Processing math: 100%
  • Title/Summary/Keyword: Channel optimization

Search Result 567, Processing Time 0.021 seconds

Optimization of Fixed-point Design on the Digital Front End in IEEE 802.16e OFDMA-TDD System (IEEE 802.16e OFDMA-TDD 시스템 Digital Front End의 Fixed-point 설계 최적화)

  • Kang Seung-Won;Sun Tae-Hyoung;Chang Kyung-Hi;Lim In-Gi;Eo Ik-Soo
    • The Journal of Korean Institute of Communications and Information Sciences
    • /
    • v.31 no.7C
    • /
    • pp.735-742
    • /
    • 2006
  • In this paper, we explain the operation scheme and fixed-point design method of DFE (Digital Front End), which performs DC offset compensation, automatic frequency control, and automatic gain control over the input signal to the UE (User Equipment) receiver of IEEE 802.16e OFDMA-TDD system. Then, we analyze the performance of DFE under ITU-R M. 1225 Veh-A 60km/h channel environment. To optimize the fixed-point design of DFE, we reduce the number of bit resulted from calculation without performance degradation, leading to the decreased complexity of the operation in H/W, and design the Loop filter with considering trade-off between the Acquisition time and the Stability.

Study of Efficient Energy Management for Ubiquitous Sensor Networks with Optimization of the RF power (전송전력 최적화를 통한 센서네트워크의 효율적인 에너지관리에 대한 연구)

  • Eom, Heung-Sik;Kim, Keon-Wook
    • Journal of the Institute of Electronics Engineers of Korea CI
    • /
    • v.44 no.3
    • /
    • pp.37-42
    • /
    • 2007
  • This paper reconsiders established power conservation models for ubiquitous sensor networks that use relay nodes instead of direct communication and proposes novel network power consumption model with consideration of the channel level and radio chip level simultaneously. We estimate the effect of minimum hop-count policy in terms of network power consumption through simulation of various situations for low power RF module CC2420. It is observed that maximum RF power and minimum hop-count results in lower energy consumption relatively. Also, in total network energy consumption, which is included re-transmission, minimum hop count policy presents decrease by 33.1% of energy consumption in compare with the conventional model.

Rate-Distortion Based Selective Encoding in Distributed Video Coding (율-왜곡 기반 선택적 분산 비디오 부호화 기법)

  • Lee, Byung-Tak;Kim, Jae-Gon;Kim, Jin-Soo;Seo, Kwang-Deok
    • Journal of Broadcast Engineering
    • /
    • v.16 no.1
    • /
    • pp.123-132
    • /
    • 2011
  • Recently, DVC (Distributed Video Coding) is receiving a lot of attention as one of the low complexity video encoding techniques suitable for various applications with computation-limited and/or power-limited environment, and is being actively studied for improving the coding efficiency. This paper proposes a rate-distortion based selective block encoding scheme. First, the motion information is obtained in the process of generating side information at decoder and received through the feedback channel, and then, based on this information, the proposed method performs a selective block encoding based on rate-distortion optimization. Experimental results show that the performance of the proposed scheme reaches up to 2.2 dB PSNR gain over the existing scheme. Moreover, it is shown that the complexity can be reduced by encoding parts of region considering rate-distortion cost.

Probabilistic Constrained Approach for Distributed Robust Beamforming Design in Cognitive Two-way Relay Networks

