SomeCast A Paradigm for Real-Time Adaptive Reliable Multi ast

Abstra t SomeCast is a novel paradigm for the reliable multi ast of real-time data to a large set of re eivers over the Internet. SomeCast is re eiver-initiated and thus s alable in the number of re eivers, the diverse hara teristi s of paths between senders and re eivers (e.g. maximum bandwidth and round-trip-time), and the dynami onditions of su h paths (e.g. ongestion-indu ed delays and losses). SomeCast enables re eivers to dynami ally adjust the rate at whi h they re eive multi ast information to enable the satisfa tion of real-time QoS onstraints (e.g. rate, deadlines, or jitter). This is done by enabling a re eiver to join Some number of on urrent multiCast sessions, whereby ea h session delivers a portion of an en oding of the real-time data. By adjusting the number of su h sessions dynami ally, lient-spe i QoS onstraints an be met independently. The SomeCast paradigm an be thought of as a generalization of the AnyCast (e.g. Dynami Server Sele tion) and ManyCast (e.g. Digital Fountain) paradigms, whi h have been proposed in the literature to address issues of s alability of UniCast and MultiCast environments, respe tively. In this paper we overview the SomeCast paradigm, des ribe an instan e of a SomeCast proto ol, and present simulation results that quantify the signi ant advantages gained from adopting su h a proto ol for the reliable multi ast of data to a diverse set of re eivers subje t to real-time QoS onstraints.