In mobile communication systems, mobility tracking operations are executed to maintain known the whereabouts of each mobile terminal (MT). In this article, we propose and analyse two new versions of the original time-based registration method, namely the Stop and Wait (S W) and the Reset and Wait (R W) time-based strategies. We also propose and study the modified S&W and R&W schemes as a result of combining the S&W and R&W policies with the enhanced time-based method in [3]. When the MT uses one of the four schemes proposed, it sends less location update (LU) messages. As a result of fewer LUs, which results in less contacts with the network, the uncertainty of the MT position increases in the proposed time-based schemes. Although the MT paging (PG) cost is lightly increased, a significant reduction in the LU cost is achieved. As it is shown, the net effect is a saving in the total location management cost per call arrival. In order to analyse the four strategies and compare them with the original and enhanced time-based schemes, a performance evaluation method based on Markovian standard tools is proposed here. The location management cost for all these time-based policies are evaluated analytically here by using this evaluation method.

When video data are transmitted via the network, the quality of video data must be carefully chosen to be best under the condition that the transmission is not influenced by other internet services. They often use the simulcast type, which uses independent streams that are stored and transmitted for the quality, considering implementation, when they select the video quality. On the other hand, we had already proposed the scalable structure, which consists of base and enhancement data, but when they require the high quality video, these data are combined using the transcoding methods. In this paper, we propose the video contents delivery methods with scalable transcoding, in which users can update the quality of video data even after the transmission by base data and differential data. In order to reduce the total time of not only users' access time, but also watching time, we compare simulcast method with proposed methods in the total content utilization time using a video contents access model, and evaluate required transcoding time to reduce the waiting time of users.

This letter proposes an improved timer-based location management scheme for packet-switched (PS) mobile communication systems. Compared to the conventional timer-based scheme with a single timer threshold, a new timer-based scheme with two timer thresholds is proposed to accommodate the bursty data traffic characteristics of PS service. The location update and paging costs of the proposed scheme are analyzed and compared with those of the conventional scheme. We show that the proposed scheme outperforms the conventional scheme in terms of total cost of both location update and paging with an appropriate selection of timer thresholds.

In this paper, we present a novel framework for analyzing and segmenting point-sampled 3D objects. Our algorithm computes a decomposition of a given point set surface into meaningful components, which are delimited by line features and deep concavities. Central to our method is the extension of the scale-space theory to the three-dimensional space to allow feature analysis and classification at different scales. Then, a new surface classifier is computed and used in an anisotropic diffusion process via partial differential equations (PDEs). The algorithm avoids the misclassifications due to fuzzy and incomplete line features. Our algorithm operates directly on points requiring no vertex connectivity information. We demonstrate and discuss its performance on a collection of point sampled 3D objects including CAD and natural models. Applications include 3D shape matching and retrieval, surface reconstruction and feature preserving simplification.

The supertask approach was proposed by Moir and Ramamthy as a means of supporting non-migratory tasks in Pfair-scheduled systems. In this approach, tasks bound to the same processor are combined into a single server task, called a supertask, which is scheduled as an ordinary Pfair task. When a supertask is scheduled, one of its component tasks is selected for execution. In previous work, Holman et al. showed that component-task deadlines can be guaranteed by inflating each supertask's utilization. In addition, their experimental results showed that the required inflation factors should be small in practice. Consequently, the average inflation produced by their rules is much greater than that actually required by the supertasks. In this paper, we first propose a notion of Transient Behavior Prediction for supertasks, which predicts the latest possible finish time of subtasks that belong to supertasks. On the basis of the notion, we present an efficient schedulability algorithm for Pfair supertasks in which the deadlines of all component tasks can be guaranteed. In addition, we propose a task merging process which combines the unschedulable supertasks with some Pfair tasks; hence, a newly supertask can be scheduled in the system. Finally, we propose the new reweighting functions that can be used when the previous two methods fail. Our reweighting functions produce smaller inflation factor than the previous work does. To demonstrate the efficacy of the supertasking approach, we present the experimental evaluations of our algorithm, which decreases substantially a number of reweights and the size of inflation when there are many supertasks in the Pfair-scheduled systems.

