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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Journal of information and communication convergence engineering
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Journal DOI :
The Korean Institute of Information and Commucation Engineering
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Volume & Issues
Volume 13, Issue 4 - Dec 2015
Volume 13, Issue 3 - Aug 2015
Volume 13, Issue 2 - Jun 2015
Volume 13, Issue 1 - Mar 2015
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Optimal Sensing Time for Maximizing the Throughput of Cognitive Radio Using Superposition Cooperative Spectrum Sensing
Vu-Van, Hiep ; Koo, Insoo ;
Journal of information and communication convergence engineering, volume 13, issue 4, 2015, Pages 221~227
DOI : 10.6109/jicce.2015.13.4.221
Spectrum sensing plays an essential role in a cognitive radio network, which enables opportunistic access to an underutilized licensed spectrum. In conventional cooperative spectrum sensing (CSS), all cognitive users (CUs) in the network spend the same amount of time on spectrum sensing and waste time in remaining silent when other CUs report their sensing results to the fusion center. This problem is solved by the superposition cooperative spectrum sensing (SPCSS) scheme, where the sensing time of a CU is extended to the reporting time of the other CUs. Subsequently, SPCSS assigns the CUs different sensing times and thus affects both the sensing performance and the throughput of the system. In this paper, we propose an algorithm to determine the optimal sensing time of each CU for SPCSS that maximizes the achieved system throughput. The simulation results prove that the proposed scheme can signiﬁcantly improve the throughput of the cognitive radio network compared with the conventional CSS.
Pseudo-symmetrically Dispersion-Managed Optical Transmission Links with Midway OPC for Compensating for Distorted WDM Signals
Lee, Seong-Real ;
Journal of information and communication convergence engineering, volume 13, issue 4, 2015, Pages 228~234
DOI : 10.6109/jicce.2015.13.4.228
The system performance improvement in dispersion managed (DM) links combined with optical phase conjugator (OPC) for compensating for optical signal distortion due to group velocity dispersion and nonlinear fiber effects has been reported. However, in DM link combined OPC, the equalities of the lengths of single-mode fibers (SMFs), the length of dispersion compensating fibers (DCFs), the dispersion coefficient of DCF, and the residual dispersion per span (RDPS) with respect to an OPC restrict a flexible link configuration. Thus, in this paper, we propose a flexible optical link configuration with inequalities of link parameters, the so-called "pseudo-symmetric configuration." Simulation results show that, in the restricted RDPS range of 450 ps/nm to 800 ps/nm, the improvement in the system performance of the proposed pseudo-symmetrically configured optical links is better than that of the asymmetrically configured optical links. Consequently, we confirmed that the proposed pseudo-symmetric configuration is effective and useful for implementing a reconfigurable long-haul wavelength-division multiplexing (WDM) network.
Decimation Chain Modeling for Dual-Band Radio Receiver and Its Operation for Continuous Packet Connectivity
Park, Chester Sungchung ; Park, Sungkyung ;
Journal of information and communication convergence engineering, volume 13, issue 4, 2015, Pages 235~240
DOI : 10.6109/jicce.2015.13.4.235
A decimation chain for multi-standard reconfigurable radios is presented for 900-MHz and 1,900-MHz dual-band cellular standards with a data interpolator based on the Lagrange method for adjusting the variable data rate to a fixed data rate appropriate for each standard. The two proposed configurations are analyzed and compared to provide insight into aliasing and the signal bandwidth by means of a newly introduced measure called interpolation error. The average interpolation error is reduced as the ratio of the sampling frequency to the signal BW is increased. The decimation chain and the multi-rate analog-to-digital converter are simulated to compute the interpolation error and the output signal-to-noise ratio. Further, a method to operate the above-mentioned chain under a compressed mode of operation is proposed in order to guarantee continuous packet connectivity for inter-radio-access technologies. The presented decimation chain can be applied to LTE, WCDMA, GSM multi-mode multi-band digital front-end which will ultimately lead to the software-defined radio.
