Analyzing short-interval-traffic behaviors is important for network performance management to realize high quality multimedia applications. However, it is difficult to measure short-interval-traffic volumes because there are complications in collecting short-interval-traffic data from routers. An example is a heavy load on routers or inaccurate measurement by the short-polling interval; it even demands expensive measurement tools. To resolve these disadvantages, an estimating method of short-interval-traffic distribution (EMSIT) has been proposed. This method estimates short-interval-traffic distributions using MIB (Management Information Base) data, which collects traffic volumes in cycles of several minutes. In this paper, we propose a new estimation method (EMSIT-LD) based on EMSIT, which applies to the case of long-term-traffic dynamics. We evaluate it using computer simulations and actual traffic data.

An authenticated encryption scheme provides a mechanism of signing and encrypting simultaneously, and furthermore, the receiver can verify and decrypt the signature at the same time. Tseng et al. proposed two efficiently authenticated encryption schemes which can check the validity of the sent data before message recovery, but in fact their schemes cannot achieve completely the function. In this article, we point out the flaw and propose an improved scheme of revision.

A new small-signal model for fully depleted silicon-on-insulator (FD-SOI) MOSFETs operating at RF frequencies is presented. The model accounts for the non-quasi-static effect by determining model parameters using a curve fitting procedure to reproduce the frequency response of FD-SOI MOSFETs. The accuracy of the model is validated by comparison of S parameters with measured results in the range from 0.2 GHz to 20 GHz.

Energy efficiency of cache memories is crucial in designing embedded processors. Reducing energy consumption in the instruction cache is especially important, since the instruction cache consumes a significant portion of total processor energy. This paper proposes a new instruction cache architecture, named Partitioned Instruction Cache (PI-Cache), for reducing dynamic energy consumption in the instruction cache by partitioning it to smaller (less power-consuming) sub-caches. When the proposed PI-Cache is accessed, only one sub-cache is accessed by utilizing the temporal/spatial locality of applications. In the meantime, other sub-caches are not accessed, leading to dynamic energy reduction. The PI-Cache also reduces dynamic energy consumption by eliminating the energy consumed in tag lookup and comparison. Moreover, the performance gap between the conventional instruction cache and the proposed PI-Cache becomes little when the physical cache access time is considered. We evaluated the energy efficiency by running a cycle accurate simulator, SimpleScalar, with power parameters obtained from CACTI. Simulation results show that the PI-Cache improves the energy-delay product by 20%-54% compared to the conventional direct-mapped instruction cache.

With the increasing demand for SoCs to include rich functionality, SoCs are being designed with hundreds of small memories with different sizes and frequencies. If memory BIST logics were individually added to these various memories, the area overhead would be very high. To reduce the overhead, memory BIST logic must therefore be shared. This paper proposes a memory-grouping method for memory BIST logic sharing. A memory-grouping problem is formulated and an algorithm to solve the problem is proposed. Experimental results show that the proposed method reduced the area of the memory BIST wrapper by up to 40.55%. The results also show that the ability to select from two types of connection methods produced a greater reduction in area than using a single connection method.

When digital broadcasting services are provided through cable television (CATV) networks, viewers watching interactive programs such as quizzes or auctions may respond to the program within a short period. If these responses are transmitted in the upstream channel of the CATV networks using TCP/IP, they will result in burst traffic. The numerous TCP connections will trigger congestion in the upstream transmission facilities and will cause a significant delay in conventional Internet services such as web-browsing. The present paper proposes a new method of controlling the CATV upstream channel to avoid such congestion. We introduce class-based queues at each cable TV station, in which each service class is related to a type of interactive service. The status of the queue is relayed to the cable modems of subscribers using a CATV-specific MAC protocol. This queue-status information is used to suspend further initiation of TCP connections at cable modems. As a result, the TCP connections will be arbitrated in the CATV network, while the delay of the response transmission is traded for smoothing of the burst traffic. We numerically evaluate the effect of the proposed method using the time distribution of responses to an actual quiz program. The results show that the proposed method successfully suppresses interference of the burst traffic with conventional best-effort services.

