隨著行動通訊世代的推進與第五代行動通訊的到來，全世界行動網路的需求日益增加，伴隨著5G行動通訊的各項應用也越來越多，造成頻譜的需求逐漸擴大，而在5G頻譜的規劃中又以FR1（頻率範圍0.41GHz-7.125GHz）在電路設計上更加成熟且電波傳播上具有優勢，因此成為全球第五代行動通訊中最為熱門的頻段。其中在C頻段具有許多固定的衛星通訊用戶使用，因此在發展5G行動通訊之餘，與既有的用戶之間需要保留多少護衛頻帶是各國皆探討的議題。本研究透過軟體定義無線電（Software Defined Radio, SDR）來實作一個測試干擾的實驗平台，搭配RF設備USRP B200與USRP B210來發射與接收訊號。本實驗以DVB-S2（Digital Video Broadcasting - Satellite - Second Generation, DVB-S2）作為實驗的受害者，在GNU Radio軟體內來同時接收干擾源與解調符合DVB-S2規格之影片檔，並發射一個符合5G NR標準的干擾源訊號。為了確認USRP發射出的干擾源訊號的功率強度大小，因此透過實體纜線連接頻譜分析儀來測量其軟體上的增益值對應於真實訊號的功率大小為何，並將其紀錄於本實驗中。以同頻干擾來實驗，將干擾源與受害者之間的距離分別設置為五種不同的距離，固定干擾源的中心頻率並調整其八種電功率，測試在不同距離之下，其八種不同干擾訊號強度對DVB-S2標準之影片的影響。實驗結果使用VLC媒體播放器觀看DVB-S2解調解碼後的影片，並以8PSK星座圖與影片的畫面來觀察受害者被干擾的程度，最後以影片的音訊遺失數、視訊遺失數、輸入丟棄數來判斷影片被干擾的程度，由實驗結果可以發現，干擾源訊號強度越大，則影響影片之品質越大；而距離越遠，則影響影片之品質越小。本研究透過設計GNU Radio上的模組實現一個可測試干擾的實驗平台，不僅節省許多成本，也體現了SDR的運用靈活度。
關鍵字：軟體定義無線電、5G、GNU Radio、DVB-S2、同頻干擾

Advent of the fifth-generation mobile communication, the demand for spectrum resources is increasing. The interference between 5G mobile communications and satellite communications in the C-band is an issue that has been discussed around the world. In this study, an experimental platform for testing interference is implemented through software-defined radio technology. In this platform the RF equipment USRP is used to transmit and receive signals. This experiment takes DVB-S2 as the victim of radio communication. On the other hand, we have an interference source that complies with the 5G NR standard. While the interference signal is received, the DVB-S2 video file is demodulated at the same time. For co-channel interference, we set five different distances between the interference source and the victim. We also fix the center frequency of the interference source and adjust its eight different radiation power. The purpose is to test the effect of different distances and different radiation power of interference on DVB-S2 films. In the experiment, we use the 8PSK constellation diagram and the picture of the video to observe the degree of interference of the victim. We also use VLC media player to observe the DVB-S2 demodulated program video. Finally, the number of audio loss, video loss, and the number of discards are employed to determine the degree of interference of the program video. From the results, we can find that the stronger the signal strength of the interference source, the greater impact on the quality of the program video. And the farther the distance, the less the impact on the quality of the video. This research realized an experimental platform that can test interference by designing modules on GNU Radio, which not only saves a lot of costs, but also reflects the flexibility of SDR in its application.

Key Words: Software Defined Radio, 5G, GNU Radio, DVB-S2, co-channel interference

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