# A Dependable Localization Algorithm for Survivable Belt-Type Sensor Networks
## 3 Hop-Distance Estimation Correction
### Mechanism of Data Broadcasting  
The maximum communication radius of an anchor node is the range of information transmission, and the typical network protocol of distance vector exchange is used to send packets to the surroundingneighbor nodes in a broadcast manner. This protocol uses bellman-ford to calculate the path. In the distance-vector routing protocol, each router does not know the topology information of the entire network. They simply announce their distance to the other routers and receive similar notices from them. The packet contains its own location coordinate information, the current time information and accumulated hops information. The packet format can be expressed as: LocInf[(\(x_{i}\),\(y_{i}\)),\(ID_{i}\),T]. At this time, the location information is transmitted as a normal data message. The sink node initiates the \"interest\" for the detection target of the location. If an anchor node responds to this \"interest\" message, its own location information is immediately broadcast and forwarded as the collected data. As shown in Figure 5.  
The random movement of nodes causes the data packet to generate multiple collisions during the broadcast, resulting in the loss of transmission information [33; 34]. In order to avoid the above situation and protect the network performance, we set the maximum data transmission hop value \(h_{max}\) in the limited broadcast range. As shown in Figure 5, the sink node does not save the \"location information\" message after the \"interest\" message is broadcasted. Only the source node with the anchor function records the \"Location interest\" message and returns the collected data. At this point, the data which is passed back is the information contained in the anchor node. The special topology of the belt-type sensor networks determines that its internal nodes have different connectivity from other wireless networks. If we use this feature, we can directly identify the approximate orientation of the unknown node. A member node \(S_{k}\) in the network issues a \"Neighboring_request\" message as soon as it finds another node which is in the same group. Within the effective communication range of the node, the message spreads quickly along the route. When the neighbor node of \(S_{k}\) receives the message, it sends the reply message \"Neighboring_act\" at once. When its neighbor node receives the packet, it immediately checks the information in it, records the relevant information of the anchor node, and creates an anchor node to access the visitor list. In this process, the node is likely to receive multiple packets from the same anchor node. By checking and comparing, the nodes only retain the group of information which has the least number of hops in its grouping. Subsequently, the hop distances from each anchor node in the bounded area are accumulated and added \"1\" to their hop count. Lately the packet is forwarded to the surrounding node. The network repeats this process until all nodes in the sensor networks record their location coordinate of each anchor node and the information of corresponding cumulative hop count. Through the above mechanism, all the sensor nodes in the belt-type sensor networks system obtain the cumulative hop distance and the minimum hop count of each anchor node. For any node that receives a message from an anchor node, we use \"\(h_{max}\)\" as the restriction range parameter for the discrimination. After adding the maximum number of hops, the unknown node is restricted to the extent of the anchor node information. It reduces the range of errors that can occur during packet delivery. More importantly, the use of this parameter reduces the probability of collision with interference information. If the message from the corresponding anchor node has been recorded in the node and the hop count value \"\(k\)\" is less than or equal to the newly received message hops, the newly received message of the node may be considered as an invalid message. Once the node  
Figure 5: The broadcast flooding mechanism in network.