摘要
分集传输技术是抑制星地光通信中大气湍流效应和链路中断的有效手段之一。文章首先介绍MISO链路模型,从理论上分析大气湍流对激光通信的影响,以及研究光束间的相关性。然后提出星地光通信无论在小天顶角还是在大天顶角时,都可以选择一个合适尺度变换-对数均方差增益因子G,MISO大气湍流信道模型等效为一个单光束信道,并通过数值仿真计算验证了模型的正确性。随光束n的增加,大天顶角MISO链路的接收光强分布从gamma-gamma分布逐渐趋于对数正态分布。最后分析MISO链路的信道误码性能。结果表明,MISO链路实质是减少接收光强的对数方差,改善MISO信道性能关键是减小光束间的相关性。
the transmit diversity technique is one of the effective moans to mitigate the effect of atmospheric turbulence and reduce the lost - tracking probability in satellite- to- ground optical communications. We first present the MISO link model and analyze the effect of atmospheric turbulence, also research channel correlation. Then it is presented that the probability density function of the received intensity with MISO link can be represented by equivalent those of single- beam with appropriate scaling G (the gain factor of log- amplitude variances), whether small zenith angles or large zenith angles. The channel model of MISO link was confirmed by simulation. When number of beam increase, the probability density function of the received power with MISO link evolves as log normal distribution from gamma - gamma distribution at large zenith angles. Finally BER performance of MISO link is evaluated. Our results demonstrate that it is essential to reduce log - amplitude variances for MISO link and that efficient separation between apertures and strict co - alignment is crucial to achieve the promised diversity gains.
出处
《激光杂志》
CAS
CSCD
北大核心
2009年第3期43-45,共3页
Laser Journal
关键词
星地光通信
分集传输
光强起伏
误码率
概率密度函数
satellite - to- ground optical communications
transmit diversity
intensity fluctuation
bit error rate
probability density function