隨著高速資料傳輸之需求不斷提升，無線傳輸技術需要更大頻寬來傳輸訊號。多頻帶正交分頻多工超寬頻訊號為高速資料傳輸技術之一。本論文主要針對多頻帶正交分頻多工超寬頻訊號於多重路徑通道之聯合訊號到達時間及訊號來向角估測進行研究。
本論文推導多頻帶正交分頻多工超寬頻系統之具有延展自由度之空間通到頻率響應模型。由於訊號頻寬延展近1.584GHz，由相位差到達時間及訊號入射角度在每個射頻子載波所引起的相位差皆納入考量。本文提出兩種適用於此空間通道頻率響應模型之聯合訊號來向角及到達時間估測(JATE)演算法。與聯合訊號到達時間及來向角估測(JTAE)方法相比之下，所提JATE方法係先估測訊號來向角再基於此來向角估測值來估測訊號到達時間，所提方法於來向角估測效能上優於JTAE方法。此外，JATE方法並無來向角與到達時間參數配對問題，且相較於JTAE和傳統超寬頻來向角估測方法能處理更多路徑數。再者，因空間通道頻率響應模型完整考量所有相位差之故，JATE大幅降低來向角和到達時間估測偏差。
第一個提出方法為基於搜尋之聯合的來向角與到達時間估測演算法 (SB-JATE)。首先，沿著空間通道頻率響應之空間維度，訊號來向角藉由使用廣義訊號估測旋轉不變技術1維搜尋得出。接著，沿著空間通道頻率響應之頻率維度，對應到來這些來向角估測之訊號到達時間的估計值藉由執行幾次的1維多重訊號分類演算法搜尋得出。第二個方法為基於求根法免搜尋之聯合的來向角與到達時間估測演算法 (SF-JATE)。在忽略由子載波間距與入射角共同造成小量相位旋轉情況下，沿著空間維度，訊號來向角藉由使用訊號估測旋轉不變技術得出。接著，將忽略的相位納入考量，根據來向角估測值建造子空間校正矩陣，使用數次的訊號估測旋轉不變技術得出到達角估測值。此方法需要額外的程序來完成參數配對。免搜尋之聯合的來向角與到達時間估測法為了更高角度解析度、更低的訊雜比臨界值、及更進一步減低複雜度而犧牲一些角度估測精準度。數值模擬在多種系統參數之下比較所提方法及現有方法的來向角與到達時間的精準度。
此外，所提方法之可行性及效能藉由在無反射實驗室實施的幾個實驗進行驗證。於實際情況中，非完美的陣列響應會大幅降低估測效能。因此，本文提出及實現基於查表法的頻率─空間陣列校正法可適用於SB-JATE，此方法能有效地去除因非完美陣列響應造成的估測誤差。雙通道實驗也驗證了SB-JATE之可行性以及呈現所提JATE方法在來向角估測上優於JTAE方法。

Due to an increasing demand on high-data-rate (HDR) transmissions, wireless transmission techniques require much wider bandwidth to transmit signals. Multi-band orthogonal frequency-division multiplexing ultra-wideband (MB-OFDM UWB) is one of the mature HDR transmission schemes. This thesis mainly addresses the problem of the joint estimation of angle of arrival (AOA) and the relative time of arrival (TOA) for MB-OFDM UWB signals in multipath channels.
The space channel frequency responses (S-CFR) with an extended degree of freedom (DOF) for the standardized MB-OFDM UWB system derived. Due to the bandwidth spread over 1.584 GHz, the phase shifts induced by TOA and AOA at every RF subcarrier are taken into consideration. Two joint AOA and TOA estimation (JATE) methods are proposed which is applicable to the S-CFR model. In contrast to joint TOA and AOA estimation (JTAE) methods, the proposed JATE methods that firstly estimate AOA and then estimate TOA based on the AOA estimates outperform JTAE methods in terms of AOA estimation. In addition, the JATE methods suffer no pairing problem of estimated AOA and TOA, and can resolve more paths than JTAE and conventional UWB AOA estimation methods. Moreover, the JATE methods greatly reduce the bias for AOA and TOA estimations since the all phase shifts are fully considered in the S-CFR model.
The first proposed method is a search-based JATE (SB-JATE) algorithm. The AOA estimates are firstly obtained by performing 1D spatial search of using the generalized estimation of signal parameters via rotational invariance techniques (G-ESPRIT) along the space dimension of the S-CFR model. Afterwards, the TOA estimates associated to these AOA can be obtained by performing few times 1D-MUSIC algorithm along the frequency dimension of the S-CFR model. The second method is a rooting-based search-free JATE (SF-JATE) algorithm. The AOA estimates are firstly obtained using 1D-ESPRIT along the space dimension under ignoring the small phase rotation induced by subcarrier spacing and the incident angle. Then, taking the ignored phase back into consideration and constructing signal subspace calibrating matrices according to the AOA estimates, the TOA estimates can be obtained using 1D-ESPRIT few times. The SF-JATE requires an additional process to achieve parameter pairing. This method sacrifices performance degradation in AOA estimation for higher angular resolution, lower signal-to-noise ratio (SNR) threshold, and further reducing the complexity. Numerical simulations against various system parameters compare the proposed methods with some existing methods in terms of AOA and TOA estimation accuracy.
In addition, this thesis conducts several experiments in a microwave anechoic chamber to verify the proposed JATE methods. In practical situations, antenna mutual coupling substantially degrades the estimation performance. A frequency-space array calibration based on a look-up table for the SB-JATE is presented and implemented. A two-path channel experiment verifies the feasibility of the SB-JATE and again shows that the proposed JATE outperforms the JTAE in terms of AOA estimation.

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