Patent ID: 8594032

Claim:
A method for performing ranging at a mobile station in a broadband wireless access system, the method comprising: receiving allocation information of at least one first ranging channel allocated to a specific frame, from a base station; determining an opportunity index of the first ranging channel by using the allocation information; receiving allocation information of at least one second ranging channel, which is dynamically allocated, from the base station; and determining an opportunity index of the second ranging channel, wherein, if the first ranging channel is a non-synchronized ranging channel (NS-RCH), the determination of the opportunity index of the first ranging channel is performed to determine an opportunity index of the non-synchronized ranging channel as an initial value of an opportunity index range which is previously set, and if the first ranging channel is a synchronized ranging channel (S-RCH), the determination of the opportunity index of the first ranging channel is performed to determine an opportunity index of the synchronized ranging channel as the last value of the opportunity index range, and wherein the determination of the opportunity index of the second ranging channel is performed by mapping each of the at least one second ranging channel into one of remaining opportunity indices in the opportunity index range except for the initial value and the last value, and wherein the allocation information of the at least one first ranging channel is received through a super frame header (SFH) if the first ranging channel is the non-synchronized ranging channel and received through the super frame header or a system configuration descriptor (AAI_SCD) message if the first ranging channel is the synchronized ranging channel, and the allocation information of the at least one second ranging channel is received through a map (A-MAP) or handover command (AAI_HO-CMD) message.