802.16 mesh standard allows for two different types of such coordinated
scheduling: centralized scheduling and distributed scheduling.
In centralized scheduling, resources (and not the transmission schedules) are granted
in a more centralized manner by a specially designated node referred to as the Mesh
BS. The Mesh BS gathers resource requirements from all the Mesh SSs within a certain
hop range. It then computes the amount of resources for each link in the network,
both in downlink and uplink, and communicates these grants to the Mesh SSs within
the hop range. Based on the resources granted to its links, the node computes its transmission
schedule.
In distributed scheduling, all the nodes coordinate their transmission in their twohop
neighborhood and broadcast their schedule to all their neighbors. The schedule
may also be established by direct requests and grants between two nodes. With all the
nodes knowing the schedule of all other nodes in the two-hop neighborhood, they can
WiMAX 485
ensure that the resulting transmissions do not cause collisions with the data and control
traffic scheduled by any other node in the neighborhood.
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