For each entry of the neighbor table, add the node's Next Xmt Time to the
node's Xmt Holdoff Time to arrive at the node's Earliest Subsequent Xmt Time.

Set TempXmtTime equal to this node's advertised Xmt Holdoff Time added to
the current Xmt Time.

所以 Earliest Subsequent Xmt Time 是別個Node的下一個傳輸時間
TempXmtTime是自己的下一個傳輸時間

用這兩個來比較，得知哪個贏得了 Oppurtunity 得以傳輸 DSCH message