There are many system proposals for satellite-based broadband communications that promise high capacity and ease of access. Many of these proposals require advanced switching technology and signal processing on-board the satellite(s). One solution is based on a geo-synchronous (GEO) satellite system equipped with on-board processing and on-board switching. An important feature of this system is allowing for a maximum number of simultaneous users, hence, requiring effective medium access control (MAC) layer protocols for connection admission control (CAC) and bandwidth on demand (BoD) algorithms. In this paper, an integrated CAC and BoD algorithm is proposed for a broadband satellite communication system with heterogeneous traffic. A detailed modeling and simulation approach is presented for performance evaluation of the integrated CAC and BoD algorithm based on heterogeneous traffic types. The proposed CAC and BoD scheme is shown to be able to efficiently utilize available bandwidth and to gain high throughput, and also to maintain good Grade of Service (GoS) for all the traffic types. The end-to-end delay for real-time traffic in the system falls well within ITU's Quality of Service (QoS) specification for GEO-based satellite systems.

Lossless video coding is required in the fields of archiving and editing digital cinema or digital broadcasting contents. This paper combines a discrete wavelet transform and adaptive inter/intra-frame prediction in the wavelet transform domain to create multiresolution lossless video coding. Based on the image statistics of the wavelet transform domains in successive frames, inter/intra frame adaptive prediction is applied to the appropriate wavelet transform domain. This adaptation offers superior compression performance. A progressive transmission scheme is also proposed for effective resolution scalability. Experiments on test sequences confirm the effectiveness of the proposed algorithm.

Recently, a novel detector was proposed by the authors for code acquisition in non-Gaussian impulsive channels [3], which dramatically outperforms the conventional squared-sum detector; however, it requires exact knowledge of the non-Gaussian noise dispersion. In this paper, a robust detector is proposed, which employs the signs and ranks of the received signal samples, instead of their actual values, and so does not require knowledge of the non-Gaussian noise dispersion. The acquisition performance of the proposed detector is compared with that of the detector of [3] in terms of the mean acquisition time. The simulation results show that the proposed scheme is not only robust to deviations from the true value of the non-Gaussian noise dispersion, but also has comparable performance to that of the scheme of [3] using exact knowledge of the non-Gaussian noise dispersion.

This paper presents a shortest path search algorithm using a model of excitable reaction-diffusion dynamics. In our previous work, we have proposed a framework of Digital Reaction-Diffusion System (DRDS)--a model of a discrete-time discrete-space reaction-diffusion system useful for nonlinear signal processing tasks. In this paper, we design a special DRDS, called an "excitable DRDS," which emulates excitable reaction-diffusion dynamics and produces traveling waves. We also demonstrate an application of the excitable DRDS to the shortest path search problem defined on two-dimensional (2-D) space with arbitrary boundary conditions.

Modern digital systems design requires us to explore a large and complex design space to find a best configuration which satisfies design requirements. Such exploration requires a sound representation of design space from which design candidates are efficiently generated, each of which then is evaluated. This paper proposes a plan-generation-evaluation framework which supports a complete process of such design space exploration. The plan phase constitutes a design space of all possible design alternatives by means of a formally defined representation scheme of attributed AND-OR graph. The generation phase generates a set of candidates by algorithmic pruning of the design space in an attributed AND-OR graph with respect to design requirements as well as architectural constraints. Finally, the evaluation phase measures performance of design candidates in a pruned graph to select a best one. A complete process of cache design is exemplified to show the effectiveness of the proposed framework.

We propose two sequence design schemes for an overloaded space-time spreading system with multiple antennas. One scheme is for a system in which the amplitude of user signals needs not be adjusted and provides tradeoffs between the user capacity and diversity order. This scheme has a certain similarity to time-sharing, but its performance is further improved by time-diversity. Another is to achieve full diversity order by varying user signal amplitudes. The diversity orders of the respective schemes are theoretically proved and their performances are demonstrated by simulation.

This letter considers the signal design problems for quaternary digital communications with nonuniform sources. The designs are considered for both the average and equal energy constraints and for a two-dimensional signal space. A tight upper bound on the bit error probability (BEP) is employed as the design criterion. The optimal quarternary signal sets are presented and their BEP performance is compared with that of the standard QPSK and the binary signal set previously designed for nonuniform sources. Results shows that a considerable saving in the transmitted power can be achieved by the proposed average-energy signal set for a highly nonuniform source.

We propose a design theory of the miniaturized high temperature superconducting (HTS) coplanar waveguide (CPW) bandpass filter (BPF), which is composed of meanderline quarter-wavelength resonator, J- and K-inverters. The J- and K-inverters are realized by using interdigital gap and meander-shape inductor. To evaluate the kinetic inductance of the K-inverter, we fabricate the YBCO resonator connected with K-inverters and redesigned the YBCO filter parameters. Finally, we designed and fabricated the YBCO CPW quarter-wavelength resonator BPF by taking account of the kinetic inductance of the K-inverter. The experimental results are in agreement with the design parameters.

