Adaptive Channel Assignment for Wireless Mesh Networks using Game Theory

In multi-channel wireless mesh networks (WMNs), it is significantly important to achieve efficient channel utilization. The channel assignment problem, which investigates how to seek a proper mapping between available channels and network interface cards (NICs) on mesh routers (MRs), is attracting more and more attention from the research community. However, most proposed channel assignment approaches assume that NICs are evenly placed on the MRs, and its amount is also pre-determined. Due to the non-uniform distribution of WMN traffic, the equal interface placement will inevitably cause that the bottleneck MRs suffer from NIC shortage, and MRs with less load only have a low utilization of NICs. Hence, in order to improve network performance and reduce network cost, interface placement should be considered carefully in the process of planning a WMN. In this paper, we investigate the joint interface placement and channel assignment problem, i.e., how to appropriately place NICs on MRs and assign channels to them. We first formulate the problem as a mixed integer linear programming (MILP) model, which aims to minimize the total number of NICs while satisfying logical link, link bandwidth, link interference and traffic demand constraints. Then, we propose an MILP-based heuristic algorithm, using iterated local search to obtain sub-optimal solutions efficiently. Finally, we conduct simulation experiments to compare the heuristic solutions with the optimal solutions, and the results show that our proposed heuristic algorithm can achieve good sub-optimal solutions. Moreover, the simulation results also demonstrate that the algorithm can be well applied in large-scale WMNs where the optimal solutions cannot be obtained, and can perform well under different traffic demands.

Wireless mesh networks (WMNs) are gaining significant momentum as a promising technology for the next-coming state-of-the-art wireless networking. Among many factors, the performance of WMNs would be largely affected by the properness of the deployed routing protocols and the efficient usage of wireless resources. Routing protocols are required to well capture WMNs' features while wireless channels should be used efficiently in order to accommodate high amount of traffics over the mesh backbone. Recently, a Tree-based Routing (TBR) protocol become a popular state-of-the-art proactive routing protocol and its tree-based broadcasting become an often used technique. Though TBR protocol is well-suited for WMNs' architecture and the skewed nature of traffic toward the root, the protocol in its current form faces issues which has to be addressed. Specifically, when some or all nodes are equipped with multiple radios, to reduce collision and co-channel interference, not only the parent-child relationship but also the sibling relationship need to be constructed by the TBR protocol in the multi-channel WMNs. In this paper, we propose a hybrid tree-based protocol for concurrent routing and channel assignment over WMNs. The protocol makes use of sibling links to mitigate the aforementioned shortcomings of TBR protocol. Moreover, in order to address high backbone traffic, the protocol integrates a receiver-based channel assignment scheme. The protocol efficiently deploys the parent-child topological relationships of nodes to enhance efficiency of broadcast transmissions over receiver-based multi-channel WMNs. Simulation results over NS-2 network simulator reveal that our proposed hybrid tree-based protocol achieves much higher performance than the utilization of the original receiver-based CA and TBR protocol.

In this paper, we propose a distributed algorithm for channel assignment in multi-radio, multi-channel mesh networks. Channel assignment in multi-radio mesh networks is complicated because, in addition to affecting the interference between spatially closely located links, binding interfaces to channels affects the topology of the network. If the channel assignment is done without taking the topology into consideration, distance between any two nodes may increase arbitrarily. We propose a novel distributed channel assignment algorithm that reduces interference and at the same time provides bounds on the distance between any two nodes in the topology resulting from channel assignment. Our algorithm is based on the concept of spanners. We also develop and implement a modification of AODV, which uses the cumulative metric WCETT [4] as the routing metric. We use this routing algorithm to analyze the performance of our channel assignment algorithm. Through extensive simulations in NS-2, we show that the proposed channel assignment algorithm provides nearly 30% improvement in throughput over a simple, minimal-connectivity preserving channel assignment algorithm.

Realistic interference-free channel assignment for dynamic wireless mesh networks using beamforming

Opportunistic routing (OR) involves multiple forwarding candidates to relay packets by taking advantage of the broadcast nature and multi-user diversity of the wireless medium. Compared with Traditional Routing (TR), OR can evidently improve the end to end throughput of Wireless Mesh Networks (WMNs). At present, there are many achievements concerning OR in the single radio wireless network. However, the study of OR in multi-radio wireless network stays the beginning stage. In this paper, we focus on OR in multi-radio multi-channel WMNs. Directly using the existing channel assignment leads to decreasing the number of candidate forwarder and the performance of OR. According to OR with one-to-more transmission mode, the Candidate Forwarder Set based Channel Assignment (CFSCA) for OR is proposed. Firstly, according to the candidate forwarder selected by routing, we bound the sender node and its candidate forwarders as a Candidate Forwarder Set(CFS). Then we calculate the interference among all the CFSs. Then the channel assignment for OR is described as a minimum CFS interference optimization problem, which must obey the constraints of the channel number of CFS and the number of radio interfaces. The evaluation results show that CFSCA improves 25.2%, 10%, 19% of the aggregative throughput than random, uniform and tradition channel assignment, respectively.Keywordswireless mesh networksmulti-radio and multi-channelopportunistic routingchannel assignment

