In the case of personal computers (PCs), interoperability among PCs are sufficiently realized with the advent of Microsoft Windows to take the position of mainstream OS, and major software applications following the mainstream for standardization, for more and more user-friendly human machine interface. Considering the case for PCs as above, it is not surprising to us at all, if the same concept is pursued in a radio communications terminal, which can freely access to different radio systems just by replacing the embedded software. This means that the prospective end user will gain the benefit to be able to change his radio set to one of the desired systems in the field, by installing the software of his choice. Such radio equipment is called Software Defined Radio (SDR), and various kinds of applications are expected for development in many fields. However, for the SDR to be in widespread use, we have many outstanding issues to be solved, which are not limited only in the technical matters. One barrier is interoperability among manufacturers. Namely, even when a technical problem is solved, the appropriate technical solution should be shared for the interoperability among as many manufacturers as possible. If such interoperability is unachievable, that technical solution could only be for internal use within the specific manufacturer, failing to take advantage of the true value of the SDR. Another barrier might be the Radio Law of Japan. Unless overcoming this barrier, the commercial implementation of the SDR is unachievable, resulting in the failure to entertain the real benefit from the SDR implication. Under such a background, this paper first describes the concept of and definition for the SDR to make them clearer for the readers. Then, the interoperability issue, which would be the key to the widespread use of SDR, is taken up as next topic. The last topic is focused on the legal and regulatory issue, to discuss what would be the problem under the Radio Law of Japan.

For real-time systems, multiprocessor support is indispensable to handle the large number of requests. Existing on-line scheduling algorithms such as Earliest Deadline First Algorithm (EDF) and Least Laxity Algorithm (LLA) may not be suitable for scheduling hard real-time tasks on multiprocessors. Although EDF has a low context switching overhead, it can produce arbitrarily low processor utilization. LLA has been shown as suboptimal, but has the potential for higher context switching overhead. We propose new on-line scheduling algorithms Earliest Deadline/Least Laxity (ED/LL) and Earliest Deadline Zero Laxity (EDZL) for identical multiprocessors. We show that ED/LL is suboptimal for multiprocessors and EDZL is suboptimal for two processors. Experimental results show that ED/LL and EDZL have low context switching overhead and low deadline miss rate.

In OFDM-CDMA down link (base-to-mobile) transmissions, each user's transmit data symbol is spread over a number of orthogonal sub-carriers using an orthogonal spreading sequence defined in the frequency-domain. The radio propagation channel is characterized by a frequency- and time-selective multipath fading channel (which is called a doubly selective multipath fading channel in this paper). Frequency-domain equalization is necessary at the receiver to restore orthogonality among different users. This requires accurate estimation of the time varying transfer function of the multipath channel. Furthermore, the noise enhancement due to orthogonality restoration degrades transmission performance. In this paper, pilot-aided threshold detection combining (TDC) is presented that can effectively suppress the noise enhancement. If the estimated channel gain is smaller than the detection threshold, it is replaced with the detection threshold in the frequency equalization. There exists an optimal threshold that can minimize the bit error rate (BER) for a given received Eb/N0. The average BER performance of OFDM-CDMA down link transmissions using the TDC is evaluated by computer simulations. It is found that TDC using optimum detection threshold can significantly reduce the BER floor and outperforms DS-CDMA with ideal rake combining.

It has been considered difficult to obtain the minimum AND-EXOR expression of a given function with six variables in a practical computing time. In this paper, a faster algorithm of minimizing AND-EXOR expressions is proposed. We believe that our algorithm can compute the minimum AND-EXOR expressions of any six-variable and some seven-variable functions practically. In this paper, we first present a naive algorithm that searches the space of expansions of a given n-variable function f for a minimum expression of f. The space of expansions are generated by using all combinations of (n-1)-variable product terms. Then, how to prune the branches in the search process and how to restrict the search space to obtain the minimum solutions are discussed as the key point of reduction of the computing time. Finally a faster algorithm is constructed by using the methods discussed. Experimental results to demonstrate the effectiveness of these methods are also presented.

A high efficiency feedforward power amplifier (FFPA) with a series diode linearizer for cellular base stations is presented. In order to achieve the highest overall efficiency of an FFPA, an improved pre-distortion diode linearizer has been used and the bias condition of the main amplifier has been optimized. The optimum bias condition has been derived from the overall efficiency analysis of the FFPA with a pre-distortion linearizer. From measured overall performances of the FFPA, efficiency enhancement of the series diode linearizer has been verified. The developed FFPA achieved the efficiency of 10% and output power of 45.6 dBm at 10 MHz offset Adjacent Channel leakage Power Ratio (ACPR) -50 dBc under Wide-band Code-Division Multiple-Access (W-CDMA) modulated 2 carriers signal. This design method can be also used to optimize the source and load impedances condition of the main amplifier FET.