We propose a method of controlling the view divergence of data freshness when copies of sites in a replicated database are updated asynchronously. The view divergence of the replicated data freshness is the difference in the recentness of the updates reflected in the data acquired by clients. Our method accesses multiple sites and provides a client with data that reflects all the updates received by the sites. First, we define the probabilistic recentness of updates reflected in acquired data as read data freshness (RDF). The degree of RDF of data acquired by clients is the range of view divergence. Second, we propose a way to select sites in a replicated database by using the probability distribution of the update delays so that the data acquired by a client satisfies its required RDF. This way calculates the minimum number of sites in order to reduce the overhead of read transactions. Our method continues to adaptively and reliably provide data that meets the client's requirements in an environment where the delay of update propagation varies and applications' requirements change depending on the situation. Finally, we evaluate by simulation the view divergence we can control using our method. The simulation showed that our method can control the view divergence to about 1/4 that of a normal read transaction for 100 replicas. In addition, the increase in the overhead of a read transaction imposed by our method is not as much as the increase in the total number of replicas.

This paper presents a novel decoding algorithm for turbo codes, in which the likelihood values for redundant parts are updated in order for those values to become more reliable. A criterion for updating the redundant likelihood values is proposed, which is based on the comparisons of the channel values with the re-generated values by the soft-input and soft-output encoders. It is shown that the proposed method can improve the error correcting capabilities, i.e., the improvement of BER/BLER performance and the achievable BER limit.

This study was designed to evaluate localized muscular fatigue induced during mouse operation in a VDT task. Ten male undergraduates from 19 to 23 years old participated in the experiment. The subject performed a pointing task with a PC mouse for about 4 hours. The EMG measurements and psychological rating of fatigue were conducted before the experimental task and after each 30-minutes block during the experimental task. The changes in the Mean Power Frequency (MPF) and Percentage Maximum Voluntary Contraction (%MVC)-shift for the constant cumulative probability in the Amplitude Probability Distribution Function (APDF) with time were explored. The correspondence between the index (MPF or APDF) and the subjective rating of localized muscular fatigue was also examined. The performance was nearly constant across all blocks. The psychological rating of fatigue tended to increase with time. The MPF tended to increase with time, although the main effect of block (time) was not statistically significant. The %MVC-shift tended to increase with time. The correspondence with the perceived sensation of localized muscular fatigue was higher when using the %MVC-shift than when using the MPF. Based on the results, the effectiveness of the indexes used for evaluating localized muscular fatigue was discussed. The %MVC-shift obtained from the APDF was found to be a sensitive index of localized muscular fatigue and corresponded well with the subjective rating of localized muscular fatigue.

The complete subtree (CS) method is widely accepted for the broadcast encryption. A new method for assigning keys in the CS method is proposed in this paper. The essential idea behind the proposed method is to use two trapdoor permutations. Using the trapdoor information, the key management center computes and assigns a key to each terminal so that the terminal can derive all information necessary in the CS method. A terminal has to keep just one key, while log2 N + 1 keys were needed in the original CS method where N is the number of all terminals. The permutations to be used need to satisfy a certain property which is similar to but slightly different from the claw-free property. The needed property, named strongly semi-claw-free property, is formalized in terms of probabilistic polynomial time algorithm, and its relation to the claw-free property is discussed. It is also shown that if the used permutations fulfill the strongly semi-claw-free property, then the proposed method is secure against attacks of malicious users.

