<p><a href="http://www.osa-jon.org/features/OWC_2005.html">Feature Issue on Optical Wireless Communications (OWC)</a></p> The propagation of an on-off keying modulated optical signal through an optical atmospheric turbulent channel is considered. The intensity fluctuations of the signal observed at the receiver are modeled using a gamma-gamma distribution. The capacity of this channel is determined for a wide range of turbulence conditions. For a zero inner scale, the capacity decreases monotonically as the turbulence strengthens. For non-zero inner scale, the capacity is not monotonic with turbulence strength. Two error-correction schemes, based on low-density parity-check (LDPC) codes, are investigated as a means to improve the bit-error rate (BER) performance of the system. Very large coding gains--ranging from 5.5 to 14 dB, depending on the turbulence conditions--are obtained by these LDPC codes compared with Reed-Solomon error-correction codes of similar rates and lengths.
© 2005 Optical Society of America
Optical Wireless Communications
Original Manuscript: April 18, 2005
Revised Manuscript: April 15, 2005
Published: August 24, 2005
Optical Wireless Communications (2005) Journal of Optical Networking
Jaime Anguita, Ivan Djordjevic, Mark Neifeld, and Bane Vasic, "Shannon capacities and error-correction codes for optical atmospheric turbulent channels," J. Opt. Netw. 4, 586-601 (2005)