Characterization of peer-to-peer (P2P) traffic is an essential step to develop workload models towards capacity planning and cyber-threat countermeasure over P2P networks. In this paper, we present a classification scheme for characterizing P2P file-sharing hosts based on transport layer statistical features. The proposed scheme is accessed on a virtualized environment that simulates a P2P-friendly cloud system. The system shows high accuracy in differentiating P2P file-sharing hosts from ordinary hosts. Its tunability regarding monitoring cost, system response time, and prediction accuracy is demonstrated by a series of experiments. Further study on feature selection is pursued to identify the most essential discriminators that contribute most to the classification. Experimental results show that an equally accurate system could be obtained using only 3 out of the 18 defined discriminators, which further reduces the monitoring cost and enhances the adaptability of the system.

This paper proposes a bit-split string matcher architecture for a memory-efficient hardware-based parallel pattern matching engine. In the proposed bit-split string matcher, multiple finite-state machine (FSM) tiles share match vectors to reduce the required number of stored match vectors. By decreasing the memory size for storing match vectors, the total memory requirement can be minimized.

This paper proposes a video-quality estimation method based on a no-reference model for realtime quality monitoring in video-streaming services. The proposed method analyzes both bitstream information and decoded pixel information to estimate video-quality degradation by transmission errors. Video quality in terms of a mean squared error (MSE) between degraded video frames and error-free video frames is estimated on the basis of the number of impairment macroblocks in which the quality degradation has not been possible to be concealed. Error-concealment effectiveness is evaluated using motion information and luminance discontinuity at the boundaries of impairment regions. Simulation results show a high correlation (correlation coefficients of 0.93) between the actual MSE and the number of macroblocks in which error concealment has not been effective. These results show that the proposed method works well in reatime quality monitoring for video-streaming services.

We have previously proposed an indoor monitoring and security system with an array sensor. The array sensor has some advantages, such as low privacy concern, easy installation with low cost, and wide detection range. Our study is different from the previously proposed classification method for array sensor, which uses a threshold to classify only two states for intrusion detection: nothing and something happening. This paper describes a novel state classification method based on array signal processing with a machine learning algorithm. The proposed method uses eigenvector and eigenvalue spanning the signal subspace as features, obtained from the array sensor, and assisted by multiclass support vector machines (SVMs) to classify various states of a human being or an object. The experimental results show that our proposed method can provide high classification accuracy and robustness, which is very useful for monitoring and surveillance applications.

An on-chip soft-start circuit based on a switched-capacitor for DC-DC switching regulator is presented. A ramp-voltage, which is generated by a switched-capacitor, is used to make pulse width slowly increase from zero, in order to eliminate the inrush current and the overshoot voltage during start-up. The post simulation results show that the regulator soft starts well with the proposed soft-start circuit.

Nowadays, software development societies have given more precedence to Open Source Software (OSS). There is much research aimed at understanding the OSS society to sustain the OSS product. To lead an OSS project to a successful conclusion, researchers study how developers change source codes called patches in project repositories. In existing studies, we found an argument in the conventional patch acceptance detection procedure. It was so simplified that it omitted important cases from the analysis, and would lead researchers to wrong conclusions. In this research, we propose an algorithm to overcome the problem. To prove out our algorithm, we constructed a framework and conducted two case studies. As a result, we came to a new and interesting understanding of patch activities.

A low power and high performance with third order delta-sigma modulator for audio applications, fabricated in a 0.18 µm CMOS process, is presented. The modulator utilizes a third order noise shaping with only one opamp by using an opamp sharing technique. The opamp sharing among three integrator stages is achieved through the optimal operation timing, which makes use of the load capacitance differences between the three integrator stages. The designed modulator achieves 101.1 dB signal-to-noise ratio (A-weighted) and 101.5 dB dynamic range (A-weighted) with 7.5 mW power consumption from a 3.3 V supply. The die area is 1.27 mm2. The fabricated delta-sigma modulator achieves the highest figure-of-merit among published high performance low power audio delta-sigma modulators.

In this paper, we propose a novel in-network aggregation scheduling scheme for forest fire monitoring in a wireless sensor network. This adaptively configures both the timeout and the collecting period according to the potential level of a fire occurrence. At normal times, the proposed scheme decreases a timeout that is a wait time for packets sent from child nodes and makes the collecting period longer. That reduces the dissipated energy of the sensor node. Conversely, the proposed scheme increases the timeout and makes the collecting period shorter during fire occurrences in order to achieve more accurate data aggregation and early fire detection.

