Common Coding and Synchronization Layer: Next Steps NASA Optical Communications Working Group 17 April /9/20151

Common Coding & Synch Proposal 3/9/20152

Common Coding & Synch Proposal: Next Steps NASA has proposed a High Data Throughput Coding & Synch White Book, including: – Physical layer framing (1024-bit header) – Forward Error Correction (DVB-S2) – Channel interleaving This White Book proposal is also NASA’s proposal for a common Coding & Sync layer – NASA is requesting participating agencies to evaluate this proposal for their high data throughput needs – Alterations or alternative proposals will be considered by Optical Comm Working Group Optical Comm Working Group should come to a consensus on the common proposal before collaboration begins with Coding & Synch Working Group 3/9/20153

Backup 3/9/20154

Physical Layer Framing 1024-bit header is appended to each (interleaved) codeword at physical layer Header contents may be encoded separately from payload data with a code that may be decoded at space relay Includes information necessary for switching, multiplexing and demultiplexing performed at physical layer – Unique ID – Content specifier (data vs. fill frame) – Channel state – Frame sequence number – Physical layer control Unique Word (384b) Interleaved Codeword (64800b) Channel State, FSN, etc. (640b) 1024-bit Header

Forward Error Correction Links primarily utilize ½-rate DVB-S2 code – Industry standard, based on ETSI EN – BCH outer code + LDPC inner code Other DVB-S2 code rates may be used with coordination between user and ground relay BCHLDPC 64,800 code bits 32,400 code bits 32,208 source bits

Channel Interleaving Channel interleaver is used for all links going through the Earth atmosphere Convolutional bit interleaver with data-rate dependent parameters