Notes on the use of RTP for shared workspace applications

The Real-time Transport Protocol, RTP, has become the dominant protocol for streaming audio and video in IP-based environments. A number of proposals have been made which attempt to build on this success and apply RTP for shared workspace applications. We discuss the needs of such applications and the features provided by RTP, with an aim to showing why RTP is not appropriate for such uses

D-BAS - A dialog-based online argumentation system

In this paper, we present D-BAS, a dialog-based online argumentation system, tailored to support e-participation processes. The main idea of D-BAS is to let users exchange proposals and arguments with each other in the form of a timeshifted dialog where arguments are presented and acted upon one-at-a-time. We highlight the key research challenges that needed to be addressed in order to realize such a system, provide solutions for those challenges, report on a full scale implementation of D-BAS and summarize the findings from a real world e-participation process, where D-BAS provided the infrastructure for online argumentation

Amerikas Schwäche im globalen Wettbewerb mit China

Der härter werdende Wettbewerb zwischen der angeschlagenen Weltmacht USA und der aufstrebenden Wirtschaftsmacht China wird auch Europa und insbesondere seine exportorientierte Führungsnation Deutschland beeinträchtigen

Nearest Neighbor Connectivity in Two-Dimensional Multihop MANETs

A Mobile Ad Hoc Network (MANET) is characterized to be a network with free, cooperative, and dynamic nodes, self-organized in a random topology, without any kind of infrastructure, where the communication between two nodes usually occurs using multihop paths. The number of hops used in the multihop path is an important metric for the design and performance analysis of routing protocols in MANETs. In this paper, we derive the probability distribution of the hop count of a multihop path between a source node and a destination node, fixed at a known distance from each other, and when a fixed number of nodes are uniformly distributed in a region of interest. This distribution is obtained by the Poisson randomization method. To obtain the multihop path, we propose a novel routing model in which the nearest distance routing protocol (NR) is analyzed. Numerical results are obtained to evaluate the performance of the NR

Robotic Wireless Sensor Networks

In this chapter, we present a literature survey of an emerging, cutting-edge, and multi-disciplinary field of research at the intersection of Robotics and Wireless Sensor Networks (WSN) which we refer to as Robotic Wireless Sensor Networks (RWSN). We define a RWSN as an autonomous networked multi-robot system that aims to achieve certain sensing goals while meeting and maintaining certain communication performance requirements, through cooperative control, learning and adaptation. While both of the component areas, i.e., Robotics and WSN, are very well-known and well-explored, there exist a whole set of new opportunities and research directions at the intersection of these two fields which are relatively or even completely unexplored. One such example would be the use of a set of robotic routers to set up a temporary communication path between a sender and a receiver that uses the controlled mobility to the advantage of packet routing. We find that there exist only a limited number of articles to be directly categorized as RWSN related works whereas there exist a range of articles in the robotics and the WSN literature that are also relevant to this new field of research. To connect the dots, we first identify the core problems and research trends related to RWSN such as connectivity, localization, routing, and robust flow of information. Next, we classify the existing research on RWSN as well as the relevant state-of-the-arts from robotics and WSN community according to the problems and trends identified in the first step. Lastly, we analyze what is missing in the existing literature, and identify topics that require more research attention in the future

Photoperiod affects the phenotype of mitochondrial complex I mutants

Plant mutants for genes encoding subunits of mitochondrial Complex I (CI, NADH:ubiquinone oxidoreductase), the first enzyme of the respiratory chain, display various phenotypes depending on growth conditions. Here, we examined the impact of photoperiod, a major environmental factor controlling plant development, on two Arabidopsis thaliana CI mutants: a new insertion mutant interrupted in both ndufs8.1 and ndufs8.2 genes encoding the NDUFS8 subunit, and the previously characterized ndufs4 CI mutant. In long day (LD) condition, both ndufs8.1 and ndufs8.2 single mutants were indistinguishable from Col-0 at phenotypic and biochemical levels, whereas the ndufs8.1 ndufs8.2 double mutant was devoid of detectable holo-CI assembly/activity, showed higher AOX content/activity and displayed a growth-retardation phenotype similar to that of the ndufs4 mutant. Although growth was more affected in ndufs4 than ndufs8.1 ndufs8.2 under short day (SD) condition, both mutants displayed a similar impairment of growth acceleration after transfer to LD as compared to the WT. Untargeted and targeted metabolomics showed that overall metabolism was less responsive to the SD-to-LD transition in mutants than in the WT. The typical LD acclimation of carbon, nitrogen-assimilation and redox-related parameters was not observed in ndufs8.1 ndufs8. Similarly, NAD(H) content, that was higher in SD condition in both mutants than in Col-0, did not adjust under LD. We propose that altered redox homeostasis and NAD(H) content/redox state control the phenotype of Complex I mutants and photoperiod acclimation in Arabidopsis

