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Separating Distributed Source Coding from Network Coding
, 2006
"... This correspondence considers the problem of distributed source coding of multiple sources over a network with multiple receivers. Each receiver seeks to reconstruct all of the original sources. The work by Ho et al. 2004 demonstrates that random network coding can solve this problem at the potenti ..."
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Cited by 61 (10 self)
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This correspondence considers the problem of distributed source coding of multiple sources over a network with multiple receivers. Each receiver seeks to reconstruct all of the original sources. The work by Ho et al. 2004 demonstrates that random network coding can solve this problem at the potentially high cost of jointly decoding the source and the network code. Motivated by complexity considerations we consider the performance of separate source and network codes. Previous work by Effros et al. 2003 demonstrates the failure of separation between source and network codes for nonmulticast networks. We demonstrate that failure for multicast networks. We study networks with capacity constraints on edges. It is shown that the problem with two sources and two receivers is always separable. Counterexamples are presented for other cases.
On optimal communication cost for gathering correlated data through wireless sensor networks
 in Proc. of ACM MobiCom
"... In many energyconstrained wireless sensor networks, nodes cooperatively forward correlated sensed data to data sinks. In order to reduce the communication cost (e.g. overall energy) used for data collection, previous works have focused on specific coding schemes, such as SlepianWolf Code or Expli ..."
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Cited by 30 (2 self)
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In many energyconstrained wireless sensor networks, nodes cooperatively forward correlated sensed data to data sinks. In order to reduce the communication cost (e.g. overall energy) used for data collection, previous works have focused on specific coding schemes, such as SlepianWolf Code or Explicit Entropy Code. However, the minimum communication cost under arbitrary coding/routing schemes has not yet been characterized. In this paper, we consider the problem of minimizing the total communication cost of a wireless sensor network with a single sink. We prove that the minimum communication cost can be achieved using SlepianWolf Code and Commodity Flow Routing when the link communication cost is a convex function of link data rate. Furthermore, we find it useful to introduce a new metric
Communicating the sum of sources over a network
 IEEE International Symposium on Information Theory (ISIT
, 2008
"... Abstract — We consider a network (that is capable of network coding) with a set of sources and terminals, where each terminal is interested in recovering the sum of the sources. Considering directed acyclic graphs with unit capacity edges and independent, unitentropy sources, we show the rate regio ..."
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Cited by 24 (2 self)
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Abstract — We consider a network (that is capable of network coding) with a set of sources and terminals, where each terminal is interested in recovering the sum of the sources. Considering directed acyclic graphs with unit capacity edges and independent, unitentropy sources, we show the rate region when (a) there are two sources and n terminals, and (b) n sources and two terminals. In these cases as long as there exists at least one path from each source to each terminal we demonstrate that there exists a valid assignment of coding vectors to the edges such that the terminals can recover the sum of the sources. I.
Network coding for multicasting
, 2006
"... In today’s practical networks, endtoend information delivery is performed by routing. Network coding generalizes routing by allowing a node to generate output data by mixing (i.e., computing certain functions of) its received data. Ahlswede et al. determined the multicast capacity in a network of ..."
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Cited by 14 (2 self)
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In today’s practical networks, endtoend information delivery is performed by routing. Network coding generalizes routing by allowing a node to generate output data by mixing (i.e., computing certain functions of) its received data. Ahlswede et al. determined the multicast capacity in a network of lossless links and showed that achieving the multicast capacity requires in general the use of network coding. This thesis presents the following research contributions to the theory and practice of network coding. Constructive network coding We propose and simulate a practical scheme for implementing network coding. We demonstrate its asymptotic optimality by analyzing the connectivity in a continuoustime trellis that models the packet transmissions. Hybrid routing/coding A fundamental theorem by Edmonds established that if all nodes other than the source are destinations, the multicast capacity can be achieved by routing. We constructively prove a theorem that contains Edmonds ’ theorem and Ahlswede et al.’s theorem as special cases. It shows the multicast capacity can still be achieved even if mixing is allowed only on links entering relay nodes.
Minimumcost subgraphs for joint distributed source and network coding
 in Proc. of Workshop on Network Coding, Theory and Applications
, 2007
"... Abstract — We consider multicast of correlated sources over a network. Assuming the use of random network coding, we provide a linear optimization formulation for allocation of link rates in the network, also known as subgraph construction. Such an approach requires joint distributed source and netw ..."
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Cited by 9 (1 self)
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Abstract — We consider multicast of correlated sources over a network. Assuming the use of random network coding, we provide a linear optimization formulation for allocation of link rates in the network, also known as subgraph construction. Such an approach requires joint distributed source and network coding, which often has a lower cost than of that required by separated source and network coding. We support this result with simulations on randomly generated networks and on network data collected from a Future Combat Systems (FCS) exercise at Lakehurst, NJ. I.