This letter evaluates the performance of an uplink multicarrier-code division multiple access (MC-CDMA) system when the frequency offsets of all users are random variables and the frequency offset for the desired user is compensated. The analysis confirms that performance degradation due to frequency offset is negligible if the estimation error of normalized frequency offset for the desired user is less than 10-1.

The label placement problem is one of the most important problems in geographic information systems, cartography, graph drawing, and graphical interface design. In this paper, we considered the label size maximization problem for points with axes-parallel rectangular labels that correspond to character strings and have different widths based on the number of characters. We propose an algorithm for computing the optimum size for the label size maximization problem in the 2-position model and a polynomial time algorithm for the problem in the 4-position model. Our algorithm cannot obtain the maximum value in the 4-position model because the label size maximization problem in the 4-position model is NP-hard. However, our algorithm is efficient in practice, as shown by computational experiments. Further, computational results for JR trains, subways and major private railroads in Tokyo are presented.

Recently, system level design languages (SLDL), which can describe both hardware and software aspects of the design, are receiving attention. Mixed-signal extensions of SLDL enable current discrete-oriented SLDLs to describe and simulate not only digital systems but also digital-analog mixed-signal systems. The synchronization between discrete and continuous behaviors is widely regarded as a critical part in the extensions. In this paper, we present an event-driven synchronization mechanism for both timed and untimed system level designs through which discrete and continuous behaviors are synchronized via AD events and DA events. We also demonstrate how the synchronization mechanism can be incorporated into the kernel of SLDL, such as SpecC. In the extended kernel, a new simulation cycle, the AMS cycle, is introduced. Three case studies show that the extended SpecC-based system level design environment using our synchronization mechanism works well with timed/untimed mixed-signal system level description.

Scenarios that describe concrete situations of software operation play an important role in software development, especially in requirements engineering. Since scenarios are informal, the correctness of scenarios is hard to be verified. The authors have developed a language for describing scenarios in which simple action traces are embellished. The purposes are to include typed frames based on a simple case grammar of actions and to describe the sequence among events. Based on this scenario language, this paper describes both (1) a correctness-checking method using rules to detect errors (lack of events, extra events, and wrong sequence among events) in a scenario and (2) a retrieval method of rules from rule DB that applicable to scenarios using pre and post- conditions.

A design of non-orthogonal 33 space-time block code (STBC) is proposed. The proposed design achieves full rate, full level diversity, and maximum coding gain by symbol rotation (SR) method. In addition, the proposed scheme has lower encoding complexity than the unitary constellation-rotation (CR) STBC, while two methods exhibit the same bit error rate (BER) performance in Rayleigh fading channel.

This paper analyzes automation surprises in human-machine systems with time information. Automation surprises are phenomena such that the underlying machine's behavior diverges from user's intention and may lead to critical situations. Thus, designing human-machine systems without automation surprises is one of fundamental issues to achieve reliable user interaction with the machines. In this paper, we focus on timed human-machine interaction and address their formal aspects. The presented framework is essentially an extension of untimed human-machine interaction and will cover the previously proposed methodologies. We employ timed automata as a model of human-machine systems with time information. Modeling the human-machine systems as timed automata enables one to deal with not only discrete behavior but also time constraints. Then, by introducing the concept of timed simulation of the machine model and the user model, conditions which guarantee the nonexistence of automation surprises are derived. Finally, we construct a composite model in which a machine model and a user model evolve concurrently and show that automation surprises can be detected by solving a reachability problem in the composite model.

We present a training algorithm to create a neural network (NN) ensemble that performs classification tasks. It employs a competitive decay of hidden nodes in the component NNs as well as a selective deletion of NNs in ensemble, thus named a pruning algorithm for NN ensembles (PNNE). A node cooperation function of hidden nodes in each NN is introduced in order to support the decaying process. The training is based on the negative correlation learning that ensures diversity among the component NNs in ensemble. The less important networks are deleted by a criterion that indicates over-fitting. The PNNE has been tested extensively on a number of standard benchmark problems in machine learning, including the Australian credit card assessment, breast cancer, circle-in-the-square, diabetes, glass identification, ionosphere, iris identification, and soybean identification problems. The results show that classification performances of NN ensemble produced by the PNNE are better than or competitive to those by the conventional constructive and fixed architecture algorithms. Furthermore, in comparison to the constructive algorithm, NN ensemble produced by the PNNE consists of a smaller number of component NNs, and they are more diverse owing to the uniform training for all component NNs.

