A novel high-throughput (6 Gb/s), fully-parallel FPGA-based 1200-bit rate-1/2 Low Density Parity Check (LDPC) decoder design is presented. The decoder features a PEG- based regular (6,3) code and a modified min-sum algorithm that improves performance without any additional hardware overhead.

This work considers the design and performance of a stream-oriented approach to turbo codes which avoids the need for data framing. The stream paradigm applies to both serial and parallel turbo codes using continuous, free-running constituent encoders along with continuous, periodic interleavers. A stream-oriented turbo code based on parallel concatenated convolutional codes (PCCC) is considered and interleaver design criteria are developed for both block and nonblock periodic interleavers. Specifically, several nonblock interleavers, including convolutional interleavers, are considered. Interleaver design rules are verified using simulations where it is shown that nonblock interleavers with small-to-moderate delay and small synchronization ambiguity can outperform block interleavers of comparable delay. For large-delay designs, nonblock interleavers are found which perform within 0.8 dB of the capacity limit with a synchronization ambiguity of N=11.

The performance and design of turbo codes using coherent BPSK signaling on the Rayleigh fading channel is considered. In low signal-to-noise regions, performance analysis uses simulations of typical turbo coding systems. For higher signal-to-noise regions beyond simulation capabilities, an average upper bound is used in which the average is over all possible interleaving schemes. Fully interleaved and exponentially correlated Rayleigh channels are explored. Furthermore, the design issues relevant to turbo codes are examined for the correlated fading channel. Turbo interleaver design criteria are developed and architectural modifications are proposed for improved performance.

This paper describes the Rainbow-II optical metropolitan area network (MAN), which supports 32 nodes each at 1 Gbit/s over a distance of 10-20 km. Rainbow-II uses optical wavelength-division multiplexing (WDM), in a broadcast star architecture. Each node uses a separate fixed wavelength for transmitting data and a tunable receiver for receiving one of several data streams. The network is implemented in the form of optical network nodes, each attached to a host computer via the high-performance parallel interface (HIPPI). Each network node contains protocol processing hardware to offload the protocol processing work from the host computer onto the node. The goal is to provide full gigabit-per-second bandwidth to end-user supercomputer applications. Preliminary protocol performance measurements in a testbed network are given.