Optimal Power Allocation Using Different Water Filling Algorithm in OFDM-Based Cognitive Radio Network

Abstract

This paper gives a brief review of research work done on optimal power allocation using different water filling methods in OFDM-based cognitive radio networks. Various water filling methods are used for optimal power allocation. Water filling methods gives an optimal and efficient solution for the problem of maximizing the throughput and mutual information of a time varying channel composed of various subchannels by adjusting the transmitted power based on channel gain and improve the transmission capacity or the sum of data rate of the cognitive system without degrading the primary user’s quality of service. In the conventional water filling algorithm there is computation complexity, in this algorithm we have to solve nonlinear equations for determining the water level but in the geometric water filling we have linear equation and by this we can calculate the exact solution without calculating water level.