This paper investigates the capacity region of the optical intensity broadcast channels (OI-BCs), where the input is subject to a peak-intensity constraint, an average-intensity constraint, or both. By leveraging the decomposition results of several random variables, i.e., uniform, exponential, and truncated exponential random variables, and adopting a superposition coding (SC) scheme, the inner bound on the capacity region is derived. Then, the outer bound is derived by applying the conditional entropy power inequality (EPI). In the high signal-to-noise ratio (SNR) regime, the inner bound asymptotically matches the outer bound, thus characterizing the high-SNR asymptotic capacity region. The bounds are also extended to the general K-user BCs without loss of high-SNR asymptotic optimality.

翻译：本文研究了光学强度广播信道（OI-BCs）的容量区域，其中输入信号受限于峰值强度约束、平均强度约束或两者兼有。通过利用若干随机变量（即均匀分布、指数分布和截断指数分布）的分解结果，并采用叠加编码（SC）方案，推导了容量区域的内界。随后，通过应用条件熵功率不等式（EPI）导出了外界。在高信噪比（SNR）区域内，内界渐近趋近外界，从而刻画了高SNR渐近容量区域。这些界还可推广至一般K用户广播信道，且不损失高SNR渐近最优性。