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 An Efficient Measure for Nonlinear Distortion Severity due to HPA in Downlink DS-CDMA Signals | Hindawi Publishing Corporation EURASIP Journal on Wireless Communications and Networking Volume 2010 Article ID 945427 10 pages doi 2010 945427 Research Article An Efficient Measure for Nonlinear Distortion Severity due to HPA in Downlink DS-CDMA Signals Tarek K. Helaly Richard M. Dansereau and Mohamed El-Tanany Department of Systems and Computer Engineering Carleton University 1125 Colonel By Drive Ottawa ON Canada K1S 5B6 Correspondence should be addressed to Tarek K. Helaly thelaly@ Received 22 June 2010 Revised 8 September 2010 Accepted 4 October 2010 Academic Editor Fabrizio Granelli Copyright 2010 Tarek K. Helaly 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 deals with the nonlinear distortion NLD effects of high power amplifiers HPAs on direct sequence-code division multiple access systems. Such a distortion drastically degrades the system performance in terms of bit error rate BER degradation and spectral regrowth. Much effort has been conducted to minimize NLD. A key requirement to do so is to define a certain measure for the HPA nonlinearity which when reduced often allows NLD to also be reduced. Several measures were proposed such as peak-to-average power ratio instantaneous power variance and cubic metric. In this paper we show that such measures are not closely related to NLD and their reduction does not always lead to optimum performance. Hence we introduce an efficient measure namely nonlinearity severity NLS to characterize NLD effects as an alternative to the existing measures. The NLS is characterized by having direct link to the system performance as it is formulated based on the signal characteristics contributing to BER performance and spectral regrowth. Additionally a major advantage of the NLS measure is that it is linked to the IBO level .
