Direction des Relations Internationales (DRI)

Programme INRIA "Equipes Associées"








Equipe-Projet INRIA : Planète

Organisme étranger partenaire : University of California, Santa Cruz

Centre de recherche INRIA : Sophia Antipolis Méditerranée

Pays : États-Unis



Coordinateur français

Coordinateur étranger

Nom, prénom

 Thierry Turletti

 Katia Obraczka


 CR1, responsable permanent EPI Planète


Organisme d'appartenance
(précisez le département et/ou le laboratoire)

 Planète Project-Team
 INRIA Sophia Antipolis Méditerranée

 Computer Engineering Department
 Jack Baskin School of Engineering
 University of California, Santa Cruz

Adresse postale

  2004, route des Lucioles, BP 93
 06902 Sophia Antipolis,
 Cedex, France

 1156 High Street
 Santa Cruz
 CA,  95064 USA









La proposition en bref

Titre de la thématique de collaboration : COMMunication in heterogeneoUs Networks prone to epIsodic connectiviTY (Communication dans les réseaux hétérogènes à connectivité épisodique)


Descriptif :


The Internet of the Future is likely to exhibit high degrees of heterogeneity, not only at the end-system level (i.e., end-user devices) but also at the network level. In other words, future internets will probably interconnect networks of different types ranging from traditional wired networks, as well as different types of wireless networks. The latter include both infrastructure-based as well as multi-hop ad hoc networks (or MANETs for short). Unlike their infrastructure-based counterparts, MANETs are characterized mainly by the fact that they do not rely on any fixed network infrastructure (e.g., routers, access points, base stations, etc.) and therefore can be deployed “on the fly” even when the fixed network infrastructure (wired or wireless) is non-existent or temporarily/permanently unavailable. MANETs are thus very attractive for impromptu deployments in both civilian and military scenarios. More recently, a new class of wireless networks has emerged motivated by the widespread availability of wireless communication capability and variety of wireless devices. These so called “delay-tolerant” or “disruption-tolerant” networks, or DTNs, are characterized by the fact that there may not be an end-to-end path between every pair of nodes at all times.  These partitions or connectivity disruptions may be caused by a number of factors including node mobility, limited power and communication range, volatility of the wireless channel (due to interference, noise, terrain, obstacles, etc.). In fact, depending on the characteristics of the environment and driving applications, the network may be disconnected more often than it is connected. As a result, message delivery in these intermittently-connected networks cannot be addressed by traditional routing approaches and thus has attracted much attention from the network research community over the past few years. DTN research can have significant societal and scientific impact as they enable applications in emergency response and disaster rescue, environmental and habitat monitoring, surveillance, etc.


This INRIA - UC Santa Cruz Team will investigate a number of research challenges raised by message delivery in environments consisting of heterogeneous networks that may be subject to episodic connectivity. The proposed work will consist of the following research thrusts:

●    Develop a unifying solution to routing that will enable message delivery (point-to-point as well as multi-point) across heterogeneous networks with varying degrees of connectivity.

●    Investigate error- and congestion control techniques in episodically connected networks.

●    Explore different mechanisms for quality-of-service (QoS) support in such environments.



Présentation détaillée de l'Équipe Associée

1.      Objectifs scientifiques de la proposition

Communication networks are traditionally assumed to be connected. However, emerging wireless applications such as vehicular networks, pocket-switched networks, etc. coupled with volatile links, node mobility, and power outages, will require the network to operate despite frequent disconnections. To this end, opportunistic routing techniques have been proposed, where a node may store-and-carry a message for some time, until a new forwarding opportunity arises [1,2,3]. Although a number of such algorithms exist, most focus on relatively homogeneous settings of nodes. However, in many envisioned applications, participating nodes may include handhelds, vehicles, sensors, etc. Furthermore, the underlying networks themselves may also differ from one another. The resulting possibly highly heterogeneous environment raises several research issues, especially when participating networks are subject to frequent and arbitrarily long-lived connectivity outages. In particular, routing is arguably one of the most challenging problems posed by networks subject to frequent and long-lived connectivity disruptions. This means that the network may be disconnected very often and for long periods of time. Traditional MANET routing protocols can tolerate some degree of disconnection but exhibit rapid and drastic performance deterioration as disconnections become more frequent and last for longer periods.


