行動通訊系統中基於馬爾可夫模式之通道模型與適應性調變技術

在本篇論文中，第一個部份我們成功地將實際量測資料描繪成一個馬爾可夫鏈隨機程序。馬爾可夫鏈隨機程序可容易地運用來評估不同組合之調變與編碼技術或多重處理技術下之系統效能。因此，我們首先提出兩階層多狀態馬爾可夫模型，將一個傳播通道之相乘衰落效應描繪成遮蔽衰落與快速衰落效應。基於有限狀態馬爾可夫鏈模型，單一階層與兩階層馬爾可夫鏈模型之基本特性、統計特性與錯誤機率效能將做進一步討論。其次，我們基於隱藏式馬爾可夫模型與影像訊號提出了一個新的通道衰落預測方法。討論隱藏式馬爾可夫模型所需之參數與利用估測方程式遞迴地訓練出最佳的模型參數。另外，以便能夠克服隱藏式馬爾可夫模型在處理狀態停留時間的缺點，我們提出具有連續密度分佈之非穩態隱藏式馬爾可夫模型，發展一個陸地行動衛星系統通道模擬器，以便能夠更加正確地預估衛星至地球傳播路徑之統計行為。最後，我們提出了寬頻馬爾可夫鏈通道模型。實測訊號與模擬訊號所得的功率延遲剖面之平均超越延遲與rms延遲擴展的統計特性將會做比較。在本論文的第二部份，我們提出一個M-陣列相位鍵移適應性調變系統。這個系統使用一個簡單的最佳模式選擇方法來決定交換模式之臨界值的集合，使得系統能夠達到最大位元傳輸率並滿足特定的位元錯誤率的需求。並且，任意形式的衰落通道於M-陣列相位鍵移適應性調變系統之位元傳輸率與位元錯誤率完整表示式將會呈現。最後，我們也分析與模擬M-陣列相位鍵移適應性調變系統於混合式瑞利-對數常態衰落通道之效能。考量於非理想的功率控制錯誤下之平均位元傳輸率與位元錯誤率。

關鍵字

傳播通道模型建立；馬爾可夫通道模型；適應性調變技術

並列摘要

The first part of this thesis, the measured data is successfully characterized as a Markov chain stochastic process, which has the advantage of easily predicting system performance under various conditions of modulation, coding and multiple access. Therefore, the two-layer multistate Markov model is firstly introduced to characterize the multiplicative processes of a propagation channel as shadowing and fast fading. Based on the finite state Markov chain model, the basic properties, statistical characteristics and error probabilities of single-layer and two-layer Markov models are discussed. Secondly, we propose a new method based on hidden Markov models (HMMs) and video images to predict channel fading. The parameters of HMM are discussed and then the optimum model parameters are trained based on the re-estimation formula. Furthermore, in order to improve the disadvantages of HMM’s state duration, using non-stationary HMM with continuous density, to predict accurately the statistical characteristics of the satellite-to-earth propagation path. Finally, a wideband Markov transition model is introduced. The statistical characteristics of mean delay and rms delay spread of power delay profile are validated between the measured and simulated data. The second part of this thesis is an M-ary phase shift keying adaptive modulation (M-PSK AM) using a simple optimum selection approach to determine the set of switching thresholds, which is able to maximize data throughput while satisfying a certain bit error rate (BER) requirement. The closed-form data throughput (BPS) and BER expressions are presented over the arbitrary fading channels. Furthermore, the performances of the M-PSK AM over the Rayleigh-Lognormal fading channel are analyzed and simulated, and present its average BER and BPS due to non-perfect power control error (PEC).

並列關鍵字

Propagation channel modeling ； Markov channel model ； adaptive modulation scheme

參考文獻

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行動通訊系統中基於馬爾可夫模式之通道模型與適應性調變技術

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