• 정보보호학회논문지
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• 제6권3호
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• pp.71-86
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• 1996

본 논문에서는 ATM(Asynchronous Transfer Mode) 망의 ABR(Available Bit-Rate) 서비스를 위한 폭주 제어 기법 내에서 사용되는 스위치 알고리즘을 제안한다. 이 알고리즘은 명시적 전송률 할당 알고리즘으로서 셀의 전송 경로 중 피드백 지연 시간을 가상적으로 단축하여 왕복 지연이 큰 망 환경과 효율성을 유지한다는 것을 시뮬레이션을 통하여 보인다.

• 한국통신학회논문지
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• 제30권4B호
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• pp.186-191
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• 2005

To provide fairness among different ONUs in EPON, the upstream channel remains idle for some time after OLT receives the buffer status from all ONUs every cycle, which decreases the utilization and increases the delay. To solve this deficiency, we present a new grant scheduling method. The method consists of dividing ONUs into several sets where OLT can schedule ONUs in one set while others will be transmitting their traffic. This method will better utilize the bandwidth of EPON. The numerical results show that the larger the number of ONU sets is the smaller the minimum overhead becomes.

• 한국산업정보학회논문지
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• 제7권2호
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• pp.46-53
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• 2002

본 논문에서는 공평성과 효율의 불균형의 차이를 줄이고자 DFBA(Differential Fair Buffer Allocation)의 개선된 형태인 MDFBA(Modified DFBA)를 제안한다. 제안하는 알고리즘은 총 버퍼 용량이 낮은 버퍼 한계 값 보다 작을 경우 모든 셀을 수용하여 효율을 향상시키려고 할 때 공평성과 효율의 차이를 줄여주는 알고리즘으로 시뮬레이션을 통하여 이를 확인하였다. 그리고 망의 상태에 따라 ${\gamma}$값을 다르게 적용함으로써 다양한 환경에서도 잘 적응하도록 하였다.

• Journal of Communications and Networks
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• 제12권2호
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• pp.130-139
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• 2010

Environmental issues and the need to reduce energy consumption for lowering operating costs have pushed power efficiency to become one of the major issues of current research in the field of wireless networks. This paper addresses a number of multiple input multiple output (MIMO) precoding and scheduling techniques across the PHY and MAC layers that can operate under a reduced link budget and collectively improve the transmit power efficiency of a base station, while maintaining the same levels of service. Different MIMO transmission and precoding schemes proposed for LTE, achieving varying degrees of multiuser diversity in both the time, frequency as well as the space domain, are examined. Several fairness-aware resource allocation algorithms are applied to the considered MIMO schemes and a detailed analysis of the tradeoffs between power efficiency and quality of service is presented. This paper explicitly examines the performance of a system serving real-time, VoIP traffic under different traffic loading conditions and transmit power levels. It is demonstrated that by use of efficient scheduling and resource allocation techniques significant savings in terms of consumed energy can be achieved, without compromising QoS.

• 아태비즈니스연구
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• 제11권1호
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• pp.115-143
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• 2020

Purpose - The purpose of this study is to expand the taxpayer's rights protections, which are covered in the previous studies, and to suggest ways to increase tax inspection efficiency as a way to induce fidelity reporting under the final tax return system and to lower tax compliance costs. Design/methodology/approach - The tax audit is a necessary system for the taxpayer to induce self-reporting in a sincere manner, but it is necessary to harmonize the realization of fair taxation and the rights of taxpayers because it is likely to infringe taxpayer rights in the process. Research implications or Originality - The purpose of this study is as follows. First, the government will seek ways to improve tax investigations to strengthen the protection of taxpayers' rights by increasing the fairness and procedural transparency of the current tax investigation system, as pointed out in the National Tax Administration Reform T / F. Second, we will consider ways to enhance the effectiveness of tax audit as a means of inducing faithful tax in Korea's tax system, which assumes sincere taxpayers.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제11권7호
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• pp.3370-3392
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• 2017

Next Generation Beyond 4G/5G systems will rely on the deployment of small cells over conventional macrocells for achieving high spectral efficiency and improved coverage performance, especially for indoor and hotspot environments. In such heterogeneous networks, the expected performance gains can only be derived with the use of efficient interference coordination schemes, such as Fractional Frequency Reuse (FFR), which is very attractive for its simplicity and effectiveness. In this work, femtocells are deployed according to a spatial Poisson Point Process (PPP) over hexagonally shaped, 6-sector macro base stations (MeNBs) in an uncoordinated manner, operating in hybrid mode. A newly introduced intermediary region prevents cross-tier, cross-boundary interference and improves user equipment (UE) performance at the boundary of cell center and cell edge. With tools of stochastic geometry, an analytical framework for the signal-to-interference-plus-noise-ratio (SINR) distribution is developed to evaluate the performance of all UEs in different spatial locations, with consideration to both co-tier and cross-tier interference. Using the SINR distribution framework, average network throughput per tier is derived together with a newly proposed harmonic mean, which ensures fairness in resource allocation amongst all UEs. Finally, the FFR network parameters are optimized for maximizing average network throughput, and the harmonic mean using a fair resource assignment constraint. Numerical results verify the proposed analytical framework, and provide insights into design trade-offs between maximizing throughput and user fairness by appropriately adjusting the spatial partitioning thresholds, the spectrum allocation factor, and the femtocell density.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제7권7호
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• pp.1533-1546
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• 2013

