This letter proposes a nonlinear DCT discriminant feature extraction approach for face recognition. The proposed approach first selects appropriate DCT frequency bands according to their levels of nonlinear discrimination. Then, this approach extracts nonlinear discriminant features from the selected DCT bands by presenting a new kernel discriminant method, i.e. the improved kernel discriminative common vector (KDCV) method. Experiments on the public FERET database show that this new approach is more effective than several related methods.

A three-dimensional semiconductor package structure with inter-chip connections was developed for broadband data transfer and low latency electrical communication between a high-capacity memory and a logic device interconnected by a feedthrough interposer (FTI) featuring a 10 µm scale fine-wiring pattern and ultra-fine-pitch through vias. This technology features co-existence of the wide-band memory accessibility of a system-on-chip (SoC) and the capability of memory capacity increasing of a system-in-package (SiP) that is made possible by the individual fabrication of memory and logic on independent chips. This technology can improve performance due to memory band widening and a reduction in the power consumed in inter-chip communications. This paper describes the concept, structure, process, and experimental results of prototypes of this package, called SMAFTI (SMAart chip connection with FeedThrough Interposer). This paper also reports the results of the fundamental reliability test of this novel inter-chip connection structure and board-level interconnectivity tests.

The public safety spectrum is generally under-utilized due to the unique traffic characteristics of bursty and mission critical. This letter considers the application of dynamic spectrum access (DSA) to the combined spectrum of public safety (PS) and commercial (CMR) users in a common shared network that can provide both PS and CMR services. Our scenario includes the 700 MHz Public/Private Partnership which was recently issued by the Federal Communications Commission. We first propose an efficient DSA mechanism to coordinate the combined spectrum, and then establish a call admission control that reflects the proposed DSA in a wideband code division multiple access based network. The essentials of our proposed DSA are opportunistic access to the public safety spectrum and priority access to the commercial spectrum. Simulation results show that these schemes are well harmonized in various network environments.

In recent years, there have been many studies on integrating a number of heterogeneous wireless networks into one network by establishing standards like IEEE 802.16. For this purpose, the base station (BS) should allocate the appropriate bandwidth to each connection with a network scheduler. In wireless networks, the signal to noise ratio (SNR) changes with time due to many factors such as fading. Hence, we estimate the SNR based on the error rate reflecting wireless network condition. Using the estimated SNR, we propose a new time slot allocation algorithm so that the proposed algorithm guarantees the delay requirement and full link utilization.

This paper describes an incremental parser based on an adjoining operation. By using the operation, we can avoid the problem of infinite local ambiguity. This paper further proposes a restricted version of the adjoining operation, which preserves lexical dependencies of partial parse trees. Our experimental results showed that the restriction enhances the accuracy of the incremental parsing.

Recent research on overlay networks has revealed that user-perceived network performance could be improved by an overlay routing mechanism. The effectiveness of overlay routing is mainly a result of the policy mismatch between the overlay routing and the underlay IP routing operated by ISPs. However, this policy mismatch causes a "free-riding" traffic problem, which may become harmful to the cost structure of Internet Service Providers. In the present paper, we define the free-riding problem in the overlay routing and evaluate the degree of free-riding traffic to reveal the effect of the problem on ISPs. We introduce a numerical metric to evaluate the degree of the free-riding problem and confirm that most multihop overlay paths that have better performance than the direct path brings the free-riding problem. We also discuss the guidelines for selecting paths that are more effective than the direct path and that mitigate the free-riding problem.

An OFDMA based channel access scheme is proposed for dynamic spectrum access to utilize frequency spectrum efficiently. Though the OFDMA based scheme is flexible enough to change the bandwidth and channel of the transmitted signals, the OFDMA signal has large PAPR (Peak to Average Power Ratio). In addition, if the OFDMA receiver does not use a filter to extract sub-carriers before FFT (Fast Fourier Transform) processing, the designated sub-carriers suffer large interference from the adjacent channel signals in the FFT processing on the receiving side. To solve the problems such as PAPR and adjacent channel interference encountered in the OFDMA based scheme, this paper proposes a novel dynamic channel access scheme using overlap FFT filter-bank based on single carrier modulation. It also shows performance evaluation results of the proposed scheme by computer simulation.

