CIF: Small: Fountain Coding Theory for Content Sharing and Multimedia Broadcasting in Overlay Networks

摘要多播应用，如内容共享和多媒体广播，是互联网上最重要的一类应用。组播应用采用覆盖网络模型，由抽象的虚拟逻辑链路连接的相关节点组成。虽然在这样的网络中的可扩展多播需要纠错编码，但由于虚拟链路不享有已知的统计信道模型的事实，经典的编码方法是非常低效的。为了克服这一挑战，本项目将开发一个系统的编码理论的基础上，一个新的喷泉通信模型，有效的组播覆盖网络。在喷泉通信中，源节点将消息编码成无限多个分组，目的节点在接收到的分组数超过一定阈值后对消息进行解码。研究者将首先开发一个喷泉编码框架，用于虚拟网络链路上的端到端组播传输。对于延迟不敏感的业务，喷泉码将被开发，以达到理想的率错误性能与线性编码复杂度。对于延迟敏感的业务，喷泉编码将与流量控制算法相结合，以确保在具有任意失真和擦除的信道上及时传递信息。目标是表征基本性能限制和开发实用的编码方案。然后，该项目将研究多用户协作通信的多播应用在节点容量限制的覆盖网络，其中每个节点的总和上传速率保持在一个预定的界限以下。对于延迟敏感的通信，目标是克服网络节点可能随机接入或从网络断开的挑战。对于延迟不敏感的通信，目标是克服“自私的对等节点”的挑战，其中对等节点断开从网络中，只要其所需的消息变得完全可解码。

AbstractMulticast applications, such as content sharing and multimedia broadcasting, is the single most important class of applications over the internet. Multicast applications assume overlay network models, which consist of relevant nodes connected by abstracted virtual logical links. While scalable multicasting in such a network requires error-correction coding, classical coding approaches are highly inefficient due to the fact that virtual links do not enjoy known statistical channel models. To overcome this challenge, this project will develop a systematic coding theory based on a new fountain communication model for efficient multicasting in overlay networks. In fountain communication, the source node encodes a message into an infinite number of packets, a destination decodes the message after the number of received packets exceeds certain threshold. The investigator will first develop a fountain coding framework for end-to-end multicast transmission over virtual network links. For delay nonsensitive traffic, fountain codes will be developed to achieve ideal rate-error performance with a linear coding complexity. For delay sensitive traffic, fountain coding will be integrated with flow control algorithms to ensure timely information delivery over channels with arbitrary distortions and erasures. The objectives are characterizing fundamental performance limitations and developing practical coding schemes. The project will then investigate multiuser cooperative communication for multicast applications in node-capacitated overlay networks, where the sum upload rate of each node is kept below a predetermined bound. For delay sensitive communication, the objective is to overcome the challenge that network nodes may randomly access or disconnect from the network. For delay nonsensitive communication, the objective is to overcome the "selfish-peer-node" challenge where a peer node disconnects from the network whenever its desired messages become fully decodable.