多輸入多輸非正交多重接取(Multiple-Input Multiple-Output Non-orthogonal multiple access, MIMO-NOMA)系統中，在接收端有嚴重的干擾問題，造成訊號無法順利解出，因此如何抑制干擾是個必須面對的議題。過去幾年，已經有很多技術被提出來解決此問題，其中利用傳送端預編碼(Precoding) 是常被拿來使用的技術之一，然而再傳送訊號前基地台(Base Station,BS) 必須先了解全局的通道狀態資訊(Channel State Information,CSI)，在實際傳輸上面臨重大挑戰，再者此方法並無法將所有使用者干擾完全消除乾淨，且在接收天線數也有所限制，因而降低整體系統效能表現。
本論文，我們提出MIMO檢測(Detection) 技術，透過使用者在接收端自行將干擾消除，不但不須回傳全局CSI，更能完全消除干擾，在接收天線數目上也有調整彈性。因此，首先我們提出三種分別 Zero-forcing、MMSE及SVD檢測方法，並設計了一個基於QR 分解檢測之MIMO-NOMA系統，對其進行中斷機率數學分析，最後利用模擬與數學推導結果進行比對，且比較各方法之性能及優缺點。

In a multiple-input multiple-output non-orthogonal multiple access (MIMO-NOMA) system, serious interference occurs at the receiver, leading to the received signal unable to be successfully decoded. In the past few years, many methods were proposed to solve this problem. Transmitter precoding is one of the widely used techniques. However, the base station (BS) must acquire the global Channel State Information (CSI) before transmission, and thus the system overhead is increased. Moreover, Precoding techniques cannot effectively eliminate inter-cluster interference as well as limit the number of receiving antennas. Due to the above disadvantage, the overall system performance is seriously degraded.
In this thesis, we propose a MIMO detection technology which can let the user eliminate interference by itself. This method not only does not need to return the global CSI, but also can completely eliminate interference. Moreover, it has the flexibility to adjust the number of receiving antennas. First, we study three different detection methods, i.e., Zero-forcing, MMSE, and SVD, and then propose a QRD-Based Signal Detection method for the MIMO-NOMA system. The mathematical analysis of outage probability is explored and the computer simulation is
performed to compare the performance for different detection methods.

[1] H. Ngo, E. G. Larsson, and T. L. Marzetta, “Energy and spectral efficiency of very large multiuser MIMO systems,” IEEE Transactions on Communications, vol. 61, no. 4, pp. 1436–1449, April 2013.
[2] F. L. Luo and C. Zhang, Signal Processing for 5G: Algorithms and Implementations. John Wiley and Sons, 2016.
[3] L. Zhang, M. Xiao, G. Wu, M. Alam, Y.C.
Liang, and S. Li, “A survey of advanced techniques for spectrum sharing in 5G networks,” IEEE Wireless Commun., vol. 24, no. 5, pp. 44–51, October 2017.
[4] H. Lee, S. Kim, and J. H. Lim, “Multiuser superposition transmission (MUST) for LTE-A systems,” in IEEE Int. Conf. Commun. (ICC), May 2016, pp. 1–6.
[5] C. Wang, J. Chen, and Y. Chen, “Power allocation for a downlink non-orthogonal multiple access system,” IEEE Wireless Commun. Lett., vol. 5, no. 5, pp. 532–535, October 2016.
[6] Z. Yang, Z. Ding, P. Fan, and N. AlDhahir,
“A general power allocation scheme to guarantee quality of service in downlink and uplink NOMA systems,” IEEE Trans. Wireless Commun., vol. 15, no. 11, pp. 7244–7257, November 2016.
[7] G. Song and X. Wang, “Comparison of interference cancellation schemes for non-orthogonal multiple access system,” in Proc.2016 IEEE 83rd Veh. Technol. Conf., May 2016, pp. 1–5.
[8] H. Haci, H. Zhu, and J. Wang, “Performance of non-orthogonal multiple access with a novel asynchronous interference cancellation technique,” IEEE Trans. Wireless Commun., vol. 65, no. 3, pp. 1319–1335, March 2017.
[9] Z. Ding, X. Lei, G. Karagiannidis, R. Schober, J. Yuan, and V. Bhargava, “A survey on non-orthogonal multiple access for 5G networks: Research challenges and future trends,” IEEE J. Sel. Areas Commun, vol. 35, no. 10, pp. 2181–2195, October 2017.
