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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: Adaptive Denoising and Equalization of Infrared Wireless CDMA System | EURASIP Journal on Applied Signal Processing 2005 1 20-29 2005 Hindawi Publishing Corporation Adaptive Denoising and Equalization of Infrared Wireless CDMA System Xavier N. Fernando Advanced Radio-Optics Integrated Technology Group ADROIT Ryerson University Toronto Canada M5B2J1 Email xavier@ieee.org Balakanthan Balendran Advanced Radio-Optics Integrated Technology Group ADROIT Ryerson University Toronto Canada M5B2J1 Email bbalendr@ee.ryerson.ca Received 19 March 2004 Revised 5 November 2004 Infrared has abundant unregulated bandwidth enabling rapid deployment at low cost. However safety limits on power emission levels IEC825 large noise due to ambient lighting and multipath dispersion remain as hurdles in diffused indoor environments. Especially the high-frequency periodic interference produced by fluorescent lights is a major concern. Spread spectrum techniques enable low-power operation and noise rejection at the expense of large processing gain. In this paper we quantify the noise received and propose an adaptive FIR filter to jointly cancel the multipath dispersion and the fluorescent light noise in an infrared CDMA system. From analytical and simulation results the adaptive filter significantly enhances the noise rejection capability of the CDMA system and tracks well the quasistationary indoor wireless channel. Our results show tenfold improvement in the BER for a given SNR and processing gain due to the adaptive filter. The filter also performs well in the multiuser environment. Keywords and phrases optical wireless adaptive filters equalization noise cancellation infrared. 1. INTRODUCTION The history of optical wireless communications free space optical links predates that of fiber optics. Optical wireless communication is in use today in many applications offering very-high-speed wireless links cost-effectively. Wireless communications based on infrared IR technology is one of the most growing areas in telecommunications. IEEE has specified IR as one of
