We define two functions fDL and fIF in NPMV, the class of all partial, multivalued functions computed nondeterministically in polynomial time. We prove that they are complete for NPMV, and show that (a) computing discrete logarithms modulo a prime reduces to fDL, and (b) computing integer factorization reduces to fIF. These are the first complete functions that have explicit reductions from significant cryptographic primitives.

This paper deals with the scattering of a TM plane wave from a periodic grating with single defect, of which position is known. The surface is perfectly conductive and made up with a periodic array of rectangular grooves and a defect where a groove is not formed. The scattered wave above grooves is written as a variation from the diffracted wave for the perfectly periodic case. Then, an integral equation for the scattering amplitude is obtained, which is solved numerically by use of truncation and the iteration method. The differential scattering cross section and the optical theorem are calculated in terms of the scattering amplitude and are illustrated in figures. It is found that incoherent Wood's anomaly appears at critical angles of scattering. The physical mechanisms of Wood's anomaly and incoherent Wood's anomaly are discussed in relation to the guided surface wave excited by the incident plane wave. It is concluded that incoherent Wood's anomaly is caused by the diffraction of the guided surface wave.

In this paper, we propose new methods which detect tampered-TCP connections at edge routers and protect well-behaved TCP connections from tampered-TCP connections, which results in fairness among TCP connections. The proposed methods monitor the TCP packets at an edge router and estimate the window size or the throughput for each TCP connection. By using estimation results, the proposed methods assess whether each TCP connection is tampered or not and drop packets intentionally if necessary to improve the fairness amongst TCP connections. From the results of simulation experiments, we confirm that the proposed methods can accurately identify tampered-TCP connections and regulate throughput ratio between tampered-TCP connections and competing TCP Reno connections to about 1.

Fault-tolerance is an important design issue in building a reliable mobile computing system. This paper considers checkpointing recovery services for a mobile computing system based on the ad-hoc network environment. Since potential problems of this new environment are insufficient power and limited storage capacity, the proposed scheme tries to reduce disk access frequency for saving recovery information, and also the amount of information saved for recovery. A brief simulation study has been performed and the results show that the proposed scheme takes advantage of the existing checkpointing recovery schemes.

This paper proposes a dual-level low voltage differential signaling (DLVDS) circuit aimed at low power consumption and reducing transmission lines for LCD driver IC's. We apply two-bit binary data to the DLVDS circuit as inputs, and then the circuit converts these two inputs into two kinds of fully differential signal levels. In the DLVDS circuit, two transmission lines are sufficient to transfer two-bit binary inputs while keeping the conventional LVDS features. The receiver recovers the original two-bit binary data through a level decoding circuit. The proposed circuit was fabricated using a commercial 0.25 µm CMOS technology. Under a 2.5 V supply voltage, the circuit shows a data rate of 1-Gbps/2-line and power consumption of 35 mW.

We present a computationally efficient Fano detection algorithm with an iterative structure for V-BLAST systems. As our previous work, we introduced a Fano-based sequential detection scheme with three interrelated steps whose computational loads are excessive. To deal with the computational inefficiency, the proposed algorithm is redesigned by the addition of two steps: preparation and iterative tree searching. In particular, it employs an early stop technique to avoid the unnecessary iteration or to stop the needless searching process of the algorithm. Computer simulation shows that the proposed scheme yields significant saving in complexity with very small performance degradation, compared with sphere detection (SD).

In this letter, we analyze symbol error probability (SEP) and diversity gain of orthogonal space-time block codes (OSTBCs) in spatially correlated Rician fading channel. We derive the moment generating function (MGF) of an effective signal-to-noise ratio (SNR) at the receiver and use it to derive the SEP for M-PSK modulation. We use this result to show that the diversity gain is achieved by the product of the rank of the transmit and receive correlation matrix, and the loss in array gain is quantified as a function of the spatial correlation and the line of sight (LOS) component.

Recently, we provided closed-form expressions involving two-dimensional (2-D) joint Gaussian Q-function for the symbol error rate (SER) and bit error rate (BER) of an arbitrary 2-D signal with I/Q unbalances over an additive white Gaussian noise (AWGN) channel [1]. In this letter, we extend the expressions to Nakagami-m fading channels. Using Craig representation of the 2-D joint Gaussian Q-function, we derive an exact and general expression for the error probabilities of arbitrary 2-D signaling with I/Q phase and amplitude unbalances over Nakagami-m fading channels.

