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Optimal Second-Order Coding Rate for Discrete Memoryless Channels with Mean and Variance Cost Constraints


Centrala begrepp
The optimal second-order coding rate for discrete memoryless channels can be characterized by a function K(r, V) that depends on the mean and variance constraints on the codeword costs.
Sammanfattning

The paper considers channel coding for discrete memoryless channels (DMCs) with a novel cost constraint that bounds both the mean and the variance of the cost of the codewords. The key insights are:

  1. The maximum (asymptotically) achievable rate under the new cost formulation is equal to the capacity-cost function, and the strong converse holds.

  2. The optimal second-order coding rate (SOCR) is finite and can be characterized in terms of a function K(r, V) that depends on the mean (r) and variance (V) constraints on the codeword costs.

  3. Feedback can strictly improve the SOCR compared to the optimal SOCR without feedback. The feedback scheme is a new variant of timid/bold coding that does not require multiple capacity-cost-achieving distributions or i.i.d. codewords.

  4. The (Γ, V) cost constraint allows i.i.d. channel inputs with a bounded variance V > 0, preserving the advantage of previous cost constraints that permitted i.i.d. codewords. However, the (Γ, V) formulation can also handle cases where i.i.d. P* codewords are not admissible.

  5. The converse and achievability results provide matching upper and lower bounds on the optimal SOCR in terms of the function K(r, V).

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Statistik
C(Γ) - nC(Γ) ≤ [C(Γ)]n ≤ C(Γ) V(Γ) - 2Jνmax/n ≤ [V(Γ)]n ≤ V(Γ) + 2Jνmax/n log Q*(yn) / Qcc(yn) ≥ -s(P*) - 1/2 log(n) - κ for n > N
Citat
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Viktiga insikter från

by Adeel Mahmoo... arxiv.org 05-07-2024

https://arxiv.org/pdf/2401.16417.pdf
Channel Coding with Mean and Variance Cost Constraints

Djupare frågor

How can the (Γ, V) cost constraint be extended to incorporate higher-order moment constraints on the codeword costs

The extension of the (Γ, V) cost constraint to incorporate higher-order moment constraints on the codeword costs can be achieved by introducing additional constraints on the moments of the cost function. In the context of the provided research, where the cost constraint bounds both the mean and the variance of the cost of the codewords, extending it to include higher-order moments would involve setting limits on the skewness, kurtosis, or other statistical moments of the cost distribution. By incorporating constraints on higher-order moments, such as skewness or kurtosis, the (Γ, V) cost constraint can be further refined to capture more detailed characteristics of the cost distribution. This extension would provide a more comprehensive framework for controlling the distribution of costs associated with the codewords, allowing for a more nuanced optimization of the coding performance.

What are the implications of the (Γ, V) cost constraint on the practical implementation of channel coding schemes, such as power allocation and interference management

The implications of the (Γ, V) cost constraint on the practical implementation of channel coding schemes are significant, particularly in the areas of power allocation and interference management. Power Allocation: The (Γ, V) cost constraint imposes limits not only on the average power consumption (mean cost) but also on the variability of power usage (variance of cost). This constraint can guide the design of power allocation strategies that balance the trade-off between power efficiency and reliability in communication systems. By considering both mean and variance constraints, power allocation algorithms can be optimized to ensure efficient resource utilization while maintaining a predictable power consumption pattern. Interference Management: In scenarios where interference management is crucial, the (Γ, V) cost constraint plays a vital role in regulating the impact of interference on the communication system. By controlling the variability of costs associated with codewords, the constraint helps in mitigating the effects of interference by ensuring a more stable and predictable transmission environment. This can lead to improved performance in the presence of external disturbances or competing signals. Overall, the (Γ, V) cost constraint provides a structured framework for addressing power-related challenges in channel coding, offering a balance between resource efficiency and reliability in practical communication systems.

Can the techniques developed in this work be applied to other information-theoretic problems beyond channel coding, such as source coding or multi-terminal communication

The techniques developed in this work, focusing on channel coding with mean and variance cost constraints, can indeed be applied to other information-theoretic problems beyond channel coding. Some potential applications of these techniques include: Source Coding: In source coding, where the goal is to efficiently represent and compress a source signal, the concept of cost constraints can be extended to optimize the trade-off between compression efficiency and distortion. By incorporating mean and variance constraints on the distortion or reconstruction error, similar to the cost constraints in channel coding, one can design source coding schemes that balance compression performance with error control. Multi-Terminal Communication: The principles of cost constraints and optimization techniques developed for channel coding can be adapted to multi-terminal communication scenarios, such as cooperative communication or network coding. By imposing constraints on the resources allocated to different terminals or nodes in a communication network, the (Γ, V) cost constraint framework can help in managing the distribution of resources effectively while ensuring reliable and efficient communication among multiple entities. By applying the methodologies and insights gained from channel coding with mean and variance cost constraints to these related areas, researchers can explore new avenues for optimizing information transmission and processing in diverse communication systems.
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