A highly collision-resistive RFID system multiplexes communications between thousands of tags and a single reader in combination with time-domain multiplexing code division multiple access (TD-CDMA), CRC error detection, and re-transmission for error recovery. The collision probability due to a random selection of CDMA codes and TDMA channels bounds the number of IDs successfully transmitted to a reader during a limited time frame. However, theoretical analysis showed that the re-transmission greatly reduced the collision probability and that an ID error rate of 2.510-9 could be achieved when 1,000 ID tags responded within a time frame of 400 msec in ideal communication channels. The proposed collision-resistive communication scheme for a thousand multiplexed channels was modeled on a discrete-time digital expression and an FPGA-based emulator was built to evaluate a practical ID error rate under the presence of background noise in communication channels. To achieve simple anti-noise communication in a multiple-response RFID system, as well as unurged re-transmission of ID data, adjusting of correlator thresholds provides a significant improvement to the error rate. Thus, the proposed scheme does not require a reader to request ID transmission to erroneously responding tags. A reader also can lower noise influence by using correlator thresholds, since the scheme multiplexes IDs by CDMA-based communication. The effectiveness of the re-transmission was confirmed experimentally even in noisy channels, and the ID error rate derived from the emulation was 1.910-5. The emulation was useful for deriving an optimum set of RFID system parameters to be used in the design of mixed analog and digital integrated circuits for RFID communication.

A two-dimensional network for motion detection constructed of simple analog circuits was proposed and designed based on the frog visual system. In the frog visual system, the two-dimensional motion of a moving object can be detected by performing simple information processing in the tectum and thalamus of the frog brain. The measured results of the test chip fabricated by a 1.2 µm complementary metal oxide semiconductor (CMOS) process confirmed the correct operation of the basic circuits in the network. The results obtained with the simulation program with integrated circuit emphasis (SPICE) showed that the proposed network can detect the motion direction and velocity of a moving object. Thus, a chip for two-dimensional motion detection was realized using the proposed network.

This paper describes a numerical design procedure of element values of RC polyphase filters with equal minima in stopband and equal ripple in passband. Determination of element values of RC polyphase filters with equal-ripple characteristic have not been solved to the best knowledge of the authors. There found a paper tackling with the problem; however, it can only give sub-optimal solutions via numerical calculation [3]. We propose a numerical element value design procedure for RC polyphase filters with equi-ripple gain in both stopband and passband by using the coefficient matching method. Some design examples are given.

This paper proposes a parity placement scheme, Row-Oblique Parity (ROP), for protecting against double disk failure in disk array systems. It stores all data unencoded, and uses only exclusive-or (XOR) operations to compute parity. ROP is provably optimal in computational complexity, both during construction and reconstruction. It is optimal in the capacity of redundant information stored and accessed. The simplicity of ROP allowed us to implement it within the current available RAID framework.

A dielectric resonator with a gap between the top plate and the rest has been useful for measuring the penetration depth (λ) of superconductor films, a parameter essential for obtaining the intrinsic microwave surface resistance (Rs) of thin superconductor films. We investigated effects of a gap on the microwave properties of TE0ml-mode sapphire resonators with a gap between the top plate and the rest of the resonator. Regardless of a 10 µm-gap in TE0ml-mode sapphire resonators, variations of the TE0ml-mode resonant frequency on temperature (Δf0) as well as TE0ml-mode unloaded Q remained almost the same due to lack of axial currents inside the resonator and negligible radiation effects. The λ of YBa2Cu3O7-δ (YBCO) films obtained from a fit to the temperature-dependent Δf0 appeared to be 195 nm at 0 K and 19.3 GHz, which was well compared with the corresponding value of 193 nm at 10 kHz measured by the mutual inductance method. The intrinsic Rs of YBCO films on the order of 1 mΩ, and the tan δ of sapphire on the order of 10-8 at 15 K and 40 GHz could be measured simultaneously using sapphire resonators with a 10 µm-gap.

In this paper by using an exactly analytic approach the clock jitter in the feedback path of the continuous time Delta Sigma modulators (CT DSM) is modeled as an additive jitter noise, providing a time invariant model for a jittery CT DSM. Then for various DAC waveforms the power spectral density (psd) of the clock jitter at the output of DAC is derived and by using an approximation the in-band power of the clock jitter at the output of the modulator is extracted. The simplicity and generality of the proposed approach are the main advantages of this paper. The MATALB and HSPICE simulation results confirm the validity of the proposed formulas.

