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무선 센서 망에서 실시간 데이터 전송을 위한 멀티캐스팅 방안
박호성(Hosung Park),이정철(Hosung Park),오승민(Seungmin Oh),임용빈(Yongbin Yim),김상하(Sang-Ha Kim) 한국정보과학회 2011 한국정보과학회 학술발표논문집 Vol.38 No.2D
실시간 데이터 멀티캐스팅은 멀티캐스트 그룹 내의 모든 멤버들에게 데이터를 주어진 제한 시간 내에 전송하는 것을 의미한다. 실시간 데이터 멀티캐스팅의 가장 어려운 부분은 소스 노드와 가장 먼 멀티캐스트 멤버에게 실시간 제약조건을 지켜 데이터를 전송하는 것이다. 무선 센서 망에서는 데이터 전송 지연시간이 물리적인 거리에 비례하기 때문이다. 따라서 우리는 소스 노드와 가장 먼 멀티캐스트 멤버와의 거리를 임계 거리 라고 명명한다. 임계 거리는 실시간 데이터 멀티캐스팅에서 가징 중요한 제약조건이 되어야 한다. 다시 말해 소스 노드에서부터 각 멀티캐스트 멤버에게 데이터가 전달되는 각각의 거리는 어떤 이유로도 임계 거리보다 길지 않아야 한다. 그러나 기존의 멀티캐스팅 방안들은 각 멀티캐스트 멤버까지의 데이터 전송 거리보다 멀티캐스팅 전체 비용 절감에 주안점을 두었기 때문에 임계 거리에 관련된 실시간 데이터 전송 제약조건을 만족하기 어렵다. 본 논문에서 우리는 무선 센서 망에서 실시간 데이터 전송을 위한 새로운 멀티캐스팅 방안을 제안한다. 제안 방안은 임계 거리라는 제약사항을 고려하여 멀티캐스트 트리를 구성함으로써 모든 멀티캐스트 멤버들에게 제한 내에 데이터를 전송할 확률을 높여준다. 시뮬레이션 결과는 제안 방안의 실시간 데이터 전송 성공 확률이 기존 멀티캐스팅 방안들에 비해 높음으로 보여준다.
Multicast Protocol for Real-Time Data Dissemination in Wireless Sensor Networks
Hosung Park,Jeongcheol Lee,Soochang Park,Seungmin Oh,Sang-Ha Kim IEEE 2011 IEEE communications letters Vol.15 No.12
<P>Real-time data dissemination to a multicast group is data delivery to each member in the multicast group within the desired time deadline. The hardest aspect of this mission is to enforce the real-time constraint in the communication between a source and the furthest member since an end-to-end delay is proportional to a physical distance in wireless sensor networks. We call it the critical distance. The critical distance should be most important constraint for real-time multicasting. That is, the delivery distance from a source to each member should not be longer than the critical distance even by any reason. However, since the traditional multicast protocols lay the strong emphasis only on the overall communication cost rather than delivery distance to each member, they may violate the real-time constraint related to the critical distance. In this letter, we propose a novel multicast protocol for real-time data dissemination.</P>
Design of Multiple-Edge Protographs for QC LDPC Codes Avoiding Short Inevitable Cycles
Hosung Park,Seokbeom Hong,Jong-Seon No,Dong-Joon Shin IEEE 2013 IEEE transactions on information theory Vol.59 No.7
<P>There have been lots of efforts on the construction of quasi-cyclic (QC) low-density parity-check (LDPC) codes with large girth. However, most of them focus on protographs with single edges and little research has been done for the construction of QC LDPC codes lifted from protographs with multiple (i.e., parallel) edges. Compared to single-edge protographs, multiple-edge protographs have benefits such that QC LDPC codes lifted from them can potentially have larger minimum Hamming distance. In this paper, all subgraph patterns of multiple-edge protographs, which prevent QC LDPC codes from having large girth by inducing inevitable cycles, are fully investigated based on a graph-theoretic approach. By using combinatorial designs, a systematic construction method of multiple-edge protographs is proposed for regular QC LDPC codes with girth at least 12 and another method is proposed for regular QC LDPC codes with girth at least 14. Moreover, a construction algorithm of QC LDPC codes based on certain liftings of multiple-edge protographs is proposed and it is shown that the resulting QC LDPC codes have larger upper bounds on the minimum Hamming distance than those lifted from single-edge protographs. Simulation results are provided to compare the performance of the proposed QC LDPC codes with progressive edge-growth (PEG) LDPC codes and with PEG QC LDPC codes.</P>
Mobile Geocasting to Support Mobile Sink Groups in Wireless Sensor Networks
Soochang Park,Euisin Lee,Hosung Park,Hyungjoo Lee,Sang-Ha Kim IEEE 2010 IEEE communications letters Vol.14 No.10
<P>Traditionally, geocasting has been known as the appropriate scheme for providing effective data dissemination from a source to all nodes in a geographically restricted region. However, since the geocasting typically assumes the restricted region is stationary, it is hard to directly adopt the traditional geocasting in order to offer effective data delivery to mobile sink groups that have geographically collective mobility. Hence, this letter proposes a novel geocasting, called M-Geocasting (Mobile Geocasting). M-Geocasting provides the representative location information of a sink group to sources. The location information contains information with respect to a restricted region in which all member sinks of the group exist. A source disseminates data to the closest node in the region; then, the node restrictedly floods the data only within the region. Also, to support local movement of member sinks toward out of scope of the region, some nodes on boundary of the region maintain the data and offer it to member sinks out of scope of the region.</P>
Reliable and flexible detection of large-scale phenomena on wireless sensor networks
Soochang Park,Hosung Park,Euisin Lee,Sang-Ha Kim IEEE 2012 IEEE communications letters Vol.16 No.6
<P>This letter proposes a novel mechanism for detecting and tracking large-scale phenomena such as spreading of wild fire and diffusion of bio-chemical material. The mechanism takes into account a two-tier grid structure in order to achieve flexibility and reliability. For flexibility, the mechanism initially constructs a proactive coarse-grained grid structure on the whole sensor field. Then, once a phenomenon happens, fine-grained grid structures are reactively established within cells of the coarse-grained grid structure where the phenomenon can be detected. In addition, with respect to reliability, small-scale cells of the fine-grained grid structures can provide the detailed shape of boundary of the phenomenon; to quickly deal with diffusion of the phenomenon the mechanism prepares fine-grained grid structures into next coarse-grained grid cells toward its diffusion direction.</P>