近年來，隨著資料傳輸以及對傳輸品質的要求遽增，促使研究者紛紛發展新的傳送技術，來達到高的throughput和spectral efficiency，例如:多輸入多輸出(MIMO)系統已廣泛的被使用在無線通訊上，但往往都忽略了一些能源消耗問題。在傳統MIMO系統上，能量使用效率會隨著使用的天線數(Multiple radio frequency (RF) chains)而線性遞減。 因此，研究者就提出了空間調變(spatial modulation,SM)的技術，SM是一種新興的多天線傳送技術，主要的概念是在大量天線的MIMO系統中，每次只使用一根傳送天線來傳送訊號，來達到減少RF chain的數量而提高能量使用的效率，如單輸入單輸出(SISO)系統一樣，但SM的資料傳輸卻能比SISO系統來的高，主要的原因是SM技術把額外的information bits資訊加載在每一根傳送天線索引上。現今，已有研究者發展大規模的MIMO(Large-scale MIMO or massive MIMO)系統，能使在傳送端能擺放很大數量的傳送天線。因此，在傳送端擁有夠多的傳送天線，SM系統就有更多的information能加載在傳送天線索引上來達到提高資料傳輸率的效果。另外，若系統同一時間啟動了兩根以上天線來傳送訊號，稱為SM-MIMO，藉此來達到更高傳輸速率，本論文主要探討SM-MIMO系統啟動兩根天線傳送訊號，提出一個聯合子集通道的概念，對每一個聯合子集通道做預先處理(pre-processing)，來降低接收端偵測器的複雜度。

In recent years, due to the transmission data rates and growing link quality demand,
researchers develop new transmission technologies to achieve high data throughputs
and spectral eciency, such as multiple-input-multiple-output (MIMO) systems that is
widely used in wireless communication. However, the energy eciency is always not
taken into consideration. In traditional MIMO system, The energy eciency decreases
linearly with the number of active antennas (RF chains). In order to increase energy
eciency in wireless communication, the researcher proposes Spatial Modulation (SM)
that is a emerging and recently developed multiple-antenna transmission technique.
The main concept of SM is that using one active antenna to transmit signal in largescale
MIMO communications. Therefore, SM can achieve to reduce the number of
RF chain and increase energy eciency, such as Single-Input- Single-Output (SISO)
system. Beside, SM can improve transmission date rates compared to Single-Input-
Single-Output (SISO) system. This is because there are addition bits to be mapped
into antenna index. Nowadays, the researcher has been developed the large-scale MIMO
system. Therefore, the more the number of antenna at transmit, the higher data rates.
In addition, if the system at the same time has more than two active antennas to
transmit signals, which is termed as SM-MIMO. It can achieve higher transmission data
rates than SM system. In this thesis, we mainly SM-MIMO with two active antennas
and propose a joint subset channel concept and pre-processing each joint subset channel
to reduce the computational complexity of detector.

[1] Raed Y. Mesleh, H. Haas, S. Sinaovic, C. W. Ahn, and S. Yun, "Spatial modulation,"in IEEE Trans. Veh. Technol., vol. 57, no. 4, July 2008, pp. 2228{2241.
[2] P.-L. Chiu and Y.-H. Huang, "A Scalable MIMO Detection Architecture with Non-Sorted Multiple-Candidate Selection," in Circuits and Systems, 2009. ISCAS
2009.IEEE International Symposium on, may 2009, pp. 689-692.
[3] X. Cao, "Local maximum likelihood detection method for MIMO systems," in Communications, Circuits and Systems, 2005. Proceedings. 2005 International Conference on, vol. 1, may 2005, pp. 203-206.
[4] M. Shabany and P. Gulak, "Scalable VLSI architecture for K-best lattice decoders,"in Circuits and Systems, 2008. ISCAS 2008.IEEE International Symposium on,may 2008, pp. 940{943.
[5] B. Hassibi and H. Vikalo, "On the Sphere-Decoding Algorithm I. Expected Complexity,"in Submitted to IEEE Transactions on Signal Processing, vol. 53, no. 8,AUGUST 2005, pp. 2806-2818.
[6] R. Mesleh, H. Haas, C. W. Ahn, and S. Yun, "Spatial modulationa new low complexity spectral eciency enhancing technique," in Proc. Conf. Comm. and Net-working in China, Oct. 2006.
[7] Chia-You Liu, "Low-complexity Detectors for Spatially Modulated MIMO Systems," Master's thesis, National Chiao Tung University, Taiwan, Feb 2014.
[8] Singh, C. K. and Prasad, S. H. and Balsara, P. T., "A Fixed-Point Implementation for QR Decomposition," in Proc. IEEE Dallas Workshop Des. Appl. Integr. Softw., vol. 57, no. 5, May 2010, pp. 1095{1102.
[9] Kuo Liang Chung and Wen Ming Yan, "The complex Householder transform," in IEEE Trans. Siganl Process, vol. 45, no. 9, Sep. 1997, pp. 2374{2376.
[10] P. Luethi, A. Burg, S. Haene, D. Perels, N. Felber, and W. Fichtner, "VLSI implementa-tion of a high-speed iterative sorted MMSE QR decomposition," in IEEE International Symposium on Circuits and Systems, May. 2007, pp. 1421-1424.
[11] A. Mohammadi and F. M. Ghannouchi, "Single RF front-end MIMO transceivers,"in IEEE Commun. Mag., vol. 49, no. 12, Dec. 2011, pp. 104-109.
[12] J. Mietzner, R. Schober, L. Lampe, W. H. Gerstacker, and P. A. Hoeher, "Multipleantenna techniques for wireless communicationsVA comprehensive literature survey,"in IEEE Commun. Surv. Tut., vol. 11, no. 2, 2nd Quart 2009, pp. 87-105.
[13] A. Younis, R. Mesleh, H. Haas, and P. Grant, "Reduced Complexity Sphere Decoder
for Spatial Modulation Detection Receivers," in 2010 IEEE Global Telecommuni-
cations Conference GLOBECOM 2010, Miami, USA, 2010, pp. 1{5.
[14] A. Younis, M. Di Renzo, R. Y. Mesleh, and H. Haas, "Sphere decoding for spatial modulation," in Proc. IEEE Int. Conf. Commun., Jun 2011, pp. 1-6.
[15] J. Jeganathan, A. Ghrayeb, and L. Szczecinski, "Spatial Modulation: Optimal Detection and Performance Analysis," in IEEE Commun. Lett., vol. 12, no. 8, Aug 2008, pp. 545-547.
[16] R. Rajashekar and K. V. S. Hari, "Sphere decoding for spatial modulation systems with arbitrary Nt," Feb 2012, [Online].Available: http://arxiv.org/pdf/1202.5187v1.pdf.
[17] Jeganathan, A. Ghrayeb, and L. Szczecinski, "Generalized space shift keying modulation for MIMO channels," in Proc. IEEE 19th International Symposium on Personal, Indoor and Mobile Radio Communications PIMRC 2008, 2008, pp. 1-5.
[18] J. P. Kermoal, L. Schumacher, K. I. Pedersen, P. E. Mogensen, and F. Frederiksen, "A stochastic MIMO radio channel model with experimental validation," in IEEE J. Sel. Areas Commun., vol. 20, no. 6, Aug 2002, pp. 1211-1226.
[19] A. V. Zelst and J. Hammerschmidt, "A single coecient spatial correlation model for multiple-input multiple-output (MIMO) radio channels," in Proc. of URSI General Assembly, Aug. 2002, pp. 1-4.