标题: 无线光通道容量分析
On the Capacity of Free-Space Optical Communication Channel
作者: 林鼎杰
Ding-Jie Lin
莫诗台方
Stefan M.Moser
电信工程研究所
关键字: 通道容量;光通道;无线;channel capacity;opitcal channel;free-space
公开日期: 2007
摘要: 本篇论文探讨无线光通道的容量大小。此通道有下列几项特性: 输入端的是以光的强度当做记量的单位,所以其值为非负值 ; 输出端会受到杂讯的影响,在此我们把此杂讯假设成相加白色高斯杂讯,因为在接收端会受到许多不同独立来源的杂讯,所以我们把它假设成白色高斯杂讯 ; 此外,电池电力的限制和使用上眼睛安全的问题,我们必须有平均能量与峰值能量大小的限制。

我们的任务是改善之前所提出的上下限,让上下限间的距离变得更靠近,我们就可夹击出真正的通道容量。首先我们先利用数值分析的方式求出一个数值的通道容量下限,然后跟之前的结果比较。之后在根据先前的比较,用理论分析的方式去求得公式。

我们所得到的数值下限与之前论文所推导出的上限在低讯杂比(SNR) 的情况下相当接近,如果我们放松对平均能量的限制,我们可以得到更好结果。而我们理论分析出来的下限,在中杂讯比的地方有明显的改善。
In this thesis we study the free-space optical communication channeld. This channel is characterized by inputs that are nonnegative representing transmitted optical intensity, and by outputs that are corrupted by additive white Gaussian noise, because in free space the disturbances arise from many independent sources. Due to battery and safety reasons the inputs are simultaneously constrained on both their average and peak power.
Our task is trying to find upper and lower bounds on the capacity of this channel. We use a numerical approach to compute the channel capacity and compare it with previous bounds. Based on the result of this comparison, we try to derive improved analytical lower bounds on capacity.
Our numerical lower bounds are very close to previous upper bounds in lower SNR region (below 5 dB) with improving performance if we loosen the average-power constraint. Our analytical lower bounds are good in medium SNR region (between 5 dB and 15 dB).
URI: http://140.113.39.130/cdrfb3/record/nctu/#GT009513545
http://hdl.handle.net/11536/38388
显示于类别:Thesis


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