Patent ID: 7885224

Claim:
A method of transmitting information for reestablishing an Internet Protocol (IP) address of a mobile subscriber station in a broadband wireless access system, the method comprising: receiving, by a first base station, a first message including information indicating that the mobile subscriber station has entered an idle mode and information indicating a subnet or a foreign agent to which a second base station is connected; and transmitting, by the first base station, a second message to the mobile subscriber station in the idle mode, the second message including a field indicating whether the mobile subscriber station is required to reestablish the IP address, wherein the second base station has approved the entry of the mobile subscriber station in the idle mode, wherein the first base station and the second base station belong to a same paging group, wherein the field of the second message is set based on the information indicating the subnet or the foreign agent to which the second base station is connected, and wherein the mobile subscriber station performs ranging for a location update and reestablishes the IP address if the field of the second message indicates that the mobile subscriber station is required to reestablish the IP address.