cdma多用户检测技术研究-通信与信息系统专业毕业论文.docx

重庆大学硕士学位论文英文摘要
Abstract
In munication system the CROSS correlations among signals ofusers result in the Multiple Access Interference国锻鸯,which is low when the number ofusers in the same channel is small,but will increases and e the mainjamming ofbroad munica矗On syStem wim the increase ofthe number ofusers or the difference ofuser’S
conventional single r。ISer detector matches the Spread-Spectrum codes for
each pletely according to the classic theory of Direetc,-Scquences Spmad
-Spectrum(DS—SS)theory,S0 its ability to resist MAI is poor.
As one ofthe most important technologies ofCDMA,Multi-user Detection(MUD) technique has a good performance ofresisting MAd and near-far effect through the USe of adequate cross correlations among spreading codes ofusers to detect the signals.
The Optimum Multiuser Detector proposed by Verdu can solve the problem of
MAI and near-far effect of munication system。But plexity of the detector appears to be exponential in the number of the number of users is
large,the detector call’t be hJ曲efficiency sub—optimum algorithms of
sub-Optimum Detectors are important to the researching On MUD+
In this dissertation the author proposed a kind of sub—optimum algorithm,a hybrid
detector based on Stochastic Hopfield -woN(SI-rNN)and Reduced Detector
(mg)for CDMA.
The similarity between the energy function of Discrete Hopfield work (DHNN)and the formula ofOMD means that using DHNN to solve the problem ofOMD is convergence process of work is the process to solve the problem of OMD。So a MUD based on DHNN has been proposed in this dissertation. Considering that the DHNN may converge to the loc氇l minima,the author introduced the SHNN to make work converge to the百obal order to decrease the searching space plexity of SHNN,to detect the users with higher power,and to
make use of氆e merits of SHNN,a Reduced Detector has been introduced。The main
merit of Reduced Detecor iS far-near r