Decentralized and unstructured peer-to-peer applications such as Gnutella are attractive because they require no centralized directories and no precise control over network topology or data placement. Search algorithm...Decentralized and unstructured peer-to-peer applications such as Gnutella are attractive because they require no centralized directories and no precise control over network topology or data placement. Search algorithm is the major component of the distributed system and its efficiency also does influence the systems performance. However the flooding-based query algorithm used in Gnutella produces huge traffic and does not scale well. Gnutella-like P2P topology has power-law characteristic, so a search algorithm was proposed based on high degree nodes of power-law network, High Degree Nodes-Based Search （HDNBS）. Extensive simulation results show that this algorithm performs on power-law networks very well, achieves almost 100% success rates, produces O（logN） messages per query and can locate target file within O（lagN） hops.展开更多
Aiming at the application of a wireless sensor network to locating miners in underground mine,we design a wireless sensor network location node system,considering the communication performance and the intrinsic safety...Aiming at the application of a wireless sensor network to locating miners in underground mine,we design a wireless sensor network location node system,considering the communication performance and the intrinsic safety. The location node system consists of a mobile node,several fixed nodes,and a sink node,all of whose circuits were designed based on CC2430. A varistor and a RC circuit were used in the reset circuit of a sensor node to guarantee the intrinsic safety by reducing discharge energy,the theoretical analysis of the discharge energy shows that the reset circuit is an intrinsic safety one. The analysis and simulation about the performance of the location node system are discussed,such as network communication delay and packet loss rate,the results show that the highest network communication delay of the system is about 0.11 seconds,and the highest packet loss rate is about 0.13,which assures the location node system has a high reliability,and can locate miners in the underground mine.展开更多
The letter proposes a three-layer manageable media distribution network system architecture called MSPnet, which is based on Session Initiation ProtocolIll and Peer to Peer （SIP P2P） technology. MSPnet performs appl...The letter proposes a three-layer manageable media distribution network system architecture called MSPnet, which is based on Session Initiation ProtocolIll and Peer to Peer （SIP P2P） technology. MSPnet performs application-level structured DHT routing and resource location among domains and unstructured ones in domain. Except for media distribution, it can be used to support a variety of P2P applications, including video broadcasting, video on demand, VoIP, etc. MSPnet is composed of three layers, namely, the signal control layer, the management layer, and the media transportation layer. The MSPnet prototype consists of the SIP server, the management server, the media server, and the node User Agent （UA）. Results from a prototype experiment in a large-scale Internet environment show that MSPnet is feasible, scalable and manageable.展开更多
文摘Decentralized and unstructured peer-to-peer applications such as Gnutella are attractive because they require no centralized directories and no precise control over network topology or data placement. Search algorithm is the major component of the distributed system and its efficiency also does influence the systems performance. However the flooding-based query algorithm used in Gnutella produces huge traffic and does not scale well. Gnutella-like P2P topology has power-law characteristic, so a search algorithm was proposed based on high degree nodes of power-law network, High Degree Nodes-Based Search （HDNBS）. Extensive simulation results show that this algorithm performs on power-law networks very well, achieves almost 100% success rates, produces O（logN） messages per query and can locate target file within O（lagN） hops.
基金Projects 20070411065 supported by the China Postdoctoral Science Foundation0801028B by the Jiangsu Postdoctoral Science Research Foundation
文摘Aiming at the application of a wireless sensor network to locating miners in underground mine,we design a wireless sensor network location node system,considering the communication performance and the intrinsic safety. The location node system consists of a mobile node,several fixed nodes,and a sink node,all of whose circuits were designed based on CC2430. A varistor and a RC circuit were used in the reset circuit of a sensor node to guarantee the intrinsic safety by reducing discharge energy,the theoretical analysis of the discharge energy shows that the reset circuit is an intrinsic safety one. The analysis and simulation about the performance of the location node system are discussed,such as network communication delay and packet loss rate,the results show that the highest network communication delay of the system is about 0.11 seconds,and the highest packet loss rate is about 0.13,which assures the location node system has a high reliability,and can locate miners in the underground mine.
基金Partially supported by National Advanced Technology Research Development Plan 863 Program (2005AA121130)Tsinghua University Media and Net-work Technology Ministry of Education-Microsoft Lab Fund, and CNGI 2006 Apoplectic Demonstration project.
文摘The letter proposes a three-layer manageable media distribution network system architecture called MSPnet, which is based on Session Initiation ProtocolIll and Peer to Peer （SIP P2P） technology. MSPnet performs application-level structured DHT routing and resource location among domains and unstructured ones in domain. Except for media distribution, it can be used to support a variety of P2P applications, including video broadcasting, video on demand, VoIP, etc. MSPnet is composed of three layers, namely, the signal control layer, the management layer, and the media transportation layer. The MSPnet prototype consists of the SIP server, the management server, the media server, and the node User Agent （UA）. Results from a prototype experiment in a large-scale Internet environment show that MSPnet is feasible, scalable and manageable.
