Enabling Partial Forwarding by Decoding-Based One and Two-Stage Selective Cooperation

With selection decode-and-forward (SDF) relaying, an accurate forwarding decision is essential to avoid error propagation and achieve full cooperation diversity. The methods in literature are either based on CRC or SNR thresholds, both resulting in poor end-to-end performance in practical wireless scenarios with non-block fading and channel coding. We propose to improve performance by accurate and frequent adaptation with partial forwarding. To achieve this in channel-coded systems, we introduce a decoding-based forwarding decision at the relay and propose (1) minimum path difference (MPD) as a non-overhead and accurate decoding-based decision metric and (2) MPD-based SDF protocols with one and two decision stages. Our performance study validates that these protocols significantly improve SDF's end-to-end BER under realistic assumptions.