Deep-Space Optical Communications Downlink Budget: Modulation and Coding
Abstract
A link budget for a deep-space optical channel depends in part on the choice of modulation format and error-control coding scheme. This article describes several properties of the channel capacity that lead to an appropriate selection of modulation format, pulse-position modulation (PPM) order, and error-control code rate. It also describes performance limits when additional constraints -- such as bounds on average power, peak power, and uncoded symbol-error rate -- are imposed. We compare these limits to the performance of Reed-Solomon codes and convolutional codes concatenated with PPM, and show that, when iteratively decoded, the concatenated convolutional codes operate approximately 0.5 dB from capacity over a wide range of signal levels, about 2.5 dB better than Reed-Solomon codes.
- Publication:
-
Interplanetary Network Progress Report
- Pub Date:
- August 2003
- Bibcode:
- 2003IPNPR.154K...1M