Multiple transmitter performance with appropriate amplitude modulation for free-space optical communication
| Autor: | Jason A. Tellez, Jason D. Schmidt |
|---|---|
| Rok vydání: | 2011 |
| Předmět: |
Physics
Scintillation business.industry Materials Science (miscellaneous) Spectral density Probability density function Industrial and Manufacturing Engineering Amplitude modulation Optics Modulation Probability distribution Business and International Management business Random variable Free-space optical communication |
| Zdroj: | Applied optics. 50(24) |
| ISSN: | 1539-4522 |
| Popis: | The propagation of a free-space optical communications signal through atmospheric turbulence experiences random fluctuations in intensity, including signal fades, which negatively impact the performance of the communications link. The gamma–gamma probability density function is commonly used to model the scintillation of a single beam. One proposed method to reduce the occurrence of scintillation-induced fades at the receiver plane involves the use of multiple beams propagating through independent paths, resulting in a sum of independent gamma–gamma random variables. Recently an analytical model for the probability distribution of irradiance from the sum of multiple independent beams was developed. Because truly independent beams are practically impossible to create, we present here a more general but approximate model for the distribution of beams traveling through partially correlated paths. This model compares favorably with wave-optics simulations and highlights the reduced scintillation as the number of transmitted beams is increased. Additionally, a pulse-position modulation scheme is used to reduce the impact of signal fades when they occur. Analytical and simulated results showed significantly improved performance when compared to fixed threshold on/off keying. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
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