Energy-Spectral Efficiency Optimization in Wireless Underground Sensor Networks Using Salp Swarm Algorithm

Table 1

Symbols and notations.

Symbol	Definition
	Battery power capacity of node
	Total number of transmissions that can be performed over the link
	Power used to transmit a packet
	UG2UG Rayleigh distributed channel between and
	UG2AG Rayleigh distributed channel between and
	Zero-mean complex Additive White Gaussian Noise (AWGN) vector with power spectral density
	System bandwidth
	Amplification factor
	UG2UG path loss
	UG2AG path loss composed by the path losses at the underground and the aboveground portions and
	Minimum power allowed for each transmission
	Maximum power allowed for each transmission
	Optimal power of node
	Remaining battery capacity of node at
	Total SNR of the link
	Maximum achievable total transmission data rate of the link
	Energy efficiency of the link
	Spectral efficiency of the link
	Resource efficiency of the link