The roadside network system for ITS services uses microcells in its access infrastructure. For the roadside network that provides the uninterrupted communication using microcells such as DSRC, an effective communication control scheme must be established so as to manage the communication passes to vehicles in the network. One of the fundamental requirements for the communication control scheme for the roadside network is to assure fault-tolerance, which means in this system that the communication control mechanism needs to be managed even in part of the base stations in the network might be in fault. On the other hand, for the communication control in the roadside network using microcells, issues to be solved are the handover mechanism for taking over connection information to provide uninterrupted communication environment, which causes the degradation of the end-to-end throughput. In order to solve those problems, the authors developed a communication control scheme. We implemented the scheme as the specific 'ADS algorism' to control the communication zone dynamically, which works effectively on the Autonomous Decentralized System (ADS) communication platform. Furthermore, we also developed the specific ADS algorism to assure fault-tolerance for the communication zone control, which can reconfigure the communication zone in case the BSs in the roadside network are in fault and can keep the operations by the reconfigured communication zone. We evaluated the ADS algorism for the communication zone control by computer simulation. The results show the effectiveness of the ADS algorism for the dynamic communication zone control mechanism and for the fault-tolerant mechanism for communication zone reconfiguration on fault.

Power saving is an important issue in the mobile computing environment. In this paper, we propose a broadcast mechanism that constructs the broadcast channels according to the access frequency of each type of message in order to save power in mobile stations. The pinwheel scheduling algorithm presented in this paper is used to organize all types of messages in the broadcast channels in the most symmetrical distribution in order to reduce both the tuning and access time. The multichannel broadcast mechanism is also discussed for use when the number of message types increases. The performance of the proposed mechanism is analyzed, and the improvement over existing methods is demonstrated numerically. The results show that the proposed mechanism is capable improving both the tuning and access time due to the presence of skewness in the access distribution among the disseminated messages. When the number of message types increase, both the tuning and access time can be further improved as long as a small number of broadcast channels are added.

A scalable multicast session announcement system is a key component of a group communication framework over the Internet. It enables the announcement of session parameters (like the {source address; group address} pair) to a potentially large number of users, according to each site administrator's policy. This system should accommodate any flavor of group communication system, like the Any-Source Multicast (ASM) and Source-Specific Multicast (SSM) schemes. In this paper we first highlight the limitations of the current Session Announcement Protocol (SAP) and study several other information distribution protocols. This critical analysis leads us to formulate the requirements of an ideal multicast session announcement system. We then introduce a new session announcement system called "Channel Reflector". It appears as a hierarchical directory system and offers an effective policy and scope control technique. We finally mention some design aspects, like the protocol messages and configuration structures the Channel Reflector uses.

Active integrated antenna techniques have high potential for giving smaller size, lighter weight, lower cost and higher efficiency, in particular to millimeter-wave circuit-antenna systems. This paper gives a review of active integrated antenna techniques with emphasis on beam steering and retrodirective antenna arrays. Various beam steering operations of integrated antenna oscillator arrays using locking phenomena are presented. Beam steering arrays of such type have the feature that phase shifters are not necessary in the arrays. Arrays with higher harmonic output radiation can enlarge the beam steering range. Arrays of locked active antennas which operate as self-oscillating mixers can be beam controllable receiving antennas.

Today, pedestrian navigation systems for mobile phones use 2-dimensional maps as a navigation media in general. But 3-dimensional maps or scenery images are easier to understand for users than 2-dimensional maps. To use 3-dimensional maps or scenery guidance, the measuring accuracy of user position is essential to understand guidance images. In this paper, we will present a pedestrian navigation system using real scenery photographs as a navigation media, and based on experiments we will report the evaluation result of influence of positioning accuracy on the understandability of navigation. It is shown that 3 meters or less error of positioning is tolerable for pedestrian navigation systems using scenery images.

This paper proposes a novel boundary scan test scheme for intellectual property (IP) core identification via watermarking. The core concept is embedding a watermark identification circuit (WIC) and a test circuit into the IP core at the behavior design level. The procedure depends on current IP-based design flow. This scheme can detect the identification of the IP provider without the need to examine the microphotograph after the chip has been manufactured and packaged. This scheme can successfully survive synthesis, placement, and routing and identify the IP core at various design levels. Experimental results have demonstrated that the proposed approach has the potential to solve the IP identification problem.

