Joint Channel Assignment and Routing in Multiradio Multichannel Wireless Mesh Networks: Design Considerations and Approaches

Table 2

C-JCAR proposals summary.

Work	Link layer and channel assignment			Traffic & routing			Topology		Objective & fairness		Notes/limitations
	CA type:	Interference:	Technology:	Traffic type:	Traffic load:	Routing scheme:	Mapping: (1-to-):	Connectivity:	Objective:	Fairness:
[19]	SCA	B-IRM	802.11	P2P	Yes	SP, MP	1	Yes	Maximize cross-section good-put	No	Optimality is not guaranteed. No accurate link capacity estimation in a heavy traffic load. Less channel diversity due to link mapping
[56]	DCA, SCA-LS	B-IRM	—	P2P	Yes	MP	0,1	Yes	Maximize λ (scaling factor)	Min-λ	Out-of-order problem and configuration complexity on routing. Switching overhead issues
[20]	SCA-LS	B-IRM	—	Internet	Yes	MP	Any	For MRs w/traffic	Maximize λ (scaling factor)	Min-λ	Radio constraints are not considered in the LP. Out-of-order problem due to multipath routing
[36]	DCA	B-IRM	—	P2P	src-des MRs	MP	Any	No	Maximize aggregated throughput	No	Out-of-order problem and configuration complexity on routing. Switching overhead issues. Optimality issue since only sufficient conditions are considered
[57]	SCA	B-IRM	802.11	P2P, Internet	Yes	SP	Any	For MRs w/traffic	Maximize min spare link capacity	Min-λ on link utilization	Using sufficient condition in MILP may not lead to global optimal solution. Single channel initial topology may lead to infeasible solution in heavy traffic load scenarios
[30]	SCA-LS	THM		Internet	Yes	MP, predefined	0,1	For MRs w/traffic	Maximize λ (scaling factor)	Min-λ	Considering only necessary condition may lead to infeasible solution. Out-of-order problem due to multipath routing
[70]	SCA	PHM (w/o accumulation)	802.11	Internet	No	MP (M-GW) L2.5 forwarding	≥1	Yes	Minimize max link utilization	No	Radio or interference constraints are not accounted in initial traffic load estimation. Assume same traffic demands in all mesh routers. Out-of-order problem due to multipath routing. Link rate assignment is considered
[31]	DCA	PRM, IRM		Internet	Yes	MP (M-GW)	Any	For MRs w/traffic	Maximize aggregated throughput	Min-λ	Out-of-order problem and configuration complexity on routing. Each radio can be operated on a subset of channels. Combination of multiple channels to single channel is possible
[32]	SCA	THM		Internet	Yes	SP	Any	Yes	Metric on hop count & interference	No	Solving subproblem with local constraints does not guarantee global optimality. Information on received power at a node when another node is transmitting is assumed available
[62]	DCA	IRM, PRM, PHM		P2P	No	SP, MP	Any	No	Maximize aggregated throughput	Max-to-Min	Equal load demand is assumed at mess routers. In single-path routing optimality is not guaranteed since mathematical formulation is for multipath
[61]	DCA	B-IRM		P2P	Yes	MP	Any	No	Maximize λ (scaling factor)	Min-λ	The quality of the solution is highly dependent on the performance of critical MIS finding algorithm
[33]	SCA	B-IRM	802.11	Internet	Lower & upper bound	MP (MGW)	Any	For MRs w/traffic	Maximize aggregated throughput	Bounded fairness	Developed for planning stage with different resources constraints. Not practical for large networks since fitness function involves solving entire network LP
[29]	SCA-LS	THM		P2P	Yes	MP (predefined)	1	Yes	Maximize aggr. achieved demands	No	Link loads used to the CA are estimated without considering radio or interference constraints. Less channel diversity due to link mapping
[37]	SCA	EM		Internet	Number of active flows	MP (SP per follow)	1	Yes	Minimize contention (CA)	No	Link loads estimated without considering radio or interference constraints. Not clearly stated where and how to implement flow rate control
[63]	SCA	B-IRM	802.11	Internet	Yes, sequence of traffic	MP	Any	For MRs w/traffic	Minimize the maximum congestion (of worst case)	No	Number of facets increase exponentially in large-scale networks; this increases the number of constraints in LP problem; however, relaxing the convex hull to box ranges affects the efficiency

Note. SCA: static channel assignment, DCA: dynamic channel assignment, LS: link scheduling, IM: interference model, IRM: interference-range model, PRM: protocol model, PHM: physical model, B-: bidirectional, THM: two-hop model, EM: empirical measurement, P2P: peer-to-peer, SP: single-path, MP: multipath, MGW: multigateway, MR: mesh router, and LL: link layer.