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arXiv 0804.0050cs.ITmath.IT
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具有PPM的高斯MIMO自由空间光信道的中断概率

Outage Probability of the Gaussian MIMO Free-Space Optical Channel with PPM

Nick Letzepis, Albert Guillen i Fabregas

摘要:

自由空间光信道具有在短部署时间内促进具有类似光纤带宽的廉价无线通信的潜力。然而,大气效应会显著降低自由空间光链路的可靠性。特别地,大气湍流导致接收到的激光束的辐照度的随机波动,通常称为闪烁。与光传输的典型大数据率相比,闪烁过程是缓慢的。因此,我们采用准静态块衰落模型,并研究了正交脉冲位置调制的假设下的信道中断概率。我们研究通过使用多个激光器和多个孔径,从而创建一个多输入多输出(MIMO)信道的闪烁缓解。非理想的光电探测也被假定为组合的散粒噪声和热噪声被认为是信号无关的加性高斯白噪声。假设理想的接收机信道状态信息(CSI),我们计算的信噪比指数的情况下,闪烁是对数正态分布,指数和伽玛-伽玛分布,其中涵盖了广泛的大气湍流条件。此外,我们示出了非常大的增益,在某些情况下大于15 dB,当发射机CSI也可通过调整发射的电功率。

英文摘要:

The free-space optical channel has the potential to facilitate inexpensive, wireless communication with fiber-like bandwidth under short deployment timelines. However, atmospheric effects can significantly degrade the reliability of a free-space optical link. In particular, atmospheric turbulence causes random fluctuations in the irradiance of the received laser beam, commonly referred to as scintillation. The scintillation process is slow compared to the large data rates typical of optical transmission. As such, we adopt a quasi-static block fading model and study the outage probability of the channel under the assumption of orthogonal pulse-position modulation. We investigate the mitigation of scintillation through the use of multiple lasers and multiple apertures, thereby creating a multiple-input multiple output (MIMO) channel. Non-ideal photodetection is also assumed such that the combined shot noise and thermal noise are considered as signal-independent Additive Gaussian white noise. Assuming perfect receiver channel state information (CSI), we compute the signal-to-noise ratio exponents for the cases when the scintillation is lognormal, exponential and gamma-gamma distributed, which cover a wide range of atmospheric turbulence conditions. Furthermore, we illustrate very large gains, in some cases larger than 15 dB, when transmitter CSI is also available by adapting the transmitted electrical power.

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