In this paper, a new Hammerstein predistorter modeling for power amplifier (PA) linearization is proposed. The key feature of the model is that the cubic splines, instead of conventional high-order polynomials, are utilized as the static nonlinearities due to the fact that the splines are able to represent hard nonlinearities accurately and circumvent the numerical instability problem simultaneously. Furthermore, according to the amplifier's AM/AM and AM/PM characteristics, real-valued cubic spline functions are utilized to compensate the nonlinear distortion of the amplifier and the following finite impulse response (FIR) filters are utilized to eliminate the memory effects of the amplifier. In addition, the identification algorithm of the Hammerstein predistorter is discussed. The predistorter is implemented on the indirect learning architecture, and the separable nonlinear least squares (SNLS) Levenberg-Marquardt algorithm is adopted for the sake that the separation method reduces the dimension of the nonlinear search space and thus greatly simplifies the identification procedure. However, the convergence performance of the iterative SNLS algorithm is sensitive to the initial estimation. Therefore an effective normalization strategy is presented to solve this problem. Simulation experiments were carried out on a single-carrier WCDMA signal. Results show that compared to the conventional polynomial predistorters, the proposed Hammerstein predistorter has a higher linearization performance when the PA is near saturation and has a comparable linearization performance when the PA is mildly nonlinear. Furthermore, the proposed predistorter is numerically more stable in all input back-off cases. The results also demonstrate the validity of the convergence scheme.

This paper considers the discrete model of the cart-pendulum system modeled by discrete mechanics, which is known as a good discretizing method for mechanical systems and has not been really applied to control theory. We first sum up basic concepts on discrete mechanics and discuss the explicitness of the linear approximation of the discrete Euler-Lagrange Equations. Next, the discrete cart-pendulum system is derived and analyzed from the viewpoint of solvability of implicit nonlinear control systems. We then show a control algorithm to stabilize the discrete cart-pendulum based on the discrete-time optimal regulator theory. Finally, some simulations are shown to demonstrate the effectiveness of the proposed algorithm.

We implement one-out-of-two bit oblivious transfer (OT) based on the assumptions used in the McEliece cryptosystem: the hardness of decoding random binary linear codes, and the difficulty of distinguishing a permuted generating matrix of Goppa codes from a random matrix. To our knowledge this is the first OT reduction to these problems only. We present two different constructions for oblivious transfer, one based on cut-and-chose arguments and another one which is based on a novel generalization of Bennett-Rudich commitments which may be of independent interest. Finally, we also present a variant of our protocol which is based on the Niederreiter cryptosystem.

A method for efficiently representing the state equation in a class of max-plus linear systems is proposed. We introduce a construct referred to as 'cell' in which the list of possible longest paths is stored. By imposing interval constraints on the system parameters, we can reduce the complexity of the state equation. The proposed method would be useful in scheduling applications for systems with adjustable system parameters.

In this paper, we consider a stabilization problem for the cart-pendulum system based on discrete mechanics, which is known as a good discretizing method for mechanical systems and has not been really applied to control theory. First, the continuous and discrete cart-pendulum systems are explained. We next propose a transformation method that converts a discrete-time input derived from the discrete-time optimal regulator theory into a continuous-time zero-order hold input, and carry out some simulations on stabilization of the cart-pendulum system by the transformation method. Then, we apply not only our proposed method but also existing methods to an experimental laboratory of the cart-pendulum system and perform some experiments in order to verify the availability of the proposed method.

Phase structure of nonlinear dynamical system is governed by the vector field and decides the trajectories. Accordingly, the power spectra of trajectories include the structural field effect on the phase space. In this paper, we develop a method for analyzing phase structure using power spectra of trajectories and reconstitute a potential function in the system.

