Over the past decade

Peer-to-Peer (P2P) media streaming technology

as a promising solution for large-scale media streaming

has always been of a great research interest for both the academia and industrial communities

and a great variety of P2P streaming systems have been developed and widely deployed on the Internet.In this paper

we present a comprehensive and in-depth survey of existing typical P2P streaming systems

in which the core technologies

including overlay network construction and data scheduling mechanism

are detailed introduced and analyzed.We also briefly discuss the enhancement technologies such as video coding

network coding

overlay network topology optimization

and security and incentive mechanisms.Performances of several typical P2P streaming systems are also compared.Finally

we point out the open issues and challenges in P2P streaming research and comment on possible future research directions.