As wireless communication and portable computing devices become increasingly more prevalent, applications such as emergency response, special operations, smart environments (e.g., smart home, highway, office, etc.), impromptu meetings and conferences, surveillance, environmental- and habitat monitoring will emerge. However, in order to make them a reality, the more general problem of message delivery over heterogeneous internets, and the more specific question of routing across these internets subject to intermittent connectivity must be solved.


The main goal of this proposal is to investigate different aspects associated with message delivery in episodically-connected internets. We will build on the collective expertise of both groups and leverage our ongoing research on routing under episodic connectivity. The main thrusts of the proposed research during the next three years are as follows:


·        Develop a unifying solution to routing that will enable message delivery (point-to-point as well as multi-point) across heterogeneous networks including under varying connectivity conditions


Today, there are no comprehensive solutions targeting message delivery in heterogeneous networked environments prone to connectivity disruptions. Existing proposals either: (1) extend MANETs to handle episodic connectivity [4,5,6,7], (2) augment the coverage of access points in infrastructure-based wireless networks by, for example, making use of multi-channel radios or switching from infrastructure- to ad-hoc mode in 802.11 [8,9,10,11], (3) provide MANETs with Internet connectivity by using special purpose gateway nodes and a mechanism to discover them as part of route discovery [12], or (4) handle heterogeneity only at higher layers of the protocol stack (e.g., Bundle Architecture [13,14]). The use of specialized nodes is very helpful in increasing reliability, and in some cases, reducing the overall delay; however, it does not scale or generalizes well.


To fill this gap, within COMMUNITY, we are proposing a new message delivery scheme based on a general, yet efficient framework for data delivery in heterogeneous internets prone to disruptions in connectivity. To cope with arbitrarily long-lived connectivity disruptions, the proposed message delivery framework we named MeDeHa, for Message Delivery in Heterogeneous, Disruption-Prone Networks includes the following features:


- MeDeHa uses available storage within the network to temporarily save messages for destinations that are currently unreachable; once these destinations re-connect, messages destined to them are delivered. Unlike existing solutions (e.g., Bundle Architecture [13,14]), MeDeHa addresses heterogeneity at lower layers, e.g., by storing data at the data link layer. This is consistent with the goal of allowing any node to carry and relay data (see below) since some intermediate nodes may not support higher-layer protocols.


- Unlike existing proposals such as message ferries [15], data mules [16], or throwboxes [17], MeDeHa does not require any special-purpose nodes in order to relay data to intended destinations, or to connect to the backbone network wherever infrastructure is available: any node can serve as message relay.


- Temporary message storage within the network  is regulated by node capability issues (e.g., available buffer and energy  capacity at nodes) as well as application-specific quality-of-service issues such as delivery delay bounds, message time-to-live (i.e., how long messages are valid for), .message priority, etc.



In its current implementation, MeDeHa performs message delivery in an internet comprised of an infrastructure-based wireless network where mobile nodes roam freely across regions of connectivity (provided by access points), and become temporarily disconnected from the network. Simulation results obtained using the OMNET++ network simulator with a variety of mobility, traffic and connectivity conditions show that MeDeHa is able to improve message delivery ratio significantly [18]. Future work will consist on extending MeDeHa with MANET support. To this end, we will migrate to the new ns-3 [19] network simulator which has improved network heterogeneity support (in particular, it allows associating multiple network interfaces to simulation nodes) and which includes more realistic models, with the possibility to use real communication stacks.




·        Explore error- and congestion control techniques in heterogeneous networks under episodic connectivity.


