Power Allocation for Cognitive Radios Based on Primary User Activity in an OFDM System

Efficient and reliable power allocation algorithm in Cognitive radio (CR) networks is a challenging problem. Traditional water-filling algorithm is inefficient for CR networks due to the interaction with primary users. In this paper, we consider reliability/availability of subcarriers or primary user activity for power allocation. We model this aspect mathematically with a risk-return model by defining a general rate loss function. We then propose optimal and suboptimal algorithms to allocate power under a fixed power budget for such a system with linear rate loss. These algorithms as we will see allocate more power to more reliable subcarriers in a water-filling fashion with different water levels. We compare the performance of these algorithms for our model with respect to water-filling solutions. Simulations show that suboptimal schemes perform closer to optimal scheme although they could be implemented with same complexity as water-filling algorithm. Finally, we discuss the lineari...

• Type: Conference
• Year: 2008
• Where: GLOBECOM
• Authors: Ziaul Hasan, Ekram Hossain, Charles L. Despins, Vijay K. Bhargava
• Keywords: Algorithm, Communications, GLOBECOM 2008, Power Allocation, Water-filling Algorithm