Judicious power loading for a cognitive relay scenario

This paper introduces a power loading strategy for relays to be used in a cognitive scenario. A cognitive relay node allows unlicensed (secondary) users to concurrently operate with licensed (primary) users, thereby improving spectral efficiency. The dynamic spectrum access in an OFDM-based cognitive relay network may lead to unwanted interference to the primary user from the side lobes of the secondary users. Two judicious algorithms are formulated by means of which the cognitive relay meets the twofold challenge of achieving optimum system throughput while ensuring minimum interference to the primary. The simulation results demonstrate that the suggested algorithms exhibit enhanced channel capacity for the secondary users as compared to traditional power allocation methods.