End-to-end reliability and congestion control in networks with intermittent connectivity are considerably more challenging given that an end-to-end path between source and destination(s) may not always exist. In fact, some end-to-end paths may never exist. For instance, consider an environmental monitoring system deployed to track a wild animal population. The network formed by the set of mobile nodes deployed on the animals themselves and the set of static nodes placed around the region the animals inhabit may never be fully connected. Therefore the feedback loop from the destination(s) back to the source used by most end-to-end reliability approaches may never -, or, at best, take a long time to close. Furthermore, control messages generated by traditional network control mechanisms (e.g., positive/negative acknowledgments, retransmissions, etc.) are quite expensive in networks with episodic connectivity in terms of node- and network resources consumed.


As part of this research thrust we will investigate:


- Error control mechanisms to address the specific needs and challenges of intermittently connected networks. Unlike the approach used by Internet protocols (e.g., TCP), error control needs to be decoupled from congestion control mechanisms. Furthermore, as hinted above, the Internet’s end-to-end paradigm for error control is no longer applicable in networks with episodic connectivity. In these networks, only hop-by-hop control is possible. However, hop-by-hop, especially when connectivity is intermittent, makes it quite challenging to support end-to-end delivery guarantees. Our goal here is to then explore different delivery guarantee semantics to address the needs of a variety of relevant applications. Then based on our findings, develop error control mechanisms to support the different semantics.


- We will pursue a similar approach to developing congestion control mechanisms for heterogeneous, intermittently connected networks. More specifically, we will define congestion indicators, i.e., metrics we will use to detect congestion building up in the network. Then, based on these congestion detection mechanisms, we will explore ways to control congestion, probably by applying backpressure-based mechanisms.


·        Investigate QoS support mechanisms in heterogeneous networks under episodic connectivity.


Questions similar to the ones presented above apply when trying to provide quality of service guarantees when networks are constantly disconnected. For example, how can we ensure that messages with explicit delay bounds will be delivered within the appropriate deadline? Within this research direction, we will explore solutions to traffic differentiation and QoS guarantees in episodically connected networks. One of the fundamental questions to be answered is what kind of guarantees can be provided and under what conditions? And, what mechanisms should be used to provide such guarantees?  Other issues to be considered are: the capability of the nodes (e.g., storage, remaining battery life, etc.) as well as inter-contact time, i.e., the time interval during which nodes remain in range of one another. The inter-contact time is thus the time nodes have to exchange info as they encounter each other.


We will start by developing a simple traffic differentiation scheme based on message tags which could be assigned by the application, for example. Upon an encounter, messages buffered at a node will be passed to the encountered node ( a relay or the final destination) based on their priority. Since the inter-contact time is finite, depending on the communication data rate, nodes are only able to exchange a limited number of messages. Messages with higher priority will be transmitted first. Note that the priority assigned to a message is not necessarily related to the message’s time-to-live. For instance, a news article may have a short time-to-live (it becomes outdated quickly) but may not be urgent. 

2. Présentation des partenaires

Planète Project-Team

            The Planète project-team conducts research in the domain of networking, with an emphasis on designing, implementing, and evaluating Internet protocols and applications. The main objective of the project-team is to propose and study new architectures, services and protocols to support efficient and secure communication through the Internet. One of our research axis focuses on the design of an evaluation environment for the future Internet: We are highly involved in the elaboration of ns-3, an efficient and realistic network simulator that includes accurate models and allows integrating real applications and communication stacks. In parallel, an important part of our activities focuses on experimental evaluation, which complements theoretical modelling and simulation. We contribute to the PlanetLab/OneLab international experimental research network in the area of platforms federation, wireless extensions and benchmarking of network protocols.

            This joint research team will consolidate our Data-Centric Networking research axis, which focuses on three specific problems in a data-centric architecture, related to the transport of the data:

·        Adaptive multimedia transmission protocols for heterogeneous and episodic connectivity networks;

·        Data dissemination paradigms in multicasting/broadcasting environments;

·        Data dissemination on a peer-to-peer architecture.

