The technological development of wireless environment has made real-time multimedia communications possible in wireless networks. Many studies have been done on real-time communications in wireless networks in order to overcome a higher bit error rate in wireless channels. However, none of work deals with firm real-time communications which can be applied to multimedia communications. In this paper, we propose an adaptive error correcting scheme for firm real-time multimedia communications in wireless networks in order to maximize the expected net profit. The proposed scheme adaptively selects an error correcting code under the current air state and the message state of a message stream. Throughout simulation results, we show that the suggested scheme provides more profit than single error-correcting code schemes.

The main contribution of this work is to present several hardware implementations of an "n choose k" counter (C(n,k) counter for short), which lists all n-bit numbers with (n-k) 0's and k 1's, and to show their applications. We first present concepts of C(n,k) counters and their efficient implementations on an FPGA. We then go on to evaluate their performance in terms of the number of used slices and the clock frequency for the Xilinx VirtexII family FPGA XC2V3000-4. As one of the real life applications, we use a C(n,k) counter to accelerate a digital halftoning method that generates a binary image reproducing an original gray-scale image. This method repeatedly replaces an image pattern in small square regions of a binary image by the best one. By the partial exhaustive search using a C(n,k) counter we succeeded in accelerating the task of finding the best image pattern and achieved a speedup factor of more than 2.5 over the simple exhaustive search.

In region-of-interest (ROI) image coding based on wavelet transforms, the tap length of the wavelet filter as well as energy compaction characteristics affect the quality of the restored image. This paper presents a wavelet transform comprised of two wavelet filter sets with different tap lengths. The wavelet filter is switched to the shorter-length set to code a ROI of an image and to the longer-length one for the remaining region, the region of non-interest (RONI). ROI coding examples demonstrate that this switching wavelet transform provides better quality levels than fixed transforms under the same total bits; the quality of the recovered ROI is improved in the lossy coding of both regions while that of the full image is improved in the lossless coding of the ROI.

In this paper, a complete X-tolerant test data compression solution is proposed for system-on-a-chip (SOC) testing. The solution achieves low-cost testing by employing not only selective Huffman vertical coding (SHVC) for test stimulus compression but also MISR-based time compactor for test response compaction. Moreover, the solution is non-intrusive, since it can tolerate any number of unknown states (also called X state) in test responses such that it does not require modifying the logic of core to eliminate or block the sources of unknown states. Furthermore, the solution achieves enhanced diagnosis capability over conventional MISR. The enhanced diagnosis requires the least hardware overhead by reusing the existing masking logic and achieves significant saving in diagnostic time. Experimental results for ISCAS 89 benchmarks as well as the evaluation of hardware implementation have proven the efficiency of the proposed test solution.

Based on the Si CMOS process, a low operating voltage and low power light emitting device is presented. It has a power transfer efficiency of 1 to 2 orders higher than previous reports and can be used as a high efficiency photodiode. Configurations using the same structure as both the light emitter and the optical receiver, and employing a simple modulation instrument is then proposed for applications in the chip-to-chip optical alignment and the signal transmission. Only single power supply is required in the emitter-receiver circuits and is compatible with other integrated circuits made by the CMOS process.

This paper compared the approaches concerning the pinball routing problem that occurs in the nested network in network mobility environment and developed the analytic framework to model. Each model was evaluated of transmission latency, memory usage, and BU's occurrence number at routing optimization process. The estimation result showed that the optimization mechanism achievement overhead existed in each model, and the full optimization of the specific model was not attained because of it. Therefore, the most appropriate approach for routing optimization in nested NEMO can be determined only after a careful evaluation, and the proposals must consider using it in combination with other approaches. The modeling framework presented in this paper is intended to quantity the relative merits and demerits of the various approaches.

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.

While mobile networks have been enhanced to support a variety of mobile multimedia services such as video telephony and rich data content delivery, a new challenge is being created by the remarkable development of micro-device technologies such as micro processor-chips, sensors, and RF tags. These developments suggest the rapid emergence of the ubiquitous computing environment; computers supporting human life without imposing any stress on the users. The combination of broadband global networks and ubiquitous computing environment will lead to an entirely new class of services, which we call ubiquitous networking services. This paper discusses how to create ubiquitous service environments comparing global networking approaches which are based on fixed and mobile networks. It is shown that the mobile approach is better from service applicability and reliability viewpoints. Networking architecture is proposed which expand 4G mobile cellular networks to real space via gateways on the edges of the mobile network (i.e. mobile terminals). A new set of technical requirements will emerge via this approach, which may accelerate the paradigm shift from the current mobile network architecture and even from the Internet of today.

