5.6 MAC Management Functions
The MAC common part sublayer is responsible for the management of the link between the SS and the network. This includes the initial setup of the link between the subscriber station and the network as well as the maintenance of the communication session. The MAC layer also includes functionality to update the configuration and software of the subscriber station, and methods to reestablish the link to the network, in case the signal is lost.
5.6.1 Connecting to the Network
The first management task of the SS after powering up is to find and connect to a network. This is done in several steps.
In the first step, the SS retrieves the last known system parameters from nonvolatile memory and listens on the last known frequency to check if a downlink channel from a base station can be detected. If unsuccessful, it will start scanning all possible channels in the bands it supports for a detectable signal. The SS recognizes valid downlink signals if it is able to successfully decode the preamble at the beginning of the frames. Decoding the preamble is possible without further information as it contains a well-known bit pattern. The device has found a valid 802.16 channel if several preambles can be decoded. At this point, the device is also aware of the length of the downlink frames. The device then decodes the beginning of the received downlink subframes to get the current system parameters and configuration from the DCD, the DL-MAP and the UL-MAP (see section ...