Several researchers are involved in this Associate Team: Chadi Barakat, Walid Dabbous and Thierry Turletti. Two PhD students are currently involved: Rao Naveed Bin Rais co-supervised by Thierry Turletti and Katia Obraczka and Mohamed Karim Sbai co-supervised by Chadi Barakat and Walid Dabbous. Both  theses focus on Routing in Delay/Disruption Tolerant Heterogeneous Networks and on data sharing over MANETs, respectively.

Thierry Turletti’s short bio

Thierry Turletti received the M.S. (1990) and the Ph.D. (1995) degrees in Computer Science both from the University of Nice - Sophia Antipolis, France. During his PhD studies in the RODEO group at INRIA Sophia Antipolis, he designed one of the first videoconferencing tool for the Internet called IVS. In 1995-96, he was a postdoctoral fellow in the Telemedia, Networks and Systems Group at the MIT Laboratory for Computer Science. He is currently a full time researcher in the Planète group at INRIA Sophia Antipolis. His current research interests include networking experimental platforms and simulators, mechanisms to support episodic connectivity and adaptive cross-layer mechanisms for multimedia transmission over wireless networks. He is a senior member of the IEEE and serves on the editorial boards of the following journals: ”Wireless Communications, Mobile Computing (WCMC)” published by John Wiley & Sons, ”Wireless Networks (WINET)” published by Springer Netherlands and ”Advances in Multimedia” published by Hindawi Publishing Corp.

UCSC’s Internet Research Group (I-NRG)

Computer networks, in particular wireless mobile networks, is one of the ``areas of excellence'' of UCSC's Baskin School of Engineering. Prof. Obraczka's Internet Research Group (I-NRG) conducts research in the design, experimental evaluation, and implementation of network protocols for internetworks consisting of wired as well as wireless networks. I-NRG’s research activities span a number of areas in computer networks and distributed systems. More specifically, in the area of network protocol design, our work span several layers of the protocol stack, including medium access, routing, transport, and application protocols. Currently, Prof. Obraczka supervises 4 PhD students and 2MSc students. Two of the PhD students are working on topics related to the work proposed here, namely routing in disruption-tolerant networks, and will benefit directly from this joint project.

In terms of its facilities, the I-NRG laboratory accommodates 10 student stations and is equipped with a dozen laptops and a dozen hand-held computing devices (PDAs). The lab has its own servers used to run computing-intensive tasks (e.g., large-scale network simulations). The lab also has two dozen motes and a half dozen single-board computers (Crossbow Stargates) equipped with Web cams.

More recently, we have embarked on developing a heterogeneous wireless networking testbed SCORPION (Santa Cruz mObile Radio Platform for Indoor and Outdoor Networks) [25] that includes a variety of nodes ranging from ground as well as autonomous aerial devices. Node diversity in terms of mobility and capabilities (e.g., processing, storage, and communication) makes SCORPION well-suited for testing and evaluating a variety of wireless network protocols including multi-radio, multi-channel medium access control, multi-hop wireless ad-hoc routing, as well as disruption-tolerant routing and message delivery protocols for networks with varying connectivity. In its current implementation, SCORPION includes nodes outfitted with three different types of vehicles, namely: (1) iRobot Create ground robots (identical to a Roomba without the vacuum), (2) a remote controlled airplane equipped with Paparazzi autopilot software and hardware, and (3) a self-stabilizing remote-controlled helicopter. Additionally, two non-autonomous mobile nodes complement the testbed, one that will be carried by people in order to mimic human mobility and another that will be installed in buses. More specifically, the bus nodes will be deployed in the UC Santa Cruz campus shuttle bus network. The testbed currently has four airplane nodes, four helicopter nodes, 20 iRobot Create nodes, 40 human carried nodes, and 40 bus nodes. The varied mobility patterns exhibited by SCORPION nodes allow for unique and innovative ways to test network protocols for current as well as next-generation network applications.  One important by-product of this collaboration is the possibility of using SCORPION to test and evaluate the protocols we develop under COMMUNITY.

