# Research on Multi-Strategy Routing Protocol in Flying Ad Hoc Networks
## 4 Forwarding Strategy Design
### Reactive Mechanism Design Based on Joint Measurement Optimization
The left-hand rule is shown in Figure 12. The current node finds the next-hop node in the plan by rotating the link with the previous hop node clockwise around itself, so it can generally traverse the interior of a face anticlockwise. X, Y and Z represent different nodes. Figure 11: Wrong search area. Figure 10: Construction of multi-projection plane. The DAF rule is composed of two sub-rules. Sub-rule 1 determines whether the initial forwarding rule is a right-hand rule or a left-hand rule, while sub-rule 2 determines when it is necessary to switch the forwarding rule from the right-hand rule/left-hand rule to the left-hand rule/right-hand rule. Suppose on the projection plane, the location of the local minimum value recorded in the packet header is \(m\), the projection of the destination node is \(d\), the projection of a 3 DRNG or 3 DGG neighbor node of the local minimum value node is \(n\), the connection between point \(m\) and node \(d\) is \(md\), the connection between point \(m\) and node \(n\) is \(mn\), a node in the forwarding process is \(r\), the last-hop node of the node \(r\) is \(s\), and the connection between point \(r\) and node \(s\) is \(rs\). Then, the two sub-rules of the DAF rule are described as follows:

Sub-rule 1: if the connecting line \(md\) rotates counterclockwise around the touchpoint \(m\) (the angle should be less than \(180^{\circ}\)) to the connecting line \(mn\), then the node \(n\) and its subsequent nodes will traverse the face with the right-hand rule; if the connecting line \(md\) rotates clockwise around the touchpoint \(m\) (the angle should be less than \(180^{\circ}\)) to the connecting line \(mn\), then the node \(n\) and its subsequent nodes will traverse the face with the left-hand rule. Sub-rule 2: if node \(s\) forwards the packets to node \(r\) through the right-hand rule/left-hand rule, and node \(r\) detects that there is a cross between line \(rs\) and line \(md\), then node \(r\) and the nodes after it need to switch to the left-hand rule/right-hand rule. Figure 13 shows an example of the DAF rule, in which node \(n_{1}\) and node \(n_{2}\) decide the initial forwarding rule according to sub-rule 1, and node \(r\) switches the right-hand rule to the left-hand rule according to sub-rule 2 and implements face switching. DAF rules expand the search area of projection face forwarding, reduce the possibility of routing loops and repeated searches, improve the probability of packets jumping out of routing holes, and also, to a certain extent, inhibit path expansion and reduce the delivery delay of packets. The specific algorithm is as follows:

Figure 12: Left-hand rule. Figure 13: An example of DAF rules. ```
1. The minimum local node encapsulates its current location information into the local minimum location field of the packet header. It sets the projection face state of the projection face parameter field to the construction state and the IP of the previous hop node to its IP, and then broadcasts the packet to the next-hop neighbor node. 2. The one-hop neighbor node of the minimum local node first constructs the 3 DRNG graph according to the relevant information. It then determines whether it is the 3 DRNG neighbor of the minimum local node. If so, it will continue with the following steps; otherwise, it will discard the data packet. 3. If the 3 DRNG neighbor node of the minimum local node judges whether it can switch to greedy forwarding or reactive mechanism forwarding, it stops the initialization of the projection face and switches to the corresponding forwarding strategy. Otherwise, it will continue with the following steps. 4. The 3 DRNG neighbor node of the minimum local node sets the projection face state of the projection face parameter field of the packet header to the forwarding state. 5.