## 5 Case Study: Application of MHAR-OLSR
### \"Node Identification Step\"  
Combining the MHAR principle and OLSR, we obtain the routing protocol MHAR-OLSR with new structures.  
1. [label=()]
2. MHAR-OLSR Hello message structure: The new Hello message (Figure 10) will contain the node position in three dimensions: the latitude, the longitude, and the altitude. This information allows the node to calculate the instantaneous speed of its neighbors in the first neighborhood. To obtain this speed, we apply the following Equation (4): \[\left\{\begin{array}{l}\mathrm{V}_{(ij)}(t)=\tilde{\mathrm{V}}_{(ij)}(t)+ \mathrm{V}_{(ij)}(t-1)\\ \mathrm{V}_{(ij)}(0)=0\end{array}\right.\] (1)  
We need the instantaneous relative velocity represented as follows:  
\[\tilde{\mathrm{V}}_{(ij)}(t)=\frac{\mathrm{d}_{(ij)}(t)-\mathrm{d}_{(ij)}(t-1 )}{\delta t} \tag{2}\]  
where:  
* \(\mathrm{d}_{(ij)}(t)\) and \(\mathrm{d}_{(ij)}(t-1)\) are the distances between two neighboring nodes (i and j) at two successive instants, or:  
\[\mathrm{d}_{(ij)}=\sqrt{\left(\left(x_{\tilde{\mathrm{j}}}-x_{\tilde{\mathrm{ i}}}\right)^{2}+\left(y_{\tilde{\mathrm{j}}}-y_{\tilde{\mathrm{i}}}\right)^{2}+ \left(z_{\tilde{\mathrm{j}}}-z_{\tilde{\mathrm{i}}}\right)^{2}\right)} \tag{3}\]  
* \(x\), \(y\), \(z\): Cartesian coordinates equivalent to the geographic coordinates of a node.  
* \(\delta t\): is the difference between the arrival time of the first and last message Hello.  
For having a more precise speed value, we add an exponential average (Alpha) to give more importance to all historical movements of the nodes since the beginning of the communication and to filter abrupt speed variations. Alpha ranges between 0 and 1 and is defined in a manner that makes sense to the application field. Then, the filtered instantaneous speed takes this new form:  
\[\left\{\begin{array}{l}\mathrm{V}_{(ij)}(t)=\alpha\tilde{\mathrm{V}}_{(ij)}( t)+(1-\alpha)\mathrm{V}_{(ij)}(t-1),\\ 0\leq\alpha\leq 1\\ \mathrm{V}_{(ij)}(0)=0\end{array}\right. \tag{4}\]  
The node range will be inserting too in this new structure of hello message.  
Figure 9: Example of MHAR-OLSR communication within an HAdN_MVF network.  
The latitude and longitude have the same form, a floating-point number stocked in 4 bytes. The altitude and range are each represented by fixed-point numbers occupying 16-bits. These 12 bytes added to the standard hello message haven't any impact on the frames size in medium and large networks.
2. MHAR-OLSR identification structure: Adding an intelligent and dynamic structure will ensure the store of the neighbors' identifiers. This structure allows the node to gather the maximum amount of information on all topology components. After each exchanged hello message, the node updates its identification structure by verifying the existence of a neighbor, the change of its position indices (which will act on its identification), or the presence of a new neighbor. After each calculation of the paths, the source node structure will add the identifiers of the nodes, which constitute the calculated paths. If one of them becomes its neighbors in an instant, it can, therefore, just update its identifier. We are going to give this structure the aspect of a database of identifiers that we can use to have a precise vision of our network.