In communications networks, the capacity region of multisource networkcoding is given in terms of the set of entropy functions Gamma*. More broadly, determination of Gamma* would have an impact on converse theorems f...
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In communications networks, the capacity region of multisource networkcoding is given in terms of the set of entropy functions Gamma*. More broadly, determination of Gamma* would have an impact on converse theorems for multi-terminal problems in information theory. this paper provides several new dualities between entropy functions and network codes. Given a function g >= 0 defined on all subsets of N random variables, we provide a construction for a network multicast problem which is "solvable" if and only if g is the entropy function of a set of quasi-uniform random variables. the underlying network topology is fixed and the multicast problem depends on g only through link capacities and source rates. A corresponding duality is developed for linear network codes, where the constructed multicast problem is linearly solvable if and only if g is linear group characterizable. Relaxing the requirement that the domain of g be subsets of random variables, we obtain a similar duality between polymatroids and the linear programming bound. these duality results provide an alternative proof of the insufficiency of linear (and abelian) network codes, and demonstrate the utility of non-Shannon inequalities to tighten outer bounds on networkcoding capacity regions.
We examine networks that employ networkcoding and are subject to Byzantine attacks. We assume that an appropriate network error correcting scheme is employed that is able to correct (up to a certain number of) Byzant...
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ISBN:
(纸本)9781424416899
We examine networks that employ networkcoding and are subject to Byzantine attacks. We assume that an appropriate network error correcting scheme is employed that is able to correct (up to a certain number of) Byzantine errors. Given this setup, we formulate the problem of locating these malicious nodes that insert errors. We utilize the subspace properties of (randomized) networkcoding to develop algorithms to locate the Byzantine attackers.
Consider a source broadcasting M packets to N receivers over independent erasure channels, where perfect feedback is available from the receivers to the source, and the source is allowed to use coding. We investigate ...
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ISBN:
(纸本)9781424416899
Consider a source broadcasting M packets to N receivers over independent erasure channels, where perfect feedback is available from the receivers to the source, and the source is allowed to use coding. We investigate offline and online algorithms that optimize delay, boththrough theoretical analysis as well as simulation results.
Very recently, an operator channel was defined by Koetter and Kschischang when they studied random networkcoding. they also introduced constant dimension codes and demonstrated that these codes can be employed to cor...
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ISBN:
(纸本)9781424416899
Very recently, an operator channel was defined by Koetter and Kschischang when they studied random networkcoding. they also introduced constant dimension codes and demonstrated that these codes can be employed to correct errors and/or erasures over the operator channel. In this paper, a Graham-Sloane type construction of constant dimension codes is presented. It is shown that the construction for the case of minimum dimension distance 4 exceeds the Gilbert type lower bound for constant dimension codes.
Rainbow network flow is a recent enquiry into rate-distortion optimized network flow of a multiple description (MD) coded source from multiple encoders to multiple sinks. this paper is a first attempt to combine netwo...
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ISBN:
(纸本)9781424416899
Rainbow network flow is a recent enquiry into rate-distortion optimized network flow of a multiple description (MD) coded source from multiple encoders to multiple sinks. this paper is a first attempt to combine networkcoding with rainbow network flow, and formulates a new problem called rainbow networkcoding (RNC). It is shown that performing linear networkcoding at intermediate nodes of a flow path can achieve higher networkthroughput than the original rainbow network flow solution. RNC is related to the linear broadcast problem defined in networkcodingtheory, but it has a different objective function that is more meaningful for lossy signal compression applicationsthan linear broadcast. We prove the RNC problem to be NP-hard, and propose some heuristic solutions. Examples are presented to study the differences between rainbow networkcoding, rainbow network flow, and linear broadcast.
In multi-hop wireless networks, networkcoding can take advantage of the bi-directional traffic flows to increase the achievable throughput. To combat fading in wireless channel, cooperative diversity is integrated in...
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In communications networks, the capacity region of multisource networkcoding is given in terms of the set of entropy functions Gamma*. More broadly, determination of Gamma* would have an impact on converse theorems f...
详细信息
ISBN:
(纸本)9781424416899
In communications networks, the capacity region of multisource networkcoding is given in terms of the set of entropy functions Gamma*. More broadly, determination of Gamma* would have an impact on converse theorems for multi-terminal problems in information theory. this paper provides several new dualities between entropy functions and network codes. Given a function g >= 0 defined on all subsets of N random variables, we provide a construction for a network multicast problem which is "solvable" if and only if g is the entropy function of a set of quasi-uniform random variables. the underlying network topology is fixed and the multicast problem depends on g only through link capacities and source rates. A corresponding duality is developed for linear network codes, where the constructed multicast problem is linearly solvable if and only if g is linear group characterizable. Relaxing the requirement that the domain of g be subsets of random variables, we obtain a similar duality between polymatroids and the linear programming bound. these duality results provide an alternative proof of the insufficiency of linear (and abelian) network codes, and demonstrate the utility of non-Shannon inequalities to tighten outer bounds on networkcoding capacity regions.
In this paper, MIMO techniques are applied to networkcoding in order to exploit the spatial diversity inherent in packet combining. this is possible because networkcoding and MIMO solve similar problems, namely to d...
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ISBN:
(纸本)9781424416899
In this paper, MIMO techniques are applied to networkcoding in order to exploit the spatial diversity inherent in packet combining. this is possible because networkcoding and MIMO solve similar problems, namely to decode a vector of transmitted symbols given a vector of received samples. this observation leads to a new approach for NC coding/decoding. Our basic idea is to move networkcoding functionalities towards the physical layer in order to jointly perform NC decoding and MIMO detection and gain the advantages of the two approaches. We refer to this new strategy as MIMO_NC. theoretical analysis and simulations prove that our system is more robust than traditional networkcoding to fading and packet losses.
We investigate the problem of constructing optimal layered multicast for heterogeneous sink nodes using networkcoding. Taking the flexibility of layered coding into account, we discuss the optimization problem that d...
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ISBN:
(纸本)9781424416899
We investigate the problem of constructing optimal layered multicast for heterogeneous sink nodes using networkcoding. Taking the flexibility of layered coding into account, we discuss the optimization problem that determines the optimal layers' bit-rates for layered multicast, and express it into a mathematical formulation. Finding that this formulation is nonlinear and difficult to solve, we reduce it into several equivalent optimization problems and further propose a new optimization scheme. Different from the min-favorable algorithm in existing work, this new scheme is a global-favorable one, which determines the optimal layers' bit-rates based on the max-flows of all sink nodes. Simulation results indicate that this new scheme could achieve the maximum of the aggregate throughput for layered multicast.
We discuss a coding technique for transmitting temporally ordered and/or successive refinements encoded multimedia data (such as MPEG video) over a multi-cast network using recently developed breakthrough network codi...
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ISBN:
(纸本)9781424416899
We discuss a coding technique for transmitting temporally ordered and/or successive refinements encoded multimedia data (such as MPEG video) over a multi-cast network using recently developed breakthrough networkcoding techniques. Hybridizing networkcoding philosophy withthat of priority encoded transmission and fountain codes, we provide a method which allows a sink to forward to higher OSI model layers (i.e. the source decoder lying in the application layer) the uncoded source data in order of importance as the network coded packets arrive. this technique avoids the delay presently incurred by waiting for the reception of a full rank networkcoding matrix before decodingthe entire block and forwarding it to higher layers.
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