This paper studies the capacity of the two-user intensity-modulation/direct-detection (IM/DD) interference channel (IC), which is relevant in the context of multi-user optical wireless communications. Despite some known single-letter capacity characterizations for general discrete-memoryless ICs, a computable capacity expression for the IM/DD IC is missing. In this paper, we provide tight and easily computable inner and outer bounds for a general two-user IM/DD IC under peak and average optical intensity constraints. The bounds enable characterizing the asymptotic sum-rate capacity in the strong and weak interference regimes, as well as the generalized degrees of freedom (GDoF) in the symmetric case. Using the obtained bounds, the GDoF of the IM/DD IC is shown to have a ‘W’ shape similar to the Gaussian IC with power constraints. The obtained bounds are also evaluated numerically in different interference regimes to show their tightness, and used to study the performance of on-chip and indoor OWC systems.

中文翻译：

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两用户 IM/DD 干扰信道的容量界限


本文研究了与多用户光无线通信背景相关的两用户强度调制/直接检测（IM/DD）干扰信道（IC）的容量。尽管通用分立无记忆 IC 有一些已知的单字母容量特征，但 IM/DD IC 的可计算容量表达式仍然缺失。在本文中，我们在峰值和平均光强度约束下为一般的双用户 IM/DD IC 提供严格且易于计算的内部和外部边界。这些界限能够表征强干扰和弱干扰情况下的渐近和速率容量，以及对称情况下的广义自由度 (GDoF)。使用获得的边界，IM/DD IC 的 GDoF 显示为“W”形状，类似于具有功率限制的高斯 IC。还对不同干扰情况下所获得的界限进行数值评估，以显示其严格性，并用于研究片上和室内 OWC 系统的性能。