Table 2.

Features of studies of beyond 5G new networks.

Features	Study 1 [23]	Study 2 [24]	Study 3 [25]
Metrics	Maximize SEE	Maximize SEE	Improve secrecy
Optimization variable	Hybrid BF	Hybrid BF	BF, Alternating Optimization
Takes into consideration imperfect CSI	Yes, for wiretap channels	Yes, for jamming and wiretap channels	Yes, for direct and cascaded channels of the legitimate and eavesdropping links
Other constraints	SINR requirements, analog precoder power, transmit power	Target rate requirements, wiretap rate requirements, transmit power constraints, RIS unit-modula constraint	Worst case QoS constraints and the UMC of the phase shifter
Use of SCA	Yes	Yes	Yes
Charnes–Cooper approach	Yes	No	No
Use of interference	No	Yes	No
EE improvements	NA	0.0814 and 0.1190 bps/Hz/Joule	NA