Adagrad	Adaptive Gradient
AI	Artificial Intelligence
AmBC	Ambient Backscatter Communication
BS	Base Station
CSI	Channel State Information
DC	Direct Current
DDPG	Deep Deterministic Policy Gradient
DNN	Deep Neural Networks
DDQN	Double Deep Q-Network
DQN	Deep Q-Network
DRL	Deep Reinforcement Learning
EM	Electromagnetic
FL	Federated Learning
GT	Ground Terminal
IoUgT	Internet of Underground Things
IoUwT	Internet of Underwater Things
IRS	Intelligent Reflecting Surface
LoS	Line of Sight
MDP	Markov Decision Process
MIMO	Multiple Input Multiple Output
ML	Machine Learning
NLoS	Non-Line of Sight
NOMA	Non-Orthogonal Multiple Access
PPO	Proximal Policy Optimization
RE	Reflecting Elements
RF	Radio Frequency
RIS	Reconfigurable Intelligent Surface
RL	Reinforcement Learning
RMSprop	Root Mean Square Propagation
RProp	Resilient Propagation
SGD	Scholastic Gradient Descent
SL	Split Learning
SNR	Signal-to-Noise Ratio
TD3	Twin Delayed DDPG
TDDRL	Twin-DDPG Deep Reinforcement Learning
UAV	Unmanned Aerial Vehicle
UWOC	Underwater Wireless Optical Communication