Punctured serial concatenated convolutional coding system and method for low-earth-orbit satellite data communication

DETAILED DESCRIPTION In accordance with this invention, a coding system ideally suited for use in a low-Earth-orbit (LEO) satellite data communication network is provided.
Data to be transmitted from one location on the earth to another location is assembled into digital data packets containing a header and a payload which collectively contain input data bits of information.
Prior to transmission, the input data bits of information are forward error correction (FEC) coded by a punctured serial concatenated convolutional encoder.
The punctured serial concatenated convolutional encoder employs an outer encoder that outer convolutionally encodes the input data bits to produce outer encoded data bits and outer encoded parity bits.
The outer encoded parity bits are punctured, and the remaining outer encoded parity bits and the outer encoded data bits are bit interleaved.
The resulting bit interleaved, outer encoded data and remaining parity bits are inner convolutionally encoded by an inner encoder to produce concatenated coded, bit interleaved inner data bits and concatenated coded, bit interleaved inner parity bits.
The concatenated coded, bit interleaved inner parity bits are punctured, and the remaining concatenated coded, bit interleaved inner parity bits and the concatenated coded, bit interleaved inner data bits are combined to produce serially concatenated convolutional coded data and parity bits.
Preferably, the inner and outer convolutional coders are both systematic and recursive.
In accordance with other aspects of this invention, the serially concatenated convolutional coded data and parity bits are decoded by a serial concatenated convolutional decoder.
First, the serially concatenated convolutional data and parity bits are decombined to separate data bits from parity bits, producing a data stream and a parity stream.
Inner convolutional encoded erasures are inserted into the parity stream to replace the parity bits eliminated by puncturing during encoding.
The resulting supplemented parity stream and the data stream are inner decoded by a soft-input soft-output (SISO) inner module to obtain updated bit probabilities of the inner encoder input and output