垂直貝爾實驗室分層空時(V-BLAST)技術為一種多輸入多輸出(MIMO)的無線系統架構，它可以在低實現複雜度的情況下，達到相當高的頻譜效率。而在本論文中，我們針對V-BLAST正交載波多工(OFDM)系統，提出了一種新型的階層訊號偵測演算法，此種偵測法使用了不同於原先OSIC偵測法的偵法排序。在我們所提出的偵測法中，對於有著最小事後偵測訊雜比(post-detection SNR)的階層，我們使用降低複雜度ML偵測法來偵測，而剩餘的其他階層，我們則是利用降低迭代OSIC偵測法來偵測。最後，經由模擬的結果顯示，我們所提出的偵測演算法，在位元錯誤率方面的效能表現，成功達到逼近最佳的ML偵測法，且在運算複雜度方面，也能有所大幅下降。

Vertical Bell Laboratories Layered Space-Time(V-BLAST) is a multiple-input multiple-output(MIMO) wireless system. V-BLAST attains very high spectral efficiency while maintaining a low complexity of implementation. In this thesis, we propose a new layered symbol detection algorithm for V-BLAST OFDM systems. The proposed algorithm uses a symbol detection ordering method which is different from that recommended in the original OSIC algorithm. In our scheme, for the layer with the smallest post-detection SNR, we use reduced complexity ML for detection, and for other layers, a reduced iterative OSIC detection scheme is developed. Simulation results show that the proposed detection algorithm achieves high detection performance which is close to the ML detection method, and significantly reduces the computational complexity.

[1] S. Alamouti, “A simple transmit diversity technique for wireless communications,”
IEEE J. Select. Areas Commun., vol. 16, no. 8, pp. 1451–1458,
Oct. 1998.
[2] V. Tarokh, H. Jafarkhani, and A. Calderbank, “Space-time block codes
from orthogonal designs,”IEEE Trans. Inform. Theory, vol. 45, no. 5, pp.
1456–1467, July 1999.
[3] G. J. FOSCHINI and M. J. GANS, “On limits of wireless communications
in a fading environment when using multiple antennas,”Bell Labs Tech. J.,
vol. 6, pp. 311–335, 1998.
[4] P. Wolniansky, G. Foschini, G. Golden, and R. Valenzuela, “V-blast: an
architecture for realizing very high data rates over the rich-scattering wireless
channel,”in Proc. IEEE Int. Symp. Signals, Systems,and Electronics, Sept.
1998, pp. 295–300.
[5] G. Golden, C. Foschini, R. Valenzuela, and P. Wolniansky, “Detection algorithm
and initial laboratory results using v-blast space-time communication
architecture,”Electron. Lett., vol. 35, no. 1, pp. 14–16, Jan. 1999.
[6] E. Viterbo and J. Boutros,“A universal lattice code decoder for fading channels,”
IEEE Trans. Inform. Theory, vol. 45, no. 5, pp. 1639–1642, July 1999.
[7] B. Hochwald and S. ten Brink, “Achieving near-capacity on a multipleantenna
channel,”IEEE Trans. Commun., vol. 51, no. 3, pp. 389–399, Mar.
2003.
[8] K. J. Kim and R. Iltis, “Joint detection and channel estimation algorithms
for qs-cdma signals over time-varying channels,”IEEE Trans. Commun.,
vol. 50, no. 5, pp. 845–855, May 2002.
[9] K. Higuchi, H. Kawai, N. Maeda, M. Sawahashi, T. Itoh, Y. Kakura, A. Ushirokawa,
and H. Seki, “Likelihood function for qrm-mld suitable for softdecision
turbo decoding and its performance for ofcdm mimo multiplexing
in multipath fading channel,”in Proc. IEEE Int. Symp. Personal, Indoor and
Mobile Radio Commun., vol. 2, Sept. 2004, pp. 1142–1148.
[10] C. Shen, H. Zhuang, L. Dai, and S. Zhou, “Detection algorithm improving
v-blast performance over error propagation,”Electron. Lett., vol. 39, no. 13,
pp. 1007–1008, June 2003.
[11] Y. Lomnitz and D. Andelman, “Efficient maximum likelihood detector
for mimo systems with small number of streams,”Electron. Lett., vol. 43,
no. 22, Oct. 2007.
[12] W. Xu, Y. Wang, Z. Zhou, and J. Wang, “A flexible near-optimum detector
for v-blast,”in IEEE Circuits and Systems Symp. on Emerging Technologies:
Frontiers of Mobile and Wireless Communication, vol. 2, May 2004,
pp. 681–684.
[13] G. J. Foschini, “Layered space-time architecture for wireless communication
in a fading environment when using multi-element antennas,”Bell Labs
Tech. J., vol. 1, pp. 41–59, Aut. 1996.
[14] A. Alimohammad, S. Fard, and B. Cockburn, “Improved layered mimo
detection algorithm with near-optimal performance,”Electron. Lett., vol. 45,
no. 13, pp. 675–677, June 2009.
[15] V. Tarokh, N. Seshadri, and A. R. Calderbank, “Space-time codes for high
data rate wireless communications : Performance criterion and code construction,”
IEEE Trans. Inform. Theory, vol. 44, pp. 744–765, Mar. 1998.
[16] J. Hagenauer and P. Hoeher, “A viterbi algorithm with soft-decision outputs
and its applications,”in Proc. GLOBECOM, vol. 3, Nov. 1989, pp.
1680–1686.
[17] S. Benedetto, D. Divsalar, G. Montorsi, and F. Pollara, “Soft-input softoutput
modules for the construction and distributed iterative decoding of code
networks,”European Trans. Telecomm., Dec. 1998.
[18] C. Douillard, M. J''ez''equel, C. Berrou, A. Picart, P. Di-dier, and A. Glavieux,
“Iterative correction of intersymbol interference: Turbo-equalization,”European
Trans. Telecomm., vol. 6, pp. 507–511, Oct. 1995.
[19] M. Tuchler, R. Koetter, and A. Singer, “Turbo equalization: principles and
new results,”IEEE Trans. Commun., vol. 50, no. 5, pp. 754–767, May 2002.
[20] R. Koetter, A. Singer, and M. Tuchler, “Turbo equalization,”IEEE Signal
Processing Mag., vol. 21, no. 1, pp. 67–80, Jan. 2004.
[21] W. Chen, X. Zhang, and W. Li,“Reduced complexity ml detection algorithm
for v-blast architectures,”in Proc. PACIIA, vol. 1, Nov. 2009, pp. 190–193.
[22] Y. Cho, J. Kim, W. Yang, and C. Kang, MIMO-OFDM Wireless Communications
with MATLAB. John Wiley & Sons, 2010.
[23] A. Paulraj, R. Nabar, and D. Gore, Introduction to Space-Time Wireless Communications,
1st ed. New York, NY, USA: Cambridge University Press,
2008.
[24] L. Zheng and D. Tse, “Diversity and multiplexing: a fundamental tradeoff
in multiple-antenna channels,”IEEE Trans. Inform. Theory, vol. 49, no. 5,
pp. 1073–1096, May 2003.