To reduce the cost of fault management in all-optical networks, it is a promising approach to detect the degradation of optical signal quality solely at the terminal points of all-optical monitoring paths. The all-optical monitoring paths must be routed so that all single-link failures can be localized using route information of monitoring paths where signal quality degradation is detected. However, route computation for the all-optical monitoring paths that satisfy the above condition is time consuming. This paper proposes a procedure for deriving the lower bounds of the required number of monitoring paths to localize all single-link failures, and proposes an efficient monitoring path computation method based on the derived lower bounds. The proposed method repeats the route computation for the monitoring paths until feasible routes can be found, while the assumed number of monitoring paths increases, starting from the lower bounds. With the proposed method, the minimum number of monitoring paths with the overall shortest routes can be obtained quickly by solving several small-scale integer linear programming problems when the possible terminal nodes of monitoring paths are arbitrarily given. Thus, the proposed method can minimize the required number of monitors for detecting the degradation of signal quality and the total overhead traffic volume transferred through the monitoring paths.

The performance of successive approximation register (SAR) analog-to-digital converter (ADC) is well balanced between power and speed compare to the conventional flash or pipeline architecture. The nonlinearities suffer from the CDAC mismatch and comparator offset degrades SAR ADC performance in terms of DNL and INL. An on chip histogram-based digitally assisted background calibration technique is proposed to cancel and relax the aforesaid nonlinearities. The calibration is performed using the input signal, watching the digital codes in the specified vicinity of the decision boundaries, and feeding back to control the compensation capacitor periodically. The calibration does not require special calibration signal or additional analog hardware which is simple and amenable to hardware or software implementations. A 9-bit SAR ADC with split CDAC has been implemented in a 65 nm CMOS technology and it achieves a peak SNDR of 50.81 dB and consumes 1.34 mW from a 1.2-V supply. +0.4/-0.4 LSB DNL and +0.5/-0.7 LSB INL are achieved after calibration. The ADC has input capacitance of 180 fF and occupies an area of 0.10.13 mm2.

Internet threats caused by botnets/worms are one of the most important security issues to be addressed. Darknet, also called a dark IP address space, is one of the best solutions for monitoring anomalous packets sent by malicious software. However, since darknet is deployed only on an inactive IP address space, it is an inefficient way for monitoring a working network that has a considerable number of active IP addresses. The present paper addresses this problem. We propose a scalable, light-weight malicious packet monitoring system based on a multi-dimensional IP/port analysis. Our system significantly extends the monitoring scope of darknet. In order to extend the capacity of darknet, our approach leverages the active IP address space without affecting legitimate traffic. Multi-dimensional monitoring enables the monitoring of TCP ports with firewalls enabled on each of the IP addresses. We focus on delays of TCP syn/ack responses in the traffic. We locate syn/ack delayed packets and forward them to sensors or honeypots for further analysis. We also propose a policy-based flow classification and forwarding mechanism and develop a prototype of a monitoring system that implements our proposed architecture. We deploy our system on a campus network and perform several experiments for the evaluation of our system. We verify that our system can cover 89% of the IP addresses while darknet-based monitoring only covers 46%. On our campus network, our system monitors twice as many IP addresses as darknet.

This paper proposes a video-quality estimation method based on a reduced-reference model for realtime quality monitoring in video streaming services. The proposed method chooses representative-luminance values for individual original-video frames at a server side and transmits those values, along with the pixel-position information of the representative-luminance values in each frame. On the basis of this information, peak signal-to-noise ratio (PSNR) values at client sides can be estimated. This enables realtime monitoring of video-quality degradation by transmission errors. Experimental results show that accurate PSNR estimation can be achieved with additional information at a low bit rate. For SDTV video sequences which are encoded at 1 to 5 Mbps, accurate PSNR estimation (correlation coefficient of 0.92 to 0.95) is achieved with small amount of additional information of 10 to 50 kbps. This enables accurate realtime quality monitoring in video streaming services without average video-quality degradation.

This paper presents fundamental concepts, overall process and recent research issues of Mining Software Repositories. The data sources such as source control systems, bug tracking systems or archived communications, data types and techniques used for general MSR problems are also presented. Finally, evaluation approaches, opportunities and challenge issues are given.

In this paper, a fifth order curer low-pass filter using as switched-capacitor (SC) architecture is proposed and fabricated with TSMC 0.18 µm CMOS process. A fully differential SC is adopted via the bilinear transform of the corresponding analogue RLC passive prototype. To reach the largest possible input dynamic range and save chip area, the method of dynamic range scaling and minimum capacitor scaling is used. Measured results show that the proposed filter achieves a pass-band of 12.1 MHz with a sampling rate of 100 MHz, a SFDR of 50 dB, a stop-band attenuation greater than 50 dB and a power consumption of 48.5 mW at 1.8 V power supply. Including pads, the chip area occupies 1.515 (1.391.09) mm2. This paper has the feature of low noise, excellent linearity of the filter, and high stability. The experimental results show that it has perfect performance for WiMAX applications and standard is recommended.

