隨著對高速通信的需求不斷增加，6GHz 以下的低頻段變得越來越擁擠，具有龐大頻譜的毫米波被視為未來無線通信中最有潛力的頻段，由於在毫米波頻段的電波會有很嚴重的能量損耗，需要藉由波束成形技術以實現長距離通信，然而行動通訊終端的移動性會導致彼此的波束未對準而有顯著的訊號下降，因此波束追蹤在第五代無線通訊系統中擔任了十分重要的角色。在本篇論文中，我們研究了一種波束追蹤的方法，其利用頻帶外的資訊來估測出行動終端相對於基地台所處的角度，使基地台能藉此資訊調整毫米波的波束方向保持通訊傳輸。相對於現有的毫米波系統只能追蹤單一使用者或只能逐個追蹤使用者，我們的方法能夠同時追蹤多個使用者，
並且建立了軟體定義無線電原型以驗證此方法。此軟體無線電同時工作於低於6GHz和28GHz 頻段，並在室外和室內環境中進行現場測量來比較提出方法和現有方法在移動場景下的效能優劣。

Millimeter-wave (mmWave) with large available spectrum is considered as the most promising frequency band for future wireless communications with the increasing demand of ultra high speed wireless communications. Since the mmWave suffers a serious path-loss, beamforming is crucial to achieve long distance communications. However, a beam misalignment due to mobility between two communicating devices can cause a significant signal drop, and thus a beam tracking technique is important to support mobility. In this thesis, a prototype based on Software Defined Radio (SDR) is developed to study the beam tracking problem based on angle estimate obtained from out-of-band information.The implemented prototype operates at both sub-6GHz and 28GHz band with the capability to track multiple users simultaneously. Filed measurements are conducted both in outdoor and indoor environment.The measurement results confirm the advantage of using out-of-band as a side information for tracking UE in comparison with the conventional method.

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