Cooperative Rate Splitting Multiple Access in Cognitive Radio Networks: Power Allocation and Location Optimization

Ultra-reliable and low-latency communication is the basic requirement for delay-sensitive applications. However, limited by the spectrum resource, delay-sensitive services may not be well supported. In order to achieve ultra-reliable and low-latency communications, we propose a novel rate split multiple access (RSMA) based scheme in the unmanned aerial vehicle (UAV) based cognitive radio networks to satisfy primary reliable and timely transmissions while providing secondary spectrum access opportunities. In the RSMA based scheme, the UAV-based secondary transmitter (ST) first receives the primary information and then divides the received primary and the secondary signals as the common and private parts. After combining the primary and secondary common parts as the common signal, the ST will broadcast the common signal, primary private signal, and secondary private signal. In the proposed scheme, the target is to maximize the secondary transmission rate constrained by the primary quality of service requirement. Then, an iterative algorithm is designed to allocate the transmit power, ST's location, and rate split parameter. Simulation results show the performance improvement in the RSMA based scheme compared with the current cooperative cognitive strategies about the secondary rate.