QoS-Based Multicast Routing in Network Function Virtualization-Enabled Software-Defined Mobile Edge Computing Networks

Table 1

Symbols.

Symbols	Meaning
	A software-defined Mobile Edge Cloud network with a set V of OpenFlow switches (OFSs) or APs and a set E of links
and e	An OFS node or an AP node and a link e
	The available computing capacity of the cloudlet attached to node
=	The k-th multicast service with source node Sk, the set of destinations Dk, the service chain SCk that consists of a sequence of VNFs, bandwidth requirement bk, and delay limitation dk
Lk	The number of VNFs in SCk
SCk =	A service chain for k-th multicast service consisting of Lk-th functions
cf,m	Computational cost to implement a VNF f on VM m
	Delay of link e(u, )
	Available bandwidth of link e(u, )
rk	Data rate of k-th multicast service
Pk	A set of unicast route from source Sk to each destination from Dk
pm	A route from source Sk to a destination
and	Transmission delay and processing delay, respectively
dk	The maximum delay of the multicast tree
bp and bm	The minimum bandwidth of a path and a multicast tree, respectively
Dk and Bk	QoS requirement of delay and bandwidth, respectively
	The cost of instantiating a new VNF instance i on node for k-th multicast service
	The cost of using an existing VNF instance i on node for k-th multicast service
Ck	The total operational cost for multicast service k
CL = (CL1, CL2, …, CLm)	A set of cloudlets that have sufficient resource to implement VNF instances
VNFL = (VNF1, VNF2, …, VNFn)	VNF that exists or can be created for a multicast service