Robust Beamforming in NOMA Cognitive Radio Networks: Bounded CSI

As a promising technique of improving the spectral efficiency (SE), cognitive radio (CR) techniques have also been investigated for decades, where the secondary users (SUs) may access the spectrum bands of the primary users, as long as the interference caused by SUs is tolerable. To address both the SE and energy efficiency (EE), a MISO new radios non‐orthogonal multiple access CR using SWIPT is considered in this chapter based on a practical non‐linear energy harvesting (EH) model. Robust beamforming design problems are studied under a pair of Channel State Information error models. The prior contributions related to the chapter can be divided into two categories based on the EH model adopted, i.e. the linear and the non‐linear EH model. In the linear EH model, the power harvested increases linearly with the input power, while the EH under the non‐linear model exhibits more realistic non‐linear characteristics especially at the power‐tail.