The Consultative Committee for Space Data Systems
CCSDS) has produced over the years a de facto standard
(
for all space-related communication systems. In the latest
versions of the standard [1] there has been an increment in
the foreseen downlink throughput for deep-space
communications, reaching up to tens of megabits per
second. Four channel coding schemes have been described
in [2] and consequently assembled into application-wise
forward-error-correction (FEC) schemes in [3]. Both turbo
[
4] and low-density-parity-check (LDPC) [5] codes are
currently contemplated for deep-space communications
[2]; while the suggested turbo codes target stricter bit error
rate (BER) constraints, LDPC codes have been recently
included in the standard and have higher rate, and they are
currently subject to CCSDS experimentation [6]. Both
turbo and LDPC codes are common in on-Earth wireless
communication systems; however, throughput
requirements are much higher than those for deep-space
communications, while frame error rate (FER) constraints
are more relaxed. In fact, spacecraft-to-Earth
communications are characterized by limited amounts of
available power and long transmission times, and a failed
reception and consequent retransmission are often
unacceptable. Thus, ad hoc powerful FEC schemes must
be devised.