Outage Probability of Hybrid Decode-Amplify-Forward Relaying Protocol for Buffer-Aided Relays

Buffer-aided cooperative relaying is often investigated either using decode and forward (DF) or amplify and forward (AF) relaying rules. However, it is seldom investigated using the hybrid decode-amplify-forward (HDAF) relaying rule. In this work, the performance of signal-to-noise ratio (SNR) based HDAF relaying rule is followed for buffer-aided cooperative relaying. Relay with the best possible corresponding channel is determined for reception or transmission. When source to relay hop is the most powerful, data is forwarded to chosen relay and its SNR is compared against the predefined SNR threshold at the relay. If it is greater than the threshold, the decoded data is saved in the corresponding buffer. Otherwise, the amplified data is saved in the respective buffer. When relay to destination link is the most powerful, data is forwarded to the destination. The famous Markov chain analytical model is used to illustrate the progression of the buffer state and to get the outage probability expression. Mathematical and simulation outcomes support our findings and prove that the outage probability performance of the proposed technique beats the existing SNR based buffer-aided relaying protocols based on DF and AF relaying rules by 2.43 dBs and 8.6 dBs, respectively.