In order to reduce the amount of interference to neighboring cells in cellular systems, we generally use base station (BS) antennas that have sharp beam patterns in the vertical plane; however, the distribution of incoming waves at the BS affects the effective gain of the BS antennas which have directional pattern. Therefore, we have to clarify the characteristics of the distribution of the incoming waves. A recent trend is decreasing the cell radius; therefore, clarifying the distribution of the incoming waves at the BS when mobile stations (MSs) are located within 1 km from the BS is important. In this report, we evaluate the effective gains of the BS antennas, which are calculated using the measured vertical power angle profile (PAP). Moreover, we examine the application of a simple incoming wave model to the evaluation of the antenna effective gains. In the model, the average power of the incoming waves is set to the Laplacian function and each wave is changed to a lognormal distribution. The antenna effective gain calculated using the model agrees well with that calculated using the measured PAP.

Linear complexity can be used to detect predictable nonrandom sequences, and hence it is included in the NIST randomness test suite. But, as shown in this paper, the NIST test suite cannot detect nonrandom sequences that are generated, for instance, by concatenating two different M-sequences with low linear complexity. This defect comes from the fact that the NIST linear complexity test uses deviation from the ideal value only in the last part of the whole linear complexity profile. In this paper, a new faithful linear complexity test is proposed, which uses deviations in all parts of the linear complexity profile and hence can detect even the above nonrandom sequences. An efficient formula is derived to compute the exact area distribution needed for the proposed test. Furthermore, a simple procedure is given to compute the proposed test statistic from linear complexity profile, which requires only O(M) time complexity for a sequence of length M.

Many content distribution systems such as CDN and P2P file sharing have been developed. In these systems, file-type contents require downloads to be completed before they can be played and they have no value before the download finishes. Therefore, a user's satisfaction depends on the length of the service latency. That is, the length of time from when the user issued a request until the user received an entire file. Reducing the sum of that time is necessary for the whole delivery system to satisfy users and maintain dependability on system performance. We discuss a hop-by-hop file delivery system suitable for delivering file contents whereby the sum of service latency is reduced by using the request conditions. Moreover, we propose a file delivery scheduling algorithm for a one-link model given that the content request frequency is unknown. The algorithm is based on a local optimal strategy. We performed a characteristic analysis by computer simulation. The results showed that our algorithm performs at nearly the theoretical efficiency limit of the hop-by-hop system when the request frequency distribution of each content has a deviation.

The generalized Hamming weight played an important role in coding theory. In the study of the wiretap channel of type II, the generalized Hamming weight was extended to a two-code format. Two equivalent concepts of the generalized Hamming weight hierarchy and its two-code format, are the inverse dimension/length profile (IDLP) and the inverse relative dimension/length profile (IRDLP), respectively. In this paper, the Singleton upper bound on the IRDLP is improved by using a quotient subcode set and a subset with respect to a generator matrix, respectively. If these new upper bounds on the IRDLP are achieved, in the corresponding coordinated two-party wire-tap channel of type II, the adversary cannot learn more from the illegitimate party.

In UMTS (universal mobile telecommunications system) networks upgraded with HSPA (high speed packet access) technology, the high access bandwidth and advanced mobile devices make it applicable to share large files among mobile users by peer-to-peer applications. To receive files quickly is essential for mobile users in file sharing applications, mainly because they are subject to unstable signal strength and battery failures. While many researches present peer-to-peer file sharing architectures in mobile environments, few works focus on decreasing the time spent in disseminating files among users. In this paper, we present an efficient peer-to-peer file sharing design for HSPA networks called AFAM -- Adaptive efficient File shAring for uMts networks. AFAM can decrease the dissemination time by efficiently utilizing the upload-bandwidth of mobile nodes. It uses an adaptive rearrangement of a node's concurrent uploads, which causes the count of the node's concurrent uploads to lower while ensuring that the node's upload-bandwidth can be efficiently utilized. AFAM also uses URF -- Upload Rarest First policy for the block selection and receiver selection, which achieves real rarest-first for the spread of blocks and effectively avoids the "last-block" problem in file sharing applications. Our simulations show that, AFAM achieves much less dissemination time than other protocols including BulletPrime and a direct implementation of BitTorrent for mobile environments.

Delay profile of ultra-wideband impulse-radio (UWB-IR) indoor channel fluctuates for a physical change such as intruder. This paper investigates a human body detection using the UWB-IR in order to protect a house, not a room, because the radio with high range resolution can penetrate into the inner walls and also the reflected paths from human body are discriminated in time domain. The usefulness is experimentally investigated under a scenario which someone intrudes into a typical house with four rooms and walks around.

