1 research outputs found
Outage Probability of the Gaussian MIMO Free-Space Optical Channel with PPM
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.Comment: 24 pages, 3 figures, 2 tables. Submitted to the IEEE Journal of
Lightwave Technolog