We analytically investigate combinatorial effects of timer control and backoff algorithms on performance of bulk data transfer over two-state Markovian packet error channels. Numerical results for throughput, energy efficiency, and the probabilities of packet loss and loss of bulk data indicate that linear backoff algorithms outperform binary exponential ones as a whole when they are employed at the logical link sublayer with timer control.

A modified 0.35 µm gate-length MOSFET large-signal microwave device model, based on the widely used BSIM3 model, is presented in this report. This large-signal microwave model includes a BSIM3 model together with the passive components required to fit the device dc and microwave characteristics over a wide range of biasing points and frequency operation. In this report, we propose a methodology to improve the device microwave linearity by controlling a suitable biasing condition, which is based on the predictions of this modified CMOS large-signal model. The input IM3 enhances more than 10 dB at a 2.4 GHz operation. Furthermore, the adjacent channel power ratio also improves 7.5 dB with proper choosing device dc bias.

This paper describes feasibility of a proposed fixed wireless access system with CDMA technology. The system adopts a primary modulation of 16 QAM and the same frequency allocation in all cells to improve spectral efficiency. The system capacity is 1 Gbps per cell within 120 MHz bandwidth. The number of available orthogonal codes corresponds to the orthogonal code length in the system. All subscribers can attain an error free condition with output power control in the presence of inter-cell interference. The following two items are considered to examine the proposed system feasibility. 1) A test modem is fabricated, and a back-to-back modem BER performance is measured. An inter-symbol interference (ISI) level of the modem is estimated with the measured performance. 2) A computer simulation of down-link power control is carried out considering inter-cell interference and impairment factors of the power control such as intra-sector interference caused by the ISI and limited ranges of total and relative output power controls. The simulation results show that the proposed system would be feasible because the obtained power penalties caused by the above impairment factors are negligible.

In this paper, a process is described for analysing the motion of a human target in a video stream. Moving targets are detected and their boundaries extracted. From these, a "star" skeleton is produced. Two motion cues are determined from this skeletonization: body posture, and cyclic motion of skeleton segments. These cues are used to determine human activities such as walking or running, and even potentially, the target's gait. Unlike other methods, this does not require an a priori human model, or a large number of "pixels on target". Furthermore, it is computationally inexpensive, and thus ideal for real-world video applications such as outdoor video surveillance.

Digital signatures whose security does not rely on any unproven computational assumption have recently received considerable attention. While these unconditionally secure digital signatures provide a foundation for long term integrity and non-repudiation of data, currently known schemes generally require a far greater amount of memory space for the storage of secret and public keys than a traditional digital signature. The focus of this paper is on methods for reducing memory requirements of unconditionally secure digital signatures. A major contribution of this paper is to propose two novel unconditionally secure digital signature schemes, one called a symmetric construction and other an asymmetric construction, which require a significantly smaller amount of memory. As a specific example, with a typical parameter setting the required memory size for a user is reduced to be approximately of that in a previously known scheme. Another contribution of the paper is to show an attack on a multireceiver authentication code which was proposed by Safavi-Naini and Wang. A simple method to fix the problem of the multireceiver authentication code is also proposed.

This paper describes a sparse realization of passive reduced-order interconnect models via PRIMA to provide the SPICE compatible models. It is demonstrated that, if the SPICE models are directly realized so that the reduced-order equations obtained via PRIMA are stamped into the MNA matrix, the simulations of networks containing the macromodels become computationally inefficient when size of the reduced-order equations is relatively large. This is due to dense coefficient matrices of the reduced-order equations resulting from congruent transformations in PRIMA. To overcome this disadvantage, we propose a sparse realization of the reduced-order models. Since the expression is equivalent to the reduced-order equations, the passivity of the SPICE models generated is also guaranteed. Computational efficiency on SPICE is demonstrated in performing the transient analysis of circuits containing the proposed macromodels.

We propose a public-key primitive modulo pkq based on the RSA primitive. The decryption process of the proposed scheme is faster than those of two variants of PKCS #1 version 2.1, namely the RSA cryptosystem using Chinese remainder theorem (CRT) and the Multi-Prime RSA. The message M of the proposed scheme is decrypted from M mod pk and M mod q using the CRT, where we apply the Hensel lifting to calculate M mod pk from M mod p that requires only quadratic complexity ((log2p)2). Moreover, we propose a trick that avoids modular inversions used for the Hensel lifting, and thus the proposed algorithm can be computed without modular inversion. We implemented in software both the proposed scheme with 1024-bit modulus p2q and the 1024-bit Multi-Prime RSA for modulus p1p2p3, where p,q,p1,p2,p3 are 342 bits. The improvements of the proposed scheme over the Multi-Prime RSA are as follows: The key generation is about 49% faster, the decryption time is about 42% faster, and the total secret key size is 33% smaller.

