Transform-Domain-Based Cognitive Radio Networks for Harsh Interference Environments

In harsh interference environments, there are all kinds of electromagnetic interference to disturb the communication links. In this article, by integrating transform domain communication system (TDCS) into cognitive radio (CR), transform-domain-based cognitive radio (TD-CR) is proposed to flexibly adopt TD-based spread spectrum technology to generate an adaptive anti-interference modulation waveform over the idle spectrum, which will improve both the anti-interference performance and spectrum efficiency of CR in the harsh interference environments. First, the transmitter and receiver of the TD-CR system are designed, where the key technologies, including spectrum sensing, spectrum magnitude shape, random phase mapping, fundamental modulation waveform, and signal detection, are described. Second, novel interleave-division multiple access and clustering multiple access for the TD-CR are proposed to improve the multiuser spectrum access ability. Thirdy, artificial-intelligence-enabled TD-CR is proposed to achieve intelligent spectrum sensing and optimal waveform transform by a cognitive engine. Then simulation results are provided to verify the anti-interference performance of the TD-CR. finally, some future research challenges are discussed.