A Comparison of Spectrum-Sensing Algorithms Based on Eigenvalues
Ali, Syed Sajjad ; Liu, Jialong ; Liu, Chang ; Jin, Minglu ;
Journal of information and communication convergence engineering, volume 13, issue 4, 2015, Pages 241~247
DOI : 10.6109/jicce.2015.13.4.241
Cognitive radio has been attracting increased attention as an effective approach to improving spectrum efficiency. One component of cognitive radio, spectrum sensing, has an important relationship with the performance of cognitive radio. In this paper, after a summary and analysis of the existing spectrum-sensing algorithms, we report that the existing eigenvalue-based semi-blind detection algorithm and blind detection algorithm have not made full use of the eigenvalues of the received signals. Applying multi-antenna systems to cognitive users, we design a variety of spectrum-sensing algorithms based on the joint distribution of the eigenvalues of the received signal. Simulation results validate that the proposed algorithms in this paper are able to detect whether the signal of the primary user exists or not with high probability of detection in an environment with a low signal-to-noise ratio. Compared with traditional algorithms, the new algorithms have the advantages of high detection performance and strong robustness
Distributed Mobility Management Strategy with Pointer Forwarding Technique
Wie, Sunghong ; Jang, Jaeshin ;
Journal of information and communication convergence engineering, volume 13, issue 4, 2015, Pages 248~256
DOI : 10.6109/jicce.2015.13.4.248
With the dramatic increase in mobile traffic in recent years, some of the limitations of mobility management frameworks have magnified. The current centralized mobility management (CMM) strategy has various problems, such as a suboptimal routing path, low scalability, signaling overhead, and a single point of failure. To overcome these weaknesses in the CMM strategy, the Internet Engineering Task Force has been discussing distributed mobility management (DMM) strategies. The fundamental concept of a DMM strategy is to distribute the mobility anchors closer to the users. While the distribution of mobility anchors results in low-cost traffic delivery, it increases the signaling cost. To reduce this higher signaling cost, we propose a new DMM strategy applying the pointer forwarding technique. The proposed strategy keeps the existing tunnels and extends the traffic path as much as possible. In this paper, we analyze the performance of the pointer forwarding-DMM strategy and discuss its pros and cons.
Threshold Voltage Properties of OFET with CuPc Active Material
Lee, Ho-Shik ; Kim, Seong-Geol ;
Journal of information and communication convergence engineering, volume 13, issue 4, 2015, Pages 257~263
DOI : 10.6109/jicce.2015.13.4.257
In this study, organic field-effect transistors (OFETs) using a copper phthalocyanine (CuPc) material as an active layer and SiO
as a gate insulator were fabricated with varying active layer thicknesses and channel lengths. Further, using a thermal evaporation method in a high-vacuum system, we fabricated a CuPc FET device of the top-contact type and used Au materials for the source and drain electrodes. In order to discuss the channel formation and FET characteristics, we observed the typical current-voltage characteristics and calculated the threshold voltage of the CuPc FET device. We also found that the capacitance reached approximately 97 pF at a negative applied voltage and increased upon the accumulation of carriers at the interface of the metal and the CuPc material. We observed the typical behavior of a FET when used as an n-channel FET. Moreover, we calculated the threshold voltage to be about 15-20 V at V
= -80 V.