Katia Obraczka’s short bio

Katia Obraczka received the B.S. and M.S. degrees in electrical and computer engineering from the Federal University of Rio de Janeiro, Brazil, and the M.S. and Ph.D. degrees in computer science from the University of Southern California (USC).  She is currently a Professor of Computer Engineering at the University of California, Santa Cruz. Before joining UCSC, she held a research scientist position at USC's Information Sciences Institute and a research faculty appointment at USC's Computer Science Department. Her research interests include computer networks, more specifically, network protocol design and evaluation in wireline as well as wireless networks, distributed systems, and Internet information systems. She has been a PI and a co-PI in a number of projects sponsored by government agencies (NSF, DARPA, NASA) as well as industry. Dr. Obraczka has authored over 100 technical papers in journals and conferences.


History of the collaboration between the two Teams:

The collaboration between the two research groups started in July 2006 when Prof. Obraczka spent the 2006-2007 academic year at INRIA Sophia-Antipolis in the Planète Project. The collaboration has already produced three publications in a distinguished workshop, conference, and journal. Drs. Turletti and Obraczka are currently co-supervising a PhD student (Naveed Bin Rais) at INRIA. Communication happens regularly through e-mail and periodic teleconferences. The funding requested here will augment the current tele-meetings with a number of face-to-face opportunities besides giving the student the opportunity of spending some time at UCSC.


3. Impact :

This proposal requests support for a collaborative research effort between the University of California, Santa Cruz and the Planète Project Team at INRIA Sophia-Antipolis Méditerranée. Our goal is to build upon the expertise of the two groups and our ongoing collaboration to make contributions to the area of message delivery in networks with episodic connectivity. Besides the PhD student at INRIA who is currently being co-supervised by Dr. Turletti from INRIA and Prof. Obraczka from UCSC, our goal is to make our collaboration grow and involve other graduate students, post-docs and researchers. For example, Dr. Barakat at the EPI Planète works on very close research topic and in particular on the optimization of communication in MANETs[22,23,24]. In particular, Dr Barakat and one of his PhD students named Karim Sbai will work on the optimization of communication mechanisms on heterogeneous ad hoc networks. The proposed EA is quite timely and we believe that by continuing our ongoing collaboration the results from our effort will have significant impact on this very active field of research. Indeed, considerable attention from the research community has been focusing on new protocols and architectures for the Future Internet and handling heterogeneous networks with varying connectivity is an essential issue to solve.  The ideas and mechanisms developed within this project will be evaluated both by simulations (in particular the new ns-3 network simulator) and by testbed experimentation (such as PlanetLab/OneLab and SCORPION). Consequently, both simulators and experimental platforms will be enriched by the outputs of the COMMUNITY project.

The requested funds will allow periodic face-to-face meetings among the two groups as well as exchange of graduate students and junior researchers. Another direct result of our collaboration is to establish an active channel for knowledge and expertise sharing through periodic exchange of faculty, researchers, and graduate students. This team will allow consolidating this collaboration channel by creating a permanent program through which graduate students could be co-supervised by UCSC and INRIA faculty/researchers.

4. Divers :

Formalizing our current collaboration through the proposed joint INRIA-UCSC team will also increase our chances to compete for funding from the US’s National Science Foundation. More specifically, once the EA is established, we will submit a proposal to NSF’s International Program requesting matching funds on the order of 10 K€. The timeliness of the proposed research and the sponsorship from INRIA will considerably increase the chances of getting an NSF award.


5. Références :

[1] E. P. Jones and P. A. Ward, “Routing strategies for delay-tolerant networks,” Submitted to Computer Communication Review, available at pasward/Publications/.

[2] T. Spyropoulos, K. Psounis, and C. S. Raghavendra, “Efficient routing in intermittently connected mobile networks: the single-copy case,” IEEE/ACM Trans. Networking., vol. 16, no. 1, pp. 63–76, 2008.