  • Chen, Xueyan;Guo, Li;Dong, Chao;Lin, Jiaru;Li, Xingwang;Cavalcante, Charles Casimiro
    • KSII Transactions on Internet and Information Systems (TIIS)
    • /
    • v.12 no.1
    • /
    • pp.21-40
    • /
    • 2018
  • In this paper, we propose the distributed robust beamforming design scheme in cognitive two-way amplify-and-forward (AF) relay networks with imperfect channel state information (CSI). Assuming the CSI errors follow a complex Gaussian distribution, the objective of this paper is to design the robust beamformer which minimizes the total transmit power of the collaborative relays. This design will guarantee the outage probability of signal-to-interference-plus-noise ratio (SINR) beyond a target level at each secondary user (SU), and satisfies the outage probability of interference generated on the primary user (PU) above the predetermined maximum tolerable interference power. Due to the multiple CSI uncertainties in the two-way transmission, the probabilistic constrained optimization problem is intractable and difficult to obtain a closed-form solution. To deal with this, we reformulate the problem to the standard form through a series of matrix transformations. We then accomplish the problem by using the probabilistic approach based on two sorts of Bernstein-type inequalities and the worst-case approach based on S-Procedure. The simulation results indicate that the robust beamforming designs based on the probabilistic method and the worst-case method are both robust to the CSI errors. Meanwhile, the probabilistic method can provide higher feasibility rate and consumes less power.

Compact Implementation of Multiplication on ARM Cortex-M3 Processors (ARM Cortex-M3 상에서 곱셈 연산 최적화 구현)

  • Seo, Hwa-jeong
    • Journal of the Korea Institute of Information and Communication Engineering
    • /
    • v.22 no.9
    • /
    • pp.1257-1263
    • /
    • 2018
  • Secure authentication technology is a fundamental building block for secure services for Internet of Things devices. Particularly, the multiplication operation is a core operation of public key cryptography, such as RSA, ECC, and SIDH. However, modern low-power processor, namely ARM Cortex-M3 processor, is not secure enough for practical usages, since it executes the multiplication operation in variable-time depending on the input length. When the execution is performed in variable-time, the attacker can extract the password from the measured timing. In order to resolve this issue, recent work presented constant-time solution for multiplication operation. However, the implementation still missed various speed-optimization techniques. In this paper, we analyze previous multiplication methods over ARM Cortex-M3 and provide optimized implementations to accelerate the speed-performance further. The proposed method successfully accelerates the execution-time by up-to 25.7% than previous works.

Effect of Prefrontal lobe Neurofeedback Training for reducing Adolescent Theta wave (청소년기 세타파 감소를 위한 전전두엽 뉴로피드백 훈련 효과)

  • Byun, Youn-Eon
    • Journal of the Korea Academia-Industrial cooperation Society
    • /
    • v.18 no.12
    • /
    • pp.459-465
    • /
    • 2017
  • This research aims to assess whether neurofeedback training can reduce theta waves in adolescents. The experiment was conducted on 35 early youths living in Gyeonggi-do at youth counseling centers during April-October. According to circumstances and opinions of participants in the pre-brain analysis, they were classified into a non-training group (A), 12-week training group (B), and 24-week training group (C), containing 10, 15, and 10 members, respectively. EEG measurement and neurofeedback training was performed using the prefrontal 2-channel NeuroharmonyS and Brain Optimization program. EEG data was processed utilizing Brain Analysis ver1.3. Deducted data was converted to SPSS 21.0 to enable statistical processing. As a strategy to reduce theta through the Beta increase training, we applied the appropriate Alpha, SMR, Beta low reward training to the individual. Study results confirmed that theta waves of adolescents decreased through the prefrontal neurofeedback training. Groups (B) and (C) exhibited a greater decrease in theta waves compared with the control group.

Optimization of Image Merging Conditions for Lumber Scanning System (제재목 화상입력시스템의 최적 화상병합 조건 구명)

  • Kim, Kwang-Mo;Kim, Byoung-Nam;Shim, Kug-Bo
    • Journal of the Korean Wood Science and Technology
    • /
    • v.38 no.6
    • /
    • pp.498-506
    • /
    • 2010
  • To use domestic softwood for structural lumber, appropriate grading system for quality, production and distribution condition of domestic lumber should be prepared. Kim et al. developed an automatic image processing system for grading domestic structural lumber (2009a and b). This study was carried out to investigate optimal image merging conditions for improving performance of image input system which is the key technique of image processing system, developed in the previous paper. To merge digital images of Korean larch lumber, choosing the green channel information of obtained image data showed the most accurate merging performance. As a pre-treatment process, applying Y-derivative Sharr's kernel filter could improve the image merging accuracy, but the effect of camera calibration was imperceptible. The optimal size of template image was verified as 30 pixel widths and 150 pixel heights. When applying the above mentioned conditions, the error length of images was 3.1 mm and the processing time was 9.7 seconds in average.

