WITH sustained growth in demands for multimedia, wireless, and broadband services, significant effort has been made to apply iterative forward error correction (FEC) coding techniques to advanced communications systems. These techniques have proved to be very effective in extending the limits and services of wireless communications, expanding the areal density of magnetic recording systems, and improving the throughput of terrestrial optical systems. Low-density parity-check (LDPC) codes [1] have emerged as one of the top contenders for such applications after their main rivals, turbo codes [2], have seen limited acceptance (particularly in optical applications) due to their high implementation complexity, decoding latency, as well as performance degradation for relatively short block-length and error-floors at high signal-to-noise ratios (SNRs). Research has shown that LDPC codes can achieve record-breaking performance for low SNR applications [3], [4], and are more amenable to rigorous analysis and design. They offer more flexibility in the choice of code parameters, and their decoders require simpler processing. These characteristics have made it possible to design appropriate LDPC codes for many communications scenarios; they have been adopted in next generation digital video broadcasting (DVB-S2) via satellite [5], and considered for adoption in wireless local area network (WLAN) air interface (802.11) [6], wireless personal area networks (WPANs) (802.12) [7], mobile broadband wireless access (MBWA) networks (802.20) [8], advanced magnetic and magneto-optic storage/recording systems [9], and long-haul optical communication systems [10].