With proliferation of smart handsets capable of mobile Internet, the severity of malware attacks targeting such handsets is rapidly increasing, thereby requiring effective countermeasure for them. However, existing signature-based solutions are not suitable for resource-poor handsets due to the excessive run-time overhead of matching against ever-increasing malware pattern database as well as the limitation of detecting well-known malware only. To overcome these drawbacks, we present a bio-inspired approach to discriminate malware (non-self) from normal programs (self) by replicating the processes of biological immune system. Our proposed approach achieves superior performance in terms of detecting 83.7% of new malware or their variants and scalable storage requirement that grows very slowly with inclusion of new malware, making it attractive for use with mobile handsets.

In this letter, we propose a new approach to SVM based speaker recognition, which utilizes a kind of novel phonotactic information as the feature for SVM modeling. Gaussian mixture models (GMMs) have been proven extremely successful for text-independent speaker recognition. The GMM universal background model (UBM) is a speaker-independent model, each component of which can be considered as modeling some underlying phonetic sound classes. We assume that the utterances from different speakers should get different average posterior probabilities on the same Gaussian component of the UBM, and the supervector composed of the average posterior probabilities on all components of the UBM for each utterance should be discriminative. We use these supervectors as the features for SVM based speaker recognition. Experiment results on a NIST SRE 2006 task show that the proposed approach demonstrates comparable performance with the commonly used systems. Fusion results are also presented.

The core of the support vector machine (SVM) problem is a quadratic programming problem with a linear constraint and bounded variables. This problem can be transformed into the second order cone programming (SOCP) problems. An interior-point-method (IPM) can be designed for the SOCP problems in terms of storage requirements as well as computational complexity if the kernel matrix has low-rank. If the kernel matrix is not a low-rank matrix, it can be approximated by a low-rank positive semi-definite matrix, which in turn will be fed into the optimizer. In this paper we present two SOCP formulations for each SVM classification and regression problem. There are several search direction methods for implementing SOCPs. Our main goal is to find a better search direction for implementing the SOCP formulations of the SVM problems. Two popular search direction methods: HKM and AHO are tested analytically for the SVM problems, and efficiently implemented. The computational costs of each iteration of the HKM and AHO search direction methods are shown to be the same for the SVM problems. Thus, the training time depends on the number of IPM iterations. Our experimental results show that the HKM method converges faster than the AHO method. We also compare our results with the method proposed in Fine and Scheinberg (2001) that also exploits the low-rank of the kernel matrix, the state-of-the-art SVM optimization softwares SVMTorch and SVMlight. The proposed methods are also compared with Joachims 'Linear SVM' method on linear kernel.

In this article, we introduce a new concept for the future information environment, called an "ambient information environment (AmIE)." We first explain it, especially emphasizing the difference from the existing ubiquitous information environment (UbIE), which is an interaction between users and environments. Then, we focus on an ambient networking environment (AmNE) which supports the AmIE as a networking infrastructure. Our approach of a biologically inspired framework is next described in order to demonstrate why such an approach is necessary in the AmIE. Finally, we show some example for building the AmNE.

The transmission of correlated messages over strong interference channels is examined. The result is the proposal of a single-letter characterization of the sum-rate capacity of strong interference channels with correlated messages. It is shown that if the messages are independent, the sum-rate capacity is equal to that of [1] obtained by Costa and El Gamal. However, it can be larger than that of [1] if the messages are correlated. It is also shown that, in terms of the sum-rate, the achievable rate region in [2] is indeed the sum-rate capacity.

Communication-free Petri nets provide a net semantics for Basic Parallel Processes, which form a subclass of Milner's Calculus of Communicating Systems (CCS) a process calculus for the description and algebraic manipulation of concurrent communicating systems. It is known that the reachability problem for communication-free Petri nets is NP-complete. Lacking the synchronization mechanism, the expressive power of communication-free Petri nets is somewhat limited. It is therefore importance to see whether the power of communication-free Petri nets can be enhanced without sacrificing their analytical capabilities. As a first step towards this line of research, in this paper our main concern is to investigate, from the decidability/complexity viewpoint, the reachability problem for a number of variants of communication-free Petri nets, including communication-free Petri nets augmented with 'static priorities,' 'dynamic priorities,' 'states,' 'inhibitor arcs,' and 'timing constraints.'