This paper proposes a reconfigurable adaptive FEC system based on Reed-Solomon (RS) code with interleaving. In adaptive FEC schemes, error correction capability t is changed dynamically according to the communication channel condition. For given error correction capability t, we can implement an optimal RS decoder composed of minimum hardware units for each t. If the hardware units of the RS decoder can be reduced for any given error correction capability t, we can embed as large deinterleaver as possible into the RS decoder for each t. Reconfiguring the RS decoder embedded with the expanded deinterleaver dynamically for each error correction capability t allows us to decode larger interleaved codes which are more robust error correction codes to burst errors. In a reliable transport protocol, experimental results show that our system achieves up to 65% lower packet error rate and 5.9% higher data transmission throughput compared to the adaptive FEC scheme on a conventional fixed hardware system. In an unreliable transport protocol, our system achieves up to 76% better bit error performance with higher code rate compared to the adaptive FEC scheme on a conventional fixed hardware system.

For multiple-channel active noise control (ANC) systems, distributed systems consisting of more than one controller are useful. In this paper, we propose a performance improvement algorithm for the distributed multiple-channel ANC system based on the simultaneous equations method. In the proposed algorithm, no estimation of error paths is required. This algorithm can provide good performance in canceling primary noises with auto-/cross-correlations and achieve stable noise reduction under a change of the error paths.

The shared time division multiplexing (shared-TDD) scheme has been proposed to accommodate asymmetric communications between uplink and downlink. The accommodation of connection-less services in Shared-TDD systems causes a difficulty of TDD boundary control. This paper proposes a TDD boundary control (resource assignment) scheme, which can optimize a position of the TDD boundary based on the ratio of uplink to downlink traffic in code division multiple access (CDMA)/shared-TDD systems with connection-less services. The proposed scheme controls the TDD boundary based on the estimated uplink and downlink traffic. Computer simulations show that the proposed scheme effectively controls the radio resource, and thus improves total system throughput performance.

This paper proposes a simple timing synchronization method in order to design a timing synchronization circuit with low-complex and low-volume digital signal processing (DSP) for orthogonal frequency division multiplexing (OFDM) packet transmission systems. The proposed method utilizes the subtraction process for acquirement of a timing metric of fast Fourier transform (FFT) window, whereas the conventional methods utilize the multiplication process. This paper adopts the proposed method to a standardized OFDM format, IEEE 802.11a, and elucidates that the proposed one shows good transmission performance as well as the conventional one in fast time-variant multi-path Rayleigh fading channels by computer simulation.

As the number of cluster system users increases, it is important to maintain stable operation. Although hardware preventive maintenance is important for sustaining smooth operation, hardware testing tools for cluster systems have received little attention. In this paper, we propose a memory testing tool for Linux cluster systems.

A policy is an execution rule (or constraint) for objects in a system to retain security and integrity of the system. We introduce a simple policy specification language and define its operational semantics. A new NFA construction algorithm that works in linear time is proposed and a model checking method for policy controlled system (PCS) is presented. We conducted verification of a sample PCS for hotel reservation by our automatic verification tool and the experimental results showed the efficiency of the proposed method.

This paper describes a method for separating a target sound from other noise arriving in a single direction when the target cannot, therefore, be separated by directivity control. Microphones are arranged in a line toward the sources to form null sensitivity points at given distances from the microphones. The null points exclude non-target sound sources on the basis of weighting coefficients for microphone outputs determined by blind source separation. The separation problem is thereby simplified to instantaneous separation by adjustment of the time-delays for microphone outputs. The system uses a direct (i.e. non-iterative) algorithm for blind separation based on second-order statistics, assuming that all sources are non-stationary signals. Simulations show that the 2-microphone system can separate a target sound with separability of more than 40 dB for the 2-source problem, and 25 dB for the 3-source problem when the other sources are adjacent.

With reference to video motion estimation in the framework of the new H.264/AVC video coding standard, this paper presents algorithmic and architectural solutions for the implementation of context-aware coprocessors in real-time, low-power embedded systems. A low-complexity context-aware controller is added to a conventional Full Search (FS) motion estimation engine. While the FS coprocessor is working, the context-aware controller extracts from the intermediate processing results information related to the input signal statistics in order to automatically configure the coprocessor itself in terms of search area size and number of reference frames; thus unnecessary computations and memory accesses can be avoided. The achieved complexity saving factor ranges from 2.2 to 25 depending on the input signal while keeping unaltered performance in terms of motion estimation accuracy. The increased efficiency is exploited both for (i) processing time reduction in case of software implementation on a programmable platform; (ii) power consumption reduction in case of dedicated hardware implementation in CMOS technology.

