The present paper proposes two new methods for constructing polyphase asymmetric zero-correlation zone (A-ZCZ) sequence sets. In previous studies, the authors proposed methods for constructing quasi-optimal polyphase A-ZCZ sequence sets using perfect sequences and for constructing optimal polyphase A-ZCZ sequence sets using discrete Fourier transform (DFT) matrices. However, in these methods, the total number of sequences in an A-ZCZ sequence set cannot exceed the period of the perfect sequence or the dimension of the DFT matrix used for constructing the A-ZCZ sequence set. We now propose two extended versions of these methods. The proposed methods can generate a quasi-optimal or optimal polyphase A-ZCZ sequence set where the total number of sequences exceeds the period of the perfect sequence or the dimension of the DFT matrix. In other words, the proposed methods can generate new A-ZCZ sequence sets that cannot be obtained from the known methods.

In 2001, Boneh and Franklin realized the first Identity-Based Encryption (IBE), and at the same time they proposed a simple way to revoke users from the system. Later, Boldyreva et al. pointed out that Boneh-Franklin's revocation method is not scalable well and they proposed the first IBE scheme with efficient revocation. Recently, Tseng and Tsai [Computer Journal, Vol.55 No.4, page 475-486, 2012] claimed that Boldyreva et al.'s scheme requires a secure channel between each user and the key generation center in the key update phase, and proposed a new revocable IBE (RIBE) with a public channel by extending the Boneh-Franklin scheme. In this paper, we revisit Tseng and Tsai's result; we first point out that secure channels (except for the initial key setup) are not mandatory in the definition of RIBE scheme formalized by Boldyreva et al. Next, we show that Boldyreva et al.'s scheme does not require any secure channels (except for the initial key setup), which is different from what Tseng and Tsai claimed and so invalidates their contribution of the first RIBE with a public channel. Moreover, we point out that there are simple techniques to remove secure channels from the Boneh-Franklin RIBE. Interestingly, we show that the secure-channel-free Boneh-Franklin RIBE scheme is secure against decryption key exposure, whereas the Tseng-Tsai RIBE scheme is vulnerable to this attack.

This paper addresses the sensing-throughput tradeoff problem by using cluster-based cooperative spectrum sensing (CSS) schemes in two-layer hierarchical cognitive radio networks (CRNs) with soft data fusion. The problem is formulated as a combinatorial optimization problem involving both discrete and continuous variables. To simplify the solution, a reasonable weight fusion rule (WFR) is first optimized. Thus, the problem devolves into a constrained discrete optimization problem. In order to efficiently and effectively resolve this problem, a lexicographical approach is presented that solving two optimal subproblems consecutively. Moreover, for the first optimal subproblem, a closed-form solution is deduced, and an optimal clustering scheme (CS) is also presented for the second optimal subproblem. Numerical results show that the proposed approach achieves a satisfying performance and low complexity.

Vector field convolution (VFC) provides a successful external force for an active contour model. However, it fails to extract the complex geometries, especially the deep concavity when the initial contour is set outside the object or the concave region. In this letter, dynamically constrained vector field convolution (DCVFC) external force is proposed to solve this problem. In DCVFC, the indicator function with respect to the evolving contour is introduced to restrain the correlation of external forces generated by different edges, and the forces dynamically generated by complex concave edges gradually make the contour move to the object. On the other hand, traditional vector field, a component of the proposed DCVFC, makes the evolving contour stop at the object boundary. The connections between VFC and DCVFC are also analyzed. DCVFC maintains desirable properties of VFC, such as robustness to initialization. Experimental results demonstrate that DCVFC snake provides a much better segmentation than VFC snake.

Morphemes, which are obtained from morphological parsing, and statistical sub-words, which are derived from data-driven splitting, are commonly used as the recognition units for speech recognition of agglutinative languages. In this letter, we propose a discriminative approach to select the splitting result, which is more likely to improve the recognizer's performance, for each distinct word type. An objective function which involves the unigram language model (LM) probability and the count of misrecognized phones on the acoustic training data is defined and minimized. After determining the splitting result for each word in the text corpus, we select the frequent units to build a hybrid vocabulary including morphemes and statistical sub-words. Compared to a statistical sub-word based system, the hybrid system achieves 0.8% letter error rates (LERs) reduction on the test set.

The link structure of the Web is generally viewed as a webgraph. One of the main objectives of web structure mining is to find hidden communities on the Web based on the webgraph, and one of its approaches tries to enumerate substructures, each of which corresponds to a set of web pages of a community or its core. Research has shown that certain substructures can find sets of pages that are inherently irrelevant to communities. In this paper, we propose a model, which we call contracted webgraphs, where such substructures are contracted into single nodes to hide useless information. We then try structure mining iteratively on those contracted webgraphs since we can expect to find further hidden information once irrelevant information is eliminated. We also explore the structural properties of contracted webgraphs from the viewpoint of scale-freeness, and we observe that they exhibit novel and extreme self-similarities.

