An Event-Driven Self-Healing Routing and Topology Maintenance Mechanism for Surface-Deployed Wireless Sensor Networks in Ocean Environments

. 2026 Jun 20;26(12):3915. doi: 10.3390/s26123915

Algorithm 3. Node Help (Node-HELP)

When node n detects that its connection to the CH is broken or its CH cannot reach the BS
     Record the current state of n as “Disconnected”
     Increment Node-HELP call count and cumulative statistics
     Node n broadcasts a Node-HELP Request packet with radius R_c1
     For each alive CH node ch within communication range
            If (ch has a valid route to BS AND ch.Upstream_ID ≠ −1)
                  ch replies with a control packet to node n
                  Calculate link stability: Score = LinkStability(n, ch)
            End if
     End for
     If node n receives one or more replies from candidate CHs
            Select best_CH with the highest stability score
            If n was previously associated with an old CH
                  Remove n from the old CH’s member list
            End if
            Update n.CH_ID = best_CH.ID and set n.is_member = True
            Add n to the best_CH member list
            Update the state of n to “Reconnected”
     Else
            Maintain the state of n as “Disconnected” and set n.CH_ID = 0
     End if
End Algorithm