ITS (Intelligent Transport Systems) wireless communications system has been developing based on the leading edge ICT (Information Communication Technologies) in Japan. The comfort driving systems for example VICS (Vehicular Information Communication system), ETC (Electronic Toll Collection), Telematics has already become popular and the safety driving support systems, such as ASV (Advanced Safety Vehicle) and SMARTWAY have been scheduled for introduction in the near future. However, there are many residual issues in the comfort driving system because of the existence of the traffic jam and the interest of the economical cars in the world. Moreover, the acceleration of the development of the Smart Grid and EV (Electric Vehicle) would affect the future development of the ITS wireless communications system. In this paper, it is clarified that the future development should be advanced considering the one of the basic business rule of 'market-in and product-out'.

To opportunistically use the licensed band, spectrum sensing has a vital role as the core component in cognitive radio systems. However, the accurate detection of the primary signal is always accompanied by significant overhead, reducing the secondary throughput. In this letter, we suggest remedying this problem by adopting multiple-stage spectrum sensing (MSS) technique. Furthermore, we investigate how our proposed MSS can be incorporated into the collaborative spectrum sensing. Our results are encouraging in that the proposed MSS with collaboration significantly reduces the sensing time compared to the conventional sensing scheme.

In this paper, we shall describe a basic fuzzy-estimation theory based on the concept of set-valued operators, suitable for available operation of extremely complicated large-scale network systems. Fundamental conditions for availability of system behaviors of such network systems are clarified in a form of β-level fixed point theorem for system of fuzzy-set-valued operators. Here, the proof of this theorem is accomplished by the concept of Hausdorff's ball measure of non-compactness introduced into the Banach space.

Pairings on elliptic curves over finite fields are crucial for constructing various cryptographic schemes. The ηT pairing on supersingular curves over GF(3n) is particularly popular since it is efficiently implementable. Taking into account the Menezes-Okamoto-Vanstone attack, the discrete logarithm problem (DLP) in GF(36n) becomes a concern for the security of cryptosystems using ηT pairings in this case. In 2006, Joux and Lercier proposed a new variant of the function field sieve in the medium prime case, named JL06-FFS. We have, however, not yet found any practical implementations on JL06-FFS over GF(36n). Therefore, we first fulfill such an implementation and we successfully set a new record for solving the DLP in GF(36n), the DLP in GF(36·71) of 676-bit size. In addition, we also compare JL06-FFS and an earlier version, named JL02-FFS, with practical experiments. Our results confirm that the former is several times faster than the latter under certain conditions.

In this study, a low-cost, power-saving and reliable Multiple Server Backup System (MSBS) was configured and tested. The MSBS is based on a Dynamic Backup Server System (DBSS) and is able to recover many different server functions. To configure the DBSS, the mode segmentation method is introduced to simplify system control design and improve applicability to other systems. Experiments based on a mail server showed that the DBSS has sufficient ability to deal with various types of issues, including software and hardware failures. Furthermore, it is important to evaluate the virtual server performance in recovering target server functions. The well-known clock time inaccuracy problem of the virtual server is solved using the network access method regardless of the failure.

In this paper, we propose efficient sequential AES CCM architecture for the IEEE 802.16e. In the proposed architecture, only one AES encryption core is used and the operation of the CTR and the CBC-MAC is processed concurrently within one round. With this design approach, we can design sequential AES CCM architecture having 570 Mbps@102.4 MHz throughput and 1,397 slices at a Spartan3 3s5000 device.

Asymptotic expansions of the amplitudes of the direct and scattered waves in a waveguide system with an imperfection core are derived for large core number and the partial cancellation of the direct wave by the scattered wave is shown in detail. The total power of light in the cross section of a waveguide system is analytically derived and it is shown that the total power of the sum of the direct and scattered waves decreases from that of the direct wave because of the cancellation, the difference of the total power transfers to the localized wave and the total power of light is conserved.

Using a single-site lightning location technique, a new portable lightning location system is developed. We incorporate an attitude detection technique using inertial sensors to detect an accurate electromagnetic field vector of sferics by palm-sized electromagnetic sensors which can have arbitrary attitude. The present paper describes the concept and the performance of the developed prototype of the portable system.

