Procedure path_algorithm (){ 
calculate the transition probability for each 
path by the formula (1); 
random=Rnd(); 
if( < random < ) 
choose the path to the sink 
}

Procedure update pheromone algorithm 
{//the node receives the ACK successfully 
if(=node.hop){ // the node.hop in the Sink 
; node.hop = ; 
}

; 
if( > th) 
calculate the volatilization coefficient by the 
formula (6); 
Else 
; 
calculate the correction value by the formula (5); 
update the pheromone by the formula (2); 
}
