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RISS 인기검색어
- 검색키워드
- 저자 : Mario Gerla (검색결과 11 건)
- 무료
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Understanding Processing Overheads of Network Coding-Based Content Distribution in VANETs
Uichin Lee,Seung-Hoon Lee,Kang-Won Lee,Gerla, Mario IEEE 2013 IEEE transactions on parallel and distributed syst Vol.24 No.11
<P>Content distribution in vehicular networks, such as multimedia file sharing and software updates, poses a great challenge due to network dynamics and high-speed mobility. In recent years, network coding has been shown to efficiently support distribution of content in such dynamic environments, thereby considerably enhancing the performance. However, the related work in the literature has mostly focused on theoretic or algorithmic aspects of network coding so far. In this paper, we provide an in-depth analysis on the implementation issues of network coding in wireless networks. In particular, we study the impact of resource constraints (namely CPU, disk, memory, and bandwidth) on the performance of network coding in the content distribution application. The contribution of this paper is twofold. First, we develop an abstract model of a general network coding process and evaluate the validity of the model via several experiments on real systems. This model enables us to find the key resource constraints that influence the network coding strategy and thus to efficiently configure network coding parameters in wireless networks. Second, we propose schemes that considerably improve the performance of network coding under resource constrained environments. We implement our overhead model in the QualNet network simulator and evaluate these schemes in a large-scale vehicular network. Our results show that the proposed schemes can significantly improve the network coding performance by reducing the coding overhead.</P>
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VAPR: Void-Aware Pressure Routing for Underwater Sensor Networks
Noh, Youngtae,Lee, Uichin,Wang, Paul,Choi, Brian Sung Chul,Gerla, Mario IEEE 2013 IEEE TRANSACTIONS ON MOBILE COMPUTING Vol.12 No.5
<P>Underwater mobile sensor networks have recently been proposed as a way to explore and observe the ocean, providing 4D (space and time) monitoring of underwater environments. We consider a specialized geographic routing problem called pressure routing that directs a packet to any sonobuoy on the surface based on depth information available from on-board pressure gauges. The main challenge of pressure routing in sparse underwater networks has been the efficient handling of 3D voids. In this respect, it was recently proven that the greedy stateless perimeter routing method, very popular in 2D networks, cannot be extended to void recovery in 3D networks. Available heuristics for 3D void recovery require expensive flooding. In this paper, we propose a Void-Aware Pressure Routing (VAPR) protocol that uses sequence number, hop count and depth information embedded in periodic beacons to set up next-hop direction and to build a directional trail to the closest sonobuoy. Using this trail, opportunistic directional forwarding can be efficiently performed even in the presence of voids. The contribution of this paper is twofold: 1) a robust soft-state routing protocol that supports opportunistic directional forwarding; and 2) a new framework to attain loop freedom in static and mobile underwater networks to guarantee packet delivery. Extensive simulation results show that VAPR outperforms existing solutions.</P>
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Vehicle location service scheme based on road map in Vehicular Sensor Networks
Yim, Yongbin,Cho, Hyunchong,Kim, Sang-Ha,Lee, Euisin,Gerla, Mario Elsevier Science Publishers B.V. 2017 Computer networks Vol.127 No.-
<P><B>Abstract</B></P> <P>Vehicular Sensor Networks (VSNs) are merging for supporting communications between roadside sensor nodes and vehicles on for notifying environment events on roads to drivers and passengers. Geographic routing has been considered as an efficient and scalable approach to send sensing data from sensor nodes to vehicles. Fundamentally, geographic routing requires sensor nodes to be aware of the location information of vehicles. Since sensor nodes are deployed around roads and vehicles move on the roads, this field property of VSNs brings about a challenging issue to provide location service of vehicles. In this paper, we propose a quorum-based location service scheme to provide sensor nodes with the location information of vehicles in VSNs. For providing the location service, the proposed scheme exploits a crossing point between a quadrangular path quorum of a location update and a line path quorum of a location query by using the road map information. Then, the proposed scheme is extended to accommodate several considerations such as voids, multiple vehicles and sources, and energy depletion. The effectiveness of the proposed scheme is analyzed and validated by extensive numerical and simulation results.</P>
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Exploiting Overlapped Bands for Efficient Broadcast in Multichannel Wireless Networks
Lim, Jae-Han,Naito, Katsuhiro,Yun, Ji-Hoon,Gerla, Mario IEEE 2017 IEEE Transactions on Vehicular Technology VT Vol.66 No.5
