Tuyển tập báo cáo các nghiên cứu khoa học quốc tế ngành hóa học dành cho các bạn yêu hóa học tham khảo đề tài: Research Article Complexity-Reduced MLD Based on QR Decomposition in OFDM MIMO Multiplexing with | Hindawi Publishing Corporation EURASIP Journal on Advances in Signal Processing Volume 2011 Article ID 525829 15 pages doi 2011 525829 Research Article Complexity-Reduced MLD Based on QR Decomposition in OFDM MIMO Multiplexing with Frequency Domain Spreading and Code Multiplexing Kouji Nagatomi 1 Hiroyuki Kawai 2 and Kenichi Higuchi1 department of Electrical Engineering Tokyo University of Science 2641 Yamazaki Noda Chiba 278-8510 Japan 2Radio Access Network Development Department NTT DOCOMO INC. 3-5 Hikari-no-oka Yokosuka Kanagawa 239-8536 Japan Correspondence should be addressed to Kenichi Higuchi higuchik@ Received 12 April 2010 Revised 30 June 2010 Accepted 19 August 2010 Academic Editor Naofal Al-Dhahir Copyright 2011 Kouji Nagatomi et al. This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use distribution and reproduction in any medium provided the original work is properly cited. This paper presents a new maximum likelihood detection- MLD- based signal detection method for orthogonal frequency division multiplexing OFDM multiple-input multiple-output MIMO multiplexing with frequency domain spreading and code multiplexing. The proposed MLD reduces the computational complexity by utilizing signal orthogonalization based on QR decomposition of the product of the channel and spreading code matrices in the frequency domain. Simulation results show that when the spreading factor and number of code multiplexed symbols are 16 the proposed MLD reduces the average received signal energy per bit-to-noise spectrum density ratio Eb N0 for the average packet error rate PER of 10 2 by approximately 12 dB compared to the conventional minimum mean-squared error- MMSE- based filtering for 4-by-4 MIMO multiplexing 16QAM with the rate-3 4 Turbo code is assumed . 1. Introduction Orthogonal frequency division multiplexing OFDM is a promising modulation radio access scheme for future .