Estimation of primary production of the waters around rack oyster farm at Wando, Korea

  • Jeong, Woo-Geon;Cho, Sang-Man
    • Fisheries and Aquatic Sciences
    • /
    • v.21 no.4
    • /
    • pp.9.1-9.7
    • /
    • 2018
  • To establish a comprehensive management strategy, as part of the optimization of cultural practice for an oyster rack culture system, we used a numerical model to estimate the primary production in the waters on the eastern coast of Wando island, South Korea. The estimated primary production ranged from 17.12 to 1052.55mgCm2day1 (204.22±224.75mgCm2day1 in average). Except for the times of peak phytoplankton blooms, the estimated primary production (PP) was consistently under 200mgCm2day1, which is more similar to the value of PP measured off the western coast of South Korea than the southern coast. No clear relationship was observed between nitrogen content and rainfall with the exception of heavy rainfall events, indicating that precipitation might not be the main source of nutrients in these waters. No clear influence was observed from Doam tidal discharge, located 24 km north from these waters due to main tide comes in this area from the channel between Gunwe-myeon in Wando island and Pukpyeong-myeon in Haenam-gun. Because of the shallow water depth and strong tidal current, resuspension of sediments, which causes an input of nitrogen into the system, could be easily caused by even mild wind and the infrequent passing of ships. Microscopic examination of the phytoplankton composition showed additional contribution of benthic species such as Paralia sulcata into the waters, which increase the productivity of oyster farms in the waters. The availability of nitrate and phosphate for primary production was temporarily limited throughout most of the spring and autumn blooming season.

Design of MMIC SPST Switches Using GaAs MESFETs (GaAs MESFET을 이용한 MMIC SPST 스위치 설계)

  • 이명규;윤경식;형창희;김해천;박철순
    • The Journal of Korean Institute of Communications and Information Sciences
    • /
    • v.27 no.4C
    • /
    • pp.371-379
    • /
    • 2002
  • In this paper, the MMIC SPST switches operating from DC to 3GHz were designed and implemented. Prior to the design of switches, the small and large-signal switch models were needed to predict switch performance accurately. The newly proposed small-signal switch model parameters were extracted from measured S-parameters using optimization technique with estimated initial values and boundary limits. In the extraction of large-signal switch model parameters, the current source was modeled by fitting empirical equations to measured DC data and the charge model was derived from extracted channel capacitances from measured S-parameters varying the drain-source voltage. To design basic series-shunt SPST switches and isolation-improved SPST switches, we applied this model to commercial microwave circuit simulator. The improved SPST switches exhibited 0.302dB insertion loss, 35.762dB isolation, 1.249 input VSWR, 1.254 output VSWR, and about 15.7dBm PldB with 0/-3V control voltages at 3GHz.

A Study on the Optimization of Library SNS Marketing (도서관 SNS 마케팅 활성화 방안에 관한 연구)

  • Kim, Ji Eun;Noh, Younghee
    • Journal of the Korean BIBLIA Society for library and Information Science
    • /
    • v.24 no.3
    • /
    • pp.157-180
    • /
    • 2013
  • With increasing interest in content marketing, SNS (social networking services) has become more popular as a method of library marketing, both at home and abroad. Accordingly, this study analyzed the operational status and problems of library SNS marketing, in an attempt to find ways to optimize its use. Results show that librarians' opinions of library marketing and library SNS marketing were very high, but the problems they faced included a lack of human resources dedicated to marketing, lack of marketing education, a lack of content to upload each week, and low numbers of contacts on social networking sites. To further develop and optimize library SNS marketing, five solutions were suggested based on the survey results: first, composing an intensive managing team for effective SNS operation; second, providing different levels of marketing training to decrease the librarians' mistakes; third, updating data continuously; fourth, providing information and services users need; and lastly, clearly identifying each channel's active operation goals.