domly chosen from the initial ranging code-set (using random selection rather than random backoff) in the initial ranging opportunity. Upon receiving a "success" status notification, the MS waits for uplink bandwidth allocation. If the MS does not receive bandwidth allocation within a certain time interval after sending the ranging preamble code, it restarts the initial ranging procedure, or it may return to downlink synchronization stage again. If the MS receives uplink bandwidth allocation, it sends a ranging request message. If the granted bandwidth allocation cannot accommodate the entire ranging request message, the message may be fragmented in order to fit to the allocated resources, and the MS may further request additional resources for the remaining message fragments. In response to the bandwidth request, the BS provides uplink allocation via a downlink control information element where the MS is identified by the same Random Access Identifier (RA-ID) that was used for the previous allocation. This RA-ID is used until completion of the ranging response. If the MS does not receive bandwidth allocation, or the ranging request and response message exchange are not completed within 128 frames, the MS re-sends the ranging preamble code and reinitiates the initial ranging procedure. The BS assigns temporary STID (TSTID) to the MS via the ranging response message upon successful ranging. The initial ranging process is concluded after receiving the ranging response message. The TSTID is used until permanent STID is assigned following successful registration. In the case where the IEEE 802. 16m mobile and base stations are interfaced with a legacy ASN, the actual MAC address is included in the ranging request message similar to that of the legacy systems [1], because the IEEE 802.16m station identifiers are not recognized by the legacy ASN. Immediately after completion of the initial ranging, the MS informs the BS of its capabilities by transmitting a capability negotiation request message with its capabilities s