• KSII Transactions on Internet and Information Systems (TIIS)
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• 제13권2호
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• pp.565-581
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• 2019

This paper investigates the wireless powered two way relay network (WPTWRN), where two single-antenna users and one single-antenna relay firstly harvest energy from signals emitted by a multi-antenna power beacon (PB) and then two users exchange information with the help of the relay by using their harvested energies. In order to improve the energy transfer efficiency, energy beamforming at the PB is deployed. For such a network, to explore the performance limit of the presented WPTWRN, an optimization problem is formulated to obtain the achievable rate region bounds by jointly optimizing the time allocation and energy beamforming design. As the optimization problem is non-convex, it is first transformed to be a convex problem by using variable substitutions and semidefinite relaxation (SDR) and then solve it efficiently. It is proved that the proposed method achieves the global optimum. Simulation results show that the achievable rate region of the presented WPTWRN architecture outperforms that of wireless powered one way relay network architecture. Results also show that the relay location has significant impact on achievable rate region of the WPTWRN.

• 한국통신학회논문지
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• 제35권7A호
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• pp.654-659
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• 2010

본 논문에서는 3GPP LTE 시스템에서 셀 주변부 및 하위 5%의 사용자 전송률을 높이기 위한 새로운 주파수 할당 기법을 제안한다. 단일 안테나 전송 방식(SISO: Single Input Single Output)에서 셀 주변부의 사용자 전송률을 늘리기 위하여 여러 가지 셀간 간섭 관리에 대한 연구가 활발히 진행되었으나, 간섭 관리 알고리즘 적용 방식이 실제 구현에 있어 상당히 복잡한 점이 있다. 제안하는 알고리즘은 모든 셀 영역에 동일한 주파수 할당 방식을 적용할 수 있어 운용의 복잡도를 낮추고, 셀 주변부의 사용자 전송량을 늘리도록 한다. 시스템 레벨 시뮬레이션(SLS: System Level Simulation)을 통하여 제안하는 알고리즘의 셀 주변부 및 하위 5% 사용자 전송률을 비교 분석한다.

• 한국항해학회지
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• 제13권1호
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• pp.55-61
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• 1989

Nowadays much efforts for evaluating the productivity of port physical distribution system to meet the rapid change of the port and shipping circumstances has been made continuously all over the world. The major part of these efforts is the improvement of the productivity of cargo handling system. The cargo equipment system as infrastructure in the cargo handling system is organized well in some degrees, but the management system of manpower as upper structure is still remained in an insufficient degree. There is little study, so far, on a systematic research for the management of port labor gang, and even those were mainly depended on rule of thumb. The object of this study is to introduce the method of optimal allocation and assignment for the labor gang in single ship, which was suggested as a first stage in dealing with them generally. The problem of optimal allocation and assignment of the labor gang can be (I) formalized with multi-stage allocation and assignment of the labor gang can be. (II) dealt with two stages in form of hierarchic structure and moreover, (III) The optimal size of labor gang was obtained through dynamic programming from the point of minimizing the summation of labor gang in every stage, (IV) For the problem of optimal assignment, the optimal policy was determined at the point of minimizing the summation of movement between hatches.

• 대한산업공학회지
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• 제41권4호
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• pp.396-407
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• 2015

The literature about intelligence assets allocation focused on mainly single or partial assets such as TOD and GSR. Thus, it is limited in application to the actual environment of operating various assets. In addition, field units have generally vulnerabilities because of depending on qualitative analysis. Therefore, we need a methodology to ensure the validity and reliability of intelligence asset allocation. In this study, detection probability was generated using digital geospatial data in MGIS (Military Geographic Information System) and simulation logic of BCTP (Battle Commander Training Programs) in the R.O.K army. Then, the optimal allocation mathematical model applied concept of simultaneous integrated management, which was developed based on the partial set covering model. Also, the proposed GA (Genetic Algorithm) provided superior results compared to the mathematical model. Consequently, this study will support effectively decision making by the commander by offering the best alternatives for optimal allocation within a reasonable time.

• Journal of Communications and Networks
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• 제10권2호
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• pp.156-162
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• 2008

Cooperative relays can provide spatial diversity and improve performance of wireless communications. In this paper, we study subcarrier power allocation at the relays for orthogonal frequency division multiplexing (OFDM)-based wireless systems. For cooperative relay with amplify-and-forward (AF) and decode-and-forward (DF) algorithms, we investigate the impact of power allocation to the mutual information between the source and destination. From our simulation results on word~error-rate (WER) performance, we find that the DF algorithm with power allocation provides better performance than that of AF algorithm in a single path relay network because the former is able to eliminate channel noise at each relay. For the multiple path relay network, however, the network structure is already resistant to noise and channel distortion, and AF approach is a more attractive choice due to its lower complexity.

