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360
Raptor codes
- IEEE Transactions on Information Theory
, 2006
"... LT-Codes are a new class of codes introduced in [1] for the purpose of scalable and fault-tolerant distribution of data over computer networks. In this paper we introduce Raptor Codes, an extension of LT-Codes with linear time encoding and decoding. We will exhibit a class of universal Raptor codes: ..."
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Cited by 577 (7 self)
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LT-Codes are a new class of codes introduced in [1] for the purpose of scalable and fault-tolerant distribution of data over computer networks. In this paper we introduce Raptor Codes, an extension of LT-Codes with linear time encoding and decoding. We will exhibit a class of universal Raptor codes: for a given integer k, and any real ε> 0, Raptor codes in this class produce a potentially infinite stream of symbols such that any subset of symbols of size k(1 + ε) is sufficient to recover the original k symbols with high probability. Each output symbol is generated using O(log(1/ε)) operations, and the original symbols are recovered from the collected ones with O(k log(1/ε)) operations. We will also introduce novel techniques for the analysis of the error probability of the decoder for finite length Raptor codes. Moreover, we will introduce and analyze systematic versions of Raptor codes, i.e., versions in which the first output elements of the coding system coincide with the original k elements. 1
LT Codes
, 2002
"... We introduce LT codes, the first rateless erasure codes that are very efficient as the data length grows. ..."
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Cited by 568 (2 self)
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We introduce LT codes, the first rateless erasure codes that are very efficient as the data length grows.
Informed Content Delivery Across Adaptive Overlay Networks
, 2002
"... Overlay networks have emerged as a powerful and highly flexible method for delivering content. We study how to optimize through-put of large, multipoint transfers across richly connected overlay networks, focusing on the question of what to put in each transmit-ted packet. We first make the case for ..."
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Cited by 247 (8 self)
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Overlay networks have emerged as a powerful and highly flexible method for delivering content. We study how to optimize through-put of large, multipoint transfers across richly connected overlay networks, focusing on the question of what to put in each transmit-ted packet. We first make the case for transmitting encoded content in this scenario, arguing for the digital fountain approach which en-ables end-hosts to efficiently restitute the original content of size n from a subset of any n symbols from a large universe of encoded symbols. Such an approach affords reliability and a substantial de-gree of application-level flexibility, as it seamlessly tolerates packet loss, connection migration, and parallel transfers. However, since the sets of symbols acquired by peers are likely to overlap substan-tially, care must be taken to enable them to collaborate effectively. We provide a collection of useful algorithmic tools for efficient es-timation, summarization, and approximate reconciliation of sets of symbols between pairs of collaborating peers, all of which keep messaging complexity and computation to a minimum. Through simulations and experiments on a prototype implementation, we demonstrate the performance benefits of our informed content de-livery mechanisms and how they complement existing overlay net-work architectures.
Extrinsic Information Transfer Functions: A Model and Two Properties,”
- in Proc. Conference on Information Sciences and Systems (CISS),
, 2002
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A Digital Fountain Approach to Asynchronous Reliable Multicast
- IEEE Journal on Selected Areas in Communications
, 2002
"... Abstract—The proliferation of applications that must reliably distribute large, rich content to a vast number of autonomous receivers motivates the design of new multicast and broadcast protocols. We describe an ideal, fully scalable protocol for these applications that we call a digital fountain. A ..."
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Cited by 174 (10 self)
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Abstract—The proliferation of applications that must reliably distribute large, rich content to a vast number of autonomous receivers motivates the design of new multicast and broadcast protocols. We describe an ideal, fully scalable protocol for these applications that we call a digital fountain. A digital fountain allows any number of heterogeneous receivers to acquire content with optimal efficiency at times of their choosing. Moreover, no feedback channels are needed to ensure reliable delivery, even in the face of high loss rates. We develop a protocol that closely approximates a digital fountain using two new classes of erasure codes that for large block sizes are orders of magnitude faster than standard erasure codes. We provide performance measurements that demonstrate the feasibility of our approach and discuss the design, implementation, and performance of an experimental system. Index Terms—Content delivery, erasure codes, forward error correction, reliable multicast, scalability. I.
Using redundancy to cope with failures in a delay tolerant network
- in Proceedings of ACM SIGCOMM
, 2005
"... We consider the problem of routing in a delay tolerant net-work (DTN) in the presence of path failures. Previous work on DTN routing has focused on using precisely known network dy-namics, which does not account for message losses due to link failures, buffer overruns, path selection errors, unsched ..."