Visibly pushdown automata (VPA), introduced by Alur and Madhusuan in 2004, is a subclass of pushdown automata whose stack behavior is completely determined by the input symbol according to a fixed partition of the input alphabet. Since it was introduced, VPA have been shown to be useful in various contexts, e.g., as specification formalism for verification and as an automaton model for processing XML streams. However, implementation of formal verification based on VPA framework is a challenge. In this paper, we propose on-the-fly algorithms to test universality and inclusion problems of this automata class. In particular, we first present a slight improvement on the upper bound for determinization of VPA. Next, in order to check universality of a nondeterministic VPA, we simultaneously determinize this VPA and apply the P-automata technique to compute a set of reachable configurations of the target determinized VPA. When a rejecting configuration is found, the checking process stops and reports that the original VPA is not universal. Otherwise, if all configurations are accepting, the original VPA is universal. Furthermore, to strengthen the algorithm, we define a partial ordering over transitions of P-automaton, and only minimal transitions are used to incrementally generate the P-automaton. The purpose of this process is to keep the determinization step implicitly for generating reachable configurations as minimum as possible. This improvement helps to reduce not only the size of the P-automaton but also the complexity of the determinization phase. We implement the proposed algorithms in a prototype tool, named VPAchecker. Finally, we conduct experiments on randomly generated VPA. The experimental results show that the proposed method outperforms the standard one by several orders of magnitude.

Petri net is a powerful modeling tool for concurrent systems. Subclasses of Petri net are suggested to model certain realistic applications with less computational cost. Structurally weakly persistent net (SWPN) is one of such subclasses where liveness is verified in deterministic polynomial time. This paper studies the computational complexity to verify whether a give net is SWPN. 3UNSAT problem is reduced to the problem to verify whether a net is not SWPN. This implies co-NP completeness of verification problem of SWPN.

As an application of the direct sequence spread spectrum (SS) communication system, there is an M-ary bi-orthogonal SS communication system. In its system, several spreading sequences (bi-orthogonal sequences) are used in a code shift keying basis. Hence, design of the spreading code synchronization system has been an issue in the M-ary bi-orthogonal SS systems. In this paper, the authors focus on a code tracking system using a differential detector and a Delay Lock Loop (DLL). They investigate a tracking performance of their code tracking system by theoretical analysis. In addition, a multi-stage interference canceler is applied to the M-ary bi-orthogonal SS system. As the result, it is shown that the tracking performance of the theoretical analysis is almost the same as that of computer simulations in a multi-user environment. It is also shown that the multi-stage interference canceler is effective in improvement of the BER performance.

For the panoramic video streaming service, this letter proposes a visual perception-based view navigation trick mode (VP-VNTM) that reduces bandwidth requirements by adjusting the quality of transmitting views in accordance with the view navigation velocity without decreasing the user's visual sensitivity. Experiments show that the proposed VP-VNTM reduces bandwidth requirements by more than 44%.

In this paper, we propose an adaptive Go-Back-N (GBN) ARQ protocol over two parallel channels with slow state transition. This proposed protocol sophisticatedly determines the order of priority of the channel usage for sending packets, by using the channel-state feedback information. We exactly analyze the throughput efficiency of the protocol and obtain its closed-form expression under the assumption that the time-varying channel is modeled by a two-state Markov chain, which is characterized by packet error rate and the decay factor. The analytical results and numerical examples show that, for a given round-trip time, the throughput efficiency depends on both the average packet-error rate and the decay factor. Furthermore, it is shown that the throughput efficiency of the proposed protocol is superior to that of the non-adaptive Go-Back-N protocol using the two channels in a fixed order in the case of slow state transition (i.e. the decay factor is positively large).

This paper presents a verification and analysis tool set for embedded systems. Recently, the development scale of embedded systems has been increasing since they are used for mobile systems, automobile platforms, and various consumer systems with rich functionality. This has increased the amount of time and cost needed to develop them. Consequently, it is very important to develop tools to reduce development time and cost. This paper describes a tool set consisting of three tools to enhance the efficiency of embedded system design. The first tool is an integrated tool platform. The second is a remote debugging system. The third is a clock-accurate verification system based on a field-programmable gate array (FPGA) for custom embedded systems. This tool set promises to significantly reduce the time and cost needed to develop embedded systems.