611 research outputs found
Bandwidth efficient CCSDS coding standard proposals
The basic concatenated coding system for the space telemetry channel consists of a Reed-Solomon (RS) outer code, a symbol interleaver/deinterleaver, and a bandwidth efficient trellis inner code. A block diagram of this configuration is shown. The system may operate with or without the outer code and interleaver. In this recommendation, the outer code remains the (255,223) RS code over GF(2 exp 8) with an error correcting capability of t = 16 eight bit symbols. This code's excellent performance and the existence of fast, cost effective, decoders justify its continued use. The purpose of the interleaver/deinterleaver is to distribute burst errors out of the inner decoder over multiple codewords of the outer code. This utilizes the error correcting capability of the outer code more efficiently and reduces the probability of an RS decoder failure. Since the space telemetry channel is not considered bursty, the required interleaving depth is primarily a function of the inner decoding method. A diagram of an interleaver with depth 4 that is compatible with the (255,223) RS code is shown. Specific interleaver requirements are discussed after the inner code recommendations
Capacity-achieving CPM schemes
The pragmatic approach to coded continuous-phase modulation (CPM) is proposed
as a capacity-achieving low-complexity alternative to the serially-concatenated
CPM (SC-CPM) coding scheme. In this paper, we first perform a selection of the
best spectrally-efficient CPM modulations to be embedded into SC-CPM schemes.
Then, we consider the pragmatic capacity (a.k.a. BICM capacity) of CPM
modulations and optimize it through a careful design of the mapping between
input bits and CPM waveforms. The so obtained schemes are cascaded with an
outer serially-concatenated convolutional code to form a pragmatic
coded-modulation system. The resulting schemes exhibit performance very close
to the CPM capacity without requiring iterations between the outer decoder and
the CPM demodulator. As a result, the receiver exhibits reduced complexity and
increased flexibility due to the separation of the demodulation and decoding
functions.Comment: Submitted to IEEE Transactions on Information Theor
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