Data Rate Error Correction System for Free Space Laser Communication

The objective of this research is to design and implement error-correction coding in a free-space laser communication channel to correct both single bit and burst errors at a user data rate of 155 Mb/s. Correcting these errors will significantly increase the reliability and weather-dependent availability of lasercom systems. Standard error-correction codes add redundant data to allow for correction of isolated errors; however, in an optical channel, atmospheric scintillation causes fading which can introduce bursts of errors. Practical real-time implementations of error-correction schemes for burst errors of this magnitude are presently nonexistent. An innovative error-correction method that allows for real-time correction of both single and burst errors will be tested by building a prototype electronic unit that will be integrated with AstroTerra's TerraLink-155 site-to-site lasercom system. This error-correction method views user data as a two-dimensional block of rows and columns; adding coding to the rows will correct single-bit errors, while adding extra bits to the columns allows for the correction of burst errors that span an entire row. Testing and evaluation will be done to optimize certain elements of this coding scheme, including the row length, column length, and the type of code used.