Threshold-based hybrid relay selection scheme

摘要

In this paper, in order to reduce error propagation for cooperative systems, we propose and analyze two new threshold-based hybrid relay selection schemes for the three-node cooperative relaying system, named as hybrid amplify-decode-forward relaying (HADF) and direct-amplify-forward relaying (HDAF). When the signal-to-noise ratio (SNR) is higher than the specific threshold, which is designed in HDAF, the relay chooses to transmit message in amplify-and-forward (AF) mode, otherwise, the source node deals with message in direct transmission (DT) mode without the relay. Similarly, in HADF scheme, a specific SNR threshold is derived to determine that the relay can choose to transmit message in decode-and-forward (DF) or AF mode. Closed-form expressions of the outage probability of the proposed HDAF and HADF schemes are derived. Theoretical analysis and simulation results show that the HADF scheme outperforms the AF and DF schemes, and the HDAF relaying scheme outperforms the DT and AF schemes. However, compared with HDAF scheme, the HADF scheme has a better outage probability in special channel condition.