Low-Complexity Architectures of a Decoder for IEEE 802.16e LDPC Codes

Low-density parity-check (LDPC) codes have recently been included as error-correcting codes in IEEE 802.16e, for wireless metropolitan area networks. This paper proposes a flexible, low-complexity LDPC decoder fully compliant with all 114 codes defined by the standard. The decoder runs the layered decoding algorithm to increase the convergence speed, and relies on a semi-parallel implementation with serial processing units working in pipeline to reduce the latency. Particularly, two different architectures are considered, and their RTL/memory complexity tradeoffs are analyzed. The resulting design yields a throughput ranging from 93 to 497 Mbps by means of 15 iterations at the clock frequency of 400 MHz. Synthesis on 65 nm CMOS technology, shows a chip area less than 0.59 mm², despite the high flexibility, which compares favourably with similar implementations.