Multi-radio Multi-channel Wireless Mesh Networks Research Articles

A Conflict-Aware Channel Assignment in Multi-Radio Multi-Channel Wireless Mesh Networks

A Conflict-Aware Channel Assignment in Multi-Radio Multi-Channel Wireless Mesh Networks

Optimizing Interference Management in Multi-Channel Multi-Radio Wireless Mesh Networks

Wireless Mesh Networks (WMNs) face challenges in load balancing due to high traffic volumes. Unequal load distribution stems from two main factors: the dispersed nature of clients and their varying demands. The primary goal is to develop multi-frequency hybrid radio network systems with dynamic frequency allocation and gateway selection. A framework termed "LACE - Load-Aware Frequency Estimation" is introduced to enhance network protection, lifespan, and quality while reducing packet loss, latency, energy consumption, and routing overhead. This approach facilitates the expansion of coverage without compromising frequency capacity by enabling dynamic frequency allocation and gateway selection in WMNs.

An Efficient Interference Aware Partially Overlapping Channel Assignment and Routing in Wireless Mesh Networks

In recent years, multi-channel multi-radio wireless mesh networks are considered a reliable and cost effective way for internet access in wide area. A major research challenge in this network is, selecting a least interference channel from the available channels, efficiently assigning a radio to the selected channel, and routing packets through the least interference path. Many algorithms and methods have been developed for channel assignment to maximize the network throughput using orthogonal channels. Recent research and test-bed experiments have proved that POC (Partially Overlapped Channels) based channel assignment allows significantly more flexibility in wireless spectrum sharing. In this paper, first we represent the channel assignment as a graph edge coloring problem using POC. The signal-to-noise plus interference ratio is measured to avoid interference from neighbouring transmissions, when a channel is assigned to the link. Second we propose a new routing metric called signal-to-noise plus interference ratio (SINR) value which measures interference in each link and routing algorithm works based on the interference information. The simulation results show that the channel assignment and interference aware routing algorithm, proposed in this paper, improves the network throughput and performance.

Internet Traffic based Channel Selection in Multi-Radio Multi-Channel Wireless Mesh Networks

Wireless Mesh Networks(WMNs) are the outstanding technology to facilitate wireless broadband Internet access to users. Routers in WMN have multiple radio interfaces to which multiple orthogonal/partially overlapping channels are assigned to improve the capacity of WMN. This paper is focused on channel selection problem in WMN since proper channel selection to radio interfaces of mesh router increases the performance of WMN. To access the Internet through WMN, the users have to associate with one of the mesh routers. Since most of the Internet Servers are still in wired networks, the major dominant traffic of Internet users is in downlink direction i.e. from the gateway of WMN to user. This paper proposes a new method of channel selection to improve the user performance in downlink direction of Internet traffic. The method is scalable and completely distributed solution to the problem of channel selection in WMN. The simulation results indicate the significant improvement in user performance.

Coefficient of Restitution based Cross Layer Interference Aware Routing Protocol in Wireless Mesh Networks

In Multi-Radio Multi-Channel (MRMC) Wireless Mesh Networks (WMN), Partially Overlapped Channels (POC) has been used to increase the parallel transmission. But adjacent channel interference is very severe in MRMC environment; it decreases the network throughput very badly. In this paper, we propose a Coefficient of Restitution based cross layer interference aware routing protocol (CoRCiaR) to improve TCP performance in Wireless Mesh Networks. This approach comprises of two-steps: Initially, the interference detection algorithm is developed at MAC layer by enhancing the RTS/CTS method. Based on the channel interference, congestion is identified by Round Trip Time (RTT) measurements, and subsequently the route discovery module selects the alternative path to send the data packet. The packets are transmitted to the congestion free path seamlessly by the source. The performance of the proposed CoRCiaR protocol is measured by Coefficient of Restitution (COR) parameter. The impact of the rerouting is experienced on the network throughput performance. The simulation results show that the proposed cross layer interference aware dynamic routing enhances the TCP performance on WMN.

