applications show an optimization speedup of 4.1 times faster than the previous work on average, which is significant improvement for practical use.

Iterative Logic Arrays (ILAs) are widely used in many applications, e.g., general-purpose processors, digital signal processors, and embedded processors. Owing to the advanced VLSI technology, new defect mechanisms exist in the fabricated circuits. In order to ascertain the quality of manufactured products, the traditional single cell fault model is not sufficient. Therefore, more realistic fault models such as sequential fault models and delay fault models should also be adopted. A cell delay fault occurs if and only if an input transition cannot be propagated to the cell's output through a path in the cell in a specified clock period. It has been shown that all SIC (single input change) pairs of a circuit are sufficient to detect all robustly detectable path delay faults within the circuit. We extend the concept of SIC pairs for iterative logic arrays. We say that an ILA is C-testable for cell delay faults if it is possible to apply all SIC pairs of a cell to each cell of the array in such a way that the number of test pairs for the array is a constant. This is based on a novel fault model, called Realistic Sequential Cell Fault Model (RS-CFM). Necessary conditions for sending this test set to each cell in the array and propagating faulty effects to the primary outputs are derived. An efficient algorithm is also presented to obtain such a test sequence. We use the pipelined array multiplier as an example to illustrate our approach. The number of test pairs for completely testing of the array is only 84. Moreover, the hardware overhead to make it delay fault testable is about 5.66%.

Many carriers are introducing multi-media services to satisfy customer demands for these services. In order to provide such services, carrier must increase their system capacity. It is well known that space division multiple access (SDMA) improves system capacity and is compatible with existing access systems. In order to evaluate the performance of SDMA, we developed an SDMA test bed. The test bed maintains the personal handy phone systems (PHS). The PHS adopts time division multiple access (TDMA). Aiming to compare the performance of SDMA and TDMA using the same analog hardware, the SDMA test bed employs a software-defined radio (SDR) technique. This paper shows the outline and performance of the test bed. The results of laboratory tests indicate that the bit error rate (BER) of the test bed operated in the SDMA mode at under 10-3 when the carrier-tointerference ratio (CIR) was larger than approximately -22 dB. Antenna patterns measured in an anechoic chamber show that the SDMA test bed produces correct antenna patterns when there are three desired signals and one interference signal. The results of the four field tests confirm that the test bed operated while two-multiplex SDMA mode doubled of the traffic and decreased the interference level as compared with the TDMA mode. Furthermore, the test bed operated while threemultiplex SDMA mode improves the traffic about 2.4 to 2.7 times. The SDMA test bed decreased the impact of the adjusted TDMA base station (BS). Therefore, we confirmed that the SDMA improves system capacity without any degradation.

This letter presents a simple A/D converter based on the circle map. The converter encodes a dc input into a binary output sequence and has the trapping window that extracts an available part of the output sequence. Using the available part, the decoder provides an estimation by a fraction with variable denominator: it can realize higher resolution. Theoretical evidences for the estimation characteristics are given.

Critical path selection is an indispensable step for AC delay test and timing validation. Traditionally, this step relies on the construction of a set of worse-case paths based upon discrete timing models. However, the assumption of discrete timing models can be invalidated by timing defects and process variation in the deep sub-micron domain, which are often continuous in nature. As a result, critical paths defined in a traditional timing analysis approach may not be truly critical in reality. In this paper, we propose using a statistical delay evaluation framework for estimating the quality of a path set. Based upon the new framework, we demonstrate how the traditional definition of a critical path set may deviate from the true critical path set in the deep sub-micron domain. To remedy the problem, we discuss improvements to the existing path selection strategies by including new objectives. We then compare statistical approaches with traditional approaches based upon experimental analysis of both defect-free and defect-injected cases.

We propose a new dependable system called PREGMA (Platform for Reliable Environment based on a General-purpose Machine Architecture). PREGMA aims to meet two requirements -- fault tolerance and low cost -- for Internet services. It can provide fault tolerance, so we can avoid system failure and prevent data corruption, even if faults occur. That is, it masks the faults by running multiple replicated servers, each possessing its own data, in a loosely synchronized manner and delivering the majority vote as output to clients. Moreover, PREGMA is composed of COTS (Commercial Off-The-Shelf) components without modification, which makes it possible to offer the services at a low cost. We investigated two approaches for achieving redundancy of the Coordinator, which is the core of PREGMA: using the primary backup method and the active replication method. We evaluated the effectiveness of PREGMA in terms of throughput overhead, data integrity and recovery time. The results for a prototype show that PREGMA using the Coordinator with the primary backup method outperforms that with the active replication method and has throughput only 3% lower than a non-redundant system. The results also show that, in the event of failure, the recovery time is only less than one second and no data corruption occurs.