Inter-Destination Multimedia Synchronization; Schemes, Use Cases and Standardization

Traditionally, the media consumption model has been a passive and isolated activity. However, the advent of media streaming technologies, interactive social applications, and synchronous communications, as well as the convergence between these three developments, point to an evolution towards dynamic shared media experiences. In this new model, geographically distributed groups of consumers, independently of their location and the nature of their end-devices, can be immersed in a common virtual networked environment in which they can share multimedia services, interact and collaborate in real-time within the context of simultaneous media content consumption. In most of these multimedia services and applications, apart from the well-known intra and inter-stream synchronization techniques that are important inside the consumers playout devices, also the synchronization of the playout processes between several distributed receivers, known as multipoint, group or Inter-destination multimedia synchronization (IDMS), becomes essential. Due to the increasing popularity of social networking, this type of multimedia synchronization has gained in popularity in recent years. Although Social TV is perhaps the most prominent use case in which IDMS is useful, in this paper we present up to 19 use cases for IDMS, each one having its own synchronization requirements. Different approaches used in the (recent) past by researchers to achieve IDMS are described and compared. As further proof of the significance of IDMS nowadays, relevant organizations (such as ETSI TISPAN and IETF AVTCORE Group) efforts on IDMS standardization (in which authors have been and are participating actively), defining architectures and protocols, are summarized.This work has been financed, partially, by Universitat Politecnica de Valencia (UPV), under its R&D Support Program in PAID-05-11-002-331 Project and in PAID-01-10, and by TNO, under its Future Internet Use Research & Innovation Program. The authors also want to thank Kevin Gross for providing some of the use cases included in Sect. 1.2.Montagud, M.; Boronat Segui, F.; Stokking, H.; Van Brandenburg, R. (2012). Inter-Destination Multimedia Synchronization; Schemes, Use Cases and Standardization. Multimedia Systems. 18(6):459-482. https://doi.org/10.1007/s00530-012-0278-9S459482186Kernchen, R., Meissner, S., Moessner, K., Cesar, P., Vaishnavi, I., Boussard, M., Hesselman, C.: Intelligent multimedia presentation in ubiquitous multidevice scenarios. IEEE Multimedia 17(2), 52–63 (2010)Vaishnavi, I., Cesar, P., Bulterman, D., Friedrich, O., Gunkel, S., Geerts, D.: From IPTV to synchronous shared experiences challenges in design: distributed media synchronization. Signal Process Image Commun 26(7), 370–377 (2011)Geerts, D., Vaishnavi, I., Mekuria, R., Van Deventer, O., Cesar, P.: Are we in sync?: synchronization requirements for watching on-line video together, CHI ‘11, New York, USA (2011)Boronat, F., Lloret, J., García, M.: Multimedia group and inter-stream synchronization techniques: a comparative study. Inf. Syst. 34(1), 108–131 (2009)Chen, M.: A low-latency lip-synchronized videoconferencing system. In: SIGCHI Conference on Human Factors in Computing Systems, CHI’03, ACM, pp. 464–471, New York (2003)Ishibashi, Y., Tasaka, S., Ogawa, H.: Media synchronization quality of reactive control schemes. IEICE Trans. Commun. E86-B(10), 3103–3113 (2003)Ademoye, O.A., Ghinea, G.: Synchronization of olfaction-enhanced multimedia. IEEE Trans. Multimedia 11(3), 561–565 (2009)Cesar, P., Bulterman, D.C.A., Jansen, J., Geerts, D., Knoche, H., Seager, W.: Fragment, tag, enrich, and send: enhancing social sharing of video. ACM Trans. Multimedia Comput. Commun. Appl. 5(3), Article 19, 27 pages (2009)Van Deventer, M.O., Stokking, H., Niamut, O.A., Walraven, F.A., Klos, V.B.: Advanced Interactive Television Service Require