Decoding Options for the Symmetric and Asymmetric Turbo-Coded Two-Way Relay Channel

In this paper, we extend our recent work on joint decoding of trellis codes for the two-way relay channel to quaternary decoding of turbo codes and evaluate two approaches for rate adaptation. More specifically, we consider the uplink phase, which has been identified as the bottleneck, and apply a quaternary joint turbo decoder for both packets. For asymmetric channels, we evaluate two methods of adapting the code rate while keeping the standard LTE turbo codes. The first approach applies puncturing which is known in LTE as rate matching and adapts the codeword lengths while the second, less well-known, method reduces the message length and is known as expurgation