Design and implementation of a belief propagation detector for sparse channels

In this paper, we address the design and implementation of the symbol detector for sparse channels which are described as having long spanning durations but sparse multipath structure. The traditional maximum-likelihood (ML) algorithm provides an optimal performance to eliminate the multipath effect, however its complexity scales exponentially with the channel length. As a more efficient symbol detection algorithm through sparse channels, the iterative belief propagation (BP) algorithm has a complexity merely dependent on the number of nonzero channel coefficients, while achieving a near-optimal error performance. We present the architecture design for a reconfigurable low-complexity high-throughput BP detector. As an example, we implement a BP detector for quadrature phase-shift keying (QPSK) modulation on Xilinx Virtex 5 FPGA with a maximum frequency of 252 MHz and equivalently a throughput of 100.8 Mb/s at 5 iterations.