This letter derives low-complexity frame and coarse frequency-offset synchronization techniques for orthogonal frequency division multiplexing (OFDM)-based HIPERLAN (HIgh PErformance Radio LAN) system. We first propose a frame detector structure directly based on the correlation method and a reduced complexity structure having the similar performance compared with conventional correlation method. We then propose a coarse frequency-offset synchronization technique and show the performance of the proposed techniques by simulation.

This paper presents a novel system-level design methodology, called quality-driven design, by which application-specific optimization can be achieved; furthermore the entire functionality can be shared to maximize design reuse. As a case of study, this paper focuses on quality-driven design for video applications and introduces an output quality adaptive approach based on variable bitwidth optimization to explore a new design space. MPEG2 video is used as the driver application to illustrate the potential of the presented methodology. Experimental results show the effectiveness of the methodology.

Deep submicron technology calls for new design techniques, in which wire and gate delays are accounted to have equal or nearly equal effect on circuit behavior. Asynchronous speed-independent (SI) circuits, whose behavior is only robust to gate delay variations, may be too optimistic. On the other hand, building circuits totally delay-insensitive (DI), for both gates and wires, is impractical because of the lack of effective synthesis methods. The paper presents a new approach for synthesis of globally DI and locally SI circuits. The method, working in two possible design scenarios, either starts from a behavioral specification called Signal Transition Graph (STG) or from the SI implementation of the STG specification. The method locally modifies the initial model in such a way that the resultant behavior of the system does not depend on delays in the input wires. This guarantees delay-insensitivity of the system-environment interface. The suggested approach was successfully tested on a set of benchmarks. Experimental results show that DI interfacing is realized with a relatively moderate cost in area and speed (costs about 40% area penalty and 20% speed penalty).

This paper proposes a high-level energy-optimizing algorithm which can synthesize low energy system VLSIs. Given an initial system hardware obtained from an abstract behavioral description, the proposed algorithm applies to it the three energy reduction techniques, 1) reducing supply voltage, 2) selecting lower energy modules, and 3) applying gated clocks. By incorporating our area/delay/power estimation, the proposed algorithm can obtain low energy system VLSIs meeting the constraints of area, delay, and execution time. The proposed algorithm has been incorporated into a high-level synthesis system and experimental results demonstrate effectiveness and efficiency of the algorithm.

Short range communication between roadside equipment and on-board equipment is very important for ITS (Intelligent Transport System). In this paper, for reliable roadside communication, the radio multi-path propagation at 2.4 GHz at roadside was measured and analyzed.

Finite-state vector quantization (FSVQ) is a well-known block encoding technique for digital image compression at low bit rate application. In this paper, an improved feature map finite-state vector quantization (IFMFSVQ) algorithm using three-sided side-match prediction is proposed for image coding. The new three-sided side-match improves the prediction quality of input blocks. Precoded blocks are used to alleviate the error propagation of side-match. An edge threshold is used to classify the blocks into nonedge or edge blocks to improve bit rate performance. Furthermore, an adaptive method is also obtained. Experimental results reveal that the new IFMFSVQ reduces bit rate significantly maintaining the same subjective quality, as compared to the basic FMFSVQ method.

Recently, information display equipment such as a navigation system has often come to be installed in a vehicle, and a variety of useful information has been offered to the driver by voice and images while driving. The necessity of improving safety when the driver receives such information has come to be stressed. As one of the means of solving this problem, we can develop a system that presents the driving and road conditions information such as a lane changing car to the driver by using a warning sound. The purpose of our study is to clarify the effectiveness of an auditory display that uses spatial sounds on such a system. An experiment for measuring the driver's reaction time and eye movements to LED lighting during actual driving has been carried out to investigate whether the spatial sound can quicken the driver's operation and decrease human error. We evaluated the effectiveness by two measures, average reaction time and the number of largely delayed reactions. We considered that the average reaction time corresponds to the quickness of the driver's operation, and the number of largely delayed reactions corresponds to the probability of human error. As a result of the experiment, the use of directional sound clearly showed better performance than the use of monaural sound and no sound in the number of largely delayed reactions. Moreover, we analyzed the factors involved in delay of the reaction by the results of eye movement measurements. Consequently, it has been found that directional sound can decrease the number of the largely delayed reactions, which lead to an accident during actual driving.

This paper presents a method of extracting car license plates captured from the arbitrary directions by using symmetry features. The generalized symmetry transform (GST) produces continuous features of symmetry between two points by combining locality constraint and reflectional symmetry, but its time complexity of GST is increased by the second power of the radius of a searching window. To achieve considerable reduction of this time complexity, we propose a scan line based GST (SLGST) which calculates the symmetry between a pair of edge pixels along the scan lines. Instead of calculating the global symmetry of a license plate, we assign the symmetry contribution acquired from SLGST to the corner point estimated from two edge points and their gradient orientations. The right angle tuned SLGST (RATSLGST) is newly proposed to detect the right angle corners more effectively. Image normalization by image warping is adopted to make such segmentation of license plate and later identification much easier. We also adopt the verifier that evaluates a candidate license plate to enhance extraction rate. Our experiments show that the proposed method for extracting perspectively distorted license plates is fairly reliable.