As the complexity of VLSI circuits increases, the routability problem becomes more and more important in modern VLSI design. In general, the flexibility improvement of the edges in a routing tree has been exploited to release the routing congestion and increase the routability in the routing stage. Given an initial rectilinear Steiner tree, the rectilinear Steiner tree can be transformed into a Steiner routing tree by deleting all the corner points in the rectilinear Steiner tree. Based on the definition of the routing flexibility in a Steiner routing tree and the timing-constrained location flexibility of the Steiner-point in any Y-type wire, the simulated-annealing-based approach is proposed to construct a better timing-constrained flexibility-driven Steiner routing tree by reassigning the feasible locations of the Steiner points in all the Y-type wires. The experimental results show that our proposed algorithm, STFSRT, can increase about 0.005-0.020% wire length to improve about 43-173% routing flexibility for the tested benchmark circuits.

We present a low-phase-noise and frequency-tunable photonic millimeter-wave (MMW) generator based on two-mode beating. The generator consists of a single-mode laser, an external optical intensity modulator, and a planar lightwave circuit (PLC) on which an arrayed-waveguide grating (AWG) and 3-dB optical combiners are integrated. Because the AWG and the optical combiners are connected with optical waveguides and the optical path length difference between the two modes filtered by the AWG is kept constant, the phase fluctuation of the generated MMW signal is suppressed. The generator can generate MMWs with a phase noise of less than -75 dBc/Hz at 100 Hz and has a frequency tunability in a range of 90 to 125 GHz. The generator can be applied for the local oscillator (LO) in 10-Gbit/s wireless links that use heterodyne detection.

In this letter, we study a hybrid Multimedia-on-Demand (MoD) system which provides broadcast, batch and interactive services. An analytical model for such an MoD system is provided. Numerical results show that with proper design, the system can provide better performance than those systems which only provide any subset of two services.

One of the main issues of Mobile IPv6 is handover latency that causes service disruption time. Although plenty of proposals significantly reduce the service disruption time, they suffer from redundant routing that causes packet misordering and bandwidth consumption during the process of inter-domain handover. In this paper, we propose a new scheme that minimizes the redundant routing during the process of inter-domain handover by utilizing forwarding routers for each correspondent node. Our proposed scheme consists of forwarding router discovery and proactive handover. We evaluate our proposed scheme in the view of packet misordering and bandwidth consumption, and clarify the efficiency of our proposed scheme. We also evaluate the impact of the forwarding routers' capacity since routers have limited resources. By strategically locating forwarding routers, e.g. next to the router that has peering to another domain, the redundant routing caused by inter-domain handover will be efficiently suppressed.

Beam control using active antenna arrays with self-oscillating harmonic mixers has been investigated. The active antenna is composed of a patch antenna receiving RF signal and a parallel feedback type oscillator which operates as the self-oscillating harmonic mixer, and down-converts the received RF signal into IF signal. The mixer has two ports for local oscillating (LO) signal. One is an output port extracting the LO signal. The other is an input port for an injection signal to synchronize the local oscillation. The mixers can be coupled unilaterally without other nonreciprocal components by connecting the output port to the input port in the next mixer. In the unilaterally coupled array, the phase differences of the LO signals between the adjacent mixers can be varied without phase shifters in injection locking state by changing the local free-running frequencies of the self-oscillating mixers. The receiving pattern can be controlled by combining the IF signals from the individual active antennas, which have phases associated with the LO signals. The IF is difference between the RF and double of the LO frequency so that arbitrary phase differences from 0 to 2π radian can be provided to the output IF signals. The experiments using the two- and three-element arrays demonstrated beam control capability.

In order to boost the translation quality of corpus-based MT systems for speech translation, the technique of splitting an input utterance appears promising. In previous research, many methods used word-sequence characteristics like N-gram clues among splitting positions. In this paper, to supplement splitting methods based on word-sequence characteristics, we introduce another clue using similarity based on edit-distance. In our splitting method, we generate candidates for utterance splitting based on N-grams, and select the best one by measuring the utterance similarity against a corpus. This selection is founded on the assumption that a corpus-based MT system can correctly translate an utterance that is similar to an utterance in its training corpus. We conducted experiments using three MT systems: two EBMT systems, one of which uses a phrase as a translation unit and the other of which uses an utterance, and an SMT system. The translation results under various conditions were evaluated by objective measures and a subjective measure. The experimental results demonstrate that the proposed method is valuable for the three systems. Using utterance similarity can improve the translation quality.

