時域干擾消除技術於未授權頻譜長期演進技術之設計與實現

Abstract

為了應付行動傳輸量驟增的現象，電信商需要取得更多的頻段來傳輸資料。因此，除了現有的商用授權頻段外，結合未授權頻段已漸漸被大家視為未來發展主軸，但需要解決與其他系統共存的問題。前人提出一個與其他文獻完全不同的作法：時域干擾消除技術來解決未授權頻譜之長期演進技術遇到的異質網路共存問題，甚至在兩邊系統訊號碰撞的情況下也可以進行解調。本論文接續前人的研究並修改演算法與考慮不理想效應，目的將其做得更加完善。之後經由軟體來模擬功率控制以及空白子訊框對時域干擾消除技術的影響。 在展示中，我們利用CPU、GPU以及NI USRP開發出軟體定義無線電(Software Defined Radio)平台，並利用GPU優越的平行處理能力壓縮執行時間，使此平台能夠在取樣率為20MHz下進行即時實收實解。藉由此SDR平台，我們可以驗證時域干擾消除技術在收到真實訊號下的可行性，並觀察功率控制以及空白子訊框比例的調整是否有益於時域干擾消除技術的執行。

In order to cope with the explosive increase in the amount of mobile transmission, telecom operators need to acquire more frequency bands to transmit data。In addition to the existing commercial licensed frequency bands, the combination of unlicensed frequency bands has gradually been regarded as high-potential development in future wireless communications, but it is necessary to solve the problem of coexistence with other systems. Previous works proposed a completely different approach from other schemes, namely time-domain interference cancellation (TDIC) technology to solve the heterogeneous network coexistence problem encountered in LTE-U system. This thesis continues this line of research and modifies the algorithm while considering a coupe of imperfect effects to make the solution more robust. The developed transceiver is then used to simulate the effects of power control and blank sub-frames to demonstrate the effectiveness of the proposed time-domain interference cancellation technology. In addition, we developed a Software Defined Radio platform using CPU, GPU and NI USRP, and used the superior parallel processing capability of the GPU to speed up the baseband signal processing of the LTE-U receiver, enabling the platform to perform the real-time demodulation at a sampling rate of 20MHz. With this SDR platform, we can verify the feasibility of the time-domain interference cancellation technology when receiving over-the-air signals. Furthermore, the SDR platform illustrates that the power control and blank subframe ratio adjustment schemes enable robust and almost error free LTE-U reception.