• 대한전자공학회:학술대회논문집
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• 대한전자공학회 1999년도 하계종합학술대회 논문집
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• pp.94-97
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• 1999

In this paper, a new real-time neural network connection admission controller is proposed. The proposed controller measures traffic flows, cell loss rate and cell delay periodically each classes. The Neural network learns the relation between those measured information and service quality by real-time. Also the proposed controller uses the DWRR multiplexer with buffer dedicated to every traffic source in order to measure the delay that cells experience in buffer. Experimental result shows that the proposed method can control effectively heterogeneous traffic sources with diverse QoS requirement.

• 한국정보과학회논문지:소프트웨어및응용
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• 제31권9호
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• pp.1150-1160
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• 2004

본 논문에서는 MPEG-2에서 정의한 시공간적 계위를 확장하여 enhanced Access Grid (e-AG) 상의 서로 다른 디스플레이 시스템 및 네트워크 환경을 가진 수신 단말의 효율적인 디스플레이를 위한 새로운 3차원 영상의 부호화 방법을 제안한다. 제안된 부호화기는 3차원 영상에 대해서 시공간적 기본 해상도 및 고 해상도의 영상을 표현 가능하도록 여러 계층의 비트 열을 생성한다. 생성된 비트 열은 수신 단말의 네트워크 환경 및 처리속도, 디스플레이 환경에 따라 다른 시공간적 해상포론 표현할 수 있도록 선택적으로 전송된다. 제안된 시공간적 계위를 이용한 3차원 영상 부호화기는 이질적인 분산환경에서의 효율적인 3차원 비디오 전송 서비스에 활용 가능하다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제11권3호
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• pp.1336-1356
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• 2017

The spectrum scarcity crisis has resulted in a shortage of resources for many emerging wireless services, and research on dynamic spectrum management has been used to solve this problem. Game theory can allocate resources to users in an economic way through market competition. In this paper, we propose a bidding game-based spectrum allocation mechanism in cognitive radio network. In our framework, primary networks provide heterogeneous wireless service and different numbers of channels, while secondary users have diverse bandwidth demands for transmission. Considering the features of traffic and QoS demands, we design a weighted interference graph-based grouping algorithm to divide users into several groups and construct the non-interference user-set in the first step. In the second step, we propose the dynamic bidding game-based spectrum allocation strategy; we analyze both buyer's and seller's revenue and determine the best allocation strategy. We also prove that our mechanism can achieve balanced pricing schema in competition. Theoretical and simulation results show that our strategy provides a feasible solution to improve spectrum utilization, can maximize overall utility and guarantee users' individual rationality.

• 한국통신학회논문지
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• 제26권12C호
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• pp.218-224
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• 2001

분산병렬처리의 목적은 다양한 내재 병렬 형태의 특징을 갖는 연산 집약적 문제를 고속 네트웍으로 연결되어진 다수의 고성능 및 병렬 컴퓨터들의 각기 다른 능력을 최대한 이용하여 해결함에 있다. 본 논문에서는 분산병렬시스템을 이용하는 경우의 성능 향상 분석을 위해 일반적인 그래프 표현 방법을 포함하는 계산 모델을 제안하고 프로그램의 수행을 위한 스케쥴링 시에 성능 향상이 어떠한 요인에 의해 달성되는지를 분석한다. 제안된 표현 방법은 동기종 및 이기종 시스템 모두에 적용되어질 수 있다. 분산병렬 시스템에서 스케줄링을 통하여 더 많은 속도향상을 얻기 위해서는 태스크와 병렬 컴퓨터간의 병렬특성의 일치가 주의 질게 다루어져야 하며 태스크의 이동으로 인한 통신 오버 헤드가 최소화 되어야 한다.

