How to build Lattice Network Graph from GPS Coordinates initially and then convert it into Small World Network??

Suppose I have n objects with random GPS coordinates. My first requirement is to create lattice graph for these coordinates and then convert it into small world network. I found WattsStrogatz(N,K,beta) function in Matlab, however, i could not adapt it to work according with GPS coordinates. I would greately appriciate any help. Thank you in advance.