We describe in this paper our experience of developing a large-scale, highly distributed multi-agent system using wireless-networked sensors. We provide solutions to the problems of localization (position estimation) and dynamic, real-time mobile object tracking, which we call PET problems for short, using wireless sensor networks. We propose system architectures and a set of distributed algorithms for organizing and scheduling cooperative computation in distributed environments, as well as distributed algorithms for localization and real-time object tracking. Based on these distributed algorithms, we develop and implement a hardware system and software simulator for the PET problems. Finally, we present some experimental results on distance measurement accuracy using radio signal strengths of the wireless sensors and discuss future work.

We have successfully produced laterally-grown grains on large (300 350 mm) glass substrates by means of a newly developed excimer laser crystallization system that features a high-precision mask stage and an auto-focusing system. The original grains were produced with a steep beam edge and their lateral growth was extended by repeated irradiation and translation. TFTs fabricated with these extended grains were found to have mobilities that remained almost constant at 270 cm2/Vs (n-ch. TFTs) and 230 cm2/Vs (p-ch. TFTs) over a wide range of laser fluence (400-600 mJ/cm2).

In this paper, three algorithms are proposed for rate maximization (RM) of transmitted data in multichannel (MC) communications, subject to joint constraints on available energy budget and tolerable degradation of service (DOS). Altogether referred to as the RM algorithms, they consist of the EADRM, the DADRM, and the fDADRM algorithms. Based on the rate-distortion optimization theory, closed-form expressions for optimally distributing the energy (for EADRM) or DOS (for DADRM and fDADRM ) among the subchannels (SC's) are derived, when the bit allocation is pre-specified. The specification of bit allocations is achieved by the use of the so-called eligible bit allocation matrix (EBAM), which is a function of the total data rate and the number of SC's. A greedy approach is adopted, where the total data rate is kept on raising until the relevant constraints can no longer be satisfied. While all three RM algorithms essentially generate identical maximum data rates, the fDADRM algorithm is much faster than the other two in computation. As compared to the result achievable by a single-channel communication scheme, the RM algorithms produce a much higher data rate for spectrally shaped channels.

This paper describes our vehicle classification system, which is based on local-feature configuration. We have already demonstrated that our system works very well for vehicle recognition in outdoor environments. The algorithm is based on our previous work, which is a generalization of the eigen-window method. This method has the following three advantages: (1) It can detect even if parts of the vehicles are occluded. (2) It can detect even if vehicles are translated due to veering out of the lanes. (3) It does not require segmentation of vehicle areas from input images. However, this method does have a problem. Because it is view-based, our system requires model images of the target vehicles. Collecting real images of the target vehicles is generally a time consuming and difficult task. To ease the task of collecting images of all target vehicles, we apply our system to computer graphics (CG) models to recognize vehicles in real images. Through outdoor experiments, we have confirmed that using CG models is effective than collecting real images of vehicles for our system. Experimental results show that CG models can recognize vehicles in real images, and confirm that our system can classify vehicles.

A siphon-trap of a Petri net N is defined as a place set S with S = S, where S = { u| N has an edge from u to a vertex of S} and S = { v| N has an edge from a vertex of S to v}. A minimal siphon-trap is a siphon-trap such that any proper subset is not a siphon-trap. The following polynomial-time algorithms are proposed: (1) FDST for finding, if any, a minimal siphon-trap or even a maximal class of mutually disjoint minimal siphon-traps of a given Petri net; (2) FDSTi that repeats FDST i times in order to extract more minimal siphon-traps than FDST. (3) STFM_T (STFM_Ti, respectively) which is a combination of the Fourier-Motzkin method and FDST (FDSTi) and which has high possibility of finding, if any, at least one minimal-support nonnegative integer invariant.

In this paper, we study a low profile top loaded monopole antenna. By changing the number, thickness, position and shape of post(s), the input and radiation characteristic due to parameters of matching post(s) are investigated. The low profile top loaded monopole antenna (TLMA) is known as a suitable way for antenna's miniaturization. But it is also reported that the parameters of matching post influence the input and radiation characteristic greatly. The FDTD method is well suit for use in analyzing both the plate and wire structure. And to improve the calculation effect efficiency, the non-uniform mesh FDTD algorithm is used. From the measurement and simulation results, we propose the most suitable parameters of matching structure for low profile top loaded monopole antenna.

The electromagnetic wave scattering from ocean-like lossy dielectric random rough surfaces is numerically analyzed by using FVTD method. We have investigated the problem of low-grazing-angle (LGA) scattering in order to gain a better understanding of experimental data for the microwave backscattering from ocean-like surfaces. It is indicated that the FVTD results are in good agreement with the experimental data.