In this paper, we propose a novel method for gathering sensing information by using an orthogonal narrowband signal for cooperative sensing in cognitive radio. It is desirable to improve the spectrum sensing performance by countering the locality effect of a wireless channel; cooperative sensing by using multiple inputs of sensing information from the surrounding sensing nodes has attracted attention. Cooperative sensing requires that sensing information be gathered at the master node for determining the existence of a primary signal. If the used information gathering method leads to redundancies, the total capacity of the secondary networks is not improved. In this paper, we propose a novel method for gathering sensing information that maps the sensing information to the orthogonal narrowband signal to achieve simultaneous sensing information gathering at the master node. In this method, the sensing information is mapped to an orthogonal subcarrier signal of an orthogonal frequency division multiplexing (OFDM) structure to reduce the frequency resource required for sensing information gathering. The orthogonal signals are transmitted simultaneously from multiple sensing nodes. This paper evaluates the performance of the proposed information gathering method and confirms its effectiveness.

In this paper an algebraic trellis vector quantization (ATVQ) that introduces algebraic codebooks into trellis coded vector quantization (TCVQ) structure is presented. Low encoding complexity and minimum memory storage requirements are achieved using the proposed approach. It exploits advantages of both the TCVQ and the algebraic codebooks to know the delayed decision, the codebook widening, the low computational complexity and the no storage of codebook. This novel vector quantization scheme is used to encode the wideband speech line spectral frequencies (LSF) parameters. Experimental results on wideband speech have shown that ATVQ yields the same performance as the traditional split vector quantization (SVQ) and the TCVQ in terms of spectral distortion (SD). It can achieve a transparent quality at 47 bits/frame with a considerable reduction of memory storage and computation complexity when compared to SVQ and TCVQ.

In this paper, we propose a bandwidth-scalable stereo audio coding method based on a layered structure. The proposed stereo coding method encodes super-wideband (SWB) stereo signals and is able to decode either wideband (WB) stereo signals or SWB stereo signals, depending on the network congestion. The performance of the proposed stereo coding method is then compared with that of a conventional stereo coding method that separately decodes WB or SWB stereo signals, in terms of subjective quality, algorithmic delay, and computational complexity. Experimental results show that when stereo audio signals sampled at a rate of 32 kHz are compressed to 64 kbit/s, the proposed method provides significantly better audio quality with a 64-sample shorter algorithmic delay, and comparable computational complexity.

In the centralized polling mode in IEEE 802.16e, a base station (BS) polls mobile stations (MSs) for bandwidth reservation in one of three polling modes; unicast, multicast, or broadcast pollings. In unicast polling, the BS polls each individual MS to allow to transmit a bandwidth request packet. This paper presents an analytical model for the unicast polling of bandwidth request in IEEE 802.16e networks over Gilbert-Elliot error channel. We derive the probability distribution for the delay of bandwidth requests due to wireless transmission errors and find the loss probability of request packets due to finite retransmission attempts. By using the delay distribution and the loss probability, we optimize the number of polling slots within a frame and the maximum retransmission number while satisfying QoS on the total loss probability which combines two losses: packet loss due to the excess of maximum retransmission and delay outage loss due to the maximum tolerable delay bound. In addition, we obtain the utilization of polling slots, which is defined as the ratio of the number of polling slots used for the MS's successful transmission to the total number of polling slots used by the MS over a long run time. Analysis results are shown to well match with simulation results. Numerical results give examples of the optimal number of polling slots within a frame and the optimal maximum retransmission number depending on delay bounds, the number of MSs, and the channel conditions.

A novel bandpass filter (BPF) for an ultra-wideband (UWB) system is proposed in this letter. The BPF consists of four coplanar stripline (CPS)-to-microstrip transitions. Each transition is employed for broad electromagnetic (EM) coupling between a short-circuited CPS and an open-circuited microstrip line. The equivalent circuit model of the proposed geometry is derived and utilized in the impedance and mode matching analysis. Measured results show good agreement with the analysis and simulated ones.

This study develops a form of digital baseband Intra-Body communication for wideband transmission. A simplified circuit model of signal and noise is constructed to analyze the contribution of the high pass filter function of the electrostatic coupling Intra-Body communication system to wideband digital transmission in electrostatic coupling Intra-Body communication. A unit step function is presented to determine the maximum high pass 3 dB pole that can ensure favorable signal quality in a baseband Intra-Body communication system. Body noise is measured to estimate the range of the high pass 3 dB pole with good Signal to Noise Ratio. A 3.3 Volt battery-powered FPGA is experimentally implemented to confirm the feasibility of the wideband Intra-Body communication system. The experimental results indicate that the digital baseband Intra-Body communication system supports a data rate of more than 16MPS.

