Pongsatorn SedtheetornMahidol University2018-07-122018-07-122008-10-065th International Conference on Electrical Engineering/Electronics, Computer, Telecommunications and Information Technology, ECTI-CON 2008. Vol.1, (2008), 337-3402-s2.0-52949143066https://repository.li.mahidol.ac.th/handle/20.500.14594/19128This paper presents an original exact analysis on the downlink spectral efficiency of DS/CDMA cellular systems in Rayleigh fading. We derive a new expression for the probability distribution function of signal to interference plus noise ratio (SINR) which accordingly leads us to propose explicit closed forms of the spectral efficiency and average bit error rate in Rayleigh fading environment. The proposed closed forms are used to accurately investigate the effects of orthogonality, prop-agational condition, and channel noise on the overall efficiency. ©2008 IEEE.Mahidol UniversityComputer ScienceEngineeringConference PaperSCOPUS10.1109/ECTICON.2008.4600441