Distributed and Dynamic Channel Assignment Schemes for Wireless Mesh Network

Wireless mesh network (WMN) with wireless backhaul technology provides last-mile Internet connectivity to the end-users. In multi-radio multi-channel WMN (MRMC-WMN), routers provide multiple concurrent transmissions among end-users. The existence of interference among concurrent transmissions severely degrades the network performance. A well-organized channel assignment (CA) scheme significantly alleviates the interference effect. But in trying to minimize interference, the CA scheme may affect the network connectivity. So, the CA scheme has to consider both these two conflicting issues. In this paper, as part of the initial configuration of WMNs, we propose a game theory-based load-unaware CA scheme to minimize the co-channel interference and to maximize the network connectivity. To adapt to the varying network traffic, we propose a dynamic channel assignment scheme. This scheme measures the traffic-load condition of the working channels of each node. Whenever a node finds an overloaded channel, it initiates a channel switch. Channel switching based on the fixed threshold may result in a channel over/underutilization. For optimal channel utilization, we propose a fuzzy logic-based approach to compute the channel switch threshold. The contending nodes and their densities and loads dominantly affect the network capacity and hence the performance. In the context of network capacity enhancement, we have addressed these factors and focused on increasing the network capacity. The simulation results indicate that our proposed load-unaware and load-aware CA schemes outperform the other related load-unaware and load-aware CA approaches.

Channel Assignment Based on CSMA-Aware Interference Model With Overlapped Channels in Multiradio Multichannel Wireless Mesh Networks

Multi-radio Multi-channel Wireless Mesh Networks (MRMC WMNs) implemented on IEEE 802.11 standards are widely used owing to their adaptability in practical network scenarios. The channel assignment problem in MRMC WMNs has been extensively studied. However, in most of the existing works, only orthogonal wireless channels are considered owing to the complexity of the channel assignment problem, which results in a low level of spatial utilization. This paper introduces partially overlapping channels into the CSMA-aware interference and shared link capacity models to fully exploit the spectrum resource and improve network capacity, utilizing both orthogonal channels and partially overlapping channels in IEEE 802.11 2.4 GHz bands. We formulate this problem as a mixed-integer linear program (MILP). We propose a traffic-demand-aware collision-free partially overlapping channel assignment (TAC-POCA), which uses all the available channels and achieves collision-free end-to-end flow transmissions to attain load balance. Simulation results show that TAC-POCA leads to better utilization of the spectrum resource and throughput improvement in both grid and random topology networks than in the case of using only orthogonal channels.

Comparison of Metaheuristic Algorithms for Interface-Constrained Channel Assignment in a Hybrid Dynamic Spectrum Access – Wi-Fi Infrastructure WMN

In this work, we evaluate the application of four different metaheuristic optimisation algorithms for solving the channel assignment problem in a multi-radio multi-channel Wireless Mesh Network (WMN) using Dynamic Spectrum Access (DSA). The work advances a near optimal channel assignment (CA) in a WMN that uses DSA by applying soft computing methods. While CA in a WMN is well-studied, and CA for secondary user cognitive radio networks has also been studied in the literature, CA for our specific scenario of an infrastructure DSA-WMN is novel. This scenario poses new challenges because nodes are spread out geographically and so may have different allowed channels and experience different levels of external interference in different channels. A solution must meet two conflicting requirements simultaneously: 1) to avoid interference within the network and with external interference sources, and 2) maintain connectivity within the network; all while staying within the radio interface constraint, i.e., only assigning as many channels to a node as it has radios. We present a novel algorithm, used alongside the metaheuristic optimisation algorithms, which ensures the feasibility of solutions in the search space. Average Signal to Interference and Noise Ratio (<inline-formula> <tex-math notation="LaTeX">$SINR$ </tex-math></inline-formula>) over the network is used as the performance measure, with the goal of optimisation being to find the highest average <inline-formula> <tex-math notation="LaTeX">$SINR$ </tex-math></inline-formula>. This is a more realistic performance measure than the binary on/off conflict-based measures most common in the literature. Our energy-based method also has the unique advantage that it is protocol-agnostic, being able to avoid interference from external sources that use different protocols and standards. The algorithms that are compared in this work are Simulated Annealing (SA), the Genetic Algorithm (GA), Particle Swarm Optimisation (PSO), and Differential Evolution (DE). These algorithms were evaluated through the use of simulation in Network Simulator 3. Various parameters were experimented with for each of the employed algorithms. The resultant best set of parameters was used for the comparison of the four metaheuristic algorithms. It was found that the population-based algorithms (PSO, GA, and DE) all perform satisfactorily for this problem, although DE is superior to the others. SA can give acceptable solutions, but performs poorly in comparison to the population-based algorithms. The paper also considers the computational complexity of the methods. It is found that SA and DE perform well in this regard.

