Multi-radio Multi-channel Wireless Mesh Networks Research Articles

Distributed joint flow-radio and channel assignment using partially overlapping channels in multi-radio wireless mesh networks

Equipping mesh nodes with multiple radios that support multiple wireless channels is considered a promising solution to overcome the capacity limitation of single-radio wireless mesh networks. However, careful and intelligent radio resource management is needed to take full advantage of the extra radios on the mesh nodes. Flow-radio assignment and channel assignment procedures should obey the physical constraints imposed by the radios as well as the topological constraints imposed by routing. Varying numbers of wireless channels are available for the channel assignment procedure for different wireless communication standards. To further complicate the problem, the wireless communication standard implemented by the radios of the wireless mesh network may define overlapping as well as orthogonal channels, as in the case of the IEEE 802.11b/g family of standards. This paper presents Distributed Flow-Radio Channel Assignment, a distributed joint flow-radio and channel assignment scheme and the accompanying distributed protocol in the context of multi-channel multi-radio wireless mesh networks. The scheme’s performance is evaluated on small networks for which the optimal flow-radio and channel configuration can be computed, as well as on large random topologies.

FD-AQM: Fairness-Aware Delay-Controlled Active Queue Management in 802.11s-Based Multi-Radio Multi-Channel Wireless Mesh Networks

Several active queue management (AQM) schemes have been proposed to address the bufferbloat issue, a long network delay and performance degradation issue caused by excess buffering of packets in network nodes. The solutions proposed up to now, however, satisfy only a subset of the key network performance metrics, i.e., end-to-end throughput, throughput fairness, and delay, in 802.11s-based multi-radio multi-channel wireless mesh networks (MRMC WMN). In this letter, we propose FD-AQM, a fairness-aware delay-controlled AQM to satisfy all three key network performance metrics simultaneously in the 802.11s-based MRMC WMN. The proposed FD-AQM achieves the goal by adopting a per-queue drop interval which is recalibrated according to the average round-trip time of flows, and a drop decision mechanism which considers average throughput as well as target delay. Through simulations, we show that FD-AQM is superior to other AQM schemes in terms of throughput and fairness.

Capacity‐Based Channel Assignment Scheme in Multi‐radio Multi‐channel Wireless Mesh Networks

The capacity of wireless mesh networks can be greatly enhanced by equipping each mesh router with multiple radios and by exploiting multiple channels to reduce network interference. It has been proved that an efficient channel assignment scheme is critical to achieve the optimal network throughput. This paper presents a centralized channel assignment scheme for multi-radio multichannel wireless mesh networks. The scheme includes a spanner-based topology control operation and a linkranking channel assignment algorithm. In the topology control procedure, several links that cause intense interference are removed from the network without damage to the basic network connectivity. The channel assignment procedure improves the network throughput via ranking links based on the principle of load balance. The simulation results demonstrate that the proposed scheme outperforms the compared centralized channel assignment approach in terms of network throughput. The experimental results also indicate that the effectiveness of the proposed scheme is even evident in the case of heavy input traffic load where the potential interference in the network is severe.

Joint topology control and routing for multi-radio multi-channel WMNs under SINR model using bio-inspired techniques

Multi-channel communication in a wireless mesh network (WMN) equipped with multi-radio routers can significantly enhance the network capacity. Channel allocation, power control and routing are three main issues involved in the performance of multi-channel multi-radio WMNs. In this paper, the joint optimization of channel allocation, power control and routing under signal-to-interference-and-noise ratio (SINR) model for multi-channel multi-radio WMNs is investigated. It is proven to be NP hard. As we know, no optimal polynomial time solutions have been proposed in the previous literatures. In order to tackle this problem, we apply bio-inspired optimization techniques for channel allocation and power control, and use linear programming for routing optimization. To reflect the cross-layer interaction property among these three issues, the routing optimization is further defined as the fitness value of a chromosome in bio-inspired optimization. Further, we propose an effective joint optimization framework, in which two representative bio-inspired optimization methods (genetic algorithm and particle swarm optimization algorithm) are hybridized to enhance the searching ability. The detailed evolution processes for both genetic algorithm and particle swarm optimization algorithm are demonstrated. Extensive simulation results show that the proposed algorithm converges fast and approaches the sub-optimal solution effectively.

A two-stage game for allocating channels and radios to links in wireless backhaul networks

Radio interfaces and channels are two sorts of resources in a multi-channel multi-radio wireless mesh network. Efficient allocation of radio resources to mesh nodes should be done under the constraints of reducing co-channel interference yet with increased network connectivity. However, these two constraints conflict in nature as far as allocating radios (i.e., transceivers) and channels to links is concerned. In consideration of physical-layer interference, this paper proposes two non-cooperative games that play in sequence for radio resource allocation. The first game assigns channels to radios while the second distributes the resulting radio-channel pairs to links. The proposed games are shown to always reach a Nash equilibrium regardless of initial configurations, and together guarantee network connectivity while minimizing co-channel interference of each individual radio. We have conducted simulations to analyze game behaviors and carried out performance comparisons. The results indicate that game convergence time depends on the behavior of the first game. The proposed approach leads to more operative links than counterpart schemes when only two radios are available at each node, but loses its advantage over centralized, greedy methods when more radios are available.

