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(붙임 3) Proposal for Collaborative Research 1. Title of Research Project: ANALYSIS AND DESIGN OF MAC AND NETWORK-LEVEL SCHEMES FOR RELIABLE GROUP COMMUNICATION IN AD-HOC NETWORKS 2. Duration of Project From May 2002 to May 2004 ( 24 Months) 3. Project Manager Name J.J. Garcia-Luna-Aceves Date of Birth Affiliation & Position Professor, University of California at Santa Cruz Present Computer Engineering Department Address University of California, Santa Cruz CA 95064 TEL 831 4594153 FAX 831 4594829 Degree & Specialty Ph.D., internetworking and wireless networks Oct 20, 1955 E-mail address [email protected] Main Scientific publications in the last five years(to a Maximum of five) The following are selected publications; a complete list of publications is available at: http://www.cse.ucsc.edu/research/ccrg/publications.html 1. L. Bao and J.J. Garcia-Luna-Aceves, "A New Approach to Channel Access Scheduling for Ad Hoc Networks," Proc. ACM MobiCom 2001-- Seventh Annual International Conference on Mobile Computing and networking, July 16-21, 2001, Rome, Italy. 2. J.J. Garcia-Luna-Aceves and A. Tzamaloukas, "Reversing The Collision-Avoidance Handshake in Wireless Networks ", Proc. ACM/IEEE Mobicom 99, Seattle, Washington, August 15--20, 1999. 3 M. Spohn and J.J. Garcia-Luna-Aceves, " Neighborhood Aware Source Routing", Proc. ACM MobiHoc 2001, October 4--5, 2001, Long Beach, California. 4. E.L. Madruga and J.J. Garcia-Luna-Aceves , "Scalable Multicasting: The Core Assisted Mesh Protocol", accepted for publication in ACM/Baltzer Mobile Networks and Applications Journal, Special Issue on Management of Mobility in Distributed Systems, First Quarter 2001. 5. M. Mosko and J.J. Garcia-Luna-Aceves," Performance of Group Communications over Ad-Hoc Networks", Proc. The Seventh IEEE Symposium on Computers and Communications (ISCC 02), Taormina/Giardini Naxos, Italy, July 1 - 4, 2002. * Please mention the year of the publication, the name and volume of the journal and main/co author 4. Applying Budget 1st year ETRI Counterpart 2nd year ETRI Counterpart 5. Members of Research Team Prof. J.J. Garcia-Luna-Aceves, Principal Investigator Marc Mosko, Graduate Research Assistant Hari Rangarajan, Graduate Research Assistant Long Yang, Graduate Research Assistant Dr. Donkyun Kim, Visiting Scientist (post-doc appointment) 6. Research Plan 6. 1. Summary Group communication over multihop wireless networks is critical to many applications in the commercial and military sectors. Data broadcast and data multicast have many uses in multimedia applications, data distribution services, and as tools for other communications protocols. More recently, the availability of less expensive sensors has prompted renewed interest in group communication within the context of sensor networks. Multicast and broadcast over multihop wireless networks presents significant problems for lost data, flow control and error correction schemes. The loss of a single packet may affect many recipients due to data replication. Because data travel simultaneously through multiple network paths, there is no single flow, so standard end-to-end approaches such as the Transmission Control protocol (TCP) do not directly apply. For reliable data delivery, packet acknowledgments or loss negative acknowledgments may flood a sender or disrupt other data packets causing further loss. A fundamental problem particular to multi-hop wireless networks is the hidden-terminal problem. Two radio nodes, for instance, may not have clear reception of each other, but both may be in contact with a third node. The third node is the focus of hidden-terminal collisions when the other two nodes simultaneously transmit. Solutions to the hidden-terminal problem follow two lines. Contention-based solutions use some form of randomized channel reservation scheme. The reservations still contend for the channel and may cause collisions of the reservation packets, but larger data packets should not collide. Schedule-based solutions devise a time-synchronous order to transmissions and avoid data packet collisions. Some protocols have features of both. Group multicast or all-node broadcast puts strains on a weak aspect of unscheduled ad-hoc protocols. Collision avoidance protocols, such as IEEE 802.11 DCF use unicast request-to-send (RTS) and clear-to-send (CTS) messages to reserve radio time. side-band carriers. Busy-tone protocols, such as BTMA, use Such mechanisms do not work for group communications, because multiple nodes would respond or busy tones would collide. These protocols become pure CSMA for broadcasts, which offers no hidden-terminal collision protection for multi-hop wireless networks. Group communications covers several forms of packet delivery mechanisms, including link-layer broadcast, group-address packets, and IP multicast. Packet losses significantly affect group communications because of correlated losses and difficulties with reliability mechanisms. Correlated losses occur from the inability