Impact Of Load Balancing Interference Routing Metric On Multi Channel Multi Radio Wireless Mesh Network

Wireless Mesh Network (WMNs) is a promising technology that has been accepted favorably by the Internet Service Providers (ISPs). ISPs use it to provide last mile broadband Internet connectivity to the end users. This popularity arises from the fact, that it inter operates well with diverse wireless systems and provides robust fault tolerance with a high degree of redundancy and reliability. Routing metrics plays a crucial part in the performance of WMN. When routing protocols are implemented, the routing metric is assigned to different paths. It calculates the optimum path to predict the best routing path. These are integrated in routing protocols to improve WMNs efficiency in terms of reliability, latency, throughput, error rate and cost. This paper compares the impact of using load balancing interference aware routing metric (LBIARM) on the performance of Multi-Channel Multi Radio WMNs (MCMR WMNs). The performance of LBIARM was evaluated by comparing it with popular standard metrics weighted cumulative expected transmission time metric and Hop Count metric. OPNET Modeler 17.5 PL1 was used as a simulation tool for implementation. Simulation results show the effectiveness of using LBIARM metric on MCMR WMNs.

Achieving Hidden-Terminal-Free Channel Assignment in IEEE802.11-Based Multi-Radio Multi-Channel Wireless Mesh Networks

Achieving Hidden-Terminal-Free Channel Assignment in IEEE802.11-Based Multi-Radio Multi-Channel Wireless Mesh Networks

Adaptive Allocation Algorithm for Multi-Radio Multi-Channel Wireless Mesh Networks

The wireless mesh network (WMN) has proven to be a great choice for network communication technology. WMNs are composed of access points (APs) that are installed and communicate with each other through multi-hop wireless networks. One or more of these APs acts as a gateway (GW) to the internet. Hosts of WMNs are stationary or mobile. According to the structure of WMNs, some network features may be affected, such as the overall performance, channel interference, and AP connectivity. In this paper, we propose a new adaptive channel allocation algorithm for a multi-radio multi-channel wireless mesh network. The algorithm is aimed to minimize the number of channel reassignments while maximizing the performance under practical constraints. The algorithm defines a decision function for the channel reassignments. The decision function aims to minimize the traffic around the GW. Whenever the traffic changes in the wireless mesh network, the decision function decides which channel radio reassignment should be done. We demonstrated the effectiveness of our algorithm through extensive simulations using Network Simulator 2 (NS-2).

EMSC: a joint multicast routing, scheduling, and call admission control in multi-radio multi-channel WMNs

This paper deals with the problem of joint multicast routing, scheduling, and call admission control in multiradio multi-channel wireless mesh networks. To heuristically solve this problem, we propose a cross-layer algorithm named “extended MIMCR with scheduling and call admission control phases (EMSC)”. Our model relies on the on-demand quality of service (QoS) multicast sessions, where each admitted session creates a unique tree with a required bandwidth. The proposed scheme extends the MIMCR algorithm to fairly schedule multiple non-interfering transmissions in the same time slot. It also exploits a call admission control mechanism to protect the QoS requirements of the multicast traffics. EMSC reduces the number of occupied time slots, with consideration of spatial reuse, both Intra-flow and Inter-flow interferences, and selecting the minimum-interference minimum-cost paths. This subsequently leads to better radio resource utilization and increases the network throughput. Simulation results show that the proposed algorithm outperforms the other algorithms and improves the network performance.

Resource Allocation for Hybrid RF/FSO Multi-Channel Multi-Radio Wireless Mesh Networks

The overwhelming data rates in next generation wireless networks impose a burden on the high-capacity network planning. One promising strategy to meet the demand for high-capacity communications is to augment radio frequency (RF) based multi-channel multi-radio (MCMR) wireless mesh network (WMN) by free-space optics (FSO). In this paper, we construct a hybrid RF/FSO MCMR WMN topology and address its resource allocation (RA) problem in terms of interface assignment, channel allocation, routing, FSO link allocation, and topology control. Considering the weather effects on FSO link availability and the fading nature of RF links, the RA problem is formulated as a two-stage optimization problem with the objective of maximizing the network throughput. In our optimization model, we formulate each stage as a mixed integer linear program, and the bottleneck RF links are gradually upgraded by FSO links. To avoid the computational complexity of the second stage optimization, an improved iterated local search algorithm is proposed. Simulation results show that our RA scheme is efficient and the throughput can be enhanced dramatically by proper FSO link augmentation.

