A method for controlling operation modes (510, 530) of a medium access control layer, the method being performed by a mobile subscriber station in a broadband wireless access communication system including the mobile subscriber station and a serving base station providing a service to the mobile subscriber station, the method comprising the steps of: mode-transiting from an awake mode into an idle mode, wherein the step of mode-transiting is performed by transmitting an idle mode transition request message to the serving base station and receiving an idle mode transition response message from the serving base station; measuring, in the idle mode, carrier to interference and noise ratios of pilot signals transmitted from neighboring base stations, determining that the mobile subscriber station has moved from the serving base station to a target base station when a carrier to interference and noise ratio of a pilot signal from the target base station is higher than the serving base station, wherein the target base station is one among the neighboring base stations, and receiving system information broadcast from the target base station, the system information containing a paging zone identifier, detecting movement of the mobile subscriber station in the idle mode into another paging zone to which the target base station belongs, by determining that the paging zone identifier broadcast from the target base station is different from a paging zone identifier of a paging zone to which the serving base station belongs; and mode-transiting into the awake mode and performing location update together with the target base station when the movement of the mobile subscriber station is detected, wherein each of the paging zones is a zone grouping a plurality of base stations and the base stations in a same paging zone use a same paging zone identifier, and wherein the step of performing the location update comprises the steps of: requesting the location update by transmitting to the target base station a location update request; and receiving a location update response which is transmitted from the target base station in response to the location update request. mode-transiting from an awake mode into an idle mode, wherein the step of mode-transiting is performed by transmitting an idle mode transition request message to the serving base station and receiving an idle mode transition response message from the serving base station; measuring, in the idle mode, carrier to interference and noise ratios of pilot signals transmitted from neighboring base stations, determining that the mobile subscriber station has moved from the serving base station to a target base station when a carrier to interference and noise ratio of a pilot signal from the target base station is higher than the serving base station, wherein the target base station is one among the neighboring base stations, and receiving system information broadcast from the target base station, the system information containing a paging zone identifier, detecting movement of the mobile subscriber station in the idle mode into another paging zone to which the target base station belongs, by determining that the paging zone identifier broadcast from the target base station is different from a paging zone identifier of a paging zone to which the serving base station belongs; and mode-transiting into the awake mode and performing location update together with the target base station when the movement of the mobile subscriber station is detected, wherein each of the paging zones is a zone grouping a plurality of base stations and the base stations in a same paging zone use a same paging zone identifier, and wherein the step of performing the location update comprises the steps of: requesting the location update by transmitting to the target base station a location update request; and receiving a location update response which is transmitted from the target base station in response to the location update request. requesting the location update by transmitting to the target base station a location update request; and receiving a location update response which is transmitted from the target base station in response to the location update request.