ERCIM “ Alain Bensoussan ” Fellowship Scientific Report

DVS (Distributed Video Streaming) is an edge streaming architecture for providing smooth video delivery. It is to divide video among multiple streaming senders in order to effectively provide the required throughput. In P2P-based streaming, if some peers are connected with high speed physical link, it is highly probable that they receive the best quality streaming stably from an original source. On these peers, we can impose the role of DVS gateway, i.e., let them translate the original streaming to distributive form and relay to the other peers who cannot connect to the original source with enough bandwidth. In dedicated infrastructure-based streaming, DVS gateway may be recruited by a content delivery company as an infrastructure node, that is to say, this infrastructure node has enough bandwidth to receive the best quality streaming from the original source, and it thus able to relay the original streaming using the distributed streaming to usual subscribers. In this paper, we consider a minimum DVS gateway deployment problem in DVS-based overlay streaming with satisfying bandwidth requirement of every peer or subscriber. We also consider the mandatory diversity and limitations of DVS gateways’ streaming capacity. The mandatory diversity is beneficial to mitigate the degradation of quality when an available bandwidth decreases suddenly, and the streaming capacity of each DVS gateway may be limited and heterogeneous. Based on recent advances in modeling techniques in flow networks, we provide a mixed integer programming formulation of the minimum DVS gateway deployment problem, and show that this problem is NP-hard. Thus we propose Lagrangian Relaxation with reduction heuristic to obtain an approximated solution. Our theoretical simulation studies show that the results obtained by our method are close to the lower bound obtained using LP relaxation. (2) Sang-Seon Byun and Chuck Yoo, “Improving inter-destination synchronization in hierarchical reliable multicast,” Telecommunication Systems, vol. 37, no. 4, Apr. 2008. Abstract In hierarchical reliable multicast schemes, the number of repair proxies and their locations influence inter-destination synchronization. The inter-destination synchronization in multicast environments means the adjustment of the output timing among destinations over the Internet. Improving the inter-destination synchronization is beneficial to collaborative applications such as multi-conference system and multi-playing online game. In this paper, we propose a scheme to find the optimal locations of repair proxies that can improve inter-destination synchronization maximally in heterogeneous network environments. The simulation results show that if repair proxies are placed by the proposed scheme, delivery delay fairness of interdestination can be improved by 0.05 maximally. In addition, we perform t-Test on the simulation results in order to verify that our optimal placement improves synchronization. (3) Sang-Seon Byun and Chuck Yoo, “Locating repair servers in hierarchical reliable multicast networks to reduce the makesapn,” accepted for the publication in International Journal of Communication Systems. Abstract