Maximize concurrent data flows in multi-radio multi-channel wireless mesh networks

Multi-radio multi-channel (MRMC) wireless mesh networks (WMNs) have emerged as the broadband networks to provide access to the Internet for ubiquitous computing with the support for a large number of data flows. Many applications in WMNs can be abstracted as a multi-flow coexistence problem to carry out multiple concurrent data transfers. More specifically, links in different channel layers must be concatenated to compose multiple data transfer paths based on nodes? free interfaces and available channels. This is typically formulated as a combinatorial optimization problem with various stages including channel assignment, path computing, and link scheduling. This paper analyzes traffic behaviors and designs a coexisting algorithm to maximize the number of concurrent data flows. Simulations are conducted in combinatorial cases of channel and radio with various traffic requests of multiple pairs. The experimental results show the efficacy of the coexisting algorithm over a randomly generated topology. This scheme can be used to develop routing and scheduling solutions for various multi-flow network applications through prior computing.

Traffic-Demand-Aware Collision-Free Channel Assignment for Multi-Channel Multi-Radio Wireless Mesh Networks

In multi-channel multi-radio wireless mesh networks (MCMR WMNs), assigning each radio with an appropriate channel to maximize the performance is a challenging problem. In this optimization, the primal concern lays on how to mitigate effects of interference to avoid performance degradation. However, collision-freedom for a given traffic demand under the limitation of precious channel resources has not been achieved yet. In this paper, we present a collision-free joint channel assignment and routing scheme called TACCA (Traffic-demand-Aware Collision-free Channel Assignment) for MCMR WMNs. To reduce the required number of channels, TACCA incorporates a property of CSMA (Carrier Sense Multiple Access), i.e., it adopts CSMA-aware interference model and a CSMA-aware shared link capacity model. We formulate a mixed integer linear programming (MILP) to optimize the network utility and enhance the practical usefulness under the given traffic demands. The evaluation results with a MILP solver show that TACCA achieves collision-freedom in both grid and random topology networks with 3-5 orthogonal channels, and exhibits good network utilization performance. In addition, the network simulation results show that TACCA achieves mostly collision-free communications under up-to-date PHY and MAC models, and presents excellent communication performance.

Distributed Rate-Control and Delay-Guaranteed Scheduling in MR-MC Wireless Mesh Networks.

Wireless mesh networks (WMNs) can provide flexible wireless connections in smart city, Internet of Things (IoT), and device-to-device (D2D) communications. The performance of WMNs can be greatly enhanced by adopting the multi-radio multi-channel (MR-MC) technique, which enables a node to communicate with more nodes simultaneously. However, increasing the number of data flows will result in network congestion and longer end-to-end delays. In this paper, a distributed rate-control and delay-aware (DRDA) scheduling algorithm is proposed based on a multidimensional conflict graph. To satisfy the arrival rate and delay constraints of a flow, two virtual queues are constructed. All the actual and virtual queues are stabilized by the Lyapunov drift optimization method. The scheduling policy of each flow is optimized only based on the local information. The simulation results show that our proposed algorithm can maintain the stability of all the queues and strictly satisfy the arrival rate and delay constraint of each flow in the network as well.

MO‐CSO‐based load‐balanced routing in MRMC WMN

The multi-radio–multi-channel wireless mesh networks (MRMC WMNs) have attracted much attention due to their low cost, reliable coverage, stable topology, and so forth. Load balancing among gateways (GWs) is a challenging task in MRMC WMNs. The GW nodes with higher loads will lead to disconnected network. GW and shortest path selection may increase traffic concentration which leads to congestion and collision in network. In this study, a multi-objective competitive swarm optimiser (MO-CSO) with analytic hierarchy process-based (AHP) load-balancing technique is proposed among the multiple GW nodes that provide communication between server and user to select the lightly loaded GWs, so that more packets will be delivered to the fixed host in Internet. The proposed method selects four GW parameters that are GW connecting degree, GW capacity indicator, traffic in collision domain, and path cost. The objective functions are minimisation of delay and maximising the channel utilisation, network throughput, and balancing network traffic. The MO-CSO with AHP method is utilised to select the best GW and path which combines all four parameters. Simulation results show that the proposed MO-CSO improves the network performance by maximum throughput while compared with the existing routing strategies such as SBR, ETX, LG, NG, and IR.