[10] L. Dai, B. Wang, Z. Ding, Z. Wang, S. Chen, and L. Hanzo, “A survey of non-orthogonal multiple access for 5G,” IEEE Commun. Surveys Tuts., vol. 20, no. 3, pp. 2294–2323, 3rd Quart. 2018.
[11] S. Islam, N. Avazov, O. A. Dobre, and K.S. Kwak, “Powerdomain non-orthogonal multiple access (NOMA) in 5G systems:Potentials and challenges,” IEEE Commun. Surveys Tuts., vol. 19, no. 2, pp. 721–742, 2nd Quart. 2017.
[12] R. Zhang and C. K. Ho, “MIMO broadcasting for simultaneous wireless information and power transfer,” IEEE Trans. Wireless Commun., vol. 12, no. 5, pp. 1989–2001, May 2013.
[13] A. J. Paulraj, D. A. Gore, R. U. Nabar, and H. Bolcskei, “An overview of MIMO communications a
key to gigabit wireless,” Proc. IEEE, vol. 92, no. 2, pp. 198–218, February 2004.
[14] R. W. Heath, N. GonzalezPrelcic, S. Rangan, W. Roh, and A. Sayeed, “An overview of signal processing techniques for millimeter wave MIMO systems,” IEEE J. Sel. Top. Signal Process., vol. 10, no. 3, pp. 436–453, April 2016.
[15] Y. Huang, C. Zhang, J. Wang, Y. Jing, L. Yang, and X. You, “Signal processing for MIMO-NOMA: present and future challenges,” IEEE Wireless Commun, vol. 25, no. 2, pp. 32–38, April 2018.
[16] S. L. B. Kim, H. Kim, S. Suh, J. Kwun, S. Choi, C. Lee, S. Lee, and D. Hong, “Non-orthogonal multiple access in a downlink multiuser beamforming system,” in IEEE Military Communications Conference, November 2013, pp. 1278–1283.
[17] J. Choi, “Minimum power multicast beamforming with superposition coding for multiresolution broadcast and application to NOMA systems,” IEEE Trans. Commun, vol. 63, no. 3, pp. 791–800, March 2015.
[18] Z. Ding, L. Dai, and H. V. Poor, “MIMO-NOMA
design for small packet transmission in the internet of things,” IEEE Access, vol. 4, pp. 1393–1405, April 2016.
[19] Y. Liu, M. Elkashlan, and Z. Ding, “Fairness of user clustering in MIMO non-orthogonal multiple access systems,” IEEE Commun. Lett, vol. 20, no. 7, pp. 1465–1468, July 2016.
[20] A. Goldsmith, S. A. Jafar, N. Jindal, and S. Vishwanath, “Capacity limits of MIMO channels,” IEEE JSAC, vol. 21, no. 5, pp. 684–702, June 2003.
[21] L. Zheng and D. N. C. Tse, “Diversity and multiplexing: a fundamental tradeoff in multiple antenna channels,” IEEE Trans. Inf. Theory, vol. 49, no. 5, pp. 1073–1096, May 2003.
[22] Z. Ding, Z. Yang, P. Fan, and H. V. Poor, “On the performance of non-orthogonal multiple access in 5G systems with randomly deployed users,” IEEE Signal Process. Lett., vol. 21, no. 12, pp. 1501–1505, December 2014.
[23] Y. Hama and H. Ochiai, “Performance analysis of matched filter detector for MIMO systems in rayleigh fading channels,” in IEEE Global Commun. Conf. (GLOBECOM), December 2017, pp. 1–6.
[24] Z. Ding, F. Adachi, and H. V. Poor, “The application of MIMO to non-orthogonal multiple access,” IEEE Trans. Wireless Commun, vol. 15, no. 1, pp. 537–552, January 2016.
[25] A.M.Tulino and S.Verdu, Foundations and Trends in
Communications and Information Theory: Random Matrix Theory and Wireless Communications. Hanover, MA, USA: Now Publishers, 2004.
[26] S. Timotheou and I. Krikidis, “Fairness for non-orthogonal multiple access in 5G systems,” IEEE Signal Process. Lett., vol. 22, no. 10, pp. 1647–1651, October 2015.
[27] M. Ali, H. Tabassum, and E. Hossain, “Dynamic user clustering and power allocation for uplink and downlink non-orthogonal multiple access (NOMA) systems,” IEEE Access, vol. 4, pp. 6325–6343, August 2016.
[28] G. H. Golub and C. F. V. n Loan, Matrix Computations. The Johns Hopkins University Press, 2013.