• Proceedings of the Korean Institute of Communication Sciences Conference
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• 2004.11a
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• pp.443-443
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• 2004

• Journal of Communications and Networks
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• v.8 no.2
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• pp.234-240
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• 2006

We study the dynamic burst assembly based on traffic prediction and offset and delay differentiation in optical burst switching network. To improve existing burst assembly mechanism and build an adaptive flexible optical burst switching network, an approach called quality of service (QoS) based adaptive dynamic assembly (QADA) is proposed in this paper. QADA method takes into account current arrival traffic in prediction time adequately and performs adaptive dynamic assembly in limited burst assembly time (BAT) range. By the simulation of burst length error, the QADA method is proved better than the existing method and can achieve the small enough predictive error for real scenarios. Then the different dynamic ranges of BAT for four traffic classes are introduced to make delay differentiation. According to the limitation of BAT range, the burst assembly is classified into one-dimension limit and two-dimension limit. We draw a comparison between one-dimension and two-dimension limit with different prediction time under QoS based offset time and find that the one-dimensional approach offers better network performance, while the two-dimensional approach provides strict inter-class differentiation. Furthermore, the final simulation results in our network condition show that QADA can execute adaptive flexible burst assembly with dynamic BAT and achieve a latency reduction, delay fairness, and offset time QoS guarantee for different traffic classes.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.13 no.6
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• pp.546-551
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• 2002

In this paper, a triple controlled type DDFS-driven PLL frequency synthesizer with reduced complexity is used to show its applications for broadband wireless communication systems by frequency synthesis control. Since the proposed DDFS-driven PLL synthesizer is very simplified to use only phase accumulator in DDFS, it improves the switching speed and power consumption than the conventional DDFS-driven PLL frequency synthesizer. It is appropriate for applications with requirements of broadband, low-power consumption and high switching speed, since the proposed synthesizer can cover a wide range of frequency bands by the triple frequency control parameters. Method and results of frequency control parameters assignment are shown for the several frequency bands applications such as GSM, IMT-2000, Bluetooth and PCS system.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.18 no.3
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• pp.497-502
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• 2014

In this paper, a design method for a broadband planar dipole antenna for terrestrial digital television (DTV) reception is studied. The dipole is modified to half bow-tie type for size reduction. The balun between feeding microstrip line and coplanar strip (CPS) line is implemented with a rectangular patch inserted along the center of the CPS line. The proposed antenna is the structure of dual resonances, one is due to the dipole and the other is due to the CPS line attached by the balun. The effects of various geometrical parameters on the antenna performance are examined, and the antenna is designed for terrestrial DTV band (470-806 MHz). The prototype antenna is fabricated on an FR4 substrate with a size of $95mm{\times}178mm$, and tested experimentally to verify the results of this study.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.18 no.7
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• pp.1706-1725
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• 2024

The unique U-shaped structure of U-Net network makes it achieve good performance in image segmentation. This network is a lightweight network with a small number of parameters for small image segmentation datasets. However, when the medical image to be segmented contains a lot of detailed information, the segmentation results cannot fully meet the actual requirements. In order to achieve higher accuracy of medical image segmentation, a novel improved U-Net network architecture called multi-scale encoder-decoder U-Net+ (MEDU-Net+) is proposed in this paper. We design the GoogLeNet for achieving more information at the encoder of the proposed MEDU-Net+, and present the multi-scale feature extraction for fusing semantic information of different scales in the encoder and decoder. Meanwhile, we also introduce the layer-by-layer skip connection to connect the information of each layer, so that there is no need to encode the last layer and return the information. The proposed MEDU-Net+ divides the unknown depth network into each part of deconvolution layer to replace the direct connection of the encoder and decoder in U-Net. In addition, a new combined loss function is proposed to extract more edge information by combining the advantages of the generalized dice and the focal loss functions. Finally, we validate our proposed MEDU-Net+ MEDU-Net+ and other classic medical image segmentation networks on three medical image datasets. The experimental results show that our proposed MEDU-Net+ has prominent superior performance compared with other medical image segmentation networks.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.10 no.12
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• pp.2151-2156
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• 2006