Communicating the sum of sources in a 3sources/3terminals network. Manuscript, 2009, available at http://www.openu.ac.il/home/mikel/ISIT09/ISIT09.pdf
"... Abstract—We consider the network communication scenario in which a number of sources si each holding independent information Xi wish to communicate the sum ∑ Xi to a set of terminals tj. In this work we consider directed acyclic graphs with unit capacity edges and independent sources of unitentropy ..."
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Cited by 8 (1 self)
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Abstract—We consider the network communication scenario in which a number of sources si each holding independent information Xi wish to communicate the sum ∑ Xi to a set of terminals tj. In this work we consider directed acyclic graphs with unit capacity edges and independent sources of unitentropy. The case in which there are only two sources or only two terminals was considered by the work of Ramamoorthy [ISIT 2008] where it was shown that communication is possible if and only if each source terminal pair si/tj is connected by at least a single path. In this work we study the communication problem in general, and show that even for the case of three sources and three terminals, a single path connecting source/terminal pairs does not suffice to communicate ∑ Xi. We then present an efficient encoding scheme which enables the communication of ∑ Xi for the three sources, three terminals case, given that each source terminal pair is connected by two edge disjoint paths. Our encoding scheme includes a structural decomposition of the network at hand which may be found useful for other network coding problems as well. I.
Practical sourcenetwork decoding
 in ISWCS 2009, 2009
"... Abstract—When correlated sources are to be communicated over a network to more than one sink, joint sourcenetwork coding is, in general, required for information theoretically optimal transmission. Whereas on the encoder side simple randomized schemes based on linear codes suffice, the decoder is r ..."
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Cited by 7 (2 self)
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Abstract—When correlated sources are to be communicated over a network to more than one sink, joint sourcenetwork coding is, in general, required for information theoretically optimal transmission. Whereas on the encoder side simple randomized schemes based on linear codes suffice, the decoder is required to perform joint sourcenetwork decoding which is computationally expensive. Focusing on maximum aposteriori decoders (or, in the case of continuous sources, conditional mean estimators), we show how to exploit (structural) knowledge about the network topology as well as the source correlations giving rise to an efficient decoder implementation (in some cases even with linear dependency on the number of nodes). In particular, we show how to statistically represent the overall system (including the packets) by a factorgraph on which the sumproduct algorithm can be run. A proofofconcept is provided in the form of a working decoder for the case of three sources and two sinks. I.
Lowcomplexity WynerZiv video coding based on robust media hashing
 Proc. of IEEE Int. Workshop on Multimedia Signal Process
, 2006
"... Abstract—To meet the requirement of distributed video coding in resourcelimited sensor networks, WynerZiv theorembased source coding with side information available at the decoder states that an intraframe encoder with interframe decoder system can achieve comparable coding efficiency of a conven ..."
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Cited by 4 (4 self)
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Abstract—To meet the requirement of distributed video coding in resourcelimited sensor networks, WynerZiv theorembased source coding with side information available at the decoder states that an intraframe encoder with interframe decoder system can achieve comparable coding efficiency of a conventional video codec. Most existing WynerZiv video coding systems are with light encoder and heavy decoder. In this paper, a new contentaware media hashbased WynerZiv video codec with light encoder and light decoder is proposed. The key is that the significant differences between a video frame and its reference frame are efficiently extracted and used for frame recovery based on robust image hashing without needing to perform motion estimation. The particular contribution of our method is its low complexity in both the encoder and decoder sides. Simulation results demonstrate the achievable coding efficiency of our method in particular for videos with small and middle motions. Keywords—WynerZiv video coding; distributed video coding; media hash; video sensor network; wireless video communication Topic area—multimedia processing. I.
Collecting correlated data through a network with minimum cost: Distance entropy and a practical asymptotically optimal design
, 2005
"... Abstract—We consider the problem of minimizing the total communication cost for collecting correlated data at a sink through a network. Previous works have focused on specific coding schemes, such as SlepianWolf (SWC) or Explicit Entropy Codes (EEC). However, the optimal scheme and the minimum comm ..."
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Cited by 2 (1 self)
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Abstract—We consider the problem of minimizing the total communication cost for collecting correlated data at a sink through a network. Previous works have focused on specific coding schemes, such as SlepianWolf (SWC) or Explicit Entropy Codes (EEC). However, the optimal scheme and the minimum communication cost under arbitrary coding/routing schemes has not yet been characterized. In this paper, we introduce distance entropy, a generalization of entropy, to characterize the data gathering limit of networked sources. When the communication cost is proportional to the link data rate, we show that distance entropy is the minimum cost achieved by a specific rate SWC and shortest path routing. More generally, we show that SlepianWolf Coding combined with commodity flow routing is optimal provided that communication costs are convex functions of the data rates. Theoretically, achieving optimality may require global knowledge of the data correlation structure, which may not be available in practice. Therefore, we propose a simple, hierarchical scheme that primarily exploits data correlation among local neighboring nodes. We show that, for several generic correlation structures, the communication cost achieved by this scheme is order optimal. This holds for two deployment strategies: a 2D grid regular network and a 2D Poisson process random network.