In this study, we propose a method of classifying a spontaneous electroencephalogram (EEG) approach to a brain-computer interface. Ten subjects, aged 21-32 years, volunteered to imagine left- and right-hand movements. An independent component analysis based on a fixed-point algorithm is used to eliminate the activities found in the EEG signals. We use a fractal dimension value to reveal the embedded potential responses in the human brain. The different fractal dimension values between the relaxing and imaging periods are computed. Featured data is classified by a three-layer feed-forward neural network based on a simple backpropagation algorithm. Two conventional methods, namely, the use of the autoregressive (AR) model and the band power estimation (BPE) as features, and the linear discriminant analysis (LDA) as a classifier, are selected for comparison in this study. Experimental results show that the proposed method is more effective than the conventional methods.

A simplified equalization method based on the band structure of the frequency domain channel matrix is proposed for the single carrier systems employing cyclic prefix (SC-CP) over time-varying wireless channels. Using both theoretical analysis and computer simulation, it is shown that the complexity of this method is proportional to the number of symbols in one SC-CP block and is less than that of traditional block equalization methods. We also show that they have similar performance.

The link structure of the Web is generally viewed as the webgraph. Web structure mining is a research area that mainly aims to find hidden communities by focusing on the webgraph, and communities or their cores are supposed to constitute dense subgraphs. Therefore, structure mining can actually be realized by enumerating such substructures, and Kleinberg's biclique model is well-known among them. In this paper, we examine some candidate substructures, including conventional bicliques, and attempt to find useful information from the real web data. Especially, we newly exploit isolated cliques for our experiments of structure mining. As a result, we discovered that isolated cliques that lie over multiple domains can stand for useful communities, which implies the validity of isolated clique as a candidate substructure for structure mining. On the other hand, we also observed that most of isolated cliques on the Web correspond to menu structures and are inherent in single domains, and that isolated cliques can be quite useful for detecting harmful link farms.

Congestion in WSN increases the energy dissipation rates of sensor nodes as well as the loss of packets and thereby hinders fair and reliable event detection. We find that one of the key reasons of congestion in WSN is allowing sensing nodes to transfer as many packets as possible. This is due to the use of CSMA/CA that gives opportunistic medium access control. In this paper, we propose an energy efficient congestion avoidance protocol that includes source count based hierarchical and load adaptive medium access control and weighted round robin packet forwarding. We also propose in-node fair packet scheduling to achieve fair event detection. The results of simulation show our scheme exhibits more than 90% delivery ratio even under bursty traffic condition which is good enough for reliable event perception.

In this paper, we consider consecutive burst transmission with burst loss recovery based on Forward Error Correction (FEC) in which redundant data is transmitted with multiple bursts. We propose two burst generation methods: Out-of Burst Generation (OBG) and In-Burst Generation (IBG). The OBG generates a redundant burst from redundant data, while the IBG reconstructs a burst from an original data block and a part of the redundant data. For both methods, the resulting bursts are transmitted consecutively. If some bursts among the bursts are lost at an intermediate node, the lost bursts can be recovered with the redundant data using FEC processing at the destination node. We evaluate by simulation the proposed methods in a uni-directional ring network and NSFNET, and compare the performances of the proposed methods with the extra-offset time method. Numerical examples show that the proposed methods can provide a more reliable transmission than the extra-offset time method for the OBS network where the maximum number of hops is large. Moreover, it is shown that the end-to-end transmission delay for our proposed methods can be decreased by enhancing the FEC processor or by increasing the number of FEC processors.

We focus our attention on the layout dependent Across Chip Linewidth Variability (ACLV) of gate-forming poly-silicon patterns as a measure for manufacturability, which is a major contributor of systematic gate-length variation. First, we study the ACLV of standard cell layouts by lithography simulation. Then, we introduce regularity in gate-forming poly-silicon patterns and how it improves the ACLV and also how it incurs area-overhead. According to the investigation, we propose two design guidelines for standard-cell layout that can reduce ACLV with reasonable area overhead. Those guidelines include on-grid fixed-pitch layout with dummy-poly insertion and stretched gate-poly extension. Design experiments assuming a 65 nm process technology indicate that a D-FF designed with the first guideline reduces ACLV by 35% with 14% area overhead and the second guideline reduces ACLV by 75% with 29% area overhead at the best focus condition. Under defocus conditions, both layouts exhibit stable characteristics whereas the variability of conventional layout grows rapidly as the level of defocus increases. Circuit-level lithography simulation over benchmark circuits also supports that the proposed guidelines considerably reduces the amount of gate length variation.