An Enhanced Algorithm for an Optimal High-Frequency Emphasis Filter Based on Fuzzy Logic for Chest X-Ray Images
Shin, Choong-Ho ; Lee, Jung-Jai ; Jung, Chai-Yeoung ;
Journal of information and communication convergence engineering, volume 13, issue 4, 2015, Pages 264~269
DOI : 10.6109/jicce.2015.13.4.264
The chest X-ray image cannot be focused in the same manner that optical lenses are and the resultant image generally tends to be slightly blurred. Therefore, the methods to improve the quality of chest X-ray image have been studied. In this paper, the inherent noises of the input images are suppressed by adding the Laplacian image to the original. First, the chest X-ray image using an Gaussian high pass filter and an optimal high frequency emphasis filter has shown improvements in the edges and contrast of flat areas. Second, using fuzzy logic_histogram equalization, each pixel of the chest X-ray image shows the normal distribution of intensities that are not overexposed. As a result, the proposed method has shown the enhanced edge and contrast of the images with the noise canceling effect.
Improved 3D Resolution Analysis of N-Ocular Imaging Systems with the Defocusing Effect of an Imaging Lens
Lee, Min-Chul ; Inoue, Kotaro ; Cho, Myungjin ;
Journal of information and communication convergence engineering, volume 13, issue 4, 2015, Pages 270~274
DOI : 10.6109/jicce.2015.13.4.270
In this paper, we propose an improved framework to analyze an N-ocular imaging system under fixed constrained resources such as the number of image sensors, the pixel size of image sensors, the distance between adjacent image sensors, the focal length of image sensors, and field of view of image sensors. This proposed framework takes into consideration, for the first time, the defocusing effect of the imaging lenses according to the object distance. Based on the proposed framework, the N-ocular imaging system such as integral imaging is analyzed in terms of depth resolution using two-point-source resolution analysis. By taking into consideration the defocusing effect of the imaging lenses using ray projection model, it is shown that an improved depth resolution can be obtained near the central depth plane as the number of cameras increases. To validate the proposed framework, Monte Carlo simulations are carried out and the results are analyzed.
Depth Extraction of Partially Occluded 3D Objects Using Axially Distributed Stereo Image Sensing
Lee, Min-Chul ; Inoue, Kotaro ; Konishi, Naoki ; Lee, Joon-Jae ;
Journal of information and communication convergence engineering, volume 13, issue 4, 2015, Pages 275~279
DOI : 10.6109/jicce.2015.13.4.275
There are several methods to record three dimensional (3D) information of objects such as lens array based integral imaging, synthetic aperture integral imaging (SAII), computer synthesized integral imaging (CSII), axially distributed image sensing (ADS), and axially distributed stereo image sensing (ADSS). ADSS method is capable of recording partially occluded 3D objects and reconstructing high-resolution slice plane images. In this paper, we present a computational method for depth extraction of partially occluded 3D objects using ADSS. In the proposed method, the high resolution elemental stereo image pairs are recorded by simply moving the stereo camera along the optical axis and the recorded elemental image pairs are used to reconstruct 3D slice images using the computational reconstruction algorithm. To extract depth information of partially occluded 3D object, we utilize the edge enhancement and simple block matching algorithm between two reconstructed slice image pair. To demonstrate the proposed method, we carry out the preliminary experiments and the results are presented.
Key Phase Mask Updating Scheme with Spatial Light Modulator for Secure Double Random Phase Encryption
Kwon, Seok-Chul ; Lee, In-Ho ;
Journal of information and communication convergence engineering, volume 13, issue 4, 2015, Pages 280~285
DOI : 10.6109/jicce.2015.13.4.280
Double random phase encryption (DRPE) is one of the well-known optical encryption techniques, and many techniques with DRPE have been developed for information security. However, most of these techniques may not solve the fundamental security problem caused by using fixed phase masks for DRPE. Therefore, in this paper, we propose a key phase mask updating scheme for DRPE to improve its security, where a spatial light modulator (SLM) is used to implement key phase mask updating. In the proposed scheme, updated key data are obtained by using previous image data and the first phase mask used in encryption. The SLM with the updated key is used as the second phase mask for encryption. We provide a detailed description of the method of encryption and decryption for a DRPE system using the proposed key updating scheme, and simulation results are also shown to verify that the proposed key updating scheme can enhance the security of the original DRPE.