A new bipolar scan waveform is proposed to increase the light emission duty factor by achieving the fast address in AC plasma display panel (AC-PDP). The new bipolar scan waveform consists of two-step scan pulse, which can separate the address discharge mode into two different discharge modes: a space charge generation mode and a wall charge accumulation mode. By adopting the new bipolar scan waveform, the light emission duty factor is increased considerably under the single scan ADS driving scheme due to the reduction of address time per single subfield.

This paper presents a novel technique for reconstructing an outdoor sculpture from an uncalibrated image sequence acquired around it using a hand-held camera. The technique introduced here uses only the silhouettes of the sculpture for both motion estimation and model reconstruction, and no corner detection nor matching is necessary. This is very important as most sculptures are composed of smooth textureless surfaces, and hence their silhouettes are very often the only information available from their images. Besides, as opposed to previous works, the proposed technique does not require the camera motion to be perfectly circular (e.g., turntable sequence). It employs an image rectification step before the motion estimation step to obtain a rough estimate of the camera motion which is only approximately circular. A refinement process is then applied to obtain the true general motion of the camera. This allows the technique to handle large outdoor sculptures which cannot be rotated on a turntable, making it much more practical and flexible.

In face recognition, simple classifiers are frequently used. For a robust system, it is common to construct a multi-class classifier by combining the outputs of several binary classifiers; this is called output coding method. The two basic output coding methods for this purpose are known as OnePerClass (OPC) and PairWise Coupling (PWC). The performance of output coding methods depends on accuracy of base dichotomizers. Support Vector Machine (SVM) is suitable for this purpose. In this paper, we review output coding methods and introduce a new sequential fusion method using SVM as a base classifier based on OPC and PWC according to their properties. In the experiments, we compare our proposed method with others. The experimental results show that our proposed method can improve the performance significantly on the real dataset.

A polarization switchable slot-coupled microstrip antenna using PIN diodes is proposed and studied. The microstrip feed line installed behind the ground plane is divided into two branches and each tip of the branches is connected to the ground plane through a PIN diode. One of the diodes is oriented from the tip to the ground plane and the other is oriented from the ground to the tip so that a slot in the ground can be selected to feed the patch by switching the dc bias between positive and negative. This selection contributes to switch the polarization between horizontal and vertical. In this paper, the authors investigate the polarization switching antenna theoretically and experimentally and confirmed sufficient differencce of antenna gain between horizontal and vertical polarization.

It is inevitable for driver assist and warning systems to consider the drivers' state of consciousness. Drowsiness is one of the important factors in estimating the drivers' state of consciousness. A Method to extract the driver's initial stage of drowsiness was developed by means of the eyelid's opening relevant to each various characteristic of objects with motion pictures processing in the actual driving environment. The result was that an increase of the long eyelid closure time was the key factor in estimating the initial stage of drivers' drowsiness while driving. And the state of drowsiness could be presumed by checking the frequencies of long eyelid closure time per unit period.

IEEE 802.11 standard and the enhanced amendments have defined several transmission rates for mobile stations to transmit and receive data frames. With the characteristic of modulation schemes, a higher network throughput can be expected by using higher level modulation scheme, but frame error probability will also become higher. Doubtlessly, it is an open issue of selecting a proper modulation scheme for a pair of mobile stations in time-varying indoor environment. This paper proposes a safe multiple access-rates transmission (SMART) scheme to enhance the reliability of data transmission in IEEE 802.11 multi-rate infrastructure wireless networks. SMART scheme provides reliable transmission by reserving a retransmission period which immediately follows the transmitted frame and is estimated by a lower transmission rate according to the transmitted frame. The performance of SMART scheme is evaluated by analytical model and simulation experiment, which show that the proposed scheme is significantly better than the IEEE 802.11 standard under the real environment with asymmetric traffic load. An enhanced SMART (ESMART) scheme is also proposed especially to improve bandwidth waste for long packet length at access point (AP). The performance measurements, such as goodput, throughput, average access delay, and service rate, are obtained and compared for the different schemes.

The present paper introduces a new construction of a class of binary sequence set having a zero-correlation zone (hereafter binary zcz sequence set). The cross-correlation function and the side-lobe of the auto-correlation function of the proposed sequence set is zero for the phase shifts within the zero-correlation zone. This paper shows that such a construction generates a binary zcz sequence set from an arbitrary pair of Hadamard matrices of common size. Since the proposed sequence construction generates a sequence set from an arbitrary pair of Hadamard matrices, many more types of sequence sets can be generated by the proposed sequence construction than is possible by a sequence construction that generates sequence sets from a single arbitrary Hadamard matrix.

