APCC'09 Proceedings of the 15th Asia-Pacific conference on Communications
Power allocation for OFDM-based cognitive radio systems with hybrid protection to primary users
GLOBECOM'09 Proceedings of the 28th IEEE conference on Global telecommunications
IEEE Transactions on Wireless Communications
EURASIP Journal on Advances in Signal Processing - Special issue on filter banks for next-generation multicarrier wireless communications
A fast power allocation strategy for OFDM systems
IEEE Transactions on Communications
IEEE Transactions on Wireless Communications
Wireless Personal Communications: An International Journal
Second order suboptimal power allocation for OFDM-based cognitive radio systems
Proceedings of the 7th International Conference on Ubiquitous Information Management and Communication
Throughput optimisation in sensor network-aided cognitive radio
International Journal of Sensor Networks
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In this paper, we investigate an optimal power loading algorithm for an OFDM-based cognitive radio (CR) system. The downlink transmission capacity of the CR user is thereby maximized, while the interference introduced to the primary user (PU) remains within a tolerable range. We also propose two suboptimal loading algorithms that are less complex. We also study the effect of a subcarrier nulling mechanism on the performance of the different algorithms under consideration. The performance of the optimal and suboptimal schemes is compared with the performance of the classical power loading algorithms, e.g., water-filling and uniform power but variable rate loading schemes that are used for conventional OFDM-based systems. Presented numerical results show that for a given interference threshold, the proposed optimal scheme allows CR base station (BS) to transmit more power in order to achieve a higher transmission rate than the classical loading algorithms. These results also show that although the proposed suboptimal schemes have certain degradation in performance compared to the optimal scheme, they outperform the classical loading algorithms. We also present numerical results for nulling mechanism. Finally, we investigate the effect of imperfect channel gain information at the transmitter.