“…For access control decisions, we require the location of a mobile device to be verified such that a dishonest user cannot fake his or her location. Many such systems have been proposed, based on WiFi networks [3][4][5][6][7][8][9][10][11], GPS [8,[12][13][14][15][16], cellular telephone networks [13,15,[17][18][19], RFID [20] and other sensor networks [21][22][23].…”