Cooperative transmission among users in multiple access wireless environments is an efficient way to obtain the powerful benefits of multi-antenna systems without the need for physical arrays. Its performance in relay networks were extensively analyzed but most papers only focused on the case of high signal-to-noise ratio (SNR) or loose power constraints. Based on the approximation of total SNR distributions of the propagation paths through relays as the exponential functions, we derive the analytical BER expression in a simple form for general relay networks under strict power restriction. Numerical and simulation results reveal the high accuracy of the distribution estimation as well as the high reliability of the deduced formula, especially at the low SNR.

The module-wise dynamic voltage and frequency scaling (MDVFS) scheme is applied to a single-chip H.264/MPEG-4 audio/visual codec LSI. The power consumption of the target module with controlled supply voltage and frequency is reduced by 40% in comparison with the operation without voltage or frequency scaling. The consumed power of the chip is 63 mW in decoding QVGA H.264 video at 15 fps and MPEG-4 AAC LC audio simultaneously. This LSI keep operating continuously even during the voltage transition of the target module by introducing the newly developed dynamic de-skewing system (DDS) which watches and control the clock edge of the target module.

Recently, a novel detector was proposed by the authors for code acquisition in non-Gaussian impulsive channels [3], which dramatically outperforms the conventional squared-sum detector; however, it requires exact knowledge of the non-Gaussian noise dispersion. In this paper, a robust detector is proposed, which employs the signs and ranks of the received signal samples, instead of their actual values, and so does not require knowledge of the non-Gaussian noise dispersion. The acquisition performance of the proposed detector is compared with that of the detector of [3] in terms of the mean acquisition time. The simulation results show that the proposed scheme is not only robust to deviations from the true value of the non-Gaussian noise dispersion, but also has comparable performance to that of the scheme of [3] using exact knowledge of the non-Gaussian noise dispersion.

A new wideband signal DOA estimation algorithm based on modified quantum genetic algorithm (MQGA) is proposed in the presence of the errors and the mutual coupling between array elements. In the algorithm, the narrowband signal subspace fitting method is generalized to wideband signal DOA finding according to the character of space spectrum of wideband signal, and so the rule function is constructed. Then, the solutions is encoded onto chromosomes as a string of binary sequence, the variable quantum rotation angle is defined according to the distribution of optimization solutions. Finally, we use the MQGA algorithm to solve the nonlinear global azimuths optimization problem, and get optimization azimuths by fitness values. The computer simulation results illustrated that the new algorithm have good estimation performance.

This letter analyzes the performance of statistical cooperative diversity based on space-time block codes (STBC) (Statistical STBC cooperative diversity) considering the effects of quantization and observation noise. Binary quantization is used. The bit error rate (BER) and average mutual information of the statistical STBC cooperative diversity with Alamouti's STBC and two active nodes are derived in the presence of general observation noise. It is shown that the performance of the statistical STBC cooperative diversity depends on the effects of observation noise and the number of cooperating nodes largely. It is also shown how much the communication between sensor nodes or feedback from the fusion center improves the performance of STBC cooperative diversity.

With the application of optical add-drop multiplexers, wavelength assignment has become an important issue in SONET/WDM design. Among wavelength assignment methods, circle construction is of great importance. In this paper, we propose a novel matrix based circle construction algorithm for all-to-all uniform traffic in a bidirectional SONET/WDM ring.

We propose a new receiving method for an information-providing system that uses LED-based traffic lights as the transmitter. We analyzed the improvements obtained when 2-dimentional image sensor replaced the conventional single-element photodiode. First, we discuss the maximum receiver's field of view (FOV) when using the 2-dimentional image sensor at a particular focal length. We analyzed the best vertical inclination for both lanes and quantified the improvements in terms of the enhancement of received signal-noise ratio (SNR) when different numbers of pixels were applied. Our results indicate that using more pixels increases the received SNR and the service area becomes wider compared to the conventional single-element system. Consequently, receivable information within the service area also increased. We also found that the optimum number of pixels to accomplish a reliable communication system is 5050 because performance degradation occured with a larger number of pixels.