Wimax standards and Security The Wimax

FIGURE 8.8
State transitions for 802.16 connections. Connection change state after receiving one of the scheduling messages. Centralized scheduling messages bring a connection to and from the UP-CSCH state. Decentralized scheduling messages bring a connection to and from the UP-DSCH state. If a connection is already scheduled by centralized or decentralized scheduling, it may be assigned bandwidth with the other scheduling protocol and come into the UP-ALL state.

In this case, it is in the UP-DSCH state. Finally, the connection could have bandwidth allocated to it with both centralized and decentralized scheduling protocol. In this case, it is in the UP-ALL state.

Change of state for a connection causes routing changes in the network. For example, if a connection goes from the DOWN state to one of the three up states, this adds a new neighbor in the network layer. Similarly, if a connection goes from one of the three up states to the DOWN state, this change removes a neighbor in the network layer. Neighbor connections do not change in the MAC layer, since MAC layer neighbors communicate in the 802.16 broadcast channel.
The combination of the mesh ID and the CID identifies each connection globally, so we refer to the 32-bit value of the combination as the global connection ID (GCID). Using fixed connection identifiers for addressing is appropriate for mesh networks since links between neighbors are static. It is also more efficient than a pair of 48-bit MAC addresses used to identify source and destination pairs in 802.11 networks.

2. 
   Mesh Network Addressing
   

The 802.16 mesh network protocol specifies how addressing is accomplished in the MAC layer. We now propose a network layer addressing scheme that keeps mesh routers simple to implement. We partition the network into access networks and the mesh backbone. There is an access network at every mesh node, allowing the WTs to connect to the mesh in the network layer (Figure 8.9). To keep the address space for the whole network small, each