在本篇論文中，我們分成兩部份探討二元分散式偵測系統，並且設計決策融合法則。在第一部份，本地偵測器使用開關調變傳送本地判斷，經過互相平行的平坦衰減通道至資料融合中心。我們在同調與非同調接收下，分別設計只需要部份即時通道資訊及完全使用通道統計特性取代即時通道資訊的融合法則。使用方法為:線性結合接收信號形成融合統計量，以降低複雜度，並且利用最大化融合統計量的偏斜係數求得結合權重。求得的結合權重會依據各個本地偵測器的效能參數與通道的品質好壞來分配。模擬結果顯示，提出的兩種融合法則具有強健的偵測效能，並且在低訊雜比時會近似於最佳概似比法則。
第二部份，在本地偵測器與資料融合中心之間的傳輸通道為非正交的情形下，透過直接序列分碼多工傳送本地判斷。並將資料融合中心分成兩個階段。第一階段利用多使用者偵測器去決定各個本地偵測器傳送資料為何，第二階段再使用融合法則做出總判斷。我們針對第一階段使用多使用者線性偵測法，在第二階段將其軟性決策作為結合權重，線性結合依據硬性決策得到之對數概似比值。模擬結果說明:將軟性決策作為結合權重的融合法則比僅使用硬性決策的概似比法則，在低訊雜比下擁有更好的偵測效能，但在高訊雜比下偵測性能較差。因此，我們在假設已知訊雜比下，設計出融合前述二者的融合法則。模擬結果顯示，此融合法則會具有較強健的偵測效能。

In this thesis, we discuss the design of the fusion rules for binary distributed detection systems in two parts. In the first part, the local sensors send their decisions to the fusion center over parallel flat-fading channels using on-off keying. We propose both coherent and non-coherent fusion rules using channel statistics. For complexity concerns, the fusion statistic is obtained by linearly combining the received signals or the instantaneous received powers at the fusion center. The deflection coefficient of the fusion statistic is maximized to obtain the combining weights, which accounts for both the detection performance of local sensors and the quality of channels. Simulation results show that the proposed fusion rules have a robust detection performance, and approximate the optimum fusion rules based on the likelihood ratio test in low channel signal-to-noise ratios (SNRs).
In the second part, the local sensors transmit decisions using the direct-sequence code-division multiple-access signaling over non-orthogonal flat-fading channels. For complexity concerns, we consider the case where the fusion rule is partitioned into two stages. The first stage performs multiuser detection which decides what information was transmitted from local sensors. The second stage accomplishes the fusion and makes the final decision. We focus on the linear multiuser detector in the first stage, and use the soft decisions as the weighting to linearly combine the log-likelihood ratios that are obtained from the hard decisions. According to the simulation results, the weighted fusion rule has a better detection performance in the low-SNR regime than the fusion rule which uses only the hard decisions, but has a poorer detection performance in the high-SNR regime. A modification is proposed to achieve a robust performance in both regimes.

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