Multiple Gain Combiner for Free Space Optical Communications
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Solution Overview
Problem
Existing free space optical communication systems face challenges such as high hardware complexity, requirement of channel state information, adaptive weight adjustment, and poor bit error rate (BER) performance, particularly in combating signal degradation due to turbulence and misalignment.
Innovation Solution
The implementation of a Multiple Gain Combiner (MGC) system that uses a bank of weighted factors, combiners, and a maximum output selector to combine signals from multiple receivers with unequal weights, reducing hardware complexity and eliminating the need for adaptive weight adjustment and channel state information, while providing improved BER performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If MIMO or relay networks are used to combat turbulence effects, then system performance is improved, but hardware complexity increases
Solution Approach 1:
The patent uses optical copying where the optical signal is copied to multiple relay nodes that forward the signal to the destination. Instead of using complex MIMO hardware at each node, simple optical copies are created and distributed through the relay network, achieving diversity gain with minimal hardware addition
Solution Approach 2:
The patent extracts the turbulence combat function from complex MIMO hardware and implements it through a simplified relay network architecture. The diversity combining function is extracted and implemented through simple optical switching and signal selection at the destination, rather than requiring complex coordinated hardware at all nodes
2Reliability
If Maximal Ratio Combining (MRC) is used to achieve optimal BER performance, then BER performance is improved, but device complexity and requirement for channel state information increases
Solution Approach 1:
The patent uses simple optical switches and signal selectors that are much simpler than MRC hardware. Instead of requiring complex adaptive weight adjustment and channel state information processing, the system uses simple optical switching elements that select the strongest signal path without requiring complex computation or feedback channels
Solution Approach 2:
The relay network automatically selects the best signal path through simple optical switching at the destination. The system self-adjusts to turbulence conditions by naturally selecting the strongest received signal through optical switching, without requiring external control or complex processing
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The MGC system achieves better BER performance compared to traditional schemes like SC and EGC, with performance close to the optimal MRC method, while being cost-effective and requiring less hardware complexity, thus addressing the limitations of existing diversity combining techniques in free space optical communications.
Implementation Method 1
convert encoded data into an optical signal
Implementation Method 2
photo detector is used for detecting the optical signal
Data Source
AI summary
Diversity combining schemes have been extensively used in wireless and free space optical communication systems. The present invention of a system and method for free space optical communications where multiple gain combiner (MGC) provides a better performance as compared to selection combining (SC) and equal gain combining (EGC) and can also be used for wireless applications. It also gives a cost effective solution with a minimal degradation in quality when maximal ratio combining (MRC) is compared in terms of hardware complexity and implementation cost. There is no need for present channel state information. Also, Adaptive weight adjustment is not required in present invention. Therefore, the MGC of system and method disclosed in the present invention is a simple, cost effective and high performance diversity combiner.