  This paper investigates the Triangle Single Parity Check (T/SPC) code, a
novel class of high-rate low-complexity LDPC codes. T/SPC is a regular, soft
decodable, linear-time encodable/decodable code. Compared to previous high-rate
and low-complexity LDPC codes, such as the well-known Turbo Product Code /
Single Parity Check (TPC/SPC), T/SPC provides higher code rates, shorter code
words, and lower complexity. This makes T/SPC very attractive for practical
implementation on integrated circuits.
  In addition, we analyze the performance of iterative decoders based on a
soft-input soft-output (SISO) equalizer using T/SPC over high-density
perpendicular magnetic recording channels. Computer simulations show that the
proposed scheme is able to achieve a gain of up to 0.3 dB over TPC/SPC codes
with a significant reduction of implementation complexity.
