  With the increasing number of wireless communication systems and the demand
for bandwidth, the wireless medium has become a congested and contested
environment. Operating under such an environment brings several challenges,
especially for military communication systems, which need to guarantee reliable
communication while avoiding interfering with other friendly or neutral systems
and denying the enemy systems of service. In this work, we investigate a novel
application of Rate-Splitting Multiple Access(RSMA) for joint communications
and jamming with a Multi-Carrier(MC) waveform in a multiantenna Cognitive
Radio(CR) system. RSMA is a robust multiple access scheme for downlink
multi-antenna wireless networks. RSMA relies on multi-antenna Rate-Splitting
(RS) at the transmitter and Successive Interference Cancellation (SIC) at the
receivers. Our aim is to simultaneously communicate with Secondary Users(SUs)
and jam Adversarial Users(AUs) to disrupt their communications while limiting
the interference to Primary Users(PUs) in a setting where all users perform
broadband communications by MC waveforms in their respective networks. We
consider the practical setting of imperfect CSI at transmitter(CSIT) for the
SUs and PUs, and statistical CSIT for AUs. We formulate a problem to obtain
optimal precoders which maximize the mutual information under interference and
jamming power constraints. We propose an Alternating Optimization-Alternating
Direction Method of Multipliers(AOADMM) based algorithm for solving the
resulting non-convex problem. We perform an analysis based on
Karush-Kuhn-Tucker conditions to determine the optimal jamming and interference
power thresholds that guarantee the feasibility of problem and propose a
practical algorithm to calculate the interference power threshold. By
simulations, we show that RSMA achieves a higher sum-rate than Space Division
Multiple Access(SDMA).
