[论文解读] Fundamental Limits of Communications in Interference Networks-Part II: Information Flow in Degraded Networks

Reza Khosravi-Farsani, Farokh Marvasti|arXiv (Cornell University)|Jul 12, 2012

Wireless Communication Security Techniques参考文献 10被引用 8

一句话总结

本论文通过一种逐次检测方案，确定了退化干扰网络的和速率容量，证明了仅需传输特定的消息子集即可实现最优性能。论文引入基于图的算法以识别该子集，并推导出一种统一的外 bound，其在多种网络配置下优于割集界，包括噪声干扰场景，以及逐次检测与将干扰视为噪声联合达到容量的情形。

ABSTRACT

In this second part of our multi-part papers, the information flow in degraded interference networks is studied. A full characterization of the sum-rate capacity for the degraded networks with any possible configuration is established. It is shown that a successive decoding scheme is sum-rate optimal for these networks. Also, it is proved that the transmission of only a certain subset of messages is sufficient to achieve the sum-rate capacity in such networks. Algorithms are presented to determine this subset of messages explicitly. According to these algorithms, the optimal strategy to achieve the sum-rate capacity in degraded networks is that the transmitters try to send information for the stronger receivers and, if possible, avoid sending the messages with respect to the weaker receivers. The algorithms are easily understood using our graphical illustrations for the achievability schemes based on directed graphs. The sum-rate expression for the degraded networks is then used to derive a unified outer bound on the sum-rate capacity of arbitrary non-degraded networks. Several variations of the degraded networks are identified for which the derived outer bound is sum-rate optimal. Specifically, noisy interference regimes are derived for certain classes of multi-user/multi-message interference networks. Also, for the first time, network scenarios are identified where the incorporation of both successive decoding and treating interference as noise achieves their sum-rate capacity. Finally, by taking insight from our results for degraded networks, we establish a unified outer bound on the entire capacity region of the general interference networks. These outer bounds for a broad range of network scenarios are tighter than the existing cut-set bound.

研究动机与目标

• 完全表征任意配置下退化干扰网络的和速率容量。
• 识别在该类网络中实现和速率容量所需的最小消息集合。
• 开发基于接收端信道强度的算法，以确定最优消息传输策略。
• 推导一般非退化干扰网络和速率容量的统一外 bound。
• 识别将逐次检测与将干扰视为噪声相结合可实现和速率容量的网络场景。

提出的方法

• 证明了逐次检测方案在退化干扰网络中为和速率最优。
• 使用有向图表示来建模消息传输流，并识别应传输的最优消息子集。
• 开发基于图的算法，以根据接收端信号强度确定哪些发射机应发送消息。
• 利用退化网络的和速率表达式，推导出适用于任意非退化网络的统一外 bound。
• 证明该外 bound 在广泛网络场景下优于割集界。
• 推导出在何种条件下，将干扰视为噪声与逐次检测联合使用可实现和速率容量。

实验结果

研究问题

• RQ1 任意配置的退化干扰网络的和速率容量是多少？
• RQ2 在退化干扰网络中，哪些消息子集足以实现和速率容量？
• RQ3 能否从退化网络的分析中推导出一般干扰网络和速率容量的统一外 bound？
• RQ4 在何种网络场景下，逐次检测与将干扰视为噪声的结合可实现和速率容量？
• RQ5 所提出的外 bound 在不同干扰场景下与现有割集界相比，其紧致性如何？

主要发现

• 对任意配置的退化干扰网络，其和速率容量被完全表征。
• 证明了在退化网络中，逐次检测方案为和速率最优。
• 仅需传输特定的消息子集——即目标为更强接收机的消息——即可实现和速率容量。
• 提供了基于图的算法，可基于接收机强度与网络拓扑显式确定最优消息子集。
• 所推导的外 bound 在广泛网络场景下（包括噪声干扰场景）优于割集界。
• 首次识别出网络场景，其中将干扰视为噪声与逐次检测联合使用可实现和速率容量。