We present a dual traveling-wave electrode InP-based Mach-Zehnder (MZ) modulator with an n-i-n waveguide structure. An electrical input/output interface placed on one side of the chip helps us to drive the modulator in a push-pull configuration. This configuration provides the modulator with great advantages such as reduced driving voltage amplitude, chirp-free operation, and the ability to support advanced modulation formats. The fabricated modulator exhibits good performance. A 40 Gb/s non-return-to-zero (NRZ) signal is successfully generated with a low driving of 1.3 Vpp. In addition, a 10-Gb/s optical duobinary (DB) signal is successfully generated and transmitted over a 240-km single-mode fiber (SMF). We also developed a wavelength tunable transmitter hybrid integrated with a modulator with a wavelength tunable laser. Full C-band 10-Gb/s operation and a 100-km SMF transmission with a low power penalty are confirmed.

We demonstrated all-optical demultiplexing of 160-Gb/s signal to 40- and 80-Gb/s by a Mach-Zehnder Interferometric all-optical switch, where the picosecond cross-phase modulation (XPM) induced by intersubband excitation in InGaAs/AlAsSb coupled double quantum wells is utilized. A bi-directional pump configuration, i.e., two control pulses are injected from both sides of a waveguide chip simultaneously, increases a nonlinear phase shift twice in comparison with injection of single pump beam with forward- and backward direction. The bi-directional pump configuration is the effective way to avoid damaging waveguide facets in the case where high optical power of control pulse is necessary to be injected for optical gating at repetition rate of 40/80 GHz. Bit error rate (BER) measurements on 40-Gb/s demultiplexed signal show that the power penalty is decreased slightly for the bi-directional pump case in the BER range less than 10-6. The power penalty is 1.3 dB at BER of 10 - 9 for the bi-directional pump case, while it increases by 0.3-0.6 dB for single pump cases. A power penalty is influenced mainly by signal attenuation at "off" state due to the insufficient nonlinear phase shift, upper limit of which is constrained by the current low XPM efficiency of 0.1 rad/pJ and the damage threshold power of 100 mW in a waveguide facet.

This letter proposes a neurobiological approach for action recognition. In this approach, actions are represented by a visual-neuron feature (VNF) based on a quantitative model of object representation in the primate visual cortex. A supervised classification technique is then used to classify the actions. The proposed VNF is invariant to affine translation and scaling of moving objects while maintaining action specificity. Moreover, it is robust to the deformation of actors. Experiments on publicly available action datasets demonstrate the proposed approach outperforms conventional action recognition models based on computer-vision features.

This paper presents a new scheme for Timed-Release Encryption (TRE), which is mainly designed for global use. TRE aims to control the timing of disclosing information. The major approach to TRE assumes that any participants can receive a time token broadcasted by a trusted agent, called a time server. Our scheme is based on this approach and allows participants to generate an encrypted message that can be decrypted using designated or any authenticated time servers including even those which are authenticated after encryption. In this sense, our scheme has a more flexible framework in terms of message decryption.

This paper studies two types of documents in which an adversary can forge a signature on a chosen document. One type is that a nonce is padded on an input document. The time-stamp protocol is a good example of this type. Another is a structured document (such as PS or PDF) whose contents are described in a body part and information (such as generated time and a generator) are in a meta part. In fact, this paper shows how to forge a time-stamp, a signature on a PDF and an X.509 certificate by the extended forgery attack and numerical examples. Forged signature by the original or the extended attacks is only accepted by the clients whose length check of zero-field is loosely implemented. As a result, we found that the latest versions of Adobe's Acrobat and Acrobat Reader accept the forged time-stamp and the forged signature on a PDF document. Target of this attack is RSASSA-PKCS1-v1_5, which does not have provable security. We also show the expanded attack might forge the signature of RSASSA-PSS, which has provable security, when the length check of zero-field is omitted or loosely implemented.

This paper reexamines reflection and transmission of a TE plane wave from a two-dimensional random slab discussed in the previous paper [IEICE Trans. Electron., Vol.E79-C, no.10, pp.1327-1333, October 1996] by means of the stochastic functional approach with the multiply renormalizing approximation. A random wavefield representation is explicitly shown in terms of a Wiener-Hermite expansion. The first-order incoherent scattering cross section and the optical theorem are numerically calculated. Enhanced scattering as gentle peaks or dips on the angular distribution of the incoherent scattering is reconfirmed in the directions of reflection and backscattering, and is newly found in the directions of forward scattering and 'symmetrical forward scattering.' The mechanism of enhanced scattering is deeply discussed.

