Abstract-In traditional mobile streaming networks such as 3G cellular networks, all users pull streams from a server. Such pull model leads to high streaming cost and problem in system scalability. In this paper, we propose and investigate a fully distributed, scalable, and cost-effective protocol to distribute multimedia content to mobiles in a peer-to-peer manner. Our protocol, termed Collaborative Streaming among Mobiles (COSMOS), makes use of broadcasting and data sharing to achieve high performance (in terms of delay, cost fairness, stream continuity, etc.). In COSMOS, only a few peers pull video descriptions from base stations. Using a free broadcast channel (such as Wi-Fi and Bluetooth), they share the streams to nearby neighbors. As a result, COSMOS greatly reduces the streaming cost and cellular bandwidth requirement. Furthermore, as video streams are supplied by multiple peers, COSMOS is robust to peer failure. Since broadcasting is used to distribute video data, COSMOS is highly scalable to large number of users. In COSMOS, peers autonomously determine whether to broadcast packets or not in order to efficiently use of the channel bandwidth. By taking turns to pull descriptions, peers can effectively share, and hence substantially reduce, streaming cost. As broadcast scope is small and peers can often obtain a number of streams from its neighbors, COSMOS achieves low delay and excellent stream continuity.

In traditional mobile streaming networks such as 3G cellular networks, all users pull streams from a server. Such pull model leads to high streaming cost and problem in system scalability. In this paper, we propose and investigate a scalable and cost-effective protocol to distribute multimedia content to mobiles in a peer-to-peer manner. Our protocol, termed Collaborative Streaming among Mobiles (COSMOS), makes use of multiple description coding (MDC) and data sharing to achieve high performance. In COSMOS, only a few peers pull video descriptions through a telecommunication channel. Using a free broadcast channel (such as Wi-Fi and bluetooth), they share the descriptions to nearby neighbors in an ad-hoc manner. This way reduces greatly the telecommunication cost and cellular bandwidth requirement. As video descriptions are supplied by multiple peers, COSMOS is robust to peer failure. Since broadcasting is used to distribute video data, the protocol is highly scalable to large number of users. By taking turns to pull descriptions, we show through simulation that peers can effectively share, and hence substantially reduce, streaming cost. As peers can often obtain a number of descriptions from nearby neighbors, they enjoy lower delay as compared to a recent scheme CHUM.

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