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

TitlePower Allocation for Cognitive Radios Based on Primary User Activity in an OFDM System
Publication TypeConference Paper
Year of Publication2008
AuthorsHasan, Z., E. Hossain, C. Despins, and V. K. Bhargava
Conference NameGlobal Telecommunications Conference, 2008. IEEE GLOBECOM 2008. IEEE
Pagination1 -6
Date Publishednov.
Keywordscognitive radio, fixed power budget, linear rate loss, OFDM modulation, OFDM system, power allocation, primary user activity, rate loss function, risk-return model, subcarrier availability, subcarrier reliability, telecommunication network reliability

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 linearity of loss function and guidelines to choose its coefficients by obtaining upper bounds on them.


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