Journal of Information Systems and Telecommunication (JIST) Journal of Information Systems and Telecommunication (JIST) 2322-143714320091221Optimization of Random Phase Updating Technique for Effective Reduction in PAPR, Using Discrete Cosine TransformOptimization of Random Phase Updating Technique for Effective Reduction in PAPR, Using Discrete Cosine Transform11010.7508/jist.2016.02.004FABabakHaji Bagher Naeeni IRIB2016716One of problems of OFDM systems, is the big value of peak to average power ratio. To reduce it, any attempt have been done amongst which, random phase updating is an important technique. In contrast to paper, since power variance is computable before IFFT block, the complexity of this method would be less than other phase injection methods which could be an important factor. Another interesting capability of random phase updating technique is the possibility of applying the variance of threshold power. The operation of phase injection is repeated till the power variance reaches threshold power variance. However, this may be a considered as a disadvantage for random phase updating technique. The reason is that reaching the mentioned threshold may lead to possible system delay. In this paper, in order to solve the mentioned problem, DCT transform is applied on subcarrier outputs before phase injection. This leads to reduce the number of required carriers for reaching the threshold value which results in reducing system delay accordingly.http://jist.ir/WebUsers/jist/UploadFiles/OK/139504261545372861-F.pdf