Among the differences in both scenarios, the major difference
is the price which SUs are willing to pay. In scenario 1,
each SU can join any network because the price each SU is
willing to pay is higher than the maximum cost of joining
any primary network. In scenario 2, a SU may be unable
to join a network owing to cost constraints. For example, in
scenario 2, the 6
th
SU can join only the 6
th
and 7
th