Network Entry and Initialization, part 3.

Upon the network entry of a client into the network, the BS scans through its frequency list attempting to synchronize with a BS. The BS performs the admission control algorithm to make a decision whether to admit the SS, based on the QoS requirements requested by the SS and the existing resource availability of the BS. If admitted, the BS generates a set of connection and Connection Identifier (CIDs), together with the management and transport connections, to connect with the SS. Three pairs of management connections are established for control packets, and the transport connection is used for data transmission.

Along with the new CIDs, the BS also assigns new service flow identifiers (SFIDs) to the new data flows linked with the station. A service flow (SF) is a unidirectional flow of MAC SDUs between a pair of BS and SS, of which is provided with a particular set of QoS parameters, and a SFID uniquely identifies the service flow.

WiMAX Network Entry and Initialization, part 2.

The network entry process can be separated into a few phases. Within each phase, particular MAC management messages  are exchanged among Base Station (BS) and Subscriber Station. On the establishment of process, the SS scans individual DL channels searching in favor of the DL-MAP and DCD messages broadcasted by the BS.

Using these messages, the SS get synchronize with the BS and obtains DL paremeters. As successfully synchronized, the SS wait for the UL-MAP and UCD messages to acquire UL parameters.

WiMAX Network Entry and Initialization, part 1.

Once a SS senses a BS, for a network entry, it will first scans for downlink channel (DL) and trying synchronizes itself with the BS. After that, SS shall obtain transmit parameters, which are integrated in the Uplink Channel Descriptor (UCD), Uplink (UL)-MAP, and Downlink (DL)-MAP. The final step would be to complete initial ranging.

The BS is required to discover different received ranging codes, approximate the timing offset and the power for every user that bears and initial ranging code. The BS then broadcast the detected ranging codes with some change instruction for the proper timing and power level. Other than that, the status notifications of either ranging successful or retransmission are also broadcasted.