Wireless mesh networks (WMNs) have emerged as a scalable, reliable, and agile wireless network that supports many types of innovative technologies such as the Internet of Things (IoT), Wireless Sensor Networks (WSN), and Internet of Vehicles (IoV). Due to the limited number of orthogonal channels, interference between channels adversely affects the fair distribution of bandwidth among mesh clients, causing node starvation in terms of insufficient bandwidth distribution, which impedes the adoption of WMN as an efficient access technology. Therefore, a fair channel assignment is crucial for the mesh clients to utilize the available resources. However, the node starvation problem due to unfair channel distribution has been vastly overlooked during channel assignment by the extant research. Instead, existing channel assignment algorithms equally distribute the interference reduction on the links to achieve fairness which neither guarantees a fair distribution of the network bandwidth nor eliminates node starvation. In addition, the metaheuristic-based solutions such as genetic algorithm, which is commonly used for WMN, use randomness in creating initial population and selecting the new generation usually leading the search to local minima. To this end, this study proposes a Fairness-Oriented Semichaotic Genetic Algorithm-Based Channel Assignment Technique (FA-SCGA-CAA) to solve node starvation problem in wireless mesh networks. FA-SCGA-CAA maximizes link fairness while minimizing link interference using a genetic algorithm (GA) with a novel nonlinear fairness-oriented fitness function. The primary chromosome with powerful genes is created based on multicriterion links ranking channel assignment algorithm. Such a chromosome was used with a proposed semichaotic technique to create a strong population that directs the search towards the global minima effectively and efficiently. The proposed semichaotic technique was also used during the mutation and parent selection of the new genes. Extensive experiments were conducted to evaluate the proposed algorithm. A comparison with related work shows that the proposed FA-SCGA-CAA reduced the potential node starvation by 22% and improved network capacity utilization by 23%. It can be concluded that the proposed FA-SCGA-CAA is reliable to maintain high node-level fairness while maximizing the utilization of the network resources, which is the ultimate goal of many wireless networks.

In this paper we present the DES-Chan framework for experimentally-driven research on distributed channel assignment algorithms in wireless mesh networks. The implementation process of channel assignment algorithms is a difficult task for the researcher since common operating systems do not support channel assignment algorithms out of the box. DES-Chan provides a set of common services required by distributed channel assignment algorithms. The modular architecture of DES-Chan allows the extensions with further modules or the modifications of existing ones. As a proof of concept, we present a reference implementation of a distributed greedy channel assignment algorithm. We evaluate its performance in the DES-Testbed, a multi-transceiver wireless mesh network (WMN) with 100 nodes at the Freie Universitat Berlin.

The frequent failures in Wireless Mesh Networks (WMNs) cause severe performance degradations during their lifetime. This increases the need of re-routing of links in WMNs. Expensive manual network management is required for their real-time recovery. This paper presents a Streamlined Re-routing Algorithm (SRA) that enables a multi-radio WMN to autonomously recover from local link failures to preserve network performance. SRA makes necessary changes in local radio and channel assignments in order to recover from failures, by using channel and radio diversities in WMNs. A default channel is used for transmission till the reconfiguration is done. Based on current channel and radio associations, feasible local configuration changes available around a faulty area are identified. SRA identifies reconfiguration plans that require the minimum number of changes for the network settings. Based on the generated configuration changes and interference aware channel assignment, the system cooperatively reconfigures network settings among local mesh routers. The results show that the proposed algorithm improves the throughput and decreases the packet drops.

Multi-channel communication in a Wireless Mesh Network with routers having multiple radio interfaces significantly enhances the network capacity. Efficient channel assignment is critical for realization of optimal throughput in such networks. In this paper, we investigate the problem of finding the largest number of links that can be connected with the overall network interference is minimized. Since the number of radios on any node can be less than the number of available channels, the channel assignment must obey the constraint that the number of different channels assigned to the links incident on any node is at most the number of radio interfaces on that node. The above optimization problem is known to be NP-hard. By presenting the theoretical model, the above task is formulated as a multi-objective problem, and then a novel channel assignment based on improved NSGA-II is proposed. Extensive empirical evaluations represent that the novel algorithm proposed in this paper can implement network connectivity with little interference rapidly and efficiently. To meet the actual demand in wireless mesh network, ns-2 simulations are used to demonstrate the performance potential of our channel assignment algorithms in 802.11-based multi-radio mesh networks.

