The least-squares probabilistic classifier (LSPC) is a computationally-efficient alternative to kernel logistic regression. However, to assure its learned probabilities to be non-negative, LSPC involves a post-processing step of rounding up negative parameters to zero, which can unexpectedly influence classification performance. In order to mitigate this problem, we propose a simple alternative scheme that directly rounds up the classifier's negative outputs, not negative parameters. Through extensive experiments including real-world image classification and audio tagging tasks, we demonstrate that the proposed modification significantly improves classification accuracy, while the computational advantage of the original LSPC remains unchanged.

Ubiquitous computing and communication are the key technology for achieving economic growth, sustainable development, safe and secure community towards a ubiquitous network society. Although the technology alone cannot solve the emerging problems, it is important to deploy services everywhere and reach real people with sensor enabled smart phones or devices. Using these devices and wireless sensor networks, we have been creating various types of ubiquitous services which support our everyday life. In this paper, we describe ubiquitous services based on a HOT-SPA model and discuss challenges in creating new ubiquitous services with smart enablers such as smart phones, wireless sensor nodes, social media, and cloud services. We first classify various types of ubiquitous service and introduce the HOT-SPA model which is aimed at modeling ubiquitous services. Several ubiquitous services, such as DIY smart object services, Twitthings, Airy Notes, and SensingCloud, are described. We then address the challenges in creating advanced ubiquitous services by enhancing coupling between a cyber and a physical space.

In this letter, we propose an improved Droptail algorithm that introduces the random packet drop strategy. Our theoretical analysis and experiments prove that the improved Droptail can match the most performance of AQM algorithms in stabilizing the TCP system and solving the global synchronization problem, while significantly reducing the complexity of the router control. This fact shows that our algorithm is superior to the most popular AQM algorithms such as RED, PI, etc.

When a link or node fails in a network, the affected flows are automatically rerouted. This increases the hop counts of the flows, which can drastically degrade network performance. Keeping the hop lengths as stable as possible, i.e., minimizing the difference in hop length between the original flow and the rerouted flow is important for network reliability. Therefore, network service providers need a method for designing networks that stabilizes the flow hop length and maintains connectivity during a link or node failure with limited investment cost. First, we formulate the network design problem used for determining the set of links to be added that satisfies the required constraints on flow hop length stability, connectivity, and node degree. Next, we prove that this problem is NP-complete and present two approximation algorithms for the optimization problem so as to minimize the number of links added. Evaluation of the performance of these algorithms by using 39 backbone networks of commercial ISPs and networks generated by two well-known models showed that the proposed algorithms provide effective solutions in sufficiently short computation time.

Source-follower-based (SFB) continuous-time low-pass filters (LPF) have the advantages of low power and high linearity over other filter topologies. The second-order SFB filter cells, which are key building blocks for high-order SFB filters, are often realized by composite source follower with positive feedback. For a single branch 2nd-order SFB cell, the linearity drops severely at high frequencies in the pass band because its slew-rate is restricted by the Q factor and the pole frequency. The folded 2nd-order SFB cell provides higher linearity because it has two DC branches, and hence has another freedom to increase the slew rate. However, because of the positive feedback, the folded and unfolded 2nd-order SFB cells, especially those with high Q factors, tend to be unstable and act as relaxation oscillators under given circuit parameters. In order to obtain higher Q factor, a new topology for the 2nd-order SFB cell without positive feedback is proposed in this paper, which is unconditionally stable and can provide high linearity. Based on the folded 2nd-order SFB cell and the proposed high-Q SFB cell, a 264 MHz sixth-order LPF with 3 stages for ultra wideband (UWB) applications is designed in 0.18 µm CMOS technology. Simulation results show that the LPF achieves an IIP3 of above 12.5 dBm in the whole pass band. The LPF consumes only 4.1 mA from a 1.8 V power supply, and has a layout area of 200 µm 150 µm.

Recent Location Based Services (LBS) extend not only information services such as car navigation services, but supporting various applications such as augmented reality and emergency services in ubiquitous computing environments. However location based services in the ubiquitous computing environment bring several security issues such as location privacy and forgery. While the privacy of the location based service is considered as the important security issue, security against location forgery is less considered. In this paper, we propose improved Han et al.'s protocol [1] that provides more lightweight computation. Our proposed model also improves the credibility of LBS by deploying multiple location sensing technologies.

In this paper, we define a discretized chaotic map as a digital realization of a one-dimensional chaos map. As a concrete example, we consider a family of pseudochaotic sequences with maximum length, referred to as maximum length pseudochaotic sequences, obtained from a class of discretized piecewise linear map. A theoretical framework for designing maximum length pseudochaotic sequences of the discretized chaotic maps is obtained. These discretized piecewise linear chaotic maps can be used in the design of binary sequences with constant autocorrelation values for several time delays.

