CCSDS telemetry channel coding: the turbo coding option

As of 1993 a new coding concept promising gains as close as 0.5 dB to the Shannon limit on bit error rates was introduced by Berrou et al. The coding scheme called turbo coding achieved immediate worldwide attention. After the first discussions in the May '96 Meeting of the Consultative Committee for Space Data Systems (CCSDS), it was decided-in agreement with NASA and other national space agencies-to include a set of turbo codes in a new issue of the CCSDS telemetry channel coding recommendation. Turbo coding will be an add-on option to the recommendations without modifying the existing coding schemes and will retain compatibility with the CCSDS Packet Telemetry recommendation. Pink sheets updating the recommendation are currently being reviewed to formally establish turbo coding as an alternative to both Reed-Solomon and convolutional coding for deep space and near-Earth missions. This paper presents the turbo codes that are being proposed for the recommendation, and their expected higher coding gain with respect to the present encoding schemes.