  We propose a novel encoding/transmission scheme called continuous chain (CC)
transmission that is able to improve the finite-length performance of a system
using spatially-coupled low-density parity-check (SC-LDPC) codes. In CC
transmission, instead of transmitting a sequence of independent codewords from
a terminated SC-LDPC code chain, we connect multiple chains in a layered
format, where encoding, transmission, and decoding are now performed in a
continuous fashion. The connections between chains are created at specific
points, chosen to improve the finite-length performance of the code structure
under iterative decoding. We describe the design of CC schemes for different
SC-LDPC code ensembles constructed from protographs: a (J,K)-regular SC-LDPC
code chain, a spatially-coupled repeat-accumulate (SC-RA) code, and a
spatially-coupled accumulate-repeat-jagged-accumulate (SC- ARJA) code. In all
cases, significant performance improvements are reported and, in addition, it
is shown that using CC transmission only requires a small increase in decoding
complexity and decoding delay with respect to a system employing a single
SC-LDPC code chain for transmission.
