毫米波頻帶擁有大量的可用頻寬，因此相當適合使用於下一世代的行動通訊系統。而為了避免毫米波短波長引起的嚴重信號衰減和路徑損耗，多輸入多輸出毫米波系統利用大量傳送、接收天線陣列以減少訊號衰減。然而大量的天線導致所需的射頻鏈和數位類比轉換器較多，導致成本與功耗也較大。因此有了類比數位混合式預編碼架構來減少所需的射頻鏈、數位類比轉換器。混合預編碼器將預編碼過程分為部分在類比端作、部分在數位端作，來減少預編碼過程中減少數位類比間所需的取樣數。本論文提出了一種基於平行資料流架構的可擴展式低複雜度混合預編碼演法，使每筆資料流獨立作計算。本論文所提出的預編碼演算法使用TSMC 40nm CMOS製程來實作成硬體。所提出的預編碼處理器使用於16x16多輸入多輸出系統，且支援最多4筆資料流。處理器的最高頻率為120MHz，功耗為139mW。且處理器在1/2/3/4個資料流可分別達到6.67M/6.67M/6.67M/6.67M通道矩陣/每秒的吞吐量。

Millimeter wave (mmWave) multiple-input and multiple-output (MIMO) system provides high throughput for next generation system. To avoid severe signal attenuation and path loss caused by short wavelength, mmWave MIMO system utilizes large antenna arrays in transmitter and receiver to reduce fading. However, the high cost of radio frequency (RF) chain and data converter limits the number of antennas. Thus, hybrid analog/digital precoding was proposed to reduce the required number of RF chains and data converters under the condition of large antenna arrays. Hybrid precoding MIMO system divides precoding process into analog domain and digital domain in order to reduce the sampled data from digital precoding process.
In this thesis, we propose a scalable low complexity hybrid precoding algorithm based on parallel data-stream hardware architecture which enables independently computing for each data stream. Moreover, the proposed scalable precoding algorithm is implemented using TSMC 40 nm CMOS process technology. The proposed precoding processor supports the transmissions of 1 to 4 data streams for 16x16 mmWave MIMO systems. The operating frequency of this chip is 120 MHz and power consumption is 139 mW. The normalized throughput of this chip achieves 6.67M/6.67M/6.67M/6.67M channel-matrices per second in 1/2/3/4 data streams.

[1] Z. Pi and F. Khan, “An introduction to millimeter-wave mobile broadband systems,” IEEE Communications Magazine, vol. 49, no. 6, pp. 101–107, 2011.
[2] S. K. Yong and C.-C. Chong, “An overview of multigigabit wireless through millimeter wave technology: potentials and technical challenges,” EURASIP Journal on Wireless Communications and Networking, vol. 2007, no. 1, pp. 1–10, 2006.
[3] S. Sun, T. S. Rappaport, R. W. Heath, A. Nix, and S. Rangan, “Mimo for millimeter-wave wireless communications: beamforming, spatial multiplexing, or both?” IEEE Communications Magazine, vol. 52, no. 12, pp. 110–121, 2014.
[4] O. El Ayach, S. Rajagopal, S. Abu-Surra, Z. Pi, and R. W. Heath, “Spatially sparse precoding in millimeter wave mimo systems,” IEEE Transactions on Wireless Communications, vol. 13, no. 3, pp. 1499–1513, 2014.
[5] Y.-Y. Lee, C.-H. Wang, and Y.-H. Huang, “A hybrid rf/baseband precoding processor based on parallel-index-selection matrix- inversion-bypass simultaneous orthogonal matching pursuit for millimeter wave mimo systems,” IEEE Transactions on Signal Processing, vol. 63, no. 2, pp. 305–317, 2015.
[6] R. Mndez-Rial, C. Rusu, N. Gonzlez-Prelcic, and R. W. Heath, “Dictionary-free hybrid precoders and combiners for mmwave mimo systems,” in in Proc. IEEE Int. Workshop Signal Process. Adv. Wireless Commun. (SPAWC). IEEE, 2015, pp. 151–155.
[7] O. El Ayach, R. W. Heath, S. Abu-Surra, S. Rajagopal, and Z. Pi, “Low complexity precoding for large millimeter wave mimo systems,” in 2012 IEEE International Conference on Communications (ICC). IEEE, 2012, pp. 3724–3729.
[8] C.-T. Chang and C.-E. Chen, “A new hybrid precoders and combiners design architecture for millimeter wave mimo systems,” Master’s thesis, National Chung Cheng University, Taiwan, 2016.
[9] X. Gao, L. Dai, S. Han, C.-L. I, and R. W. Heath, “Energy-efficient hybrid analog and digital precoding for mmwave mimo systems with large antenna arrays,” IEEE Journal on Selected Areas in Communications, vol. 34, no. 4, pp. 998–1009, 2016.
[10] X. Zhang, A. F. Molisch, and S.-Y. Kung, “Variable-phase-shift-based rf-baseband codesign for mimo antenna selection,” IEEE Transactions on Signal Processing, vol. 53, no. 11, pp. 4091–4103, 2005.
[11] E. Zhang and C. Huang, “On achieving optimal rate of digital precoder by rfbaseband codesign for mimo systems,” in 2014 IEEE 80th Vehicular Technology Conference (VTC2014-Fall). IEEE, 2014, pp. 1–5.
[12] K.-N. Hsu, C.-G. He, and Y.-H. Huang, “Low-complexity hybrid beam-tracking algorithms and architectures for mmwave mimo systems,” in 2016 IEEE International Symposium on Circuits and Systems (ISCAS). IEEE, 2016, pp. 1902–1905.
[13] Q. Spencer, B. Jeffs, M. Jensen, and A. Swindlehurst, “Modeling the statistical time and angle of arrival characteristics of an indoor multipath channel,” Selected Areas in Communications, IEEE Journal on, vol. 18, no. 3, pp. 347–360, 2000.
[14] P. F. M. Smulders and L. Correia, “Characterisation of propagation in 60 ghz radio channels,” Electronics Communication Engineering Journal, vol. 9, no. 2, pp. 73–80, 1997.
[15] G. Huang and L. Wang, “High-speed signal reconstruction with orthogonal matching pursuit via matrix inversion bypass,” in Signal Processing Systems (SiPS), 2012 IEEE Workshop on. IEEE, 2012, pp. 191–196.
[16] C.-K. Ho and Y.-H. Huang, “Low complexity hybrid precoding algorithm using multiple orthogonal codebook matrices and local search,” Master’s thesis, National Tsing Hua University, Taiwan, 2016.
[17] C. Rusu, R. M´endez-Rial, N. Gonz´alez-Prelcicy, and R. W. Heath, “Low complexity hybrid sparse precoding and combining in millimeter wave mimo systems,” in 2015 IEEE International Conference on Communications (ICC). IEEE, 2015, pp. 1340–1345.
[18] W.-L. Hung, C.-H. Chen, C.-C. Liao, C.-R. Tsai, and A.-Y. A. Wu, “Lowcomplexity hybrid precoding algorithm based on orthogonal beamforming codebook,” in 2015 IEEE Workshop on Signal Processing Systems (SiPS). IEEE, 2015, pp. 1–5.