Switched parasitic capacitors of sleep blocks with a tri-mode power gating structure are implemented to reduce on-chip resonant supply noise in 1.2 V, 65 nm standard CMOS process. The tri-mode power gating structure makes it possible to store charge into the parasitic capacitance of the power gated blocks. The proposed method achieves 53.1% and 57.9% noise reduction for wake-up noise and 130 MHz periodic supply noise, respectively. It also realizes noise cancelling without discharging time before using parasitic capacitors of sleep blocks, and shows 8.4x boost of the effective capacitance value with 2.1% chip area overhead. The proposed method can save the chip area for reducing resonant supply noise more effectively.

With the proliferation of IEEE 802.11 wireless local area networks, large numbers of wireless access points have been deployed, and it is often the case that a user can detect several access points simultaneously in dense metropolitan areas. Most owners, however, encrypt their networks to prevent the public from accessing them due to the increased traffic and security risk. In this work, we use pricing as an incentive mechanism to motivate the owners to share their networks with the public, while at the same time satisfying users' service demand. Specifically, we propose a “federated network” concept, in which radio resources of various wireless local area networks are managed together. Our algorithm identifies two candidate access points with the lowest price being offered (if available) to each user. We then model the price announcements of access points as a game, and characterize the Nash Equilibrium of the system. The efficiency of the Nash Equilibrium solution is evaluated via simulation studies as well.

This paper proposes an all-digital process variability monitor based on a shared structure of a buffer ring and a ring oscillator. The proposed circuit monitors the PMOS and NMOS process variabilities independently according to a count number of a single pulse which propagates on the ring during the buffer ring mode, and an oscillation period during the ring oscillator mode. Using this shared-ring structure, we reduce the occupation area about 40% without loss of process variability monitoring properties compared with the conventional circuit. The proposed shared-ring circuit has been fabricated in 65 nm CMOS process and the measurement results with two different wafer lots show the feasibility of the proposed process variability monitoring scheme.

The susceptibility of a static random access memory (SRAM) core against static and dynamic variation of power supply voltage is evaluated, by using on-chip diagnosis structures of memory built-in self testing (MBIST) and on-chip voltage waveform monitoring (OCM). The SRAM core of interest in this paper is a synthesizable version applicable to general systems-on-a-chip (SoC) design, and fabricated in a 90 nm CMOS technology. RF power injection to power supply networks is quantified by OCM. The number of resultant erroneous bits as well as their distribution in the cell array is given by MBIST. The frequency-dependent sensitivity reflects the highly capacitive nature of densely integrated SRAM cells.

“Internet of Things” (IoT) requires information to be collected from “anything”, “anytime”, and “anywhere”. In order to achieve this, wireless devices are required that have (1) automatic data acquisition capability, (2) small size, (3) long life, and (4) long range communication capability. One way to meet these requirements is to adopt active Radio Frequency Identification (RFID) systems. Active RFID is more advantageous than passive RFID and enables higher data reading performance over longer distances. This paper surveys active RFID systems, the services they currently promise to provide, technical problems common to these services, and the direction in which research should head in the future. It also reports the results of EPCglobal (EPC: Electronic Product Code) pilot tests conducted on global logistics for tracking ocean/air container transportation using active RFID systems for which we developed several new types of active RFID tags. The test results confirm that our active RFID tags have sufficient capability and low power consumption to well support ocean/air transportation and logistics service.

Service providers should monitor the quality of experience of a communication service in real time to confirm its status. To do this, we previously proposed a packet-layer model that can be used for monitoring the average video quality of typical Internet protocol television content using parameters derived from transmitted packet headers. However, it is difficult to monitor the video quality per user using the average video quality because video quality depends on the video content. To accurately monitor the video quality per user, a model that can be used for estimating the video quality per video content rather than the average video quality should be developed. Therefore, to take into account the impact of video content on video quality, we propose a model that calculates the difference in video quality between the video quality of the estimation-target video and the average video quality estimated using a packet-layer model. We first conducted extensive subjective quality assessments for different codecs and video sequences. We then model their characteristics based on parameters related to compression and packet loss. Finally, we verify the performance of the proposed model by applying it to unknown data sets different from the training data sets used for developing the model.