A new algorithm for fast detection and tracking of moving targets using a mobile video camera is presented. Our algorithm is based on image feature detection and matching. To detect features, we used edge points and their accumulated curvature. When the features are detected they are matched with their corresponding points using a new method called fuzzy-edge based feature matching. The proposed algorithm has two modes: detection and tracking. In the detection mode, background motion is estimated and compensated using an affine transformation. The resultant motion-rectified image is used for detection of the target location using split and merge algorithm. We also checked other features for precise detection of the target. When the target is identified, algorithm switches to the tracking mode, which also has two phases. In the first phase, the algorithm tracks the target with the intention to recover the target bounding-box more precisely and when the target bounding-box is determined precisely, the second phase of tracking algorithm starts to track the specified target more accurately. The algorithm has good performance in the environment with noise and illumination change.

In this letter, a linear variable resistor circuit using an FG-MOSFET (floating-gate MOSFET) is proposed. This is based on Schlarmann's variable resistor and is very simple. The advantage of the proposed circuit is a wide-input range. The utility of the proposed circuit was confirmed by HSPICE simulation with 1.2 µm CMOS process parameters. The simulation results are reported in this letter.

One conventional technique for source localization is to utilize the time-difference-of-arrival (TDOA) measurements of a signal received at spatially separated sensors. A simple TDOA-based location algorithm that combines the advantages of two efficient positioning methods is developed. It is demonstrated that the proposed approach can give optimum performance in geolocation via satellites at different noise conditions.

We succeeded in detoxification of hexachloro-benzene adsorbed on artificially produced fly ash in air by irradiating microwave (2.45 GHz) in the presence of activated carbon powder. Hexachlorobenzene was decomposed by 50-90% at 200-300 by MW irradiation of 1-1.5 min when the ash contained activated carbon by 12 wt% and water by 10 wt%. Chlorinated benzene derivatives are dechlorinated through substitution of chloride anion with hydroxylation produced by basic CaO in the co-presence of activated carbon effectively heated by MW. This method using microwave irradiation enables us to treat the contaminated fly ash in a shorter time and decompose hexachlorobenzene more efficiently than the conventional heating.

The application of fault injection in the context of dependability benchmarking is far from being straightforward. One decisive issue to be addressed is to what extent injected faults are representative of the considered faults. This paper proposes an approach to analyze the effects of real and injected faults.

Among the many scheduling algorithms which can guarantee delay bounds of sessions, the EDF scheduler with regulators has received wide attention since it can admit a very high number of sessions. However, due to regulators, EDF with regulators has difficulty in scalable implementation. To implement a regulator, a buffer and a timer are needed to restrict the incoming traffics. Given N number of sessions, N regulators are required. Moreover, due to regulators, the entire scheduling algorithm is not work-conserving. To enforce work-conserveness, it is known in the literature that additional buffers and a complex mechanism are required to bypass regulators. Thus, scalable implementation becomes much more difficult in the case of the work-conserving EDF with regulators. In this paper, however, we show that the buffers and timers used to implement regulators are unnecessary to guarantee delay bounds of admitted sessions in fixed-sized packet networks. Then, we can remove those unnecessary buffers and timers. By the removal, the resulting scheduling algorithm can be implemented in a scalable way and becomes work-conserving for free.

Two important lemmas on the determinant of random matrixes are deduced in this paper. Then based on these results, expression for the mean capacity of MIMO system over Rayleigh fading channels is obtained. This expression requires little calculation and is simple and efficient compared with conventional methods, and furthermore, it gives an explicit relation on the mean capacity of MIMO systems with antenna numbers and the relation of mean capacity with signal to noise ratio (SNR). Accuracy of this theoretic formula has been verified by computer simulation.

In this letter, iterative sequence estimation technique based on expectation-maximization (EM) algorithm is considered for quadrature amplitude modulation (QAM)-orthogonal frequency division multiplexing (OFDM) signals. For QAM-OFDM signaling, the optimal EM algorithm requires high computational complexity due to the inversion of complex matrix executed at each iteration. To avoid this problem, we propose a sub-optimal iterative sequence estimation algorithm with some approximations, which results in reduced computational complexity for QAM-OFDM signals. Moreover, we use two different approaches to obtain initial estimate for beginning iteration of proposed algorithm. One is for less time-dispersive but fast fading channel and the other is for highly time-dispersive but relatively slow fading channel. The bit error rate (BER) performances of the proposed algorithm are evaluated using computer simulations. The results show that the proposed algorithm performs nearly as well as the optimal EM algorithm.