This paper proposes two types of electromagnetic bandgap (EBG) structures aimed for SAR reduction on a mobile phone antenna. The EBG structures, one which uses vias while the other does not can reduce the surface wave and prevent the undesired radiation from the antenna. Thus, these structures can reduce the electromagnetic fields toward the human head direction and reduction the SAR value. Tests demonstrate the reduction of SAR values and therefore, the human body can be protected from hazard electromagnetic fields by using the proposed EBG structures, regardless of whether vias are used or not.

This paper presents a prototype group modem for a hyper-multipoint data gathering satellite communication system. It can handle arbitrarily and dynamically assigned FDMA signals by employing a novel FFT-type block demultiplexer/multiplexer. We clarify its configuration and operational principle. Experiments show that the developed modem offers excellent performance.

This paper proposes a novel image inpainting method based on bandelet transform. This technique is based on a multi-resolution layer to perform image restoration, and mainly utilizes the geometrical flow of the neighboring texture of the damaged regions as the basis of restoration. By performing the warp transform with geometrical flows, it transforms the textural variation into the nearing domain axis utilizing the bandelet decomposition method to decompose the non-relative textures into different bands, and then combines them with the affine search method to perform image restoration. The experimental results show that the proposed method can simplify the complexity of the repair decision method and improve the quality of HVS, and thus, repaired results to contain the image of contour of high change, and in addition, offer a texture image of high-frequency variation. These repair results can lead to state-of-the-art results.

This paper describes the architecture and implementations of an automatic digital tuning circuit for a complex bandpass filter (BPF) in a low-power and low-cost transceiver for applications such as personal authentication and wireless sensor network systems. The architectural design analysis demonstrates that an active RC filter in a low-IF architecture can be at least 47.7% smaller in area than a conventional gm-C filter; in addition, it features a simple implementation of an associated tuning circuit. The principle of simultaneous tuning of both the center frequency and bandwidth through calibration of a capacitor array is illustrated as based on an analysis of filter characteristics, and a scalable automatic digital tuning circuit with simple analog blocks and control logic having only 835 gates is introduced. The developed capacitor tuning technique can achieve a tuning error of less than 3.5% and lower a peaking in the passband filter characteristics. An experimental complex BPF using 0.18 µm CMOS technology can successfully reduce the tuning error from an initial value of -20% to less than 2.5% after tuning. The filter block dimensions are 1.22 mm1.01 mm; and in measurement results of the developed complex BPF with the automatic digital tuning circuit, current consumption is 705 µA and the image rejection ratio is 40.3 dB. Complete evaluation of the BPF indicates that this technique can be applied to low-power, low-cost transceivers.

This letter presents the construction and design equations of a lumped element Wilkinson divider with dual-band operation. This divider is constructed of series and parallel LC resonant circuits, and an isolation resistor. The element values can be uniquely determined by giving the two frequencies for operation as a Wilkinson divider and the load resistance. An 800 MHz/2 GHz dual-band Wilkinson divider is treated as a design example, and its operation is verified by simulation and experiment. The fabricated divider has compact dimensions of 3.564 mm2.

Recently, Kempf and Koodli have proposed a security protocol for Fast Mobile IPv6 (FMIPv6). Through the SEcure Neighbor Discovery (SEND) protocol, it achieves secure distribution of a handover key, and consequently becomes a security standard for FMIPv6. However, it is still vulnerable to redirection attacks. In addition, due to the SEND protocol, it suffers from denial of service attacks and expensive computational cost. In this paper, we present a security protocol, which enhances Kempf-Koodli's one with the help of the AAA infrastructure.

A low-power K-band CMOS current-mode up-conversion mixer is proposed. The proposed mixer is realized using four analog current-squaring circuits. This current-mode up-conversion mixer is fabricated in 0.13-µm 1P8M triple-well CMOS process, and has the measured power conversion gain of -5 dB. The fabricated CMOS up-conversion mixer dissipates only 3.1 mW from a 1-V supply voltage. The VCO can be tuned from 20.8 GHz to 22.7 GHz. Its phase noise is -108 dBc/Hz at 10-MHz offset frequency. It is shown that the proposed mixer has great potential for low-voltage and low-power CMOS transmitter front-ends in advanced nano-CMOS technologies.