New Four-State Space-Time Trellis Codes for Multi-pair Two-way Relaying in MIMO Cooperative Networks

Multiple-input multiple-output (MIMO) cooperative networks have been intensively studied as an emerging research issue due to their abilities for increasing spatial diversity. Two-way communication in MIMO cooperative networks could significantly increase spectral efficiency, where each pair of source nodes (SNs) exchanges information through a relay node (RN). The two-way relay channel (TWRC) has been proposed in the previous work for multi-pair of SNs using amplify-and-forward (AF). However, it could provide only the diversity gain. On the other hand, the network performance can also be improved by coding advantage. Therefore, this paper proposes a new four-state space-time trellis codes (STTC) for multi-pair TWRC with a single multi-antenna RN using AF relaying strategy. The system model for applying the proposed STTC is introduced. Then, the performance of the proposed STTC is evaluated in terms of pairwise-error probability as a performance metric of signal-to-noise ratio (SNR) for the Rayleigh fading channel. Moreover, the proposed code search is obtained using a systematic code approach. The result shows that the proposed STTC could improve the network performance compared to the previous codes in which a significant coding gain is provided by the proposed codes. Thus, the proposed STTC for the networks has the advantage of both diversity and coding gain.