The performance of Multi-Channel Multi-Radio (MC-MR) Wireless Mesh Networks (WMNs) can be improved significantly with the increase in number of channels and radios. Despite the availability of multiple channels in several of the current wireless standards, only a few of them are non-overlapping and many channels are partially overlapped. In this paper, we formulate the joint channel assignment and flow allocation problem for MC-MR WMNs as a Mixed Integer Linear Program (MILP). Unlike most of the previous studies, we consider the case of using both non-overlapped and partially overlapped channels. We consider an objective of maximizing aggregate end-to-end throughput and minimizing queueing delay in the network, instead of the sum of link capacities, since the traffic characteristics of a multihop WMN are quite different from a single hop wireless network. Our formulation takes into consideration several important network parameters such as the transmission power of each node, path loss information, signal to interference plus noise ratio at a node, and frequency response of the filters used in the transmitter and receiver. We show by simulations that our MILP formulation makes efficient use of the spectrum, by providing superior channel assignments and flow allocations with the addition of partially overlapped channels, without the use of any additional spectrum.

We consider the channel assignment problem in wireless mesh networks. Due to the limited number of radio interfaces that each node is equipped with, channel assignment must ensure that the interface constraint is obeyed, i.e., the number of different channels assigned to the links incident on a node must be no greater than the number of interfaces the node is equipped with. However, interface constraint may be one of the causes that hinder the performance of some of the existing heuristics. In this paper, we use simulated annealing to solve the channel assignment problem in wireless mesh networks. We propose two neighbor generating approaches that handle the interface constraint in different ways. The first approach starts with an infeasible random solution, and by using the penalty function technique the solution finally converges to a feasible one. The second approach, on the contrary, allows only feasible solutions to be generated during the simulated annealing process. Simulations are conducted that compare our proposed simulated annealing algorithms together with a tabu-based algorithm under different network traffic scenarios. The results show that our algorithms exhibit lower network interference than the tabu-based algorithm.

In this paper, a model for the static channel assignment in multi-radio multi-channel wireless mesh networks is proposed. We describe an interference model in wireless communication environment. The degree of detail in the model determines the accuracy of channel assignment. In many wireless mesh networks studies, the simplistic protocol interference model is adopted, but the model is usually not realistic and practical. Therefore, we construct a physical interference model and put forward a pure integer quadratic programming (PIQP) model to solve the channel assignment problem and maximize the capacity of wireless mesh networks. The feasibility and effectivity of the channel assignment solution are suggested by the results of simulation.

Interference among wireless links is the main reason for capacity reduction in wireless mesh networks. Allowing multiple radio interface use in a mesh router with different frequency channel is often presented as a possible way to improve the network capacity. One efficient way is using a centralized controller to assign proper frequency channel to radio interfaces which would significantly reduce the interference. Furthermore, proposing a routing protocol which consider interference as a leading factor for finding a path can noticeably increase the overall throughput. Since Software-Defined Networking provide more flexible and manageable networks by decoupling between control plane and data plane and implementing the control and management in a logically centralized controller, it can be a good choice. This paper is supposed to use a controller in a SDN wireless mesh networks to assign channels based on a static channel assignment algorithm and making routing decision based on the remained interference between links.

Breadth First Search Channel Assignment(BFSCA) is a hybrid channel assignment algorithm that utilize multiple radio interfaces to improve the throughput and minimize the interference within the wireless mesh network and between the mesh network and co-located wireless mesh networks. This new channel assignment scheme allows different nodes in the same network to communicate with each other without causing too much interference to their neighbors. It is introducing Multiradio Conflict Graph(MCG) to model interference in the wireless mesh network. Breadth First Search Channel Assignment considers both the fixed channels (static) and the dynamic channels to reduce interference of the network. BFSCA will increase the network throughput greatly.

Wireless mesh networks are a special kind of ad hoc networks in which most nodes are static. The application purpose of wireless mesh networks is also different than that of ad hoc networks and is focused on broadband access services to the Internet. Recent studies have shown that nodes in a wireless mesh network have to be equipped with several radio interfaces for high performance. However, one of the challenges that still faces high performance wireless mesh networks is the capacity reduction due to interference of wireless links. In this paper, we address the problem of assigning channels to nodes in wireless mesh networks. For this, we propose and study the Cluster Channel Assignment (CCA) approach with the goal of reducing the network interference to increase the overall network performance.