利用中繼站來擴大無線通訊覆蓋範圍為提升新一代行動網路傳輸效能的重要方法，
較常見的中繼站傳送機制為放大傳輸 (Amplify-and-Forward, AF) 與解碼傳輸 (Decode-and-Forward,
DF)。 AF 中繼站因為不需要複雜的編解碼，因此 AF 中繼運算雖具有低複雜度但亦存在雜訊累積的效應，而 DF
中繼法利用編解碼技術，在某些情況下可提升接收資料的可靠度。本文探討以 AF 與 DF
的傳輸錯誤機率模型作為選擇混合式中繼站策略的依據，我們分析了 BPSK 與 $M$-QAM 調變方式在此系統的錯誤率，並利用切爾諾夫邊界
(Chernoff bound) 取上界計算平均錯誤率，以利於中繼站可依此做傳輸策略的決策。

Using relays is an important technique to expand communication
coverage in modern mobile communication systems. Amplify-and-Forward
(AF) and Decode-and-Forward (DF) are the most two popular strategies
in the relaying methods. AF has low complexity but the noise can be
amplified while in contrast, DF improves transmission reliability in
some situations using the coding scheme to suppress the noise.
In this paper, we explore the symbol error probabilities of the AF
and DF models for the hybrid AF/DF relaying strategy, in which the
BPSK and M-QAM modulation types are considered, along with
calculating the average bit error rate based on the Chernoff upper
bound.

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