Future personal communication service (PCS) networks consider smaller cells to accommodate continuously growing population of subscribers. That results in frequent location update and consequently higher signaling cost. Among various schemes proposed for improving the efficiency of location management, the distance-based and the direction-based location update methods work well for just certain mobility patterns. In this paper, we propose a hybrid location update (HLU) scheme, which takes into account both the moving distance and the moving direction when deciding on updating the location. We analyze the performance of the HLU under different mobility patterns and call-to-mobility ratios based on a 2D Markov walk model. The numerical results demonstrate that the HLU scheme can achieve better performance than the distance-based or the direction-based methods applied individually.

This paper deals with broadcast encryption schemes, in which a sender can send information securely to a group of receivers excluding some receivers over a broadcast channel. In this paper we propose modifications of the Complete Subtree (CS), the Subset Difference (SD) and the Layered Subset Difference (LSD) methods based on the Master Key Tree (MKT). Our modifications eliminate log N keys or labels from receivers' storage, in exchange for an increase in the computational overhead, where N is the total number of receivers. We also propose modifications of the SD and LSD methods by applying the Trapdoor One-way Permutation Tree (TOPT) which is originally proposed in order to modify the CS method. Our modifications based on TOPT also eliminate log N labels, and the computational cost is much smaller than MKT based methods.

The complete subtree (CS) method is one of the most well-known broadcast encryptions which do not enforce the receivers to keep "online." This paper is to reduce the size of secret information which must be stored in a terminal of the method. In the original CS method, the size of the secret information increases as the number of terminals increases. It is shown in this paper that, by making use of a one-way trapdoor permutation, we can make the size constant regardless of the number of terminals. The security of the proposed scheme is investigated, and detailed comparison with other similar schemes is presented. The proposed scheme is suitable for practical implementations of the CS method.

As the number of mobile terminals (or users) keeps explosively increasing, the location management to track mobile terminals in cellular networks is becoming more important. However, the location management schemes presently adopted in cellular networks use static location information without considering the moving direction of a mobile terminal. This approach is insufficient in reflecting the different directional behaviors of mobile terminals. Thus, there is a need to develop a dynamic location management scheme more adaptive to the moving direction of a mobile terminal. This paper proposes a direction-based scheme (DBS) that can determine a location update and vary a paging area dynamically according to the moving direction. The direction vector was defined to represent the moving direction and to compute the distance from the cell where a location update occurs to the current cell. The offset operation of direction vectors represented the location of a mobile terminal in a paging area. This allowed the mobile terminal to determine whether a location update would be performed or not. In addition, simulations showed that DBS outperforms other location management schemes in most cases except in those with a low call-to-mobility ratio (CMR), particularly if a mobile terminal has directional behavior.

This paper presents a novel layout approach using dual supply voltage technique. In Placing and Routing (P&R) phase, conventional approaches for dual supply voltages need to separate low supply voltage cells from high voltage ones. Consequently its layout tends to be complex compared with single supply voltage layout. Our layout approach uses cells having two supply voltage rails. Making these cells is difficult in bulk due to increase in area by n-well isolation or in delay by negative body bias caused by sharing n-well. On the other hand, making cells with two supply voltage rails is easy in body-tied PD-SOI owing to trench isolation of each body of transistor. Since our approach for dual supply voltages offers freedom for placement as much as conventional ones for single supply voltage, exsting P&R tools can be used without special operation. Simulation results with MCNC circuits and adders show that our approach reduces power by 23% and 25%, respectively, showing almost the same delay with single supply voltage layout.

The most important function of a router is to perform IP lookup that determines the output ports of incoming IP packets by their destination addresses. Hence, IP lookup is one of the main issues in implementing high-speed routers. The IP lookup algorithm implemented in IQ2200 Chipset with two-level table architecture can efficiently use memory. However, it wastes processor resource for full re-construction of the forwarding tables whenever every route insertion/deletion is requested. In order to improve the utilization of processor resource, we propose an IP lookup algorithm with three-level table architecture for high-speed routers. We evaluate the performance of the proposed algorithm in terms of the memory size required for storing lookup information and the number of memory access in constructing forwarding tables. Being compared with the IQ2200 scheme, the proposed scheme can reduce the number of memory access up to 99% even though it needs about 16% more memory.

