Capacity Improvement of a Free Space Optical Satellite Uplink using Transmitter Power and Rate Adaptation

2017 ◽  
Vol 38 (4) ◽  
Author(s):  
Pooja Gopal ◽  
V. K. Jain ◽  
Subrat Kar

AbstractDegradation due to atmospheric turbulence leads to significant outage in a free space optical satellite uplink with fixed transmitter parameters. If the channel state is known at the transmitter, then its parameters can be suitably changed, and there could be a considerable improvement in channel capacity. However, the extremely long link length of an Earth-to-Geostationary Earth Orbit (GEO) satellite link would render feedback of channel state from the receiver infeasible, before the channel changes. In this paper, a channel pre-estimation method at the transmitter is proposed, and the expression for capacity with transmitter power and rate adaptation is derived. The results are compared with that of the capacity with outage. It is observed that there can be an improvement by a factor of 1.66 in achievable average capacity per Hertz with the adaptive transmitter. Also, the outage probability is reduced from 18.02 % to almost 0.

2012 ◽  
Vol 571 ◽  
pp. 382-389
Author(s):  
Zhong Hua Yang ◽  
Qi Wen Ran ◽  
Jing Ma ◽  
Li Ying Tan ◽  
Shi Chen Wu ◽  
...  

Adaptive interleaving method implemented by a hybrid system is proposed to deal with burst errors caused by long and deep channel fades in free space optical communications (FSOC) through atmospheric turbulence. Actually, considerable memory can be saved by changing the interleaving depth at transmitter and receiver according to the updated burst information from channel estimator. Combining with error correcting codes, anti-burst performance of the proposed method is evaluated by simulations based on channel state information from laser transmission experiments over an 11.8 km urban link. Simulation results show that 1~2 or even higher orders of magnitude of a memory can be saved when comparing with the maximum memory interleaving. The results have proved that the cost of anti-burst performance can be minimized to 10% or even smaller by the adaptive interleaving method when joint use with error correcting codes.


2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Disha Srivastava ◽  
Gurjit Kaur ◽  
Garima Singh ◽  
Prabhjot Singh

AbstractFree Space Optical (FSO) communication systems are gaining popularity due to its tremendous speed, advanced capacity, cost effectiveness, secure and easy to deploy wireless networks. This technology has proven an effective choice for last mile applications and hard to reach areas where deployment of optical fibre links is not feasible. But FSO link is highly weather dependent and as signal passes through the atmospheric channel, the main impairments are the atmospheric turbulence, which induce fading and deteriorate the system performance. Delhi has a great potential for FSO communication because of its clear skies. Since there is no analysis for weather condition found in Delhi, this work provides analysis of typical Delhi weather condition ranging from heavy to light rain, fog and clear sky. The performance of FSO link is analysed in terms of attenuation and link length margin under different weather condition. The results are concluded to identify which atmospheric condition influences more on FSO link performance.


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