In hybrid free space optical/radio frequency (FSO/RF) systems, switching between the optical and RF links depends on the optical and RF signal to noise ratio (SNR) threshold levels; therefore, the correct choice of these threshold levels is essential to make best use of the complementary nature of optical and RF links. Optimal selection of these threshold levels is the prime objective of this paper. A hybrid FSO/RF system using modified switching scheme with two optical and one RF threshold is considered. Here, we propose an algorithm to obtain the optimized thresholds, which yield minimum bit error rate (BER) for a given outage probability under a constraint on maximum transmitted power. The optimized thresholds are dependent on the average optical and RF SNR. Hybrid FSO/RF system use both optical as well as RF power. The average system SNR is computed by considering the actual optical and RF power consumption. Also the performance of the hybrid FSO/RF system is studied with respect to average system SNR using optimized optical and RF thresholds. This analysis reveals the existence of a critical operating point of average optical SNR, beyond which the system should be preferably operated to ensure minimum BER.

中文翻译：

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存在强烈大气湍流的混合FSO / RF系统切换方案门限优化

在自由空间光/射频混合（FSO / RF）系统中，光链路和RF链路之间的切换取决于光和RF信噪比（SNR）阈值水平；因此，正确选择这些阈值水平对于充分利用光链路和RF链路的互补特性至关重要。这些阈值水平的最佳选择是本文的主要目标。考虑了使用改进的切换方案的FSO / RF混合系统，该方案具有两个光学和一个RF阈值。在这里，我们提出一种算法，以获取优化的阈值，该阈值在最大发射功率的约束下，对于给定的中断概率产生最小的误码率（BER）。优化的阈值取决于平均光学和RF SNR。混合FSO / RF系统同时使用光功率和RF功率。通过考虑实际的光和RF功耗来计算平均系统SNR。此外，还使用优化的光学和RF阈值针对平均系统SNR研究了混合FSO / RF系统的性能。该分析揭示了平均光学SNR的关键工作点的存在，超过该临界工作点，系统应优先运行以确保最小BER。