# Movable Platform-Based Topology Detection for a Geographic Routing Wireless Sensor Network
## 4 Evaluation  
### Experiment Setup  
In this paper, simulations are made with matlab software. In simulation, we did not set a specific unit of length, just 1 as the unit length. In every \(1\times 1\) grid, a node is randomly distributed. The maximum communication distance of the node is 2 (there is no super node in the network, and the communication range of the base station is 2). In practical application, the numerical conversion can be carried out in equal proportion. There are 256 nodes in the target network including the base station. Each node knows the distance between the neighbor node and itself, and the distance between the neighbor node and the base station (according to the referenced routing protocol rules). In the research, when the target network is set as the initial stage of network deployment and the network is completed, energy consumption is not the main basis for nodes to select routing nodes. In addition, in order to better simulate the actual working state of wireless sensor networks, we set up a time counter, whose range is from 1 to 19,200, and divide 19,200 times into 32 time periods on average. In each time period, 50% (adjustable) nodes are randomly selected as the source nodes to send information to the base station, and the communication process from all the source nodes randomly generated to the base station is completely simulated. In the process of communication, the sub node adopts the MAC protocol of TDMA (other MAC protocols can be simulated by adjusting the proportion of the source node and the clock of the sub node). Within the specified time range, the platform will dynamically detect the topology of the target network according to the predetermined method. In the research, the sampling speed of the platform is set to 0.5 unit length/unit time. If a pair of nodes communicate at I time, and the platform just enters the overlapping area of the communication range of the two nodes at I time, it will automatically determine that the platform captures the position of the two nodes and identifies the communication direction of the node pair. When the platform enters the base station communication area and the base station has communication, it is automatically determined as the location of the capture base station. In the whole network sampling process, one node is randomly selected as the node detected by the platform in a circle whose radius is 0.5 unit length with the platform as the center. The time counter stops after platform detection. And the target network mainly sets three routing protocols, GEAR routing protocol, GEM routing protocol and the universal routing protocol where Equation (9) serves as cost equation (according to the cost Equation (3) of GEAR routing protocol, we constructed Equation (9) as the general cost equation that considers no node energy consumption. In early network arrangement stage, most location-based routing protocols can be simulated by adjusting coefficient \(\alpha\) and \(\beta\). GEAR and GEM routing protocols are deemed as two special universal routing protocols.) \[D\left(i\right)=L\left(i\right)\star\alpha+R\left(i\right)\star\beta \tag{9}\]  
\(D(i)\) is the cost of the \(i\)th neighbour node of source node, \(L(i)\) is the distance from node \(i\) to the station, \(R(i)\) is the distance from node \(i\) to source node, and \(\alpha\) and \(\beta\) are adjusting coefficients. Energy factors are not taken into consideration by these three routing protocols. We supposed the network that the platform monitors is in its initial state and all nodes are full of energy, and there is no need to consider energy factors. The target network contains 256 nodes, each of which is randomly distributed inside each \(1\times 1\) square box, and the maximum communication distance between nodes is 2. With 50 m as the actual maximum communication distance of nodes, the target network can simulate 1600 m\({}^{2}\) WSN in a real scene during the simulation.