Blind Compute-and-Forward

Compute-and-forward (C&F) relaying usually requires channel state information (CSI) at the receivers so that an "optimal" scale factor can be computed for the purposes of decoding. In this paper, a blind C&F scheme-i.e., one not requiring CSI-is developed. Rather than attempting to compute the optimal scale factor, this new scheme seeks one (or more) "good" scalars, i.e., scalars which allow correct decoding despite possibly being sub-optimal. The region of all such good scalars is characterized. To find a good scalar, a computationally efficient scheme, involving error-detection and a hierarchically organized list, is proposed. Simulation results show that this blind C&F scheme achieves-for a class of lattices admitting an efficient trellis decoder-the same throughput as its CSI-enabled counterpart, at the expense of, approximately, a ten-fold increase in computational complexity in the high-throughput region.