It is well known that the problem to solve a set of randomly chosen multivariate quadratic equations over a finite field is NP-hard. However, when the number of variables is much larger than the number of equations, it is not necessarily difficult to solve equations. In fact, when n ≥ m(m+1) (n,m are the numbers of variables and equations respectively) and the field is of even characteristic, there is an algorithm to find one of solutions of equations in polynomial time (see [Kipnis et al., Eurocrypt '99] and also [Courtois et al., PKC '02]). In the present paper, we propose two new algorithms to find one of solutions of quadratic equations; one is for the case of n ≥ (about) m2-2m 3/2+2m and the other is for the case of n ≥ m(m+1)/2+1. The first one finds one of solutions of equations over any finite field in polynomial time, and the second does with O(2m) or O(3m) operations. As an application, we also propose an attack to UOV with the parameters given in 2003.

Video applications such as video conferencing among multiple users and video surveillance systems require multiple video connections and QoS guarantee. These days the video systems equipped with IEEE 802.11 LAN interfaces allows a broadband wireless access to the Internet at a reasonable price. However, according to the current IEEE 802.11e HCCA standard, if more than two video sessions are to be established simultaneously, some of them must share the TXOP because the available number of TSIDs for video transmission is restricted to two. In order to resolve this problem, we devise a scheme which can establish up to 13 video sessions by slightly modifying the frame structure while maintaining the compatibility with the current standard. Our scheme is implemented on the NCTUns 4.0 network simulator, and evaluated numerically in terms of throughput, delay, and PSNR. Also real video clips are used as input to our simulation. The results showed that our scheme guarantees the transmission bandwidth requested by each video session.

A new compact form of the sliding window recursive least squares (SWRLS) algorithm, the I-SWRLS algorithm, is derived using an indefinite matrix. The resultant algorithm has a form similar to that of the traditional recursive least squares (RLS) algorithm, and is more computationally efficient than the conventional SWRLS algorithm including two Riccati equations. Furthermore, a computationally reduced version of the I-SWRLS algorithm is developed utilizing a shift property of the correlation matrix of input data. The resulting fast algorithm reduces the computational complexity from O(N2) to O(N) per iteration when the filter length (tap number) is N, but retains the same tracking performance as the original algorithm. This fast algorithm is much easier to implement than the existing SWC FTF algorithms.

Admission control is a procedure to guarantee a given level of Quality of Service (QoS) by accepting or rejecting arrival connection requests. There are many studies on backlog or loss rate evaluation formulas for admission control at a single node. However, there are few studies on end-to-end evaluation formulas suitable for admission control. In a previous paper, the authors proposed a new stochastic network calculus for many flows using an approach taken from large deviations techniques and obtained asymptotic end-to-end evaluation formulas for output burstiness and backlog. In this paper, we apply this stochastic network calculus to a heterogeneous tandem network with many forwarding flows and cross traffic flows constrained by leaky buckets, and obtain a simple evaluation formula for the end-to-end backlog. In this formula, the end-to-end backlog can be evaluated by the traffic load at the bottle neck node. This result leads us to a natural extension of the evaluation formula for a single node.

Owing to the concerns about electromagnetic interference (EMI) from wireless local area networks (WLAN), an investigation into its impact on medical equipment is carried out. The results indicate that there is no evidence of 802.11 Wireless LAN systems being unsafe for installation inside hospital premises and only one piece of equipment was found to be susceptible to IEEE 802.11b standard.

High resolution direction-of-arrival (DOA) estimation algorithm for array antennas becomes popular in these days. However, there are several error factors such as mutual coupling among the elements in actual array. Hence array calibration is indispensable to realize intrinsic performance of the algorithm. In the many applications, it is preferable that the calibration can be done in the practical environment in operation. In such a case, the incident wave becomes coherent multipath wave. Calibration of array in the multipath environment is a hard problem, even when DOA of elementary waves is known. To realize array calibration in the multipath environment will be useful for some applications even if reference signals are required. In this report, we consider property of reference waves in the multipath environment and derive a new calibration technique by using the multipath coherent reference waves. The reference wave depends on not only the DOA but also complex amplitude of each elementary wave. However, the proposed technique depends on the DOA only. This is the main advantage of the technique. Simulation results confirm the effectiveness of the proposed technique.

This paper presents a strategy together with tool support for the translation of state machines from equational theories into rewrite theories, aiming at automatically generating rewrite theory specifications. Duplicate effort can be saved on specifying state machines both in equational theories and rewrite theories, when we incorporate the theorem proving facilities of CafeOBJ with the model checking facilities of Maude. Experimental results show that efficiencies of the generated specifications by the proposed strategy are significantly improved, compared with those that are generated by three other existing translation strategies.

