• 한국멀티미디어학회논문지
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• 제17권4호
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• pp.433-440
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• 2014

Wireless communication offers the flexibility to the node movement at the spatial dimension more than the wire communication not only in IP architecture but also in Content-Centric Networking. Although it gives such advantage, the intra-domain movement of a node especially the data source node affects the communication to the access point node which in the end affects the acceptance ratio of the client node that requests the data packets from the data source node. In this paper, we use time-division access method to maintain the acceptance ratio of the client node as the effect of the intra-domain data source node movement in Content-Centric Networking. The simulation result shows that the acceptance ratio of the client node can be maintained using the time-division access method as long as the interval access time is less than the coherence time.

• 한국통신학회논문지
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• 제13권1호
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• pp.63-73
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• 1988

본 논문에서는 확률적 방향성 그래프에서 시점(source node)과 종점(terminal node) 간의 통신할 수 있는 확률인 단점간 신뢰도를 계정하는 알고리즘을 제시하였다. Satyanarayana의 factoring $theorem^{(7)}$을 이용하여 확률적 방향성 그래프에서 시점에 연결되어 있는 에지(edge)를 개방(open)과 단락(short)상태로 감축하여 원래의 그래프를 2개의 감축된 그래프로 분리한 후, 본 논문이 제시한 에지제거법과 일반적인 직, 병렬 감축법을 분리된 그래프에 적용한다. 이 에지 감축(edge reduction)을 source node와 terminal node가 단일 에지로 연결될때까지 반복한다. 또한 복잡하고 규모가 큰 망에 대한 단점간 신뢰도를 계정하기 위해서 전산기 프로그램을 제시하였다.

• 전기학회논문지
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• 제65권12호
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• pp.2262-2269
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• 2016

In IEEE 802.11 wireless LANs, when a source node with low data rate occupies the channel resource for a long time, network performance degrades. In order to improve performance, the cooperative communication has been proposed. In the previous cooperative communication protocols, relay nodes deliver data packets only for a source node. In this paper, we propose an additional transmission scheme in which relay nodes select an additional source node based on several information and deliver data packets for the original source node and the selected additional source node. The proposed scheme improves performance and provides fairness among source nodes. Performance of the proposed scheme is investigated by simulation. Our results show that the proposed scheme outperforms the previous protocol in terms of fairness index and throughput.

• 생물환경조절학회지
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• 제15권2호
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• pp.173-176
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• 2006

The relationship between source leaf position and photo-assimilate translocation and distribution was characterized for tomato (Lycopersicon esculentum Mill) grown in the greenhouse. Three different positions of source leaf on the stem (first node above or below the first fruit cluster and $5^{th}$ node above the first fruit cluster) were tested for their influence on $^{14}CO_2$ assimilation and transfer to different parts of the plant. The leaves at the $5^{th}$ node above the first fruit cluster transferred the highest (57%) proportion of $C^{14}$ to other plant parts, followed by leaves home on the first node below the first fruit cluster (50%), and the first node above the first fruit cluster (39%). In all treatments, fruits served as the strongest sink for $C^{14}$, followed by stem, leaf, and root tissues. The leaf home on the $5^{th}$ node above the first fruit cluster transferred the largest amount of $C^{14}$ to the second fruit cluster.

• 대한전기학회논문지:시스템및제어부문D
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• 제50권2호
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• pp.93-99
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• 2001

A new type geometric and mathematical network reduction model is introduced. Large-scale network is analyzed with analytic approach. The graph has many nodes, branches and loops. Circuit equation are obtained from these elements and connection rule. In this paper, the analytic relation between voltage source has a mutual different graphic property. Node-reduction procedure is achieved with this circuit property. Consequently voltage source value is included into the adjacent node-analyzing equation. A resultant model equations are reduced as much as voltage source number. Matrix rank is (n-1-k), where n, k is node and voltage source number. The reduction procedure is described and verified with geometric principle and circuit theory. Matrix type circuit equation can be composed with this technique. The last results shall be calculated by using computer.

• 한국정보처리학회:학술대회논문집
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• 한국정보처리학회 2004년도 춘계학술발표대회
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• pp.1529-1532
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• 2004

A Mobile Ad Hoc NETwork (MANET) is a collection of wireless mobile nodes that forms a temporary network without the need for any existing network infrastructure or centralized administration. Therefore, such a network is designed to operate in a highly dynamic environment due to node mobility. In mobile ad hoc network, frequent topological changes cause routing a challenging problem and without the complete view of the network topology, establishing the shortest path from the source node to the destination node is difficult. In this paper, we suggest a routing approach which utilizes location information to setup the shortest possible path between the source node and the destination node. Location information is obtained through Global Positioning System (GPS) and this geographical coordinate information of the destination node is used by the source node and intermediate nodes receiving route request messages to determine the shortest path to the destination from current node.