Cross-document personal name resolution is the process of identifying whether or not a common personal name mentioned in different documents refers to the same individual. Most previous approaches usually rely on lexical matching such as the occurrence of common words surrounding the entity name to measure the similarity between documents, and then clusters the documents according to their referents. In spite of certain successes, measuring similarity based on lexical comparison sometimes ignores important linguistic phenomena at the semantic level such as synonym or paraphrase. This paper presents a semantics-based approach to the resolution of personal name crossover documents that can make the most of both lexical evidences and semantic clues. In our method, the similarity values between documents are determined by estimating the semantic relatedness between words. Further, the semantic labels attached to sentences allow us to highlight the common personal facts that are potentially available among documents. An evaluation on three web datasets demonstrates that our method achieves the better performance than the previous work.

Based on the observation that foveation analysis can be used to find most critical content in terms of human visual perception in video and image, one effective error resilience method is proposed for robust transmission of H.264 intra-coded frame in wireless channel. It firstly exploits the results of foveation analysis to find foveated area in picture, and then considers the results of pre-error concealment effect analysis to search for the center of foveation macro-blocks (MB) in foveated area, finally new error resilient alignment order of MB and new coding order of MB are proposed that are used in video encoder. Extensive experimental results on different portrait video sequences over random bit error wireless channel demonstrate that this proposed method can achieve better subjective and objective effect than original JM 8.2 H.264 video codec with little effect on coding rate and image quality.

With the increasing demand for IP telephony services using Voice over IP (VoIP) technology, techniques for monitoring speech quality in actual networks are required to manage the quality of VoIP services constantly. Since the speech quality of VoIP is affected by IP network performance factors, non-intrusive methods of monitoring the quality of service (QoS) by passively measuring network performance are being watched with keen interest. VQmon technology is one of the non-intrusive quality monitoring methods. Although the monitoring functions of the VQmon for post-arrived packet behavior events at VoIP-gateways are effective, the estimating algorithm does not take differences in the implementations of VoIP-gateway products into account. We therefore propose a non-intrusive method of monitoring QoS that works in conjunction with ITU-T Recommendation P.862 "PESQ" that takes the characteristics of VoIP-gateway products into consideration. We compared the performance of non-intrusive quality monitoring technology such as VQmon and the proposed method in terms of estimating the accuracy of speech quality and mouth-to-ear delay. The experimental results revealed that the proposed method outperforms the conventional one, achieving sufficient accuracy for quality monitoring of VoIP services.

This paper presents a way of using a linear regression model to produce a single-valued criterion that indicates the perceived importance of each block in a stream of speech blocks. This method is superior to the conventional approach, voice activity detection (VAD), in that it provides a dynamically changing priority value for speech segments with finer granularity. The approach can be used in conjunction with scalable speech coding techniques in the context of IP QoS services to achieve a flexible form of quality control for speech transmission. A simple linear regression model is used to estimate a mean opinion score (MOS) of the various cases of missing speech segments. The estimated MOS is a continuous value that can be mapped to priority levels with arbitrary granularity. Through subjective evaluation, we show the validity of the calculated priority values.

Double-sided YBa2Cu3O7 (YBCO) films were successfully prepared on 50-mm-diameter CeO2-buffered sapphire substrates by metalorganic deposition (MOD) process using an acetylacetonate coating solution. Mapping analysis of superconducting current densities (Jc) at 77.3 K revealed that Jc values of the double-sided films indicated in excess of 2 MA/cm2 in the center parts with a small decrease of Jc at the outer side of the specimens. The Jc values of one side (A) are higher than those of the other side (B). Microwave surface resistance (Rs) of sides A and B of the film exhibited 0.57 and 0.60 mΩ, respectively, at 70 K (12 GHz). The difference in the Rs values should be attributed to the slight difference in the Jc values, which arose from the surface morphology of the CeO2 buffer layer and heat treatment conditions during the firing process in MOD.

This study is devoted to a half-wave dipole with a conductor plane at a distance much smaller than a quarter wavelength which we designate as an ultra low profile dipole (ULPD) antenna in this paper. The concerns of ULPD antenna are the feeding method and the impedance matching, because the input impedance usually tends to be lowered by the existence of a metallic structure in its proximity. In this paper, we propose a ULPD antenna with an excellent impedance matching and a coaxial feed built within the antenna structure so that the external matching and a balun are not required. A coaxial cable is used as a feed line and extended to be a half of a half wavelength dipole. The other half is made up of a parasitic element, which is connected to the outer conductor of the coaxial radiator. To make a matching, the outer conductor of the coaxial radiator is stripped off at a suitable length, and the total length of a dipole is considered for its resonance at a desired frequency of 2 GHz. The experiment has been conducted. The results show the return loss of -27 dB and the maximum gain of 9 dBi in the normal direction to the conductor plane. The computational results are also obtained, which agree well with the experimental results.