Capacity of wireless optical communications
Capacity of wireless optical communications
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DOI：
10.1109/jsac.2003.816618
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发表时间：
2003-10
期刊：
影响因子：
--
通讯作者：
S. M. Haas;J. Shapiro
中科院分区：
文献类型：
--
作者：
S. M. Haas;J. Shapiro
本文研究了湍流大气中多个发射和接收孔径的直接检测光通信系统的各态历经容量和容量与中断概率的关系。我们假设散粒噪声有限的操作中，检测器的输出是双随机泊松过程，其速率是成比例的发送功率的总和，按对数正态随机衰落，加上背景噪声。在高和低信号背景比制度，我们表明，这种衰落信道的遍历容量等于或超过确定性路径增益的信道。此外，当信号背景比高时，不需要这些路径增益的知识来实现容量。在低信号与背景比状态下，当使用中等数量的发射孔径时，路径增益知识提供最小的容量改进。我们还开发的能力与中断概率在高和低信号背景比制度的表达式，通过矩匹配近似的对数正态随机变量的总和的分布。蒙特卡罗模拟表明，这些容量与中断近似是相当准确的中等数量的孔。
We consider the ergodic capacity and capacity-versus-outage probability of direct-detection optical communication through a turbulent atmosphere using multiple transmit and receive apertures. We assume shot-noise-limited operation in which detector outputs are doubly stochastic Poisson processes whose rates are proportional to the sum of the transmitted powers, scaled by lognormal random fades, plus a background noise. In the high and low signal-to-background ratio regimes, we show that the ergodic capacity of this fading channel equals or exceeds that for a channel with deterministic path gains. Furthermore, knowledge of these path gains is not necessary to achieve capacity when the signal-to-background ratio is high. In the low signal-to-background ratio regime, path-gain knowledge provides minimal capacity improvement when using a moderate number of transmit apertures. We also develop expressions for the capacity-versus-outage probability in the high and low signal-to-background ratio regimes, by means of a moment-matching approximation to the distribution for the sum of lognormal random variables. Monte Carlo simulations show that these capacity-versus-outage approximations are quite accurate for moderate numbers of apertures.