of switching nodes to replicate packets. Downstream nodes, possibly many, suffer correlated loss when one upstream switching node loses a packet. Standard unicast reliability mechanics, such as end-to-end or hop- by-hop acknowledgments, involve significant overhead or prohibitive network load for communications in a large group. We propose to study reliable group communication over multihop wireless networks. Although several proposals exist for supporting unreliable multicast over multihop wireless networks, very limited work has been reported on effective approaches for reliable group communication in ad hoc networks, and the impact of the MAC layer has been ignored until very recently. We will investigate modifications to MAC protocols for more efficient support of reliable multicasting and broadcasting. We will also investigate network-level schemes for reliable mutlicasting and broadcasting in mobile ad hoc networks, and the interaction between mechanisms at the MAC layer and the network layer for reliable group communication. A particular problem that needs attention is the effect that changes in the neighborhood of a node (i.e., additions and deletions of neighbors) has on its ability to disseminate data reliably to a group of other nodes in the network. 6. 2. Development Approach Our approach will take advantage of our recent work on scheduled channel access and reliable broadcasting over contention-based MAC protocols. More specifically, we will carry out the following three main tasks. The first task aims at developing a network-level scheme for information dissemination on demand; the other two tasks aim at developing schemes for the transmission of information to multiple receivers efficiently. Together, these schemes should improve the throughput and delay characteristics of a mutlihop ad hoc network substantially in the presence of multipoint data traffic. Reliable information dissemination with a publish-subscribe paradigm: We will develop and simulate in ns2 a protocol for reliable information dissemination using a publish-subscribe approach. The protocol will take advantage of extension to a traditional collision-avoidance handshake and the use of “content tables” to allow network nodes to disseminate data on demand. This task is an extrapolation of the SPIN protocol, introduced by Heinzelman et al (W. Heinzelman et al., “Adaptive Protocols for Information Dissemination in Wireless Sensor Networks,” Proc. MobiCom 99) and directed diffusion, advocated by Intanagonwiwat et al (C. Intanagonwiwat et al., “Directed Diffusion: A Scalable and Robust Communication Paradigm for Sensor Networks,” Proc. MobiCom 2000) and will take into account the effects of the MAC layer in information dissemination, which has been neglected in the main proposals to date. Scheduling of multicast transmissions over contention-based MAC protocols: We will develop extensions to collision-avoidance protocols, such that the transmissions of nodes originating or forwarding data reliably are paced in order to reduce or eliminate collisions of data packets. Our approach is based on work done to date by Mosko and Garcia-Luna-Aceves on reliable broadcasting in ad hoc networks. We will develop heuristics to establish an implicit or explicit transmission schedule based on knowledge of the 2-hop neighborhood of a node, and additional information if needed. Scheduling of multicast transmissions over conflict-free MAC protocols: We will develop extension to our conflict-free MAC protocols to schedule the transmission of multicast packets in a way that minimizes or reduces substantially the number of times a given relay receives replicas of any given packet. Current proposals for conflict-free channel access do not take into account the need to minimize unnecessary replicas of broadcast or multicast packets received by a given relay. 6. 3. Project Milestones (Classified by period) The projected milestones are the following: Year 1: Draft description of the first design of the proposed protocols within 3 months of the start of the project. Report addressing the correctness of the proposed protocols, when applicable, within 6 months of the start of the project. Report describing results of simulations in ns2 of the proposed protocol within 8 months of the start of the project. Manuscript(s) describing the design, correctness, and performance of the proposed protocol within 8 months from the start of the project. Annual technical report describing the results achieved during the first year of performance. Year 2: Report addressing the design and correctness of the proposed protocols, when applicable, within 18 months of the start of the project. Report describing the design, correctness, and performance of the proposed protocol within 20 months from the start of the project. Annual technical report describing the results achieved during the second year of performance. The ns2 code that we will be written will be public domain, and therefore ETRI can have access to it. Signature of Project Manager