Coding techniques under study at NASA

Abstract

NASA is studying coding techniques in an effort to achieve communications from spacecraft at lower effective isotropic radiated power. Presently NASA's coding standards support a (2,1,6) convolutional inner code and a Reed-Solomon (255,223'8) outer code; during the past two years studies were conducted on the performance of a long constraint length (2,1,14) convolutional code and the Turbo codes. Flight experiments will lead to results on the actual performance, complexity and implementation of such coding systems.

Performance estimation of bit-interleaved coded modulation based on information processing characteristics

“…In case of nonsystematically encoded convolutional codes, the minimum ratio E b /N 0 is attained at non-zero rate (indicated with a marker). These points indicate an optimum operating point for an additional outer coding scheme.Selecting the outer code rate accordingly, the concatenated coding scheme operates with highest powerefficiency (basically, this is an explanation for the excellent performance of the concatenation of an inner rate-1/2 convolutional code and an outer high-rate Reed-Solomon code, e.g., in the NASA standard [21]). If set-partition labeling is applied, the optimum outer rate is slightly larger compared to Gray-labeling.…”