The electrostatic discharge (ESD) effect in GMR heads in the deshunting process is studied in order to prevent the damage in this process. The simulation and experiment results are investigated and compared. It is found from these results that sequences of deshunting process, currently operating, can cause the damage of GMR heads due to the ESD effect, based on the charged device model, CDM. This also shows that the voltage across GMR head, as the tweezers is used, can be raised up to 3.7 V which is about harmful to damage the head. Examples of damage heads confirmed by the SEM are also shown.

Screen pattern used in offset-printed documents has been one of great obstacles in developing document recognition systems that handle color documents. This paper proposes a selective smoothing method for filtering the screen patterns/noise in high-resolution color document images. Experimental results show that the method yields significant improvements in character pattern extraction.

Recently, the integration of wired and wireless networks has become an interesting issue. The introduction of extending Mobile IP to mobile ad hoc networks not only helps the mobile nodes connect to the Internet but also broadens the scope of the ad hoc networks and increases their application. However, these hybrid schemes faces several security problems from the inherent weakness of ad hoc routing. In this paper, we propose a hybrid authentication scheme of Mobile IP assistance for ad hoc routing security. The regular Mobile IP registration scheme has been refined to an ad hoc key-aided version and now incorporates a novel routing packet authentication mechanism in the ad hoc routing operation. A distinct character of this hybrid scheme is that a Mobile Agent can form a secure ad hoc network where the mobile hosts can be authorized and authenticated by the refined Mobile IP registration scheme. In these findings, we shall propose that the mobile hosts can follow a novel routing packet authentication mechanism to secure the routing packets by using the cryptography of the simple geometric properties of lines. Since the novel routing authentication mechanism does not need digital signatures for completing the routing packet integrity, in this hybrid authentication scheme, the cryptographic computation cost on the mobile hosts' side is relatively minimized.

A new technique called the Dual Parasitic Beam (DPB) technique is proposed to suppress grating lobes in a rectangular waveguide broad wall transverse slot array. This technique involves an extra layer of parasitic strip dipoles that generate the DPB to suppress the grating lobes without opposing the main beam of the original slot linear array. A full wave EM analysis in Method of Moments (MoM) is conducted to compute the coupling excitation coefficients as well as the far field patterns of the slot and dipole currents. Analysis shows that a suitable dimension and arrangement of dipoles are needed to get a desired level of dipole excitations to meet the grating suppression condition. It is found that the grating lobes can be suppressed as much as 15 dB in the presence of the parasitic dipoles. Experiments are conducted to confirm the computed results.

According to the proliferation of ubiquitous computing, various products which contain large-size embedded software have been developed. One of most typical features of embedded software is concurrency of software and hardware factors. That is, software has connected deeply into hardware devices. The existence of various hardware make quality assurance of embedded software more difficult. In order to assure quality of embedded software more effectively, this paper discusses features of embedded software and an effective method for quality assurance for embedded software. In this paper, we first analyze a failure distribution of embedded software and discuss the effects of hardware devices on quality of embedded software. Currently, in order to reduce hardware related faults, huge effort for testing with large number of test items is required. Thus, one of the most important issues for quality assurance of embedded software is how to reduce the cost and effort of software testing. Next, focusing on hardware constraints as well as software specifications in embedded software, we propose an evaluation metrics for determinating important functions for quality of embedded software. Furthermore, by referring to the metrics, undesirable behaviors of important functions are identified as root nodes of fault tree analysis. From the result of case study applying the proposed method to actual project data, we confirmed that test items considering the property of embedded software are constructed. We also confirmed that the constructed test items are appropriate to detect hardware related faults in embedded systems.

Mobile ad-hoc networks consist of mobile nodes interconnected by multihop path that has no fixed network infrastructure support. Due to the limited bandwidth and resource, and also the frequent changes in topologies, ad-hoc network should consider these features for the provision of security. We present a secure routing protocol based on identity-based signcryption scheme. Since the proposed protocol uses an identity-based cryptosystem, it does not need to maintain a public key directory and to exchange any certificate. In addition, the signcyption scheme simultaneously fulfills both the functions of digital signature and encryption. Therefore, our protocol can give savings in computation cost and have less amount of overhead than the other protocols based on RSA because it uses identity-based signcryption with pairing on elliptic curve. The effectiveness of our protocol is illustrated by simulations conducted using ns-2.