- 學位論文
可適性多輸入多輸出正交分頻多工系統之基頻收發機設計與硬體實作
Design and Implementation of Baseband Transceiver with Adaptive MIMO-OFDM Technology
摘要
本論文從系統設計的角度出發，完整地設計一可適性多輸入多輸出正交分頻多工系統(Adaptive MIMO OFDM System)，並致力於將系統以硬體實現，最後再整合射頻端之儀器，建構出一完整的基頻可適性收發機，完成系統驗證。 在本論文中，參考高速無線區域網路IEEE 802.11協定，設定系統規格，並提出可適性多輸入多輸出正交多頻分工收發機架構及電路設計。接收機的主要架構可分為初始同步、追蹤迴路、通道估計、資料回復與資訊回傳及雜訊估測等可適性調變所需之模組。其中初始同步包括封包偵測、符元邊界粗估與細估、載波頻率飄移的粗估與細估，由封包中的舊有短訓練欄位與舊有長訓練欄位作估計，論文中提出的改良之符元邊界粗估的方法，能讓估計的結果不會有false alert，以及normalized後的延遲相關值使得threshold的設定上簡單許多；追蹤迴路包括殘餘分數載波頻率偏移與取樣時脈偏移的聯合估計，乃是利用封包中資料符元的領航碼作追蹤；奇異值分解電路使用了直觀的公式解，優點為速度快、運算量小，缺點為只能適用於2x2的天線設置；雜訊估測方面利用了高速長訓練符元的特性，套用ren’s estimator的概念，計算量相當小，且不需要額外的編碼；另外，以舊有長訓練符元與高速長訓練符元作通道的估計，用於MIMO訊號偵測，在偵測訊號時，以傳輸模式的不同決定等化方式，以VBLAST模式傳輸時，相較SVD傳輸模式於有較好的系統效能，而SVD傳輸模式讓我們實現可適性調變的功能，可以得到更高的throughput，缺點是SVD對於通道的變化相當敏感。論文中也提出了相較於文獻更低運算量的可適性調變演算法及另一個可以在符合JAER的情況下將throughput提高更多的改良之可適性調變演算法，並且經由模擬驗證。 最後經由電路設計及結合射頻無線電平台、現場可編輯邏輯閘陣列，完成了real-time、over-the-air的可適性多輸入多輸出正交多頻分工收發機系統驗證、證實了其可實現性。
並列摘要
Based on the perspective of system design, this thesis proposed an integrated adaptive MIMO OFDM system. We dedicated to realize the whole baseband receiver with hardware language and yet to integrate the system on FPGA with Universal Software Radio Peripheral (USRP) to complete the system verification. In this thesis, we define the system specification based on IEEE 802.11n, and proposed the architecture of adaptive MIMO OFDM transceiver with hardware circuit design. The primary modules of the baseband circuit are composed of initial acquisition, tracking loop, channel estimation, data recovery, CSI feedback, and noise variance estimation. We exploited legacy short/long training field to implement initial acquisition including packet detection, coarse/fine symbol boundary detection, and coarse/fine frequency offset estimation. Also in this thesis we proposed an improved method of CSBD which can mitigate the false alertion from data symbols, and by normalized delayed correlation, the value of threshold will be easier to set. Tracking loop which we use pilots among data symbols to estimate is for residual CFO and SCO. To accelerate the speed and to lower computation, we came out an intuitive approach to derive the solution of SVD, yet the drawback of this approach is that it is not expandable for higher dimension of antennas. We implemented two MIMO detection methods including VBLAST and SVD transmission while the later is for the purpose of adaptive transmission. And we used high throughput long training field to estimate noise variance based on the concept of ren’s estimator. Other than hardware architecture, we have also proposed two methods of adaptive modulation. In the first method, the computation is relatively low compared to the previous work of our group. The second method achieves higher throughput while still meets the JAER (Just Acceptable Error Rate). The most important contribution of this thesis is to realize the whole adaptive MIMO OFDM system by integrating the hardware design on FPGA and Universal Software Radio Peripheral (USRP). Lastly, we proved that the system is feasible with real-time field trial and demodulation of the signal over the air instantly.
參考文獻
延伸閱讀
- 連瑞屏（2005）。應用於感知無線電系統之多重輸入輸出正交分頻多工基頻收發機設計〔碩士論文，國立臺灣大學〕。華藝線上圖書館。https://doi.org/10.6342/NTU.2005.02559
- 王健豪（2017）。使用開放計算語言之非正交多工存取系統基頻接收機設計與實作〔碩士論文，國立臺灣大學〕。華藝線上圖書館。https://doi.org/10.6342/NTU201700153
- 張剛銓（2007）。適用於行動式無線都會區域網路中正交分頻多工存取模式之基頻接收機設計與實作〔碩士論文，國立臺灣大學〕。華藝線上圖書館。https://doi.org/10.6342/NTU.2007.02207
- 蘇建忠（2008）。多輸入多輸出正交分頻多工系統之適應性混合式的自動重傳機制〔碩士論文，國立臺北科技大學〕。華藝線上圖書館。https://doi.org/10.6841/NTUT.2008.00154
- 姚 崴（2004）。Design and Implementation of Digital Baseband Transceiver for SCM-based VDSL System〔碩士論文，國立臺灣大學〕。華藝線上圖書館。https://doi.org/10.6342/NTU.2004.01276