  Generalized low-density parity-check (GLDPC) codes, where single parity-check
(SPC) constraint nodes are replaced with generalized constraint (GC) nodes, are
a promising class of codes for low latency communication. In this paper, a
practical construction of quasi-cyclic (QC) GLDPC codes is proposed, where the
proportion of generalized constraints is determined by an asymptotic analysis.
We analyze the message passing process and complexity of a GLDPC code over the
additive white gaussian noise (AWGN) channel and present a
constraint-to-variable update rule based on the specific codewords of the
component code. The block error rate (BLER) performance of the GLDPC codes,
combined with a complementary outer code, is shown to outperform a variety of
state-of-the-art code and decoder designs with suitable lengths and rates for
the 5G Ultra Reliable Communication (URC) regime over an additive white
gaussian noise (AWGN) channel with quadrature PSK (QPSK) modulation.
