POWER ALLOCATION USING GEOMETRIC WATER FILLING AND DYNAMIC CHANNEL SENSING ALGORITHM IN COGNITIVE RADIO NETWORK

Abstract

As spectrum scarcity is a big problem cognitive radio is an efficient solution to this problem. Orthogonal frequency
division multiplexing (OFDM) is a potential technology providing many advanced functionalities in terms of power band rate
control for cognitive radio networks (CRNs). Power allocation for CRNs is an important part for reduction of interference. In
this paper we compare two water filling algorithm geometric water filling and dynamic channel sensing algorithm. This
algorithm is optimized in a way to maximize the sum rate of secondary users by allocating power more efficiently, while
constraining the 1) total transmit power, 2) individual sub channel transmit power as well as 3) individual subcarrier peak
power of secondary users, for a given interference level to the primary users. Numerical results show that these algorithms
provide better utilization of power resources thus maximizes the sum rate than the existing algorithms. And the power
allocation is optimal. Geometric water filling is a dynamic power distribution process. The state of this process is the
difference between the individual peak power sequences and the current power distribution sequence obtained by the
Algorithm GWF and dynamic channel sensing algorithm provide optimal solution in terms of power is allocated intelligently
and with less complexity.