Method for Allocating Group Resource in a Broadband Wireless Access System

A method of transmitting a signal from a base station to a mobile station through Group Resource Allocation (GRA) includes allocating the mobile station to any one of a plurality of groups each including one or more mobile stations, transmitting, to the mobile station, a group configuration message including one or more pieces of burst size information used in the group, to which the mobile station is allocated, and one or more pieces of resource allocation bitmap information which is differently configured according to burst sizes, and transmitting bursts to the mobile station through a resource unit indicated by the resource allocation bitmap.