Multiple antenna systems are promising architectures for overcoming the effects of multi-path interference and increasing the spectrum efficiency. In order to be able to investigate these systems, in this article, we derive generalized spatial correlation equations of a circular antenna array for two typical angular energy distributions: a Gaussian angle distribution and uniform angular distribution. The generalized spatial correlation equations are investigated carefully by exact and approximate analyses.

A flexible symbol-timing synchronization met-hod is a one that uses a common sampling clock to find synchronization points for radio communication systems that have different symbol rates. This method estimates synchronization points from state patterns calculated using the symbol rate, sampling clock, and number of observed symbols. Decreasing the number of state patterns is one of best ways to reduce the amount of device resources needed to store the patterns. In this paper, we propose a new pattern generation method in which the number of generated patterns does not increase when the sampling clocks of the communications systems are different. To show the feasibility of this method for symbol-timing synchronization, we analyzed a relationship between the number of samples and the number of state patterns and calculated the BER (bit error rate) in AWGN (additive white Gaussian noise) and one-path flat Rayleigh fading environments by computer simulation.

Many carriers are introducing multi-media services to satisfy customer demands for these services. In order to provide such services, carrier must increase their system capacity. It is well known that space division multiple access (SDMA) improves system capacity and is compatible with existing access systems. In order to evaluate the performance of SDMA, we developed an SDMA test bed. The test bed maintains the personal handy phone systems (PHS). The PHS adopts time division multiple access (TDMA). Aiming to compare the performance of SDMA and TDMA using the same analog hardware, the SDMA test bed employs a software-defined radio (SDR) technique. This paper shows the outline and performance of the test bed. The results of laboratory tests indicate that the bit error rate (BER) of the test bed operated in the SDMA mode at under 10-3 when the carrier-tointerference ratio (CIR) was larger than approximately -22 dB. Antenna patterns measured in an anechoic chamber show that the SDMA test bed produces correct antenna patterns when there are three desired signals and one interference signal. The results of the four field tests confirm that the test bed operated while two-multiplex SDMA mode doubled of the traffic and decreased the interference level as compared with the TDMA mode. Furthermore, the test bed operated while threemultiplex SDMA mode improves the traffic about 2.4 to 2.7 times. The SDMA test bed decreased the impact of the adjusted TDMA base station (BS). Therefore, we confirmed that the SDMA improves system capacity without any degradation.

This paper proposes an efficient method for design space exploration of the global optimum configuration for parameterized ASIPs. The method not only guarantees the optimum configuration, but also provides robust speedup for a wide range of processor architectures such as SoC, ASIC as well as ASIP. The optimization procedure within this method takes a two-steps approach. Firstly, design parameters are partitioned into clusters of inter-dependent parameters using parameter dependency information. Secondly, parameters are optimized for each cluster, the results of which are merged for global optimum. In such optimization, inferior configurations are extensively pruned with a detailed optimality mapping between dependent parameters. Experimental results with mediabench applications show an optimization speedup of 4.1 times faster than the previous work on average, which is significant improvement for practical use.

Both Cr2O3 and NiO absorb 28 GHz milli-meter-wave energy well and this strong coupling with millimeter-waves can be used to promote a chemical reaction with La2O3 to form perovskite-type LaCrO3 or LaNiO3 ceramics. In La2O3-Cr2O3 system, the reaction proceeded rapidly and single phase LaCrO3 could be synthesized within 15 min even at lower temperature (400) as compared to conventional synthesis (T > 800). In the case of LaNiO3, the reaction proceeded rapidly in the early stage of heating (t < 15 min), but not completed even after prolonged millimeter-wave irradiation. The results suggest an importance of millimeter-wave penetration depth, especially for processing of conductive materials.

Using various rare earth sesquioxides as additives, silicon nitride (Si3N4) samples were sintered at 1700 for 4 h by millimeter-wave heating performed in an applicator fed by a 28 GHz Gyrotron source under a nitrogen pressure of 0.1 MPa. A comparative study of densification, grain growth behavior and mechanical properties of silicon nitride fabricated by millimeter-wave and conventional sintering was carried out. Bulk densities were measured by Archimedes' technique. Except for the Eu2O3 containing sample, all samples were densified to relative densities of above 97.0%. Microstructure of the specimens was analyzed by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). To investigate quantitatively the effect of millimeter-wave heating on grain growth, image analysis was carried out for grains in the specimens. Fracture toughness was determined by the indentation-fracture method (IF method) in accordance with Japan Industrial Standards (JIS). Fully dense millimeter-wave sintered silicon nitride presenting a bimodal microstructure exhibited higher values of fracture toughness than materials processed by conventional heating techniques. Results indicate that millimeter-wave sintering is more effective in enhancing the grain growth and in producing the bimodal microstructure than conventional heating. It was also confirmed that localized runaway in temperature, depending upon the sintering additives, can occur under millimeter-wave heating.