在此研究中, 我們提出一種新的全多樣化結合演算法可應用於自調式通道估測和等化, 此演算法利用多重路徑通道之全多樣化好處來大大改善以 Kalman濾波器為基礎自調式等化器之性能。所提出全多樣化自調式等化器是以比重式高斯和 (Weighted Gaussian Sum, WGS) 技術和延伸式 (Extended) Kalman網路濾波器為基礎, 運用此延伸式 Kalman網路濾波器之預測誤差來達到最大可能性 (Maximum Likelihood, ML) 之最佳解。因此,所提出的演算法在快速時變相互干擾通道中可以同時有效的估測通道係數和傳送資料。此快速時變相互干擾通道是由一兩階自退化過程 (Autoregressive Process, AR(2)) 依照行動電話網路的 Doppler 頻率來模擬。電腦模擬結果驗證所提出的全多樣化自調式等化器可以比傳統的 Kalman 網路自調式等化器更準確的估測快速時變通道。在傳送資料的偵測方面, 所提出的全多樣化結合自調式等化器亦驗證比傳統式的 WGS-IMM (Interacting Multiple Model) 自調式等化器在位元錯誤率 (BER) 上有大幅改善。
此外, 從性能和計算複雜度的觀點來考慮, 所提出的修改版2-多樣化 (2-Diversity) 自調式等化器對於以比重式高斯和 (WGS) 為基礎的自調式等化器來說, 是一個不錯的選擇; 因所提出的2-多樣化 (2-Diversity) 自調式等化器可避免計算複雜度以指數方式增加, 使其在無線通訊應用上可行性大幅增加。

In this study, we propose a novel full-diversity combination algorithm for blind channel estimation and equalization, which takes advantage of the full-diversity gain of the multipath fading channel and executes a smoother filter operation to significantly improve the performance of the network Kalman-based blind equalizers. The proposed full-diversity blind equalizer based on the weighted Gaussian sum (WGS) technique and the network of extended Kalman filters, employs the prediction errors of network of Kalman filters to achieve the maximum likelihood (ML) solution. Therefore, the proposed algorithm can effectively estimate both the channel coefficients and the transmitted symbols over the fast time-varying inter-symbol interference (ISI) fading channels. The fast time-varying ISI fading channel is modeled by a second order autoregressive (AR(2)) process according to the Doppler frequency shift in cellular networks. Simulation results illustrate that the proposed blind equalizer based on the full-diversity combination algorithm can track the fast time-varying fading channel much more accurately than the conventional network Kalman-based blind equalizers. For symbol detection, the proposed diversity combination blind equalizers demonstrate a significant improvement compared with the conventional WGS-IMM (Interacting Multiple Model) blind equalizers in the bit error rate (BER) performance.
Besides, from the trade-off consideration between the performance and the computational complexity, the proposed modified 2-Diversity blind equalizer is a best choice for the WGS-based blind equalizer. Because the proposed 2-Diversity blind equalizer avoids the exponential growth of the computational complexity making it feasible for wireless communication systems.

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