[3] T. Spyropoulos, K. Psounis, and C. S. Raghavendra, “Efficient routing in intermittently connected mobile networks: the multiple-copy case,” IEEE/ACM Trans. Networking, vol. 16, no. 1, pp. 77–90, 2008.

[4] N. Sarafijanovic-Djukic, M. Piorkowski, and M. Grossglauser, “Island Hopping: Efficient Mobility-Assisted Forwarding in Partitioned Networks”, Proc. of IEEE SECON, 2006.

[5] Jörg Ott, Dirk Kutscher, Christoph Dwertmann, “Integrating DTN and MANET Routing”, Proc. of ACM SIGCOMM workshop on Challenged Networks (CHANTS), 2006.

[6] A. Vahdat and D. Becker, “Epidemic routing for partially connected ad hoc networks”, Technical Report CS-200006, Duke University, 2000.

[7] T. Spyropoulos, K. Psounis, C.S. Ragha Vendra, “Spray and Wait: An Efficient Routing Scheme for Intermittently Connected Mobile Networks”, ACM SIGCOMM Workshops WDTN, Philadelphia PA, August 2005.

[8] J.-C. Chen, S. Li, S.-H. Chan, J.-Y. He, “WIANI: wireless infrastructure and ad-hoc network integration”, in: Proc. IEEE International Conference on Communications, Seoul, Korea, 2005, pp. 3623-3627.

[9] J He J. Chen, S.-H. G. Chan and S.-C. Liew. “Mixed-mode wlan : The integration of ad hoc mode with wireless LAN infrastructure”, IEEE Globecom 2003.

[10] Carlo Parata, Gabriella Convertino, Vincenzo Scarpa, "Flex-WiFi: a mixed infrastructure and ad-hoc IEEE 802.11 network for data traffic in a home environment", The First IEEE WoWMoM Workshop on Autonomic and Opportunistic Communications, 2007.

[11] R. Chandra, P. Bahl, and P. Bahl, “MultiNet: Connecting to Multiple IEEE 802.11 Networks Using a SingleWireless Card”, in IEEE Infocom, Hong Kong, 2004.

[12] U. Korner A. Hamidian and A. Nilsson. “Performance of internet access solutions in mobile ad hoc networks”, Dagstuhl-Workshop ”Mobility and Wireless in Euro-NGI”, pages 189–201, 2005.

[13] K. Scott, S. Burleigh, “RFC 5050, Bundle Protocol Specifications”, IRTF DTN Research Group, November 2007.

[14] V. Cerf, S. Burleigh, A. Hooke, L. Torgerson, R. Durst, K. Scott, K. Fall, H. Weiss, “RFC 4838, Delay-Tolerant Networking Architecture”, IRTF DTN Research Group, April 2007.

[15] W. Zhao , M. Ammar , E. Zegura, “A message ferrying approach for data delivery in sparse mobile ad hoc networks”, Proc. of ACM/IEEE MOBIHOC, 2004.

[16] R. Shah, S. Roy, S. Jain, W. Brunette, “Data MULEs: Modeling a Three-tier Architecture for Sparse Sensor Networks”, IEEE SNPA Workshop, May 2003.

[17] Wenrui Zhao, Yang Chen, Mostafa Ammar, Mark Corner, B.N. Levine, and Ellen Zegura, “Capacity Enhancement using Throwboxes in DTNs”, IEEE International Conference on Mobile Ad hoc and Sensor Systems (MASS), Vancouver, Canada, October 2006.

[18] T. Spyropoulos, T. Turletti, K. Obraczka, "Utility-based Message Replication for Intermittently Connected Heterogeneous Networks", in Proc. of 1st IEEE WoWMoM Workshop on Autonomic and Opportunistic Communications (AOC), Helsinki, Finland, June 2007.

[19] The ns-3 network simulator, see .

[20] T. Spyropoulos, T. Turletti, K. Obraczka, "Routing in Delay Tolerant Networks Comprising Heterogeneous Node Populations", to appear on IEEE Transaction on Mobile Computing journal (TMC).

