GSFC-STD-9100

Abstract

<strong>Purpose</strong> <br>The purpose of this standard is to establish a common GSFC channel coding protocol for bandwidth efficient spacecraft communications. Currently many Goddard missions use the concatenated Reed-Solomon and convolutional coding technique for space to ground links. While this standard has served NASA well in the past it is bandwidth inefficient. The need for bandwidth efficiency has prompted the Microwave and Communication Systems Branch (Code 567) to search for a new channel code that require less bandwidth without paying a heavy penalty in power requirement and complexity. This document details the result of that search. It gives a technical description of this new channel coding called low density parity check (LDPC) coding (Section 4.1.3). A description of the base LDPC code and its' encoding is given in Section 4.2 and 4.3 and Appendix A. However, the base code needs to be modified to ease implementations for current space and ground systems. This modification is the standard and is described in Section 4.4. In addition, Section 4.5 outlines synchronization issues and the Appendices B and C discuss complexity issues and performance testing respectively. The reader is assumed to have a basic understanding of channel coding theory (linear algebra also) and digital communications. (The reader is encouraged to review [7] for an overview of linear block codes). <br><strong>Applicability</strong> <br>This standard is intended for any space to ground communication link that requires data high reliability and power efficiency, and is applicable when cited in contract, program, and other Agency documents as a technical requirement. Mandatory requirements are indicated by the word "shall." Tailoring of this standard for application to a specific program or project shall be approved by the Technical Authority for that program or project.