A total-field/scattered-field (TF/SF) boundary which is commonly used in the finite-difference time-domain (FDTD) method to illuminate scatterers by plane waves, is developed for use in the constrained interpolation profile (CIP) method. By taking the numerical dispersion into account, the nearly perfect TF/SF boundary can be achieved, which allows us to calculate incident fields containing high frequency components without fictitious scattered fields. First of all, we formulate the TF/SF boundary in the CIP scheme. The numerical dispersion relation is then reviewed. Finally the numerical dispersion is implemented in the TF/SF boundary to estimate deformed incident fields. The performance of the nearly perfect TF/SF boundary is examined by measuring leaked fields in the SF region, and the proposed method drastically diminish the leakage compared with the simple TF/SF boundary.

The dispersion and the splice characteristics of optical fibers with trench-index profile are investigated. The normalized distance between core and trench is preferably larger than 3.0 to realize complete compatibility with the standard G.652 fiber in terms of chromatic dispersion. The optical fiber realizes compatibility with ITU-T Recommendation G.652 fiber and bend-insensitivity simultaneously. Fabricated fibers with the trench-index profiles can be spliced to standard single-mode fiber with low losses, which have similar values with simulation results.

A design method is proposed for a low-profile dual-shaped reflector antenna for the mobile satellite communications. The antenna is required to be low-profile because of mount restrictions. However, reduction of its height generally causes degradation of antenna performance. Firstly, an initial low-profile reflector antenna with an elliptical aperture is designed by using Geometrical Optics (GO) shaping. Then a Physical Optics (PO) shaping technique is applied to optimize the gain and sidelobes including mitigation of undesired scattering. The developed design method provides highly accurate design procedure for electrically small reflector antennas. Fabrication and measurement of a prototype antenna support the theory.

An application profile specifies a set of terms, drawn from one or more standard namespaces, for annotation of data, and constrains their usage and interpretations in a particular local application. An approach to representation of and reasoning with application profiles based on the OWL and OWL/XDD languages is proposed. The former is a standard Web ontology language, while the latter is a definite-clause-style rule language that employs XML expressions as its underlying data structure. Semantic constraints are defined in terms of rules, which are represented as XDD clauses. Application of the approach to defining application profiles with fine-grained semantic constraints, involving implicit properties of metadata elements, is illustrated. A prototype application profile development environment equipped with metadata validation features has been implemented based on the proposed framework.

This paper proposes a new method for realizing the web page recommendation system by sharing users' web browse history on an anonymous P2P network. Our scheme creates a user profile, a summary of the user's web browse trends, by analyzing the contents of the web pages browsed. The scheme then provides a P2P network to exchange web browse histories so as to create mutual web page recommendations. The novelty of our method lies in its P2P network formulation; it is formulated in a way so that users having similar user profiles are automatically connected, yet their user profiles are protected from being disclosed to other users. The proposed method intentionally distributes bogus user profiles on the P2P network, while not harming the efficiency of the web browse history sharing process.

This study examines treatment of a boundary between media to simulate an acoustic field using the CIP method. The handling of spatial derivatives of fields is extremely important for CIP acoustic field analysis. We demonstrate a method of handling this boundary and report results of CIP acoustic field analysis using the present treatment.

A biometrics system for identifying individuals using the pattern of veins in a finger was previously proposed. The system has the advantage of being resistant to forgery because the pattern is inside a finger. Infrared light is used to capture an image of a finger that shows the vein patterns, which have various widths and brightnesses that change temporally as a result of fluctuations in the amount of blood in the vein, depending on temperature, physical conditions, etc. To robustly extract the precise details of the depicted veins, we developed a method of calculating local maximum curvatures in cross-sectional profiles of a vein image. This method can extract the centerlines of the veins consistently without being affected by the fluctuations in vein width and brightness, so its pattern matching is highly accurate. Experimental results show that our method extracted patterns robustly when vein width and brightness fluctuated, and that the equal error rate for personal identification was 0.0009%, which is much better than that of conventional methods.

With advances in ubiquitous environments, user demand for easy data-lookup is growing rapidly. Not only users but intelligent ubiquitous applications also require data-lookup services for a ubiquitous computing framework. This paper proposes a backward-compatible, searchable virtual file system (S-VFS) for easy data-lookup. We add search functionality to the VFS, the de facto standard abstraction layer over the file system. Users can find a file by its attributes without remembering the full path. S-VFS maintains the attributes and the indexing structures in a normal file per partition. It processes queries and returns the results in a form of a virtual directory. S-VFS is the modified VFS, but uses legacy file systems without any modification. Since S-VFS supports full backward compatibility, users can even browse hierarchically with the legacy path name. We implement S-VFS in Linux kernel 2.6.7-21. Experiments with randomly generated queries demonstrate outstanding lookup performance with a small overhead for indexing.

