透鏡天線陣列下的欠定到達角度估計

Abstract

毫米波大規模多輸入多輸出系統已經成為未來無線通訊系統中實現多用戶高速率通訊的重要技術，然而大量的射頻電路造成過高的硬體和功率成本。為了克服訊號能量的衰減與降低成本考量，透鏡天線陣列藉由其能量聚焦和路徑分割特性，將其應用在毫米波多輸入多輸出系統中逐漸具有吸引力。 透鏡天線陣列主要由一個電磁透鏡和相對應的天線陣列組成，對應的天線陣列擺放在電磁透鏡焦距弧上。在準穩態訊號模型下，本篇論文考慮在毫米波多輸入多輸出系統中運用透鏡天線陣列，並提出一個新的演算法用於估測比天線數量還多的來源訊號到達角度，也就是欠定的估測。提出的方法利用傅立葉轉換來分析訊號的相位，透過相位差來提高估測訊號來向角度的自由度。模擬結果展現所提出的演算法可以透過較少的資料取樣點來提高自由度，並探討多重訊號分類方式、根多重訊號分類方式與透過旋轉不變估測訊號參數方式之間的均方根誤差效能表現。

Millimeter wave (mmWave) massive multiple-input multiple-output (MIMO) systems have emerged as an essential technology for future wireless systems to achieve multi-user high-rate communication. However, ultra-high frequencies and a large number of radio-frequency (RF) chains cause prohibitive hardware and power consumption costs. To overcome the attenuated signal energy and reduce the cost, lens antenna array (LAA) has recently become attractive for mmWave MIMO systems due to its energy-focusing and path-division properties. Lens antenna array is mainly composed of an electromagnetic (EM) lens and the corresponding antenna array with elements located in the focal arc of the EM lens. This thesis considers the mmWave MIMO systems utilizing lens antenna array and presents a novel algorithm for direction of arrival (DoA) estimation of more sources than antennas, an underdetermined case. The proposed approach exploits the Fourier transform (FT) of signal to analyze the signal phase. The estimation degree of freedom (DoF) can increase by taking advantage of the phase difference. Simulation results show that the proposed algorithm can raise estimation DoF by fewer data samples and discuss root mean square error (RMSE) performance and detection error probability (DEP) performance.