Methods for changing an authority of control for a controller in environment having multiple controllers

A method for changing a role over control authorization performed in a second controller, the method comprising:

• transmitting a role-request message requesting a role change of the second controller to a master controller to a communication apparatus;
• receiving a role-reply message indicating acceptance or error on the role change from the communication apparatus;
• and
• changing a role of the second controller to a master controller if the role-reply message indicating acceptance on the role change is received from the communication apparatus.

A method for changing a role over control authorization performed in a communication apparatus, the method comprising:

• receiving a role-request message, from a second controller which is to be a new master controller, including a request of a role change of the second controller to a master controller;
• checking validity of the request of the role change by comparing identification information included in the role-request message with pre-stored identification information;
• and
• transmitting an error message to the second controller if the request of the role change is not valid.