LT codes are the first practical rateless codes whose reception overhead totally depends on the degree distribution adopted. The capability of LT codes with a particular degree distribution named robust soliton has been theoretically analyzed; it asymptotically approaches the optimum when the message length approaches infinity. However, real applications making use of LT codes have finite number of input symbols. It is quite important to refine degree distributions because there are distributions whose performance can exceed that of the robust soliton distribution for short message length. In this work, a practical framework that employs evolutionary algorithms is proposed to search for better degree distributions. Our experiments empirically prove that the proposed framework is robust and can customize degree distributions for LT codes with different message length. The decoding error probabilities of the distributions found in the experiments compare well with those of robust soliton distributions. The significant improvement of LT codes with the optimized degree distributions is demonstrated in the paper.

Power consumption has become a critical factor for embedded systems, especially for battery powered ones. Caches in these systems consume a large portion of the whole chip power. Embedded systems usually adopt set-associative caches to get better performance. However, parallel accessed cache ways incur more energy dissipation. This paper proposed a region-based way-partitioning scheme to reduce cache way access, and without sacrificing performance, to reduce the cache power consumption. The stack accesses and non-stack accesses are isolated and redirected to different ways of the L1 data cache. Under way-partitioning, cache way accesses are reduced, as well as the memory reference interference. Experimental results show that the proposed approach could save around 27.5% of L1 data cache energy on average, without significant performance degradation.

This letter presents a method of adding a virtual halo effect to an object of interest in video sequences. A modified graph-cut segmentation algorithm extracts object layers. The halo is modeled by the accumulation of gradually changing Gaussians. With a synthesized blooming effect, the experimental results show that the proposed method conveys realistic halo effect.

We describe an In-Cell Projected Capacitive Touch Panel in a display using IGZO TFT technology. The prototype demonstrates high signal-to-noise ratio (SNR) and pen input operation. The possibility of enlarging the display size beyond current limits makes this a highly promising approach for In-Cell Capacitive touch panels.

A new theoretical formulation based on BIBO (Bounded Input Bounded Output) operators is proposed for a general feedback amplifier circuit. Several fundamental theorems are derived in this letter. The main theorem provides a basis for a realization of an inverse of a feedback-branch linear or nonlinear BIBO operator satisfying the associative law.

In this paper, we introduce a new multi-operator pico eNodeB (eNB) concept for cellular networks. It is expected that mobile data offloading will be performed effectively after installing the pico eNBs in cellular networks, owing to the rapid increase in mobile traffic. However, when several different operators independently install the pico eNBs, high costs and large amounts of space will be required for the installation. In addition, when several different operators accommodate their own user equipments (UEs) in the pico eNBs, not enough UEs can be accommodated. This is because the UEs are not evenly distributed in the coverage area of the pico eNBs. In this paper, the accommodation of the UEs of different operators in co-sited pico eNB is discussed as one of the solutions to these problems. For the accommodation of the UEs of different operators, wireless resources should be allocated to them. However, when each operator independently controls his wireless resources, the operator is not provided with an incentive to accommodate the UEs of the other operators in his pico eNBs. For this reason, an appropriate rule for appropriate allocation of the wireless resources to the UEs of different operators should be established. In this paper, by using the concepts of game theory and mechanism design, a resource allocation rule where each operator is provided with an incentive to allocate the wireless resources to the UEs of different operators is proposed. With the proposed rule, each operator is not required to disclose the control information like link quality and the number of UEs to the other operators. Furthermore, the results of a throughput performance evaluation confirm that the proposed scheme improves the total throughput as compared with individual resource allocation.

Source routing multicast has been gathering much more attention rather than traditional IP multicast, since it is thought to be more scalable in terms of the number of groups at the cost of higher traffic loads. This paper introduces a mathematical framework to analyze the scalability of source routing multicast and IP multicast by leveraging previous multicast studies. We first analyze the amount of data traffic based on the small-world nature of networks, and show that source routing multicast can be as efficient as IP multicast if a simple header fragmentation technique (subgrouping) is utilized. We also analyze scalability in terms of group numbers, which are derived under the equal budget assumption. Our analysis shows that source routing multicast is competitive for low bit-rate streams, like those in the publish/subscribe service, but we find some factors that offset the advantage. This is the first work to analytically investigate the scalability of source routing multicast.

Light weight RLSAs with a honeycomb-type parallel plate are promising candidates for satellite antennas. However, the design of slot lengths and positions in honeycomb RLSAs consisting of a core, skin and adhesive layers involves time-consuming EM analysis. In this paper, an equivalent double layer model is devised for fast slot coupling analysis by the Method of moments (MoM) together with a simplified array design procedure. A fabricated antenna with a diameter of 900mm demonstrates the high directivity of 48.3dBi and a gain of 44.6dBi at 32GHz, with the reflection below -15dB. This antenna weighs only 1.16kg.