Synchronization, IWSSIP 2008. Bratislava, June (2008)Premchaiswadi, W., Tungkasthan, A., Jongsawat, N.: Enhancing learning systems by using virtual interactive classrooms and web-based collaborative work. In: Proceedings of the IEEE Education Engineering Conference (EDUCON 2010), pp. 1531–1537. Madrid, Spain (2010)Diot, C., Gautier, L.: A distributed architecture for multiplayer interactive applications on the internet. IEEE Netw 13(4), 6–15 (1999)Mauve, M., Vogel, J., Hilt, V., Effelsberg, W.: Local-lag and timewarp: providing consistency for replicated continuous applications. IEEE Trans. Multimedia 6(1), 45–57 (2004)Hosoya, K., Ishibashi, Y., Sugawara, S., Psannis, K.E.: Group synchronization control considering difference of conversation roles. In: IEEE 13th International Symposium on Consumer Electronics, ISCE ‘09, pp. 948–952 (2009)Roccetti, M., Ferretti, S., Palazzi, C.: The brave new world of multiplayer online games: synchronization issues with smart solution. In: 11th IEEE Symposium on Object Oriented Real-Time Distributed Computing (ISORC), pp. 587–592 (2008)Ott, D.E., Mayer-Patel, K.: An open architecture for transport-level protocol coordination in distributed multimedia applications. ACM Trans. Multimedia Comput. Commun. Appl. 3(3), 17 (2007)Boronat, F., Montagud, M., Guerri, J.C.: Multimedia group synchronization approach for one-way cluster-to-cluster applications. In: IEEE 34th Conference on Local Computer Networks, LCN 2009, pp. 177–184, Zürich (2009)Boronat, F., Montagud, M., Vidal, V.: Smooth control of adaptive media playout to acquire IDMS in cluster-based applications. In: IEEE LCN 2011, pp. 617–625, Bonn (2011)Huang, Z., Wu, W., Nahrstedt, K., Rivas, R., Arefin, A.: SyncCast: synchronized dissemination in multi-site interactive 3D tele-immersion. In: Proceedings of MMSys, USA (2011)Kim, S.-J., Kuester, F., Kim, K.: A global timestamp-based approach for enhanced data consistency and fairness in collaborative virtual environments. ACM/Springer Multimedia Syst. J. 10(3), 220–229 (2005)Schooler, E.: Distributed music: a foray into networked performance. In: International Network Music Festival, Santa Monica, CA (1993)Miyashita, Y., Ishibashi, Y., Fukushima, N., Sugawara, S., Psannis K.E.: QoE assessment of group synchronization in networked chorus with voice and video. In: Proceedings of IEEE TENCON’11, pp. 393–397 (2011)Hesselman, C., Abbadessa, D., Van Der Beek, W., et al.: Sharing enriched multimedia experiences across heterogeneous network infrastructures. IEEE Commun. Mag. 48(6), 54–65 (2010)Montpetit, M., Klym, N., Mirlacher, T.: The future of IPTV—Connected, mobile, personal and social. Multimedia Tools Appl J 53(3), 519–532 (2011)Cesar, P., Bulterman, D.C.A., Jansen, J.: Leveraging the user impact: an architecture for secondary screens usage in an interactive television environment. ACM/Springer Multimedia Syst. 15(3), 127–142 (2009)Lukosch, S.: Transparent latecomer support for synchronous groupware. In: Proceedings of 9th International Workshop on Groupware (CRIWG), Grenoble, France, pp. 26–41 (2003)Steinmetz, R.: Human perception of jitter and media synchronization. IEEE J. Sel. Areas Commun. 14(1), 61–72 (1996)Stokking, H., Van Deventer, M.O., Niamut, O.A., Walraven, F.A., Mekuria, R.N.: IPTV inter-destination synchronization: a network-based approach, ICIN’2010, Berlin (2010)Mekuria, R.N.: Inter-destination media synchronization for TV broadcasts, Master Thesis, Faculty of Electrical Engineering, Mathematics and Computer Science, Department of Network architecture and Services, Delft University of Technology (2011)Pitt Ian, CS2511: Usability engineering lecture notes, localisation of sound sources. http://web.archive.org/web/20100410235208/http:/www.cs.ucc.ie/~ianp/CS2511/HAP.htmlNielsen, J.: Response times: the three important limits. http://www.useit.com/papers/responsetime.html (1994)ITU-T Rec G. 1010: End-User Multimedia QoS Categories. International Telecommunication Union, Geneva (2001)Biersack, E., Geyer, W.: Synchronized delivery and playout of distributed stored multimedia streams. ACM/Springer Multimedia Syst 7(1), 70–90 (1999)Xie, Y., Liu, C., Lee, M.J., Saadawi, T.N.: Adaptive multimedia synchronization in a teleconference system. ACM/Springer Multimedia Syst. 7(4), 326–337 (1999)Laoutaris, N., Stavrakakis, I.: Intrastream synchronization for continuous media streams: a survey of playout schedulers. IEEE Netw. Mag. 16(3), 30–40 (2002)Ishibashi, Y., Tsuji, A., Tasaka, S.: A group synchronization mechanism for stored media in multicast communications. In: Proceedings of the INFOCOM ‘97, Washington (1997)Ishibashi, Y., Tasaka, S.: A group synchronization mechanism for live media in multicast communications. IEEE GLOBECOM’97, pp. 746–752 (1997)Boronat, F., Guerri, J.C., Lloret, J.: An RTP/RTCP based approach for multimedia group and inter-stream synchronization. Multimedia Tools Appl. J. 40(2), 285–319 (2008)Ishibashi, I., Tasaka, S.: A distributed control scheme for group synchronization in multicast communications. In: Proceedings of International Symposium Communications, Kaohsiung, Taiwan, pp. 317–323 (1999)Lu, Y., Fallica, B., Kuipers, F.A., Kooij, R.E., Van Mieghem, P.: Assessing the quality of experience of SopCast. Int. J. Internet Protoc. Technol 4(1), 11–19 (2009)Shamma, D.A., Bastea-Forte, M., Joubert, N., Liu, Y.: Enhancing online personal connections through synchronized sharing of online video, ACM CHI’08 Extended Abstracts, Florence (2008)Ishibashi, Y., Tasaka, S.: A distributed control scheme for causality and media synchronization in networked multimedia games. In: Proceedings of 11th International Conference on Computer Communications and Networks, pp. 144–149, Miami, USA (2002)Ishibashi, Y., Tomaru, K., Tasaka, S., Inazumi, K.: Group synchronization in networked virtual environments. In: Proceedings of the 38th IEEE International Conference on Communications, pp. 885–890, Alaska, USA (2003)Tasaka, S., Ishibashi, Y., Hayashi, M.: Inter–destination synchronization quality in an integrated wired and wireless network with handover. IEEE GLOBECOM 2, 1560–1565 (2002)Kurokawa, Y., Ishibashi, Y., Asano, T.: Group synchronization control in a remote haptic drawing system. In: Proceedings of IEEE International Conference on Multimedia and Expo, pp. 572–575, Beijing, China (2007)Hashimoto, T., Ishibashi, Y.: Group Synchronization Control over Haptic Media in a Networked Real-Time Game with Collaborative Work, Netgames’06, Singapore (2006)Nunome, T., Tasaka, S.: Inter-destination synchronization quality in a multicast mobile ad hoc network. In: Proceedings of IEEE 16th International Symposium on Personal, Indoor and Mobile Radio Communications, pp. 1366–1370, Berlin, Germany (2005)Brandenburg, R., van Stokking, H., Van Deventer, M.O., Boronat, F., Montagud, M., Gross, K.: RTCP for inter-destination media synchronization, draft-brandenburg-avtcore-rtcp-for-idms-03.txt. In: IETF Audio/Video Transport Core Maintenance Working Group, Internet Draft, March 9 (2012)ETSI TS 181 016 V3.3.1 (2009-07) Telecommunications and Internet converged Services and Protocols for Advanced Networking (TISPAN); Service Layer Requirements to integrate NGN Services and IPTVETSI TS 182 027 V3.5.1 (2011-03) Telecommunications and Internet converged Services and Protocols for Advanced Networking (TISPAN); IPTV Architecture; IPTV functions supported by the IMS subsystemETSI TS 183 063 V3.5.2 (2011-03) Telecommunications and Internet converged Services and Protocols for Advanced Networking (TISPAN); IMS-based IPTV stage 3 specificationBrandenburg van, R., et al.: RTCP XR Block Type for inter-destination media synchronization, draft-brandenburg-avt-rtcp-for-idms-00.txt. In: IETF Audio/Video Transport Working Group, Internet Draft, Sept 24, 2010Williams, A., et al.: RTP Clock Source Signalling, draft-williams-avtcore-clksrc-00. In: IETF Audio/Video Transport Working Group, Internet Draft, February 28, 201