Wireless multicast is considered as an effective transmission mode for the future mobile social contact services supported by Long Time Evolution (LTE). Though wireless multicast has an excellent resource efficiency, its performance suffers deterioration from the channel condition and wireless resource availability. Cognitive Radio (CR) and Device to Device (D2D) are two solutions to provide potential resource. However, resource allocation for cognitive wireless multicast based on D2D is still a great challenge for LTE social networks. In this paper, a joint sub-carriers and power allocation model based on D2D for general cognitive radio multicast (CR-D2D-MC) is proposed for Orthogonal Frequency-Division Multiplexing (OFDM) LTE systems. By opportunistically accessing the licensed spectrum, the maximized capacity for multiple cognitive multicast groups is achieved with the condition of the general scenario of imperfect spectrum sensing, the constrains of interference to primary users (PUs) and an upper-bound power of secondary users (SUs) acting as multicast source nodes. Furthermore, the fairness for multicast groups or unicast terminals is guaranteed by setting a lower-bound number of the subcarriers allocated to cognitive multicast groups. Lagrange duality algorithm is adopted to obtain the optimal solution to the proposed CR-D2D-MC model. The simulation results show that the proposed algorithm improves the performance of cognitive multicast groups and achieves a good balance between capacity and fairness.

• Journal of information and communication convergence engineering
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• 제4권4호
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• pp.141-146
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• 2006

In these days, wireless data services are becoming ubiquitous in our daily life because they offers several fundamental benefits including user mobility, rapid installation, flexibility, and scalability. Moreover, the requests for various multimedia services and the Quality of Service (QoS) support have been one of key issues in wireless data communications. Therefore the research relative to Medium Access Control (MAC) has been progressing rapidly. Especially a number of QoS-aware MAC schemes have been introduced to extend the legacy IEEE 802.11 MAC protocol which has not guaranteed any service differentiation. However, none of those schemes fulfill both QoS features and channel efficiency although these support the service differentiation based on priority. Therefore this paper studies a novel MAC scheme, referred to as Enhanced Distributed Coordination Function with Network Adaptation (EDCF-NA), for enhancements of both QoS and medium efficiency. It uses a smart factor denoted by ACK rate and Network Load Threshold (TH). In this paper, we study how the value of TH has effect on MAC performance and how the use of optimal TH pair improves the overall MAC performance in terms of the QoS, channel utilization, collision rate, and fairness. In addition, we evaluate and compare both the performance of EDCF-NA depending on several pairs of TH and the achievement of various MAC protocols through simulations by using Network Simulator-2 (NS-2).

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제9권1호
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• pp.149-168
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• 2015

In cognitive radio networks (CRNs), hybrid overlay and underlay sharing transmission mode is an effective technique for improving the efficiency of radio spectrum. Unlike existing works in the literature, where only one secondary user (SU) uses overlay and underlay modes, the different transmission modes should be allocated to different SUs, according to their different quality of services (QoS), to achieve the maximal efficiency of radio spectrum. However, hybrid sharing mode allocation for heterogeneous services is still a challenge in CRNs. In this paper, we propose a new resource allocation method for hybrid sharing transmission mode of overlay and underlay (HySOU), to achieve more potential resources for SUs to access the spectrum without interfering with the primary users. We formulate the HySOU resource allocation as a mixed-integer programming problem to optimize the total system throughput, satisfying heterogeneous QoS. To decrease the algorithm complexity, we divide the problem into two sub-problems: subchannel allocation and power allocation. Cutset is used to achieve the optimal subchannel allocation, and the optimal power allocation is obtained by Lagrangian dual function decomposition and subgradient algorithm. Simulation results show that the proposed algorithm further improves spectrum utilization with a simultaneous fairness guarantee, and the achieved HySOU diversity gain is a satisfactory improvement.

• 한국위성정보통신학회논문지
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• 제7권1호
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• pp.65-74
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• 2012

다양한 유형의 사용자 패킷들이 다중화 되어 사용자 단말(RCST, Return Channel via Satellite Terminal)들에게 전달되는 위성 포워드링크에서 패킷들 간의 중요도에 따른 QoS 보장은 매우 중요하다. 특히 강우와 같은 기상상태에 따라 무선 채널 상태가 변화하는 위성망의 경우에는 가용 대역폭을 고려하면서 QoS가 보장 되도록 패킷을 처리해야 한다. DVB-S2에서는 강우감쇠에 대한 대책으로서 적응형 부호 및 변조(Adaptive Coding and Modulation, ACM) 기법을 사용하여 전송효율을 증가시킨다. 하지만 위성링크의 전송 지연시간이 크기 때문에, RCST들이 피드백 하는 리턴채널 데이터를 기반으로 전송모드를 결정하는 ACM 기법을 효율적으로 적용하기 위해서는 채널 예측 알고리즘이 필요하다. 이에 본 논문에서는 RCST가 피드백 하는 강우감쇠 값 데이터와 미리 저장된 참조데이터를 이용하여 위성 링크의 채널을 예측하는 알고리즘 및 QoS와 공평성을 동시에 보장하는 스케줄링 기법을 제안한다. 성능평가 결과 제안하는 알고리즘이 채널을 정확히 예측함은 물론 QoS를 보장하면서 동시에 각 RCST들 간의 사용 대역폭의 공평성을 지원함을 보였다.