Blind Signal Detection Under Synchronization Errors for FSO Links With High Mobility

Abstract

We consider the use of free-space optical communication for fast moving platforms such as high-speed trains where the sampling clock offset is randomly changing and, in addition, the receiver does not have any information on the instantaneous channel fading coefficient. By employing multiple samplers at the receiver, we propose a class of sequence detection methods for the case of OOK signaling without using any training sequence. First, we study maximum likelihood based detection, which has a relatively high computational complexity. Second, by employing generalized likelihood ratio test, we propose a more practical blind sequence detection method of reduced complexity. To further reduce the computational complexity, third, we propose a novel scheme that uses two wavelengths at the transmitter and differential blind detection at the receiver. Fourth, to benefit from diversity gain with this differential scheme, we consider the use of sufficiently different wavelengths, where we propose an efficient blind detection method. The pros and cons of each proposed detection method are contrasted through numerical results and their processing load are compared as well.

Achieved Throughput of Hovering UAV-Based Optical Wireless Communications

“…According to the results presented in Figs. 2a-2c, by decreasing σ θ that leads to an increase in G, the ergodic capacity (17) becomes close to that derived in (8). For instance, we observe from Fig.…”

“…For instance, we observe from Fig. 2b that for G = 3.6, the ergodic capacity obtained with ( 17) is close to that derived with (8). Notice that the gap between the simulation and analytical results at low values of w z is due to the approximation used in (4).…”

“…In [7], the authors proposed an optical UAV-assisted network that collects data from sensors based on multiple BS and multiple collection trees. In [8], the authors proposed a novel technique to detect optical signals for fast moving platforms where the sampling time is suffering from random errors. Spatial tracking of optical signal under UAV fluctuations is studied in [9] for the receiver equipped by photodetector array.…”

Improving the Efficiency of FSO Communication Using a Hybrid Optimization Based U-NET Model in 6G Applications

“…The wind speeds affect the FSO performance, building sways which lead to the receiver and laser source misalignment. It induces pointing errors while considering these factors [12][13][14].…”

Measurement Approaches and Implementation of a Fading Characterization Tester for Evaluating Optical Turbulent Channels

“…The optical path differences resulting from fractions can bring about different timing delays at the receiving lens, which causes ISI [11,12]. The ISI also leads from synchronization errors, which always occur in the OWC links with high mobility [13]. Besides, additional outage events can be incited by pointing errors [14,15].…”