One of 3-D devices to achieve high density arrays was adopted in this study, where source and drain junctions are formed along the silicon fin. The screening by adjacent high fins for large sensing margin makes it hard to ion-implant with high angle so that vertical ion implantation is inevitable. In this study, the dependency of current characteristics on doping profiles is investigated by 3-D numerical analysis. The position of concentration peak and the doping gradient are varied to look into the effects on driving currents. Through these analyses, the optimum condition of ion implantation for 3-D devices is estimated.

In peer-to-peer (P2P) networks, reputation is used to estimate the trustworthiness of servents and to help prevent untrustworthy resources from spreading by malicious servents. However, in dynamic scenarios with arrivals and departures of servents and resources, servent reputation is not enough to reduce the impacts of malicious behaviors such as lying, whitewashing, etc. In this paper, we propose a new reputation management model using both servent and resource reputation and demonstrate detail protocols to implement our model in structured P2P networks. Simulation results show that our model can reduce the rate of downloading untrustworthy resources more rapidly than the previous models even in dynamic scenarios where servents can rejoin with new identities, introduce new untrustworthy resources, and send wrong feedbacks. Also, we show that the proposed model and protocol can effectively share the load between servents.

High power consumption and slow access of enlarged and multiported register files make it difficult to design high performance superscalar processors. The clustered architecture, where the conventional monolithic register file is partitioned into several smaller register files, is expect to overcome the register file issues. In the clustered architecture, the more a monolithic register file is partitioned, the lower power and faster access register files can be realized. However, the partitioning causes losses of IPC (instructions per clock cycle) due to communication among register files. Therefore, degree of partitioning has a strong impact on the trade-off between power consumption and performance. In addition, the organization of partitioned register files also affects the trade-off. In this paper, we attempt to investigate appropriate degrees of partitioning and organizations of partitioned register files in a clustered architecture to assess the trade-off. From the results of execute-driven simulation, we find that the organization of register files and the degree of partitioning have a strong impact on the IPC, and the configuration with non-consistent register files can make use of the partitioned resources more effectively. From the results of register file access time and energy modeling, we find that the configurations with the highly partitioned non-consistent register file organization can receive benefit of the partitioning in terms of operating frequency and access energy of register files. Further, we examine relationship between IPS (instructions per second) and the product of IPC and operating frequency of register files. The results suggest that highly partitioned non-consistent configurations tends to gain more advantage in performance and power.

This paper surveys and introduces propagation studies and models that are expected to contribute to the development of broadband wireless systems. The survey focused on theory-based propagation models, experimental measurement data useful for modeling, and transmission characteristic evaluations using propagation models. The survey did not attempt to cover all papers in the research fields, but rather took key papers for various relevant subjects and described them in some detail. The basic characteristics of multipath propagation are summarized from the viewpoints of narrow-band (NB), wide-band (WB), and ultra wide-band (UWB). Recent studies on spatio-temporal propagation models and the relationship between models and systems are introduced. To clarify the relationship between OFDM, which is a representative of wideband data transmission schemes, and wave propagation factors, problems due to large delay spread and large Doppler spread are highlighted. Finally, studies on UWB propagation measurement and propagation models are introduced.

Providing data availability in a high performance computing environment is very important, especially in this data-intensive world. Most clusters either equip with RAID (Redundant Array of Independent Disks) devices or use redundant nodes to protect data from loss. However, neither of these can really solve the reliability problem incurred in a striped file system. Striping provides an efficient way to increase I/O throughput both in the distributed and parallel paradigms. But it also reduces the overall reliability of a disk system by N fold, where N is the number of independent disks in the system. Parallel Virtual File System (PVFS) is an open source parallel file system which has been widely used in the Linux environment. Its striping structure is good for performance but provides no fault tolerance. We implement Reliable Parallel File System (RPFS) based on PVFS but with reliability support. Our quantitative analysis shows that MTTF (Mean Time To Failure) of our RPFS is better than that of PVFS. Besides, we propose a parity cache table (PCT) to alleviate the penalty of parity updating. The evaluation of our RPFS shows that its read performance is almost the same as that of PVFS (2% to 13% degradation). As to the write performance, 28% to 45% improvement can be achieved depending on the behavior of the operations.

Modern processors have large instruction windows to improve performance. They usually adopt register renaming, where every active instruction with a valid destination needs a physical register. As the instruction windows get larger, however, bigger physical register files are required. To solve this problem, we proposed a physical register sharing technique. It shares a physical register among multiple instructions based on a value similarity. As a result, we achieved performance improvement without increasing the size of the physical register file. In addition, the proposed technique can also be used to reduce the timing, complexity and area overhead of the physical register file.