<P>In wireless networks, broadcasting is a fundamental communication primitive for network management and information sharing. However, in multichannel networks, broadcast efficiency is very poor as devices are distributed across various channels. Thus, a sender tries all channels to broadcast a single message, causing large overhead. In this paper, we propose a novel, drastically different scheme for efficient broadcast in multichannel networks. Our scheme leverages an overlapped band of adjacent channels, which is the frequency range that partially overlapped channels share within their channel boundaries. Specifically, a sender advertises a rendezvous channel through the overlapped band of adjacent channels; message sharing is done on the rendezvous channel. Our scheme employs signaling via overlapped band (SOB), which defines a new signal processing mechanism for communication via the overlapped band. SOB is integrated with the following Multiple Access Control (MAC) layer mechanisms: 1) Reserve idle spectrum fragment to reduce waiting time, 2) multisender agreement on rendezvous channel to support multisender broadcasts, and 3) reinforce switch notification to reduce the residing time at a wrong channel. Our scheme can also be integrated with two remarkably simple but efficient mechanisms for improving the packet delivery ratio and reducing delay in a multiple contention domain. We implemented our scheme on the SORA software radio platform. Experimental results validated communication through the overlapped band. Intensive simulation studies showed that our scheme dramatically outperformed a previous approach.</P>
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Efficient Peer-to-Peer File Sharing Using Network Coding in MANET
이의진,Joon-Sang Park,Seung-Hoon Lee,노원우,Giovanni Pau,Mario Gerla 한국통신학회 2008 Journal of communications and networks Vol.10 No.4
Mobile peer-to-peer (P2P) systems have recently got in the limelight of the research community that is striving to build efficient and effective mobile content addressable networks. Along this line of research, we propose a new peer-to-peer file sharing protocol suited to mobile ad hoc networks (MANET). The main ingredients of our protocol are network coding and mobility assisted data propagation, i.e., single-hop communication. We argue that network coding in combination with single-hop communication allows P2P file sharing systems in MANET to operate in a more efficient manner and helps the systems to deal with typical MANET issues such as dynamic topology and intermittent connectivity as well as various other issues that have been disregarded in previous MANET P2P researches such as addressing, node/user density, non-cooperativeness, and unreliable channel. Via simulation, we show that our P2P protocol based on network coding and single-hop communication allows shorter file downloading delays compared to an existing MANET P2P protocol.
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DOTS: A Propagation Delay-Aware Opportunistic MAC Protocol for Mobile Underwater Networks
Youngtae Noh,Uichin Lee,Seongwon Han,Wang, Paul,Torres, Dustin,Jinwhan Kim,Gerla, Mario IEEE 2014 IEEE Transactions on Mobile Computing Vol.13 No.4
<P>Mobile underwater networks with acoustic communications are confronted with several unique challenges such as long propagation delays, high transmission power consumption, and node mobility. In particular, slow signal propagation permits multiple packets to concurrently travel in the underwater channel, which must be exploited to improve the overall throughput. To this end, we propose the delay-aware opportunistic transmission scheduling (DOTS) protocol that uses passively obtained local information (i.e., neighboring nodes' propagation delay map and their expected transmission schedules) to increase the chances of concurrent transmissions while reducing the likelihood of collisions. Our extensive simulation results document that DOTS outperforms existing solutions and provides fair medium access even with node mobility.</P>
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Efficient Peer-to-Peer File Sharing Using Network Coding in MANET
Lee, Uichin,Park, Joon-Sang,Lee, Seung-Hoon,Ro, Won-W.,Pau, Giovanni,Gerla, Mario The Korea Institute of Information and Commucation 2008 Journal of communications and networks Vol.10 No.4
Mobile peer-to-peer (P2P) systems have recently got in the limelight of the research community that is striving to build efficient and effective mobile content addressable networks. Along this line of research, we propose a new peer-to-peer file sharing protocol suited to mobile ad hoc networks (MANET). The main ingredients of our protocol are network coding and mobility assisted data propagation, i.e., single-hop communication. We argue that network coding in combination with single-hop communication allows P2P file sharing systems in MANET to operate in a more efficient manner and helps the systems to deal with typical MANET issues such as dynamic topology and intermittent connectivity as well as various other issues that have been disregarded in previous MANET P2P researches such as addressing, node/user density, non-cooperativeness, and unreliable channel. Via simulation, we show that our P2P protocol based on network coding and single-hop communication allows shorter file downloading delays compared to an existing MANET P2P protocol.
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