On the power of cooperation: Can a little help a lot?

This paper treats point-to-point, multiple access and random access lossless source coding in the finite-blocklength regime. A random coding technique is developed, and its power in analyzing the third-order-optimal coding performance is demonstrated in all three scenarios. Results include a thirdorder-optimal characterization of the Slepian-Wolf rate region and a proof showing that for dependent sources, the independent encoders used by Slepian-Wolf codes can achieve the same thirdorder-optimal performance as a single joint encoder. The concept of random access source coding, which generalizes the multiple access scenario to allow for a number of participating encoders that is unknown a priori to both the encoders and the decoder, is introduced. Contributions include a new definition of the probabilistic model for a random access-discrete multiple source (RA-DMS), a general random access source coding scheme that employs a rateless code with sporadic feedback, and an analysis for the proposed scheme demonstrating via a random coding argument that there exists a deterministic code of the proposed structure that simultaneously achieves the third-order-optimal performance of Slepian-Wolf codes for all possible numbers of encoders. While the analysis for random access codes focuses on a class of permutation-invariant RA-DMSs, it also extends to more general sources.

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“…Taking γ = M in (26) yields (25). So all remains is to show (26). The proof of (26) is based on random coding.…”

Section: Main Results: New Achievability Bounds Based On Random Comentioning

confidence: 99%

Lossless Source Coding in the Point-to-Point, Multiple Access, and Random Access Scenarios

Chen

Effros

Kostina

2020

IEEE Trans. Inform. Theory

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“…that satisfy the cost constraints (6). Similarly, P(X [k] ) is the set of all distributions on X [k] that satisfy (6).…”

Section: B Sum-capacity Gainmentioning

confidence: 99%

The Unbounded Benefit of Encoder Cooperation for the k-User MAC

Noorzad

Effros

Langberg

2018

IEEE Trans. Inform. Theory

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Cooperation strategies allow communication devices to work together to improve network capacity. Consider a network consisting of a k-user multiple access channel (MAC) and a node that is connected to all k encoders via rate-limited bidirectional links, referred to as the "cooperation facilitator" (CF). Define the cooperation benefit as the sum-capacity gain resulting from the communication between the encoders and the CF and the cooperation rate as the total rate the CF shares with the encoders. This work demonstrates the existence of a class of k-user MACs where the ratio of the cooperation benefit to cooperation rate tends to infinity as the cooperation rate tends to zero.Examples of channels in this class include the binary erasure MAC for k = 2 and the k-user Gaussian MAC for any k ≥ 2. Index TermsConferencing encoders, cooperation facilitator, cost constraints, edge removal problem, multiple access channel, multivariate covering lemma, network information theory.

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“…where S 1,k1 and S 2,k2 are defined by (4). Let N A denote the number of ones in the K 1 ×K 2 matrix A = (a k1k2 ) k1,k2 .…”

Section: A Theorem 1 (Reliability Under the Cf Model)mentioning

confidence: 99%

Can negligible cooperation increase network reliability?

Noorzad

Effros

Langberg

2016

2016 IEEE International Symposium on Information Theory (ISIT)

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In network cooperation strategies, nodes work together with the aim of increasing transmission rates or reliability. This paper demonstrates that enabling cooperation between the transmitters of a two-user multiple access channel, via a cooperation facilitator that has access to both messages, always results in a network whose maximal-and average-error sum-capacities are the same-even when those capacities differ in the absence of cooperation and the information shared with the encoders is negligible. From this result, it follows that if a multiple access channel with no transmitter cooperation has different maximal-and average-error sum-capacities, then the maximal-error sum-capacity of the network consisting of this channel and a cooperation facilitator is not continuous with respect to the output edge capacities of the facilitator. This shows that there exist networks where sharing even a negligible number of bits per channel use with the encoders yields a non-negligible benefit.

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On the power of cooperation: Can a little help a lot?

Cited by 12 publications

References 13 publications

Lossless Source Coding in the Point-to-Point, Multiple Access, and Random Access Scenarios

Lossless Source Coding in the Point-to-Point, Multiple Access, and Random Access Scenarios

The Unbounded Benefit of Encoder Cooperation for the k-User MAC

Can negligible cooperation increase network reliability?

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