3. Notice that, although an
entire path is selected at the sender node, the algorithm is executed for each node in the
network independently by assuming each node is the sender and considering only the
network (and MSDU) subset corresponding to the node of interest. This ensures that the
algorithm can scale well under a variety of topologies. In addition, in this way, potential
network variations that invalidate the error, bandwidth or queuing-delay assumptions used
when scheduling at the sender node, can be incorporated/corrected during the scheduling of
a subsequent node. Finally, the independent algorithm execution at each node ensures that
expired MSDUs will not propagate through the entire network unnecessarily. This
facilitates the conservation of network resources in the mesh topology and reduces link
congestion.
The algorithm of Figure 5.3 searches through all the possible routing configurations
(line 4) that emerge under varying modulation strategies (line 6) and determines the
retransmission limit for each case (line 8). The utility function is evaluated (line 9) and the
overall maximum is retained. Although this is a greedy approach, it is guaranteed to obtain
the maximum under dynamic feedback from the overlay network (parameters calculated in
line 7).
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