Optimal and Suboptimal Power Allocation Schemes for OFDM-based Cognitive Radio Systems

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 OFDMbased 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 alt...

• Type: Journal
• Year: 2008
• Where: TWC
• Authors: Gaurav Bansal, Md. Jahangir Hossain, Vijay K. Bhargava
• Keywords: Algorithms, Classical Loading Algorithms, Suboptimal Schemes, TWC 2008