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 2. Cluster Head Help (CH-HELP)

When CH node n detects a disconnection in its path to BS
    Record the current state of n as “Disconnected”
    Set S_up(n) = 0
    If a direct BS connection is feasible under the R_c2 based local confirmation condition
        Set the BS as the upstream of n
        Set n.Hop = 1
        Set S_up(n) = 1
        Update the state of n to “Reconnected”
    Else
        CH n broadcasts a CH-HELP Request packet with radius R_c2
        For each alive CH node m within communication range
            If S_up(m) = 1 has been confirmed in the current BS-outward validation order AND the bounded validation in Section 4.3 confirms that the upstream chain of m does not contain n
                Calculate Score(n,m) using Equation (7)
                Reply with a control packet containing the score to node n
            End if
        End for
        If node n receives one or more reply packets
            Select best_m with the highest score as the new upstream
            Update upstream ID of n to best_m
            Update hop level: n.Hop = best_m.Hop + 1
            Set S_up(n) = 1
            Propagate the route-recovery update to direct downstream child CHs
            Update the state of n to “Reconnected”
        Else
            Maintain the state of n as “Disconnected”
            Keep S_up(n) = 0
        End if
    End if
End Algorithm