In designing a video-on-demand system, one of the major challenges is how to reduce the client's waiting time maintaining the concurrently used channels. For this reason, the hybrid architectures which integrate the multicast streams with the unicast streams were suggested in order to improve channel efficiency in recent years. In combining multicast with unicast, the ways to group the channels together are important so that more clients can share the multicast transmission channels. This paper proposes a hybrid video-on-demand system which gathers the unicast and multicast transmission channels efficiently by using dynamic channel allocation architecture. The newly proposed architecture can reduce the average client's waiting time significantly. The numerical results demonstrate that the dynamic channel allocation architecture in some case (e.g., 100-channel and 10-video system at 0.5 requests/second) achieves performance gain of 551% compared to existing architecture. This paper presents procedure of channel release and reuse, performance analysis, and simulation results of the dynamic channel allocation architecture.

This paper presents an analysis of the Slotted DS-CDMA system with modified node components in order to construct a load control structure in which the service rates of each node can be dynamically adapted without using feedback information. In contrast to the traditional Slotted DS-CDMA which is widely represented with single queue, prior emphasis of the approach is laid on the usage of an additional queue which is applied to manage the collided packet traffic while its queue size is also used as a load control parameter. Semi-Markov process is applied to describe the statistic behavior of the system in steady state. Trade-offs between two major performance parameters, i.e., delay and throughput, are presented and compared with those of the traditional system. Results obtained from the simulation and numerical analysis using queuing concept are compared. With these results, an advantage performance for group packets is shown, and we finally extend the concept based on the obtained results to describe a simple algorithm using one way control message as the tool to alleviate the stability problem.

The recognition limit of luminance difference in the human visual system (HVS) has not been studied systematically. In this paper, surround adapted Weber-Fechner fraction is calculated based on the crispening effect. It is found that surround adapted fractions have reduced to 1/3 of the traditional Weber-Fechner fractions. As compared with Breitmeyer's experiments, the presented result is a reasonable one. It can be used as some guide to design the digital display system when a designer needs to decide bit count of digital signal in considering of the limit of brightness level, and as the inspection tool of display manufacturing of brightness smear, defect, and so on.

We have launched "Highly-Reliable Embedded Software Development" Project, held as a part of e-Society Project, supported by Ministry of Education, Culture, Sports, Science and Technology (MEXT), Japan. The aim of this project is to enable the industry to produce highly reliable and advanced software by introducing latest software technologies into embedded software development. In this paper, we introduce the overview of the projects and our activities and results so far.

This paper presents new encoding methods for the binary genetic algorithm (BGA) and new converting methods for the real-coded genetic algorithm (RCGA). These methods are developed for the specific case in which some parameters have to be searched in wide ranges since their actual values are not known. The oversampling effect which occurs at large values in the wide range search are reduced by adjustment of resolutions in mantissa and exponent of real numbers mapped by BGA. Owing to an intrinsic similarity in chromosomal operations, the proposed encoding methods are also applied to RCGA with remapping (converting as named above) from real numbers generated in RCGA. A simple probabilistic analysis and benchmark with two ill-scaled test functions are carried out. System identification of a simple electrical circuit is also undertaken to testify effectiveness of the proposed methods to real world problems. All the optimization results show that the proposed encoding/converting methods are more suitable for problems with ill-scaled parameters or wide parameter ranges for searching.

In this paper, the throughput performance of the CSK/SSMA ALOHA system with nonorthogonal sequences which combines the ALOHA system with Code Shift Keying using nonorthogonal sequences is analyzed. In this system, the nonorthogonal sequences are constructed by concatenating Mcon orthogonal sequences. The throughput performance of the CSK/SSMA ALOHA system with nonorthogonal sequences is analyzed in consideration that the number of packets changes at intervals of one orthogonal sequence. Moreover, the throughput performance of our system with Channel Load Sensing Protocol (CLSP) is also analyzed. We also examine the influence of unreachable control signal of CLSP. Consequently, it is found that the throughput performance of our system decreases significantly by this analysis. It is also found that the throughput performance of our system improves greatly by using CLSP. However, the unreachable control signal affects the throughput performance of this system, seriously.