在無線通訊系統中，訊號傳輸常受到通道衰減、多路徑效應以及雜訊干擾的影響而造成錯誤率上升，合作式通訊可以透過鄰近節點作為中繼端轉傳訊號，使接收端能獲得額外的空間多樣性增益，以改善傳統點對點傳輸在衰減通道下的限制。本論文探討量化映射轉傳（Quantize-Map-and-Forward, QMF）合作式通訊系統於多候選中繼架構下之傳輸效能，比較多候選中繼環境之最佳中繼選擇機制，並最終以諧和平均作為中繼選擇準則。所提出方法同時衡量來源端-中繼端、中繼端-目的端的通道品質以評估整體傳輸能力，接收端則結合來源端直傳訊號與中繼轉傳訊號進行判決，以提升系統之偵測可靠度。
在通道模型方面，本論文導入改良型 Jake’s Rayleigh模型分析系統於不同中繼數目與不同SNR條件下之位元錯誤率表現。並且為了更貼近實際工業通訊場景，本論文亦納入 Bernoulli-Gaussian 脈衝雜訊模型，以探討非高斯雜訊對 QMF 合作系統之影響。最終模擬結果顯示，諧和平均中繼選擇方法在多中繼 QMF 合作通訊系統相較於其他常見中繼選擇準則，更能有效降低位元錯誤率，提升系統整體傳輸可靠度。

In wireless communication systems, signal transmission is often affected by channel fading, multipath effects, and noise interference, which lead to an increase in the error rate.Cooperative communication can employ neighboring nodes as relays to forward signals,thereby enabling the receiver to obtain additional spatial diversity gain and alleviating the limitations of conventional point-to-point transmission over fading channels. This thesis investigates the transmission performance of a Quantize-Map-and-Forward (QMF) cooperative communication system under a multi-candidate relay architecture. Different relay selection mechanisms are compared in a multi-relay environment, and the harmonic mean is ultimately adopted as the relay selection criterion. The proposed method jointly evaluates the channel qualities of the source-to-relay and relay-to-destination links in order to assess the overall transmission capability, while the receiver combines the directly transmitted signal from the source with the relayed signal for detection, thereby improving system detection reliability.
For the channel model, this thesis adopts the modified Jake’s Rayleigh model to analyze the bit error rate (BER) performance of the system under different numbers of relays and different SNR conditions. In addition, to better reflect practical industrial communication scenarios, a Bernoulli-Gaussian impulsive noise model is incorporated to investigate the impact of non-Gaussian noise on the QMF cooperative system. Simulation results show III that, compared with other common relay selection criteria, the harmonic-mean-based relay selection method can more effectively reduce the BER and improve the overall transmission reliability of the multi-relay QMF cooperative communication system.

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