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Cited by 146 (4 self)
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We consider the problem of routing in a delay tolerant net-work (DTN) in the presence of path failures. Previous work on DTN routing has focused on using precisely known network dy-namics, which does not account for message losses due to link failures, buffer overruns, path selection errors, unscheduled de-lays, or other problems. We show how to split, replicate, and erasure code message fragments over multiple delivery paths to optimize the probability of successful message delivery. We provide a formulation of this problem and solve it for two cases: a 0/1 (Bernoulli) path delivery model where messages are ei-ther fully lost or delivered, and a Gaussian path delivery model where only a fraction of a message may be delivered. Ideas from the modern portfolio theory literature are borrowed to solve the underlying optimization problem. Our approach is directly relevant to solving similar problems that arise in replica place-ment in distributed file systems and virtual node placement in DHTs. In three different simulated DTN scenarios covering a wide range of applications, we show the effectiveness of our ap-proach in handling failures.
Network Coding for Efficient Communication in Extreme Networks
, 2005
"... Some forms of ad-hoc networks need to operate in extremely performance-challenged environments where end-to-end connectivity is rare. Such environments can be found for example in very sparse mobile networks where nodes ”meet ” only occasionally and are able to exchange information, or in wireless s ..."
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Cited by 128 (3 self)
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Some forms of ad-hoc networks need to operate in extremely performance-challenged environments where end-to-end connectivity is rare. Such environments can be found for example in very sparse mobile networks where nodes ”meet ” only occasionally and are able to exchange information, or in wireless sensor networks where nodes sleep most of the time to conserve energy. Forwarding mechanisms in such networks usually resort to some form of intelligent flooding, as for example in probabilistic routing. We propose a communication algorithm that significantly reduces the overhead of probabilistic routing algorithms, making it a suitable building block for a delay-tolerant network architecture. Our forwarding scheme is based on network coding. Nodes do not simply forward packets they overhear but may send out information that is coded over the contents of several packets they received. We show by simulation that this algorithm achieves the reliability and robustness of flooding at a small fraction of the overhead.
P5: A Protocol for Scalable Anonymous Communication
- PROC. IEEE SYMP. SECURITY AND PRIVACY
, 2002
"... We present a protocol for anonymous communication over the Internet. Our protocol, called P 5 (Peer-to-Peer Personal Privacy Protocol) provides sender-, receiver-, and sender-receiver anonymity. P 5 is designed to be implemented over the current Internet protocols, and does not require any special i ..."
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Cited by 93 (2 self)
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We present a protocol for anonymous communication over the Internet. Our protocol, called P 5 (Peer-to-Peer Personal Privacy Protocol) provides sender-, receiver-, and sender-receiver anonymity. P 5 is designed to be implemented over the current Internet protocols, and does not require any special infrastructure support. A novel feature of P 5 is that it allows individual participants to trade-off degree of anonymity for communication efficiency, and hence can be used to scalably implement large anonymous groups. We present a description of P 5, an analysis of its anonymity and communication efficiency, and evaluate its performance using detailed packet-level simulations.
Growth codes: Maximizing sensor network data persistence
- in Proc. ACM SIGCOMM
"... Sensor networks are especially useful in catastrophic or emergency scenarios such as floods, fires, terrorist attacks or earthquakes where human participation may be too dangerous. However, such disaster scenarios pose an interesting design challenge since the sensor nodes used to collect and commun ..."
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Cited by 92 (0 self)
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Sensor networks are especially useful in catastrophic or emergency scenarios such as floods, fires, terrorist attacks or earthquakes where human participation may be too dangerous. However, such disaster scenarios pose an interesting design challenge since the sensor nodes used to collect and communicate data may themselves fail suddenly and unpredictably, resulting in the loss of valuable data. Furthermore, because these networks are often expected to be deployed in response to a disaster, or because of sudden configuration changes due to failure, these networks are often expected to operate in a “zero-configuration ” paradigm, where data collection and transmission must be initiated immediately, before the nodes have a chance to assess the current network topology. In this paper, we design and analyze techniques to increase “persistence ” of sensed data, so that data is more likely to reach a data sink, even as network nodes fail. This is done by replicating data compactly at neighboring nodes using novel “Growth Codes ” that increase in efficiency as data accumulates at the sink. We show that Growth Codes preserve more data in the presence of node failures than previously proposed erasure resilient techniques.
Digital Fountains: A Survey and Look Forward
, 2004
"... We survey constructions and applications of digital fountains, an abstraction of erasure coding for network communication. Digital fountains effectively change the standard paradigm where a user receives an ordered stream of packets to one where a user must simply receive enough packets in order to ..."
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Cited by 89 (0 self)
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We survey constructions and applications of digital fountains, an abstraction of erasure coding for network communication. Digital fountains effectively change the standard paradigm where a user receives an ordered stream of packets to one where a user must simply receive enough packets in order to obtain the desired data. Obviating the need for ordered data simplifies data delivery, especially when the data is large or is to be distributed to a large number of users. We also examine barriers to the adoption of digital fountains and discuss whether they can be overcome.
