Terms Description C The set of running cloudlets, C = {[c.sub.1], [c.sub.2], ..., [c.sub.N]} K The set of tasks running on the cloudlets, K = {[K.sub.1], [K.sub.2],..., [k.sub.M]} A The set of APs deployed in WMAN, A = {[a.sub.1], [a.sub.2], ..., [a.sub.w]} E(t) The total energy consumption without VM migrations [g.sub.n] The number
ofVM instances [c.sub.n] (n = {1, 2,..., N}) accommodates.
It can facilitate migration
ofVMs between physical servers in order to (i) pull out physical servers from an overloaded state when the sum of VMs capacities mapped to a physical server becomes higher than its capacity and (ii) turn off a physical server when the VMs mapped to it can be moved to other physical servers.