應用於多輸入多輸出正交分頻多工無線系統之實虛部不平衡及相位雜訊補償之研究

IQ Imbalance and Phase Noise Mitigation for Wireless MIMO-OFDM Systems

蔡忠晉(Chung-Jin Tsai)

指導教授 ： 闕志達

國立臺灣大學/電機資訊學院/電機工程學研究所/碩士(2008年)

https://doi.org/10.6342/NTU.2008.01446

摘要

正交分頻多工系統為目前最熱門的無線傳輸調變技術，在許多新一代的傳輸標準制定上皆採用了此調變技術，而近年來隨著晶片製造技術的進步，以及為了達到接收機降低成本、節省消耗功率的需求下，利用直接降頻接收機架構來整合類比以及數位電路在同一顆晶片上的目標，成為當前以及未來無線接收機設計的趨勢，但由於直接降頻接收機架構有著嚴重的前端射頻電路不理想特性，實虛部不平衡以及相位雜訊，將使得接收訊號受到失真，造成傳輸品質上的衰減。尤其在正交分頻多工系統中又對實虛部不平衡以及相位雜訊的效應特別敏感，容易造成傳輸品質上嚴重的衰減。
本論文討論分析了實虛部不平衡以及相位雜訊在正交分頻多工系統中所造成的效應，並且分別在單獨考慮接收端前端電路不理想特性，或同時考慮傳送端以及接收端前端電路不理想特性的效應下，提出利用基頻訊號處理的方法來補償前端電路的不理想特性，以達到改善系統傳輸品質，以及減輕對前端類比電路精確度的要求，達到低成本、低消耗功率接收機架構的設計。

關鍵字

多輸入多輸出正交分頻多工 ； 實虛部不平衡 ； 相位雜訊

並列摘要

OFDM modulation has been adopted in many wireless communications systems such as IEEE 802.11a/g/n, IEEE 802.16a/e, DVB-T/H, etc. Although OFDM has many advantages for wireless communications, its receivers are quite sensitive to front-end imperfection, such as IQ imbalance and phase noise. These effects oftentimes cause significant degradation in receiver error rate performance.
With rapid advance in VLSI technology, the gap in performance/complexity/cost between digital and analog circuit is getter wider. This trend will become more significant in the future. Therefore, using digital calibration and compensation to mitigate the effect of imperfection in analog circuits is getting more and more popular.
This thesis provides several digital baseband processing estimation and compensation schemes for impairments from receiver analog front-ends, specifically IQ imbalance and phase noise. Two different scenarios are considered: IQ imbalance and phase noise occur at the receiver only and there exist IQ imbalance and phase noise in both the transmitter and the receiver. In both cases, the proposed solution can effectively mitigate the impairments and relax the required specifications on the receiver analog frontends.

並列關鍵字

MIMO-OFDM ； IQ imbalance ； phase noise

參考文獻

[5] Behzad Razavi, RF Microelectronics. Prentice-Hall, NJ, 1998.

[6] Shahriar Mirabbasi and Ken Martin “Classical and modern receiver architectures,” IEEE Communication Magazine, Vol.38, No. 11, PP. 132-139, Nov. 2000.

[7] Behzad Razavi “Design considerations for direct-conversion receivers,” IEEE Transaction on Circuits and System, Vol. 44, No. 6, PP. 428-435, June 1997.

[8] Asad A. Abidi, “Direct-conversion radio transceivers for digital communications,” IEEE Journal of Solid-State Circuits, Vol. 30, No. 12, PP. 1399-1410, Dec. 1995.

[12] Marcel J. M. Pelgrom, Aad C. J. Duinmaijer and Anton P. G. Welbers, “Matching Propoertis of MOS Transistors,” IEEE Journal of Solid-State Circuits, Vol. 24, No. 5, PP. 1433-1439, Oct. 1989.