This paper addresses a new surface reconstruction scheme for approximating the isosurface from a set of tomographic cross sectional images. Differently from the novel Marching Cubes (MC) algorithm, our method does not extract the iso-density surface (isosurface) directly from the voxel data but calculates the iso-density point (isopoint) first. After building a coarse initial mesh approximating the ideal isosurface by the cell-boundary representation, it metamorphoses the mesh into the final isosurface by a relaxation scheme, called shrink-wrapping process. Compared with the MC algorithm, our method is robust and does not make any cracks on surface. Furthermore, since it is possible to utilize lots of additional isopoints during the surface reconstruction process by extending the adjacency definition, theoretically the resulting surface can be better in quality than the MC algorithm. According to experiments, it is proved to be very robust and efficient for isosurface reconstruction from cross sectional images.

In 1995, Vanstone and Zuccherato proposed a novel method of generating RSA moduli having a predetermined set of bits which are the ASCII representation of user's identification information (i.e., name, email address, etc.). This could lead to a savings in bandwidth for data transmission and storage. In this paper, we apply this idea of Vanstone and Zuccherato for reducing the storage requirement of RSA public moduli to integer factoring based public-key schemes with their moduli of the form prq. More precisely, we explicitly propose two efficient methods for specifying high-order bits of prime factors of their public-keys. We also consider the security of the proposed methods.

A fair exchange scheme is a protocol by which two parties Alice and Bob swap items or services without allowing either party to gain an advantage by quitting prematurely or otherwise misbehaving. Verifiably committed signature is a generalized and unified model for non-interactive optimistic fair exchange scheme. The state-of-the-art verifiably committed signature that enjoys the off-line, setup-free and stand-alone properties is due to Zhu and Bao [1]. In this article, we show that the Zhu-Bao's verifiably committed signature is insecure in the multi-user setting and then consider possible countermeasures.

This paper presents an efficient diagnosis scheme for RAMs. Three March-based algorithms are proposed to diagnose simple functional faults of RAMs. A March-15N algorithm is used for locating and partially diagnosing faults of bit-oriented or word-oriented memories, where N represents the address number. Then a 3N March-like algorithm is used for locating the aggressor words (bits) of coupling faults (CFs) in word-oriented (bit-oriented) memories. It also can distinguish the faults which cannot be identified by the March-15N algorithm. Thus, the proposed diagnosis scheme can achieve full diagnosis and locate aggressors with (15N + 3mN) Read/Write operations for a bit-oriented RAM with m CFs. For word-oriented RAMs, a March-like algorithm is also proposed to locate the aggressor bit in the aggressor word with 4 log2B Read/Write operations, where B is the word width. Analysis results show that the proposed diagnosis scheme has higher diagnostic resolution and lower time complexity than the previous fault location and fault diagnosis approaches. A programmable built-in self-diagnosis (BISD) design is also implemented to perform the proposed diagnosis algorithms. Experimental results show that the area overhead of the BISD is small--only about 2.17% and 0.42% for 16 K8-bit and 16 K128-bit SRAMs, respectively.

Sensor networks are often deployed in unattended environments, thus leaving these networks vulnerable to false data injection attacks in which an adversary injects forged reports into the network through compromised nodes, with the goal of deceiving the base station or depleting the resources of forwarding nodes. Several research solutions have been recently proposed to detect and drop such forged reports during the forwarding process. Each design can provide the equivalent resilience in terms of node compromising. However, their energy consumption characteristics differ from each other. Thus, employing only a single filtering scheme for a network is not a recommendable strategy in terms of energy saving. In this paper, we propose a fuzzy-based adaptive filtering scheme selection method for energy saving. A fuzzy rule-based system is exploited to choose one of three filtering schemes by considering the false traffic ratio, the security threshold value, distance, and the detection power of the filtering scheme. The adaptive selection of the filtering schemes can conserve energy, and guarantee sufficient resilience.

Multiple-antenna wireless systems, also known as multiple-input multiple-output (MIMO) cellular networks, can improve the capacity and reliability of communications. To realize these advantages, a packet scheduler should effectively allocate radio resources to users in a fair way. The previously proposed MIMO schedulers have problems such as ignoring traffic arrival process or complexity. We propose a load adaptive multi-output fair queueing (LA-MO-FQ) scheduler, which is based on a fair queueing algorithm with mechanisms for rate selection, compensation of lagging users, and virtual time system. Since some of the scheduler's system parameters are sensitive to the traffic load, it dynamically adjusts them in a way with low complexity so the system performs better. Intensive simulation studies considering the mobility of users and the traffic arrival demonstrate the good performance of LA-MO-FQ. Furthermore, we also propose in this paper some formulae for the time and service fairness comparisons of MIMO schedulers and we use them for comparison with some famous existing schedulers.