Static hybrid multihop relaying and two hops hybrid relaying using DSTC

In this paper, we propose a static hybrid multihop relaying protocol where some relays amplify the received signal whereas the remaining ones use decode and forward (DF) relaying. The relaying mode in each relay is set using the distance between the different nodes and the average SNR. The exact and asymptotic bit error probabilities, the block error probability and the throughput of hybrid automatic repeat request (HARQ) protocols are derived. Simulation results are provided in different contexts to compare the performance of hybrid relaying to conventional AF and DF relaying. In the second part of the paper, we propose a static hybrid amplify and forward (AF) and DF relaying using distributed space-time coding (DSTC). Relays close to the source amplify the received signal, and the remaining relays transmit only if they correctly decoded. All AF relays and DF relays that have correctly decoded transmit using DSTC in order to benefit from spatial diversity. The proposed protocol offers better performance than AF relaying using DSTC and similar performance to DF relaying using DSTC. However, the complexity and transmission delays of the proposed static hybrid AF-DF relaying is lower than that of DF relaying since decoding is not performed at AF relays.