System for coding system

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Having summarized the present invention, reference will now be made in detail to the description of the invention as illustrated in the drawings.
While the invention will be described in connection with these drawings, there is no intent to limit it to the embodiment or embodiments disclosed therein.
On the contrary, the intent is to cover all alternatives, modifications and equivalents included within the spirit and scope of the invention as defined by the appended claims.
Background on Multilevel Encoding and Multistage Decoding Before discussing the preferred embodiment of the present invention, a background on multilevel encoding and multistage decoding will first be provided.
In this regard, reference is made to FIG.
1, which is a block diagram illustrating the structure of a simple multilevel encoder 10.
The illustrated encoder is an L level encoder having a serial to parallel converter 12 at the front end.
As is known, the serial to parallel converter 12 includes an input and a plurality of outputs.
Most of the outputs are associated with, and directed to an encoder 14, 16, 17.
Each of the encoders 14, 16, 17 will receive one or more bits for encoding, and output the encoded bits to a symbol selector 18.
As illustrated, uncoded bits may be communicated directly from the serial to parallel converter 12 to the symbol selector 18 across one or more lines 19.
Multilevel coding has been recognized as an efficient way of combining error correction coding with modulation.
Multilevel coding, is generally a combination of several error correction codes applied to subsets of some signal constellation.
As is known, a typical code of this kind is, based on a set S.
sub.
0 and an L level partition chain S.
sub.
0 /S.
sub.
1 .
.
.
/S.
sub.
L.
In the multilevel encoder 10 of FIG.
1, the sequence of bits associated with the partition S.
sub.
i-1 /S.
sub.
i is a codeword of the binary code C.
sub.
i (n.
sub.
i, k.
sub.
i), and E.
sub.
i is the corresponding encoder.
The multilevel code may be made up of convolutional component codes, block codes, or a combination thereof An important parameter of a coded modulation scheme is the computational complexity of the decoder