Beamforming for underwater acoustic communication (UAC) is affected by the broadband feature of UAC signal, which has relatively low currier frequency as compared to the signal bandwidth. The narrow-band assumption does not hold good in UAC. In this paper, we discuss a broadband FIR beamformer for UAC using the baseband equivalent way signal model. We consider the broadband FIR beamformer for QPSK UAC with carrier frequency 25kHz and symbol rate 5kHz. Array geometry is a uniform linear way with 8 omni-directional elements and sensor spacing is the half of the carrier wavelength. The simulation results show that the broadband n beamformer achieves nearly optimum signal to interference and noise ratio (SINR) and outperforms the conventional narrowband beamformer by SINR 0.5dB when two-tap FIR filter is employed at each sensor and the inter-tap delay is a quarter of the symbol interval. The broadband FIR beamformer performance is more degraded as the FIR filter length is increased above a certain value. If the inter-tap delay is not greater than half of the symbol period, SINR performance does not depend on the inter-tap delay. More training period is required when the inter-tap delay is same as the symbol period.

• Proceedings of the Acoustical Society of Korea Conference
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• 1998.06c
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• pp.351.1-355
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• 1998

Network-based real-time multimedia applications require guaranteed performances of communication service. Also according to increased bandwidth and processing performance in the future high speed networks, it is possible to make multimedia real-time applications such as distributed real-time applications including video conference, medical imaging, and video education. These applications have characteristics of stringent performance requirements in terms of delay, delay jitter and maximum loss rate. This paper proposes a new delay control for Broadband networks with FCFS queueing. The delay control provides an alternative solution to a current problem in real-time communication; traffic distortion, which makes it difficult to meet such real-time requirements. In simulations, it shows that the proposed delay control can guarantee local and end-to-end delay.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.10 no.12
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• pp.2289-2295
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• 2006

In this paper, We have proposed an Heterodyne technique to generate millimeter-wave signal. Microwave signals in cellular broadband mobile communication networks and distributed networks can favorably be generated and distributed by optical techniques. In principle, these techniques have already been investigated for optical control of phase-array antennas, characterization of photo-detector and phase locking of millimeter-wave oscillators and now being applied to wireless communications. The generation and transmission of millimeter-wave radio signals by optical means is of interest for future pico-cell broadband mobile communication system, especially for systems operating at frequencies of 300GHz.

• The Journal of the Korea institute of electronic communication sciences
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• v.17 no.4
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• pp.563-570
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• 2022

We designed a biconical antenna with sleeve baluns that exhibited an improved radiation pattern from 3-40 GHz. In the antenna, the edges of the ring of the upper cone are blended to a cylinder. Sleeve baluns operating at specific frequencies are connected to the antenna to minimize leakage currents on the surface of the feeding coaxial cable. The radiation pattern was improved with the sleeve baluns, and the angular 3-dB beamwidth ranged from 67.1-101.1° over 3-40 GHz, which is much broader than the 21-99° of the conventional antenna.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.18 no.5
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• pp.1369-1389
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• 2024

In the era of 6G, the rapid increase in communication data volume poses higher demands on traditional channel estimation techniques and those based on deep learning, especially when processing large-scale data as their computational load and real-time performance often fail to meet practical requirements. To overcome this bottleneck, this paper introduces quantum computing techniques, exploring for the first time the application of Quantum Generative Adversarial Networks (QGAN) to broadband channel estimation challenges. Although generative adversarial technology has been applied to channel estimation, obtaining instantaneous channel information remains a significant challenge. To address the issue of instantaneous channel estimation, this paper proposes an innovative QGAN with a dual-module design in the generator. The adversarial loss function and the Mean Squared Error (MSE) loss function are separately applied for the parameter updates of these two modules, facilitating the learning of statistical channel information and the generation of instantaneous channel details. Experimental results demonstrate the efficiency and accuracy of the proposed dual-module QGAN technique in channel estimation on the Pennylane quantum computing simulation platform. This research opens a new direction for physical layer techniques in wireless communication and offers expanded possibilities for the future development of wireless communication technologies.