Dear Nilmani,
I think this project is all about a number of identical robots, which can move around independently, and are able to communicate with each other, sharing data like their current position and all with each other and also with the base station. From base station we can control them, like we can send commands to move to a particular position point.
The robots then communicate with each other to assume their respective position points.
GPS can be used to detect the position and for this kind of complex wireless communication you should use Zigbee modules.