The combination of OFDM and multiple antennas in either the transmitter or receiver is attractive to increase a diversity gain. However, multiple antennas system requires an antenna separation of 5-10 λ to keep the correlation coefficient below 0.7 for the space diversity, so this may be difficult to implement in a mobile station with high mobility. Recently, the polarization transmit diversity is considered in a mobile station. However, polarization transmit diversity requires twice transmit powers to compare with the conventional transmit diversity, since only vertically polar antenna cannot receive the horizontal signal components. In this paper, we express the cross correlation of each polarization antenna and the cross polarization discrimination (XPD) of multiple polarization antennas with simple model, and we propose an wideband OFDM using Alamouti coded heterogeneous polarization antennas for reducing the previous problem. From the simulated results, the proposed system shows better BER performance than that of the conventional STBC/OFDM.

We propose a new cell configuration which newly employs discharge deactivation film (DDF). DDF is formed on MgO surface in stripe figure to cover it around the boundary of neighboring display lines. DDF prevents discharge cross talk between the lines even in case of stripe rib structure by virtue of its low secondary electron emission coefficient (γi). DDF also makes better address discharge response because it presumably moves address discharge closer to the surface dischage gap. On behalf of mass productivity for large size PDPs DDF is formed by simple screen-printing and firing method. And it consists of very fine Al2O3 grains without any inorganic binder. Such DDF is visually transparent and then helpful for high luminance and luminous efficiency. In addition to it, such DDF is presumably equipped with gas purifying character and then helpful for deep blue color and good white color balance accordingly. Further, DDF combined with sustain electrodes in specific figure which we call "CAPABLE DDF" brings about so high luminous efficiency for stripe rib structure as it may surpass box rib one. This probably means that vertically open discharge space in stripe rib structure is advantageous for high luminous efficiency. In our latest work for 46 inch-high definition PDPs, 2.1 lm/W and 1200 cd/m2 were both achieved under practical driving condition. Still it will be as high as 2.4 lm/W if each sustain electrode is shared by neighboring display lines. CAPABLE DDF allows more tolerance in DDF printing process. It also makes optical cross talk negligible even in stripe rib structure. And its durability against long time operation proved to have no specific problem. This presumably means that re-landing of sputtered MgO never reaches DDF surface. We believe this new technology can promise the future of stripe rib.

In this letter, we show the effects of the chip waveform selection on the detection performance of the energy detector in DS/SS communications. Three chip waveforms such as rectangular, half-sine and raised-cosine are examined as the DS/SS chip waveform. It is demonstrated that the partial-band detection can enhance the detection performance of the energy detector approximately 50-70% compared with the full-band detection. When the chip rate is identical, the raised-cosine waveform shows lower detection probability due to its wider spreading bandwidth. However, when the spreading bandwidth is identical, the rectangular waveform shows lower detection probability due to its lower partial-band energy factor.

The hardware implementation of a neural network model using stochastic logic has been able to integrate numerous neuron units on a chip. However, the limitation of applications occurred since the stochastic neurosystem could execute only discrete-time dynamics. We have contrived a neuron model with continuous-time dynamics by using stochastic calculations. In this paper, we propose the circuit design of a new neuron circuit, and show the fabricated neurochip comprising 64 neurons with experimental results. Furthermore, a new asynchronous updating method and a new activation function circuit are proposed. These improvements enhance the performance of the neurochip greatly.

This paper proposes a learning classifier based on Support Vector Domain Description (SVDD) for two-class problem. First, by the description of the training samples from one class, a sphere boundary containing these samples is obtained; then, this boundary is used to classify the test samples. In addition, instead of the traditional quadratic programming, multiplicative updates is used to solve the Lagrange multiplier in optimizing the solution of the sphere boundary. The experiment on CBCL face database illustrates the effectiveness of this learning algorithm in comparison with Support Vector Machine (SVM) and Sequential Minimal Optimization (SMO).