Finite Dimensional Nested Lattices based Wyner-Ziv Coding for Two-Way Relay Channel

Two-way relay channel (TWRC) models a cooperative communication situation performing duplex transmission via a relay station. For this channel, we have shown previously that a lattice-based physical layer network coding strategy achieves, at the limit of arbitrarily large dimension, the same rate as that offered by the random coding-based regular compressand-forward. In this paper, we investigate this scheme in finite dimension in order to propose a practical coding scheme that achieves a reasonable performance-complexity trade-off. The algorithm is based on finite dimensional nested lattices for WynerZiv coding. The relay uses the weaker side information available at the receivers to broadcast a quantized version of its output that is destined to be recovered at the two receivers with different distortions. We characterize the rate region allowed by our coding scheme, discuss the design criteria, and illustrate our results with some numerical examples.