Many families install a pet door for their pets. Pet doors
are adapted to be fitted in the lower portion of a wall or
existing full-sized door. Pet doors allow family pets to
pass the door easily. Figure 2(a) shows the system diagram
of the pet door. The pet door system consists of one
control server, one smart pet door, several environment
nodes, and the tag on collars. The pet wears a sensing tag
on its collar, and the collar broadcasts the pet ID for
every 20 seconds continuously. Figure 1 shows the collar
design. The pet door detects the pet’s location and
periodically requests the pet activity list from the server.
Accordingly, when the device on the pet door receives
the broadcast packet from the pet tag, the device will
measure the estimated distance by the RSSI (Received
Signal Strength Indicator) value between them, the measuring
equation is listed as follows,