Internet Traffic based Channel Selection in Multi-Radio Multi-Channel Wireless Mesh Networks

Wireless Mesh Networks(WMNs) are the outstanding technology to facilitate wireless broadband Internet access to users. Routers in WMN have multiple radio interfaces to which multiple orthogonal/partially overlapping channels are assigned to improve the capacity of WMN. This paper is focused on channel selection problem in WMN since proper channel selection to radio interfaces of mesh router increases the performance of WMN. To access the Internet through WMN, the users have to associate with one of the mesh routers. Since most of the Internet Servers are still in wired networks, the major dominant traffic of Internet users is in downlink direction i.e. from the gateway of WMN to user. This paper proposes a new method of channel selection to improve the user performance in downlink direction of Internet traffic. The method is scalable and completely distributed solution to the problem of channel selection in WMN. The simulation results indicate the significant improvement in user performance.

Performance Analysis on Hybrid Wireless Mesh Network Topology using Interference Aware Bandwidth Reservation

Ubiquitous of modern era which utilises Hybrid Wireless Mesh Network (HWMN) topology which gave birth to ample of modern application which demands reliability, fault tolerance and scalability. HWSN topology utilises minimum of two or multiple standard network architectural topologies, in a fashion that the resultant network architecture doesn’t depict any particular topologies like bus, star or ring but as a combination of any of those standard topologies. Prime motive of the proposed Optimised Channel Assignment Algorithm (OCSA) is which focuses on priority oriented interference minimization for all the trees which are existed, and constraint in terms of delay for evolving tree addition. Interference Aware Bandwidth Reservation (IABR) provides controllability over data flow admission for end-to-end optimal bandwidth accommodation in Multi-Radio Multi-Channel (MRMC) wireless mesh network. Proposed Priority Based Interference Aware Bandwidth Reservation (PBIABR) utilises disseminated and polynomial-time heuristic oriented assignment in channel to minimize interference in WMN with the awareness of channel priority as a primary consideration. Interference and Priority of the channel are made indirectly proportional to each other. For the channel of high priority the path which has low interference is opted. In PBIABR the whole path delay constraint of tree is sub organised into multiple node, based on delay to identify the best node which embodies minimal interference. Dominant Performance Parameters (DPP) like Throughput, Packet Size, Propagation Interval and Average Energy under HWSN Scenario. All the DPP parameters are analysed for multiple flow parameters for Interference Aware Bandwidth Reservation (IABR) and Proposed Priority Based Interference Aware Bandwidth Reservation (PBIABR) conditions. Simulation results have been captured using Network Simulator 2 tools for HWSN creation and crafted to same readings as a graph for deep analysis. The proposed simulation results for hybrid scenario highlights a considerable performance hike for the performance parameters like Throughput (bps) vs Packet size (bytes), Average Energy (joule) vs Interval (sec) and Residual Energy (joule) vs Interval (sec) under PBIABR conditions compared with IABR simulation outcome. The results have been analysed for comparative study of each parameter deeply. Inference from the comparative analysis highlights the performance parameters of PBIABR is efficient than IABR.

Online multicast tree construction with bandwidth and delay constraints in multi-channel multi-radio wireless mesh networks

This paper deals with online QoS multicast tree construction problem, which is essential to support multimedia services, in multi-channel multi-radio wireless mesh networks. The proposed algorithm satisfies both delay and bandwidth requirements of each arrived session. It breaks down the original problem into two phases of satisfying delay and bandwidth constraints. The first phase devotes to preserving delay constraint of the arrived session, in which a number of delay-bounded paths are determined between each receiver and the source node. In the proposed scheme, to diminish the utilized bandwidth, the overlapping of the regarding paths of the receivers is maximized as much as possible. We propose a mathematical model to satisfy bandwidth requirement in the second phase, which constructs the tree over the selected paths. The data transmission rate on the tree is set to the requested rate by the session, to satisfy its bandwidth requirement. The proposed model has a global view over the network and constructs the most appropriate trees. It also exploits wireless broadcast advantage property to enhance the performance. Through extensive simulations, the effectiveness of the proposed algorithm is verified. In particular, it improves the acceptance rate by 60% compared to previous schemes.