No.	Abbreviations	Full Description
1	AF	Amplify-and-forward
2	AWGNs	Additive white Gaussian noises
3	BS	Base station
4	CDF	Cumulative distribution function
5	CSI	Channel state information
6	DF	Decode-and-forward
7	EE	Energy efficient
8	FD	Full-duplex
9	Fig.	Figure
10	FG	Fixed gain
11	G-WNs	Green-wireless networks
12	HD	Half-duplex
13	NOMA	Non-orthogonal multiple access
14	PDF	Probability density function
15	PSM	Protocol switching mechanism
16	PSS	Protocol switching selection
17	QoS	Quality of service
18	S	Source
19	SIC	Successive interference cancellation
20	SINR	Signal-to-interference-plus-noise ratio
21	SNR	Signal-to-noise ratio
22	$U_i$	The i-th user
23	VG	Variable gain