• 한국통신학회논문지
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• 제37권8B호
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• pp.677-686
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• 2012

In the presence of a high power cellular network, picocells are added to a Macro-cell layout aiming to enhance total system throughput from cell-splitting. While because of the different transmission power between macrocell and picocell, and co-channel interference challenges between the existing macrocell and the new low power node-picocell, these problems result in no substantive improvement to total system effective throughput. Some works have investigated on these problems. Pico Cell Range Expansion (CRE) technique tries to employ some methods (such as adding a bias for Pico cell RSRP) to drive to offload some UEs to camp on picocells. In this work, we propose two solution schemes (including cell selection method, channel allocation and serving process) and combine new adaptive frequency partitioning reuse scheme to improve the total system throughput. In the simulation, we evaluate the performances of heterogeneous networks for downlink transmission in terms of channel utilization per cell (pico and macro), call blocking probability, outage probability and effective throughput. The simulation results show that the call blocking probability and outage probability are reduced remarkably and the throughput is increased effectively.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제15권6호
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• pp.2225-2239
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• 2021

To assist in data collection, the use of a mobile sink has been widely suggested in the literature. Due to the limited sensor node's storage capacity, this manner to collect data induces huge latencies and drop packets. Their buffers will be overloaded and lead to network congestion. Recently, a new bio-inspired optimization algorithm appeared. Researchers were inspired by the swarming mechanism of salps and thus creating what is called the Salp Swarm Algorithm (SSA). This paper improves the sink mobility to enhance energy dissipation, throughput, and convergence speed by imitating the salp's movement. The new approach, named the Mobile Sink based on Modified Salp Swarm Algorithm (MSSA), is approved in a heterogeneous Wireless Sensor Network (WSN) data collection. The performance of the MSSA protocol is assessed using several iterations. Results demonstrate that our proposal surpass other literature algorithms in terms of lifespan and throughput.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제15권7호
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• pp.2650-2667
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• 2021

In this paper, we derive the expression of the cache hitting probability with random caching policy and propose the joint optimization algorithm based on difference of convex algorithm (DCA) in the three-tier caching heterogeneous cellular network assisted by macro base stations, helpers and users. Under the constraint of the caching capacity of caching devices, we establish the optimization problem to maximize the cache hitting probability of the network. In order to solve this problem, a convex function is introduced to convert the nonconvex problem to a difference of convex (DC) problem and then we utilize DCA to obtain the optimal caching probability of macro base stations, helpers and users for each content respectively. Simulation results show that when the density of caching devices is relatively low, popular contents should be cached to achieve a good performance. However, when the density of caching devices is relatively high, each content ought to be cached evenly. The algorithm proposed in this paper can achieve the higher cache hitting probability with the same density.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제9권12호
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• pp.4856-4871
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• 2015

Backpressure based scheduling has been considered as a promising technique for improving the throughput of a wide range of communication networks. However, this scheduling technique has not been well studied for heterogeneous wireless networks. In this paper, we propose a virtual-queue based backpressure scheduling (VQB) algorithm for heterogeneous multi-hop wireless networks. The VQB algorithm introduces a simple virtual queue for each flow at a node for backpressure scheduling, whose length depends on the cache size of the node. When calculating flow weights and making scheduling decisions, the length of a virtual queue is used instead of the length of a real queue. We theoretically prove that VQB is throughput-optimal. Simulation results show that the VQB algorithm significantly outperforms a classical backpressure scheduling algorithm in heterogeneous multi-hop wireless networks in terms of the packet delivery ratio, packet delivery time, and average sum of the queue lengths of all nodes per timeslot.

• 한국정보과학회:학술대회논문집
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• 한국정보과학회 2007년도 한국컴퓨터종합학술대회논문집 Vol.34 No.1 (A)
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• pp.105-106
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• 2007

• 한국항행학회논문지
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• 제15권1호
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• pp.76-82
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• 2011

다수의 이종 무선망들 중에서 스케일러블 비디오 스트리밍 서비스에 적합한 망을 선택하는 경우, 기존에는 망 품질만을 고려하였다. 그러나 사용자 중심의 체감품질을 고려하지 않고 망 선택을 함에 따라 서비스에 대한 체감 만족이 낮아지는 문제가 있다. 이에 따라, 본 논문에서는 스케일러블 비디오 스트리밍 서비스를 위해 망의 품질뿐만 아니라 일반 사용자, 가격민감 사용자, 품질민감 사용자로 사용자의 소비성향을 구분하고 비디오 품질열화에 대한 서비스 가격 만족도 등을 고려한 체감품질기반의 망 선택 알고리즘을 제안한다. 실험결과 일반 사용자보다 가격민감 사용자와 품질민감 사용자는 각각 36%, 9% 정도 체감만족 향상을 갖는 망을 선택할 수 있었다.