在通訊技術快速發展的當下，人們對於流量的需求也在急遽的增加。為了應對如此快速增加的流量以及各種不同應用場景的頻譜需求，使用非授權頻譜(unlicensed spectrum)將會是一個可行的解決方法。因此第三代合作夥伴計劃(3rd generation partnership project, 3GPP)提出了新無線電非授權頻譜技術(new radio unlicensed, NR-U)，將新無線電技術(new radio, NR)應用於非授權頻譜上。然而，由於使用非授權頻譜的關係，不同無線電接入技術(radio access technology, RAT)之間可能會發生由於隱藏節點(hidden node)所產生的碰撞。雖然NR-U可以透過使用60GHz以上之毫米波(millimeter wave, mmWave)頻段以及使用波束成型(beamforming)技術來減少大部分的隱藏節點問題，但是仍不能完全避免此一情況的發生，且波束成型的高度指向性可能會改變現有的隱藏節點干擾嚴重程度。因此本篇論文將會針對60GHz毫米波頻段中，在NR-U與無線千兆通訊技術(wireless gigabit, WiGig)皆使用波束成型的情況下，針對不同波束寬度(beamwidth)下發生隱藏節點的機率進行數學分析，並使用MATLAB透過蒙地卡羅法進行模擬。從我們的模擬結果與分析中可以觀察到，當波束寬度由大到小變化時，發生隱藏節點的機率也隨之下降。此外由於使用了定向天線(directional antenna)，雖然當波束寬度由大到小變化時，可能發生隱藏節點的區域面積佔比隨之上升。但與過往使用全向天線(omnidirectional antenna)相比，由於定向天線與波束成型技術帶來的高度指向性，使得節點就算位於可能發生隱藏節點的區域，只要其波束並未對齊並干擾到其餘節點的話，我們便不會認定該節點為隱藏節點。因此儘管波束寬度由大到小變化時，可能發生隱藏節點的區域面積佔比逐漸上升，但實際上發生隱藏節點的機率是逐漸下降的，而這也證實了透過使用定向天線並適當的調整波束寬度可以降低隱藏節點問題的發生機率。

In the current era of rapid advancements in communication technology, there is a steep increase in people's demand for wireless data traffic. To cope with the rapid increase in traffic and the spectrum requirements of various application scenarios, utilizing unlicensed spectrum has become a viable solution. The 3rd generation partnership project (3GPP) has therefore introduced new radio unlicensed (NR-U), which allows the use of new radio (NR) in the unlicensed spectrum. However, due to the nature of the unlicensed spectrum, collisions caused by hidden nodes may occur between different radio access technologies (RATs). While NR-U can mitigate most hidden node issues by leveraging millimeter-wave (mmWave) band above 60 GHz and beamforming, it cannot eliminate such occurrences. Moreover, the highly directional nature of beamforming may change the severity of existing hidden node interference. Therefore, this paper focuses on the mathematical analysis of the probability of hidden node under different beamwidth in the 60 GHz mmWave band when both NR-U and wireless gigabit (WiGig) utilize beamforming. The Monte Carlo method is utilized for simulation using MATLAB. From the simulation results and analysis, it can be observed that as the beamwidth decreases from larger to smaller values, the probability of hidden node also decreases. Furthermore, due to the usage of directional antennas, the area percentage of hidden nodes may increase as the beamwidth decreases. However, compared to omnidirectional antennas, the highly directional nature of the antennas and beamforming ensures that nodes in potentially hidden node areas are not considered hidden node unless their beams align and interfere with other nodes. Hence, despite the increase in the proportion of area prone to hidden nodes with decreasing beamwidth, the actual probability of hidden node decreases. This confirms that the usage of directional antennas and appropriate adjustment of beamwidth can effectively reduce the probability of hidden node.

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