Recent works on MIMO receiver design were mainly focused on sphere decoding, which provides a trade-off between the performance and complexity by suitably choosing the “radius” or the number of candidates in the search space. Meanwhile, another approach, called poly-diagonalization and trellis detection, has been proposed to compromise the complexity and performance. In this paper, we compare various MIMO receiver algorithms in terms of both performance and complexity. The performance is evaluated in a frequency selective fading channel environment on the basis of orthogonal frequency division multiplexing with channel coding, for which the generation of soft decision values is crucial. The simulations show that the poly-diagonalization approach matches the performance of sphere decoding at similar computational complexity.

In this paper, we propose a novel iterative transmit/receive equalization technique for single-carrier (SC) block transmission in a severe frequency-selective fading channel. Iterative frequency-domain inter-symbol interference (ISI) cancellation (FDIC) is introduced to the previously proposed joint iterative transmit/receive frequency-domain equalization (FDE) based on the minimum mean square error (MMSE) criterion. 1-tap FDE is employed at the transmitter. At the receiver, a 1-tap FDE and FDIC are jointly used and they are updated in an iterative manner. The transmit FDE weight is derived based on the MMSE criterion by taking into account the reduction of residual ISI in the receiver. To derive the weight, the transmitter assumes that the receiver can partially reduce the residual ISI after the FDIC. We conduct a computer simulation to investigate the achievable bit error rate (BER) performance to confirm the effectiveness of our proposed technique.

We propose a scheduling method called SCQ (Smoothly Changing Queue) which can control service rate by bulk size of video streaming services such as IPTV and VoD. Since SCQ allows queue length to change smoothly, video streaming services can be stably provided with low jitter. Queueing analysis results show that SCQ can more stably deliver video streaming with low jitter and loss than existing AQMs or queue length-based rate control methods.

We have studied the transport property of the Vertical MOSFET (V-MOSFET) with an impurity from the viewpoint of quantum electron dynamics. In order to obtain the position dependence of impurity for the electron transmission property through the channel of the V-MOSFET, we solve the time-dependent Shrodinger equation in real space mesh technique We reveal that the impurity in the source edge can assist the electron transmission from the source to drain working as a wave splitter. In addition, we also reveal the effect of an impurity in the surface of pillar is limited because of its dimensionality. Furthermore, we obtained that the electron injection from the source to the channel becomes difficult due to the energy difference between the subbands of the source and the channel. These results enable us to obtain the guiding principle to design the V-MOSFET in the 10 nm pillar. The results enable us to obtain the guiding principle to design the V-MOSFET beyond 20 nm design rule.

In this paper, a 24 GHz frequency source for low phase noise is presented in a 0.18 µm CMOS process. The 24 GHz frequency source chip is composed of a 12 GHz voltage controlled oscillator (VCO) and a 24 GHz balanced frequency doubler with class B gate bias. Compared to a conventional complementary VCO, the proposed 12 GHz VCO has phase noise improvement by using resistor current sources and substituting the nMOS cross-coupled pair in the conventional complementary VCO for a gm-boosted nMOS differential Colpitts pair. The measured phase noise and fundamental frequency suppression are -107.17 dBc/Hz at a 1 MHz offset frequency and -20.95 dB at 23.19 GHz frequency, respectively. The measured frequency tuning range is from 23.19 GHz to 24.76 GHz drawing 2.72 mA at a supply voltage of 1.8 V not including an output buffer.

Due to the reuse factor reduction, the attendant increase in co-channel interference (CCI) becomes the limiting factor in the performance of the orthogonal frequency division multiplexing (OFDM) based cellular systems. In the previous work, we proposed the least mean square-blind joint maximum likelihood sequence estimation (LMS-BJMLSE) algorithm, which is effective for CCI cancellation in OFDM systems with only one receive antenna. However, LMS-BJMLSE requires a long training sequence (TS) for channel estimation, which reduces the transmission efficiency. In this paper, we propose a subcarrier identification and interpolation algorithm, in which the subcarriers are divided into groups based on the coherence bandwidth, and the slowest converging subcarrier in each group is identified by exploiting the correlation between the mean-square error (MSE) produced by LMS and the mean-square deviation (MSD) of the desired channel estimate. The identified poor channel estimate is replaced by the interpolation result using the adjacent subcarriers' channel estimates. Simulation results demonstrate that the proposed algorithm can reduce the required training sequence dramatically for both the cases of single interference and dual interference. We also generalize LMS-BJMLSE from single antenna to receiver diversity, which is shown to provide a huge improvement.