[21] R.N. Bin Rais, T. Turletti, K. Obraczka, "Coping with Episodic Connectivity in Heterogeneous Networks", in Proc.of ACM MSWiM, Vancouver, Canada, October 2008.

[22] M.K. Sbai, C. Barakat, J. Choi, A.A. Hamra, T. Turletti, "Adapting BitTorrent to wireless ad hoc networks", 7th International conference on ad hoc networks and wireless (AD-HOC NOW), Sophia Antipolis, France, September 2008.

[23]  A. Krifa, C. Barakat, T. Spyropoulos, “An Optimal Joint Scheduling and Drop Policy for Delay Tolerant Networks”, in proceedings of the WoWMoM Workshop on Autonomic and Opportunistic Communications, Newport Beach (CA), June 2008.

[24]  A. Krifa, C. Barakat, T. Spyropoulos, “Optimal Buffer Management Policies for Delay Tolerant Networks”, in proceedings of the 5th IEEE Conference on Sensor, Mesh and Ad Hoc Communications and Networks (SECON 2008), San Francisco, June 2008 (Slides). Best Paper award.

[25] M. Bromage, V. Petkov, B. Nunes, K. Obraczka, J. Koshimoto, S. Bromage, C. Engstrom, ”SCORPION: A Heterogeneous Wireless Networking Testbed”, poster at the ACM MobiCom 2008, September 2008.





Programme de travail


The scientific program is detailed in Section I.1 of this proposal. More specifically, our work program for 2009 will focus on the following research areas:

·        Add to the support of MANET to the MeDeHa mechanism. We will have to port MeDeHa on the new NS-3 network simulator instead of the OMNET++ simulator in order to use multiple interfaces per mobile node. MANETs will add significant complexity to MeDeHa; we need to add new heuristics features and to validate performance of the overall mechanism.

·        Investigate mechanisms for efficient multipoint communication under episodic connectivity conditions. It is clear that the Internet multicast model will not work in environments prone to intermittent connectivity. Like the point-to-point case, the proposed solution must use in-network storage. However, how can that be done efficiently to support group communication? What kind of delivery semantics should be supported? This question is in fact related to the error- and congestion control research thrust delineated below.

·        Design mechanisms to support various levels of reliability taking into account the type of applications.

·        Try to evaluate the different mechanisms not only using simulations but also with real implementations on experimental platforms.



Programme d'échanges avec budget prévisionnel


1. Echanges

The following scientific exchanges to work on the planned activities are envisaged in 2009:

·        Thierry Turletti will visit UCSC in 2009 (about 1 week duration); Chadi Barakat plans to visit UCSC in 2009 or in 2010.

·        Naveed Bin Rais and Karim Sbai (INRIA Phd students) will visit UCSC in 2009 (one or two months each)

·        Katia Obraczka will visit INRIA to work on the planned research activities for 2009 (about 2 weeks).

·        Vladi Petkov and Matt Bromage (UCSC Phd students) will visit INRIA in 2009 (one or two months each)



Nombre de personnes

Coût estimé

Chercheurs confirmés


5 K€






10 K€




Autre (précisez) :





15 K€


Nombre de personnes

Coût estimé

Chercheurs confirmés


5 K€






10 K€




Autre (précisez) :





15 K€


2. Cofinancement

As previously mentioned, we will submit a proposal to NSF’s International Program requesting 10 K€ matching funds to support the proposed joint team INRIA-UC Santa Cruz. We expect that once the project is formally endorsed by INRIA, funding from NSF should follow.


3. Demande budgétaire


Indiquez, dans le tableau ci-dessous, le coût global estimé de la proposition et le budget demandé à la DRI dans le cadre de cette Equipe Associée (maximum 20 K€).



A. Coût global de la proposition

30 K€

B. Cofinancements utilisés

10 K€

Financement "Équipe Associée" demandé (A.-B.)

20 K€



© INRIA - mise à jour le 11/08/2008