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Mobile free space optical (FSO) links suffer from frequent link blockages due to opaque obstructions or link degradations that can result in degraded or failed networks. In this paper, a dynamic layer-1 based topology and routing control methodology is presented for assuring connectivity in networks with fragile links. Core components of this methodology are described with special emphasis on the...
In this paper, we investigate the performance of the sub-carrier multiplexed-free space optics (SCM-FSO) for transmitting code division multiple access (CDMA) signals in terms of carrier-to-noise-plus-interference ratio (CNIR) and bit error rate (BER), under Gamma-Gamma turbulent FSO channel. We propose an analytical model for optimization of the SCM-FSO link and a closed-form BER expression taking...
Applications such as situational awareness are becoming more prevalent in highly dynamic tactical mesh networks and are placing high demand on existing RF network capacity. These applications require high aggregate data capacity but have some flexibility in packet by packet latency. Combined radio frequency and free space optical communication within a heavily scintillated atmospheric path behaves...
The techniques of Terminal transmit adaptation are critical for achieving maximal channel throughput when the link loss exhibits large variation. In this paper, some technical issues regarding transmit power control and mode adaptation in satellite communication (SATCOM) systems are addressed. The transmit adaptation is explored in terms of optimizing the link availability. The analysis extends the...
Scintillation mitigation is an important aspect of free-space optical (FSO) communications link design. While a number of hardware-based mitigation techniques have been proposed in the literature and deployed in experimental systems (e.g., aperture averaging, wavelength diversity, etc.), novel baseband signal processing approaches have the potential to complement - or even supplant - these traditional...
In this paper, an analytical time-domain model is presented to analyze the radio over free space optical (RoFSO) systems under two turbulence channels, the log-normal and the exponential channel. This analytical model uses general cases of a dual-drive Mach-Zehnder modulator (DD-MZM) and photodetector (PD) for typical optical double sideband (ODSB) and single sideband (OSSB) signals under turbulence...
Mobile free space optical (FSO) and directional RF communications links suffer from frequent link blockages due to opaque obstructions that can result in degraded or failed networks. In this paper, a methodology is presented for assuring connectivity in networks with fragile links. The frequency and duration of link blockages are characterized using modeling and emulation tools developed for realistic...
Ground and air testing of mobile FALCON free-space optical (FSO) communications terminals was performed in New Mexico by ITT Corporation, JHU/APL and AFRL. The testing verified the operation of the terminals pointing, acquisition, tracking and data transmission for ground to ground link distances up to 36 km and air to air and air to ground link distances up to 65 km. The FALCON terminals have a nominal...
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