We observe that P2P traffic has peculiar characteristics as opposed to the other type of traffic such as web browsing and file transfer. Since they exploit swarm effect -- a multitude of end points downloading the same content piece by piece nearly at the same time, thus, increasing the effectiveness of caching -- the same pieces of data end up traversing the network over and over again within mostly a short time window. In the light of this observation, we propose a network layer packet-level caching for reducing the volume of emerging P2P traffic, transparently to the P2P applications -- without affecting operations of the P2P applications at all -- rather than banning it, restricting it, or modifying P2P systems themselves. Unlike the other caching techniques, we aim to provide as generic a caching mechanism as possible at network layer -- without knowing much detail of P2P application protocols -- to extend applicability to arbitrary P2P protocols. Our preliminary evaluation shows that our approach is expected to reduce a significant amount of P2P traffic transparently to P2P applications.

We propose an architecture of Intrusion Detection System (IDS) for VoIP using a protocol specification-based detection method to monitor the network traffics and alert administrator for further analysis of and response to suspicious activities. The protocol behaviors and their interactions are described by state machines. Traffic that behaves differently from the standard specifications are considered to be suspicious. The IDS has been implemented and simulated using OPNET Modeler, and verified to detect attacks. It was found that our system can detect typical attacks within a reasonable amount of delay time.

In this letter, we propose a cache organization that substantially reduces the memory bandwidth of motion compensation (MC) in the H.264/AVC decoders. To reduce duplicated memory accesses to P and B pictures, we employ a four-way set-associative cache in which its index bits are composed of horizontal and vertical address bits of the frame buffer and each line stores an 8 2 pixel data in the reference frames. Moreover, we alleviate the data fragmentation problem by selecting its line size that equals the minimum access size of the DDR SDRAM. The bandwidth of the optimized cache averaged over five QCIF IBBP image sequences requires only 129% of the essential bandwidth of an H.264/AVC MC.

The share of leakage in cache power consumption increases with technology scaling. Choosing a higher threshold voltage (Vth) and/or gate-oxide thickness (Tox) for cache transistors improves leakage, but impacts cell delay. We show that due to uncorrelated random within-die delay variation, only some (not all) of cells actually violate the cache delay after the above change. We propose to add a spare cache way to replace delay-violating cache-lines separately in each cache-set. By SPICE and gate-level simulations in a commercial 90 nm process, we show that choosing higher Vth, Tox and adding one spare way to a 4-way 16 KB cache reduces leakage power by 42%, which depending on the share of leakage in total cache power, gives up to 22.59% and 41.37% reduction of total energy respectively in L1 instruction- and L2 unified-cache with a negligible delay penalty, but without sacrificing cache capacity or timing-yield.

Transmission of correlated messages over interference channels with strong interference is considered. As a result, an achievable rate region is presented. It is shown that if the messages are correlated, the achievable rate region can be larger than the capacity region given by Costa and El Gamal. As an example, the Gaussian interference channel is considered.

In this letter, we derive a very accurate closed-form approximate formula for the average achievable rate of stacked orthogonal space-time block code (OSTBC) in Rayleigh fading channels. Some simulations are performed to demonstrate that the derived formula shows better agreement with Monte-Carlo simulation results than the existing closed-form approximate expressions.

In recent years, heterogeneous devices have been employed frequently in mobile storage systems because a combination of such devices can supply a synergistically useful storage solution by taking advantage of each device. One important design constraint in heterogeneous storage systems is to mitigate I/O performance degradation stemming from the difference between access times of different devices. To this end, there has not been much work to devise proper buffer cache management algorithms. This paper presents a novel buffer cache management algorithm which considers both I/O cost per device and workload patterns in mobile computing systems with a heterogeneous storage pair of a hard disk and a NAND flash memory. In order to minimize the total I/O cost under varying workload patterns, the proposed algorithm employs a dynamic cache partitioning technique over different devices and manages each partition according to request patterns and I/O types along with the temporal locality. Trace-based simulations show that the proposed algorithm reduces the total I/O cost and flash write count significantly over the existing buffer cache algorithms on typical mobile traces.

We propose a feasible V-BLAST detector based on modified Householder QRD (M-H-QRD) over spatially correlated fading channel, which can almost match the performance of the V-BLAST algorithm with much lower complexity and better numerical stability. Compared to the sorted QRD (S-QRD) detector, the proposed detector requires a smaller minimum word-length to reach the same value of error floor for fixed-point (FP) numerical precision despite no significant performance difference for floating-point machine precision. All these advantages make it attractive when implemented using FP arithmetic.