Fast Suboptimal Algorithm for Power Allocation in OFDM-based Cognitive Radio Systems

Cognitive Radio (CR) is a technique to improve spectrum efficiency. Orthogonal Frequency Division Multiplexing (OFDM) is used in CR systems due to its advantages. The performance of OFDM-based CR systems can be improved by using adaptive algorithms to assign power of subcarriers of OFDM systems. Hence, in this paper we investigate adaptive power allocation algorithm in OFDM-based CR systems. Our purpose is maximizing the total achievable rate for secondary user (SU) while keeping the interference powers introduced by SU on primary user (PU) band less than the specific value. To achieve this purpose, we study optimal and conventional algorithms for allocating power to each subcarrier and then introduce a fast and novel low-complexity suboptimal algorithm. In the numerical results sections, the performance of our algorithm is compared by optimal and conventional algorithms. Numerical results indicate our algorithm has better performance than the conventional algorithms while its complexity is less than the optimal algorithm.

کلیدواژه ها:

Cognitive Radio ، OFDM ، Interference Constraints ، Power Allocation