Tuyển tập báo cáo các nghiên cứu khoa học quốc tế ngành hóa học dành cho các bạn yêu hóa học tham khảo đề tài: Research Research Article On the Performance Gain of Hybrid Decode-Amplify-Forward Cooperative Communications | Hindawi Publishing Corporation EURASIP Journal on Wireless Communications and Networking Volume 2009 Article ID 479463 10 pages doi 2009 479463 Research Article On the Performance Gain of Hybrid Decode-Amplify-Forward Cooperative Communications Trung Q. Duong and Hans-Jurgen Zepernick Radio Communications Group Blekinge Institute of Technology 37225 Ronneby Sweden Correspondence should be addressed to Trung Q. Duong Received 5 September 2008 Revised 1 April 2009 Accepted 11 May 2009 Recommended by Michael Gastpar We investigate the performance of adaptive decode-forward ADF amplify-forward AF and hybrid decode-amplify-forward HDAF relaying protocol. Specifically we derive the closed-form expression of symbol error probability SEP for these three relaying protocols. For the AF protocol we derive a simpler and more tractable final result than previously published work. Furthermore analyzing the high signal-to-noise ratio SNR regime we derive an asymptotically tight approximation for SEP. The approximation is used to assess an important aspect between the three different relaying protocols . the SEP performance gain of HADF over the two conventional relaying schemes ADF and AF. It is shown that the performance gain of HDAF over ADF and AF significantly depends on the relative value of channel conditions between source-to-relay and relay-to-destination links. Interestingly it is shown that HDAF has no benefit compare to the two others if the relay is located close to the source. In contrast the performance gains of HDAF over the ADF and AF scheme are remarkably large as the relay moves nearby the destination. Specifically the numerical results given as well as our analysis indicate that for QPSK modulation HDAF outperforms ADF and AF with a performance improvement by 5 dB and 6 dB respectively. Copyright 2009 T. Q. Duong and . Zepernick. This is an open access article distributed under the Creative Commons Attribution License .