An Ldi/dt effect model based on float ground in a plamsa display panel (PDP) driver system is established in this paper. The model is to analyze the noise which appears in power supply and float ground pins of driver integrated circuits. Considering printed circuit board wiring and switching parasitic parameters, firstly Ldi/dt effect due to integrated circuits transition, is explained on the entire float-ground circuit operation. Then an analytic model is deduced and validated, and good agreement is obtained with experimental results. Based on the model, sensitivity analyses of key parameters are done. Finally, design optimisations to prevent the Ldi/dt effect based on float ground are proposed and verified in a PDP system.

In this letter, we investigate the performance of cooperative decode-and-forward multiple-input multiple-output relaying system using orthogonal space-time block codes with piecewise-linear (PL) receiver over correlated Nakagami-m fading channels for integer values of m. We derive the closed-form expression for the exact bit error rates of binary phase shift keying signals. The analytical expression is validated through numerical results. It is shown that the performance of PL receiver outperforms that of conventional maximal ratio combining receiver.

In this letter, we present a novel cooperative spectrum sensing scheme for cognitive radio systems. The proposed approach is based on a consensus algorithm. Using the received signals, we set up a formula for the consensus algorithm, which guarantees a convergence to an agreement value. The simulation results exhibit that the performance of the consensus-based cooperative scheme is much better than that of the conventional cooperative technique in the case that the cooperative nodes for spectrum sensing are sparsely distributed in cognitive radio systems.

Nature-inspired devices and architectures are attracting considerable attention for various purposes, including the development of novel computing techniques based on spatiotemporal dynamics, exploiting stochastic processes for computing, and reducing energy dissipation. This paper demonstrates that networks of optical energy transfers between quantum nanostructures mediated by optical near-field interactions occurring at scales far below the wavelength of light could be utilized for solving a constraint satisfaction problem (CSP), the satisfiability problem (SAT), and a decision making problem. The optical energy transfer from smaller quantum dots to larger ones, which is a quantum stochastic process, depends on the existence of resonant energy levels between the quantum dots or a state-filling effect occurring at the larger quantum dots. Such a spatiotemporal mechanism yields different evolutions of energy transfer patterns in multi-quantum-dot systems. We numerically demonstrate that networks of optical energy transfers can be used for solution searching and decision making. We consider that such an approach paves the way to a novel physical informatics in which both coherent and dissipative processes are exploited, with low energy consumption.

A deeply-coupled system can feed the INS information into a GNSS receiver, and the signal tracking precision can be improved under dynamic conditions by reducing tracking loop bandwidth without losing tracking reliability. In contrast to the vector-based deep integration, the scalar-based GNSS/INS deep integration is a relatively simple and practical architecture, in which all individual DLL and PLL are still exist. Since the implementation of a deeply-couple system needs to modify the firmware of a commercial hardware GNSS receiver, very few studies are reported on deep integration based on hardware platform, especially from academic institutions. This implementation-complexity issue has impeded the development of the deeply-coupled GNSS receivers. This paper introduces a scalar-based MEMS IMU/GNSS deeply-coupled system based on an integrated embedded hardware platform for real-time implementation. The design of the deeply-coupled technologies is described including the system architecture, the model of the inertial-aided tracking loop, and the relevant tracking errors analysis. The implementation issues, which include platform structure, real-time optimization, and generation of aiding information, are discussed as well. The performance of the inertial aided tracking loop and the final navigation solution of the developed deeply-coupled system are tested through the dynamic road test scenarios created by a hardware GNSS/INS simulator with GPS L1 C/A signals and low-level MEMS IMU analog signals outputs. The dynamic tests show that the inertial-aided PLL enables a much narrow tracking loop bandwidth (e.g. 3Hz) under dynamic scenarios; while the non-aided loop would lose lock with such narrow loop bandwidth once maneuvering commences. The dynamic zero-baseline tests show that the Doppler observation errors can be reduced by more than 50% with inertial aided tracking loop. The corresponding navigation results also show that the deep integration improved the velocity precision significantly.

We estimated the dependence of the perceived depth on luminance ratio by increasing the distance between the front and rear planes of a depth-fused 3-D (DFD) display. When the distance is great, the perceived depth has the tendency of nonlinear dependence on luminance ratio, which is very different from the almost linear dependence in a short-distance conventional DFD display. In a long-distance DFD display, the perceived depth is split to near the front plane at 0-40% of the rear luminance, near the rear plane at 70-100%, and the midpoint of the front and rear planes at 40-60%. Thus, the luminance-ratio dependence of perceived depth changes widely with the distance.