Explain signal variation for particular time in graph?

The TV and RW graph are created in 2 steps. First, the RW model is simulated to identify the time-varying coordinates over time. The model then simulates some sensors that are moving around a square space with random directions and speed. The time-varying data is obtained in correspondence to the position of every sensor at a particular given time. The number of sensors is N=36 and the speed of the motion is between 0.05 to 0.5 m/sec. In the second step, the nearest neighbour graph is constructed at a particular time from the data position.