• Journal of Communications and Networks
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• 제3권4호
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• pp.365-373
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• 2001

We propose a new channel reservation protocol which can reduce message delay by using a counter for detection of d source conflict in a WDM single-hop network with non-equivalent propagation delay. A source convict occurs when a source node has the right to transmit more than or equal to two messages simultaneously, which are transmitted using different wavelengths. In such a case, the source node has to newly obtain the right to transmit the message. In the proposed protocol, by using a source conflict counter a source node can detect a source conflict before a wave-length assignment is performed. Therefore, the source node can start a procedure to newly obtain the right to transmit the message which cannot be transmitted due to a source conflict. We analyse the throughput performance by taking the effect of a source conflict into account, and show that the approximate analysis and the computer simulated results are close. Also, from computer simulated results, we show that our proposed protocol can reduce mean message delay dramatically without degrading throughput performance as the offered load becomes large.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제7권8호
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• pp.1786-1804
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• 2013

We consider a specific interference-limited wireless relay system that comprises several cooperation units (CUs) which are defined as a source and destination node pair with an associated relay node. In the wireless relay system, all source nodes simultaneously transmit their own signals and the relay node in each CU then forwards the received signal to the destination node, causing co-channel interference at both the relay node and the destination node in each CU. The co-channel interference at the relay node is closely related to that at the destination node in each CU. We first derive the end-to-end outage probability in a CU over Rayleigh slow-fading channels with interference for the decode-and-forward (DF) relaying strategy. Then, on the assumption that each CU is allocated with equal power we design an optimal power allocation between the source node and the relay node in each CU to minimize the outage probability of the investigated CU. At last, in the case that each CU is not allocated with equal power and the sum of their power is constrained, we present an optimal power allocation between CUs to minimize the sum of the outage probability of all CUs. The analytical results are verified by simulations.

• 한국통신학회논문지
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• 제38A권5호
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• pp.436-442
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• 2013

본 논문에서는 두 개 이상의 안테나를 사용하는 소스 노드, 두 개의 안테나를 사용하는 릴레이 노드, 두 개의 안테나를 사용하는 목적지 노드로 구성된 특별한 경우의 half-duplex (HD) dynamic decode and forward (DDF) 릴레이 프로토콜에 대한 diversity multiplexing tradeoff (DMT) 함수를 유도하였다. 본 논문에서 유도한 프로토콜의 DMT 함수를 동일한 안테나 개수를 사용하는 노드들로 구성된 HD NAF 프로토콜에 대한 DMT 함수와 비교하였으며, 더불어 두 개의 안테나를 사용하는 소스 노드, 두 개 이상의 안테나를 사용하는 릴레이 노드, 두 개의 안테나를 사용하는 목적지 노드로 구성된 HD DDF 릴레이 프로토콜에 대한 DMT 함수와 비교하였다.

• 대한전자공학회논문지TC
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• 제45권4호
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• pp.31-37
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• 2008

기존의 협력통신은 목적지 노드에서 소스 노드와 릴레이 노드들로부터 독립적인 채널의 동일한 신호를 수신하므로 공간 다이버시티와 경로손실감소 이득을 얻을 수 있다. 하지만, 릴레이 노드의 사용으로 인해 주파수 효율이 저하되고, maximal ratio combining (MRC) 결합 방식을 사용함으로써 수신단의 복잡도가 증가하는 문제를 초래하였다. 본 논문에서는 이러한 단점을 개선하는 동시에 우수한 BER 성능을 얻을 수 있는 협력 ARQ 프로토콜을 제안하였다. 이 방식은 소스 노드로부터 수신한 신호를 우선적으로 목적지 노드에서 평가하여 만족되어질 경우, ACK 메시지를 소스 노드와 릴레이 노드로 전송하고 수신한 신호를 복구하므로 기존의 협력통신에 비해 주파수 효율을 높일 수 있다. 또한, ARQ 메시지가 NACK일 경우 릴레이 노드는 선택적 재전송을 하므로 소스 노드가 재전송하는 일반적인 ARQ 프로토콜에 비해 시스템의 신뢰성을 높일 수 있다. 제안하는 프로토콜에서의 선택적 전송과 ARQ 메시지의 정보는 각각 소스 노드로부터 수신한 신호의 log-likelihood ratio (LLR) 계산 값과 임의의 문턱 값을 비교하여 결정하므로 기존의 CRC 부호를 위한 대역폭 할당을 요구하지 않으며, 목적지 노드에서 부가적인 결합방식을 사용하지 않음으로써 수신단의 복잡도를 줄일 수 있었다. 레일리 페이딩과 AWGN를 고려한 Monte-Carlo 시뮬레이션을 통해 주파수 효율과 BER 성능을 검증하였다.