1. Field of the Invention
The present invention relates to a method for minimizing the overhead of an UpLink (UL) allocation request transmitted for allocation of UL resources.
2. Discussion of the Related Art
In a conventional broadband wireless access system, a Mobile Station (MS) requests a UL bandwidth in a random access procedure illustrated in FIG. 1.
Referring to FIG. 1, the MS determines a Bandwidth Request (BR) code and transmits the BR code to a Base Station (BS) in step 110. Upon receipt of the BR code from the MS, the BS allocates UL resources to the MS, for use in transmission of a BandWidth REQuest (BW-REQ) message from the MS in step 120. If the MS fails to be allocated the UL resources until expiration of its timer (contention-based reservation timeout or T3) activated after the BW code transmission, it retransmits the BR code.
In step 130, the MS transmits a BW-REQ message through the allocated UL resources to the BS. Upon receipt of the BW-REQ message, the BS allocates UL resources to the MS in step 140. Finally, the MS transmits data through the allocated UL resources in step 150.
In the broadband wireless access system, the MS may request a UL bandwidth by using a random access procedure illustrated in FIG. 2. The BS may support both a 5-step regular access procedure (steps 210 to 250) and a 3-step quick access procedure (steps 210, 240 and 250).
The 5-step regular access procedure may be used independently of the 3-step quick access procedure or as an alternative to the 3-step quick access procedure.
In the 3-step quick access procedure, the MS transmits a BR indicator including UL BR information (e.g. an MS Identifier (ID), information about a BR size, etc.) to the BS in step 210. Upon receipt of the BR indicator, the BS allocates UL resources to the MS in step 240. In step 250, the MS transmits data through the allocated UL resources. Also, the MS may transmit additional UL BR information.
In the 5-step regular access procedure, the MS transmits a BR indicator in step 210. Upon receipt of the BR indicator, the BS allocates UL resources to the MS, for use in transmission of a BW-REQ message from the MS in step 220. In step 230, the MS transmits a BW-REQ message through the allocated UL resources. Upon receipt of the BW-REQ message, the BS allocates UL resources to the MS in step 240 and the MS transmits data through the allocated UL resources in step 250. Here, the MS may transmit additional UL BR information.
In the conventional broadband wireless access system, the MS transmits information required for resource allocation along with a BR code, for fast allocation of UL resources. The information may include a station ID, a Quality of Service (QoS) level, a BR size, etc. The BS determines a UL resource area (size) to be allocated, taking into account the amount of information to be transmitted and a predicted maximum number of MSs, because it cannot estimate the number of MSs requesting resource allocation at a specific point of time and the same number of MSs do not request resource allocation every time. The MS may also transmit UL BR information (e.g. a station ID, a BR size, etc.) by a BW-REQ message, occupying as much UL resources as the amount of the UL BR information. Accordingly, there exists a need for a method for minimizing the amount of information to be transmitted without affecting a resource allocation procedure in order to reduce resources (overhead) taken for UL resource allocation.