• BMB Reports
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• 제57권4호
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• pp.176-181
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• 2024

Memory allocation, which determines where memories are stored in specific neurons or synapses, has consistently been demonstrated to occur via specific mechanisms. Neuronal allocation studies have focused on the activated population of neurons and have shown that increased excitability via cAMP response element-binding protein (CREB) induces a bias toward memory-encoding neurons. Synaptic allocation suggests that synaptic tagging enables memory to be mediated through different synaptic strengthening mechanisms, even within a single neuron. In this review, we summarize the fundamental concepts of memory allocation at the neuronal and synaptic levels and discuss their potential interrelationships.

• 한국통신학회논문지
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• 제38A권5호
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• pp.443-450
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• 2013

본 논문에서는 셀룰러 시스템 상향 링크에서 가상 여러입력 여러출력 (multiple input multiple output: MIMO)를 적용할 때 사용자 쌍 선택 및 자원 할당 문제를 고려한다. 다중 접속 방식으로 LTE (long term evolution) 시스템의 SC-FDMA (single carrier frequency division multiple access)보다 자원 할당이 유연한 DFTS-OFDMA(discrete Fourier transform spread orthogonal FDMA) 방식을 적용하고 서로 다른 제약 조건에서 전송률을 최대로 하는 사용자 쌍 및 자원 할당 최적화 문제를 공식화하였다. 이 때 비연속 부반송파 자원을 할당하고 중복 사용자 할당을 허용하는 DFTS-OFDMA 방식은 SC-FDMA보다 전달해야 할 자원 할당 제어 정보 양은 늘어나지만 최적화 해를 쉽게 얻을 수 있고 전송률을 향상시킴을 볼 수 있다.

• 한국통신학회논문지
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• 제15권3호
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• pp.243-251
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• 1990

본 논문에서는 광대역 ISDN용 대역폭 할당방식의 성능을 컴퓨터 시뮬레이션을 통하여 분석하였다. 일반적으로 처리율, 지연시간, 블럭킹 확률 특성면에서 보면 다중채널 대역할당 방식의 성능이 단일채널 대역할당 방식의 성능보다 우월하였다. 또한 FIFO 서비스를 사용할때에는 각 트래픽에 대한 처리율, 지연시간, 블럭킹 확률특성이 거의 일정하였으나 우선 서비슬르 적용할 경우에는 높은 우선도를 갖는 트래픽의 성능이 처리율, 지연시간, 블럭킹 확률 특성면에서 낮은 우선도를 갖는 트래픽의 성능보다 훨씬 개선되었다. 또한 다양한 광대역 ISDN 트래픽을 서비스 하기 위해서는 서비스 규칙과는 무관하게 단일채널 대역할당 방식보다는 다중채널 대역할당방식을 사용하는 것이 더 바람직함을 알 수 있었다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제11권4호
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• pp.1889-1910
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• 2017

This paper investigates a protocol so-called Adaptive Harvest Then Transmit (AHTT) for wireless powered communication networks (WPCNs) in multiple-input single-output (MISO) downlink systems, which assists in transmitting signals from a multi-antenna transmitter to a single-antenna receiver. Particularly, the power constrained relay is supplied with power by utilizing radio frequency (RF) signals from the source. In order to take advantage of multiple antennas, two different linear processing schemes, including Maximum Ratio Combining (MRC) and Selection Combination (SC) are studied. The system outage capacity and ergodic capacity are evaluated for performance analysis. Furthermore, the optimal power allocation is also considered. Our numerical and simulation results prove that the implementation of multiple antennas helps boost the energy harvesting capability. Therefore, this paper puts forward a new way to the energy efficiency (EE) enhancement, which contributes to better system performance.

• Journal of Information Processing Systems
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• 제11권2호
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• pp.295-309
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• 2015

Beacon scheduling is considered to be one of the most significant challenges for energy-efficient Low-Rate Wireless Personal Area Network (LR-WPAN) multi-hop networks. The emerging new standard, IEEE802.15.4e, contains a distributed beacon scheduling functionality that utilizes a specific bitmap and multi-superframe structure. However, this new standard does not provide a critical recipe for superframe duration (SD) allocation in beacon scheduling. Therefore, in this paper, we first introduce three different SD allocation approaches, LSB first, MSB first, and random. Via experiments we show that IEEE802.15.4e DSME beacon scheduling performs differently for different SD allocation schemes. Based on our experimental results we propose an adaptive SD allocation (ASDA) algorithm. It utilizes a single indicator, a distributed neighboring slot incrementer (DNSI). The experimental results demonstrate that the ASDA has a superior performance over other methods from the viewpoint of resource efficiency.