End-to-End Route Reliability in Pervasive Multi-Channel Multi-Radio (PMCMR) Scheme for MANETS

Multi-channel multi radio wireless communications technologies have changed the trend of traditional routing based Quality of Service (QoS) in wireless-mesh networks. This avalanche of growth in multimedia communication is trigged by Multi-Channel Multi-Radio Wireless Mesh Networks (MCMR-WMNs). It is forecasted that in the near future, societal networks will have latest state of the art radio devices with Multi Channel and Multi Radio (MCMR) communication power with enhanced reliability, throughput and self-healing features. Despite of marked improvements in data link layer and physical layer in the IEEE 802.11 standards, optimized throughput, performance and network availability of MCMR wireless mesh networks still depend upon the efficient routing metric or protocol. We carried out a set of experiment and observed that cross layer routing in mesh networks is highly influenced by traffic load, interference between channel and interference between nodes. Proposed scheme used ‘conjugate distribution method’ which was designed to evaluate end-to-end route and communication reliability using posterior distribution function. Routing metric is evaluated based on load aware, intra and inter-interface aware, packet average delivery ration, latency and overhead with considered criteria of average path length. Competitive study revealed that proposed technique is efficient and applicable especial in environment where end-to-end reliability is required.

QoS Guaranteed Intelligent Routing Using Hybrid PSO-GA in Wireless Mesh Networks

Abstract In Multi-Channel Multi-Radio Wireless Mesh Networks (MCMR-WMN), finding the optimal routing by satisfying the Quality of Service (QoS) constraints is an ambitious task. Multiple paths are available from the source node to the gateway for reliability, and sometimes it is necessary to deal with failures of the link in WMN. A major challenge in a MCMR-WMN is finding the routing with QoS satisfied and an interference free path from the redundant paths, in order to transmit the packets through this path. The Particle Swarm Optimization (PSO) is an optimization technique to find the candidate solution in the search space optimally, and it applies artificial intelligence to solve the routing problem. On the other hand, the Genetic Algorithm (GA) is a population based meta-heuristic optimization algorithm inspired by the natural evolution, such as selection, mutation and crossover. PSO can easily fall into a local optimal solution, at the same time GA is not suitable for dynamic data due to the underlying dynamic network. In this paper we propose an optimal intelligent routing, using a Hybrid PSO-GA, which also meets the QoS constraints. Moreover, it integrates the strength of PSO and GA. The QoS constraints, such as bandwidth, delay, jitter and interference are transformed into penalty functions. The simulation results show that the hybrid approach outperforms PSO and GA individually, and it takes less convergence time comparatively, keeping away from converging prematurely.

Partially overlapped channel assignment for multi-channel multi-radio wireless mesh networks

AbstractPartially overlapped channels (POCs)-based design has been identified recently as an emerging technology to further eliminate interference and improve network capacity. However, there are only few studies of channel assignment algorithms for POCs. In this paper, we research on utilizing POCs to improve network capacity and propose a traffic-irrelevant channel assignment algorithm, which assigns channels for all links in the network while minimizing total network interference. Theoretical calculation approach is utilized to obtain the direct relationship between interference ranges and channel separations, which can be easily applied to mesh networks with various configurations without modification. As traffic between the Internet and clients is considered to be dominant, distance from the gateway, number of neighbors, and interference are used to determine the channel assignment order of links. Simulation results reveal that network throughput and end-to-end delay performance can be dramatically improved by fully exploiting POCs as well as orthogonal channels.

On channel assignment for multicast in multi-radio multi-channel wireless mesh networks: A survey

The major challenge faced by wireless mesh networks is the capacity reduction caused by interference, and interference can be reduced or even eliminated through appropriate channel assignment. This article presents a comprehensive survey of channel assignment schemes for multicast in multi-radio multi-channel wireless mesh networks. We analyze the state-of-the-art channel assignment schemes for multicast and provide comprehensive taxonomy of the latest work. In general, we classify the channel assignment schemes for multicast into two types, that is, sequential multicast routing and channel assignment (SMRCA) and joint multicast routing and channel assignment (JMRCA). Detailed review of channel assignment schemes in each category is provided. Possible future research directions and corresponding solutions are also explored to motivate research interests in the field of channel assignment for multicast in wireless mesh networks.

Joint anti-attack scheme for channel assignment in multi-radio multi-channel wireless mesh networks

Nowadays, multi-radio multi-channel wireless mesh networks have been widely exploited to provide high-speed Internet access. By assigning different channels, the interference between wireless mesh network nodes can be greatly reduced, leading to a better network performance. However, the channel assignment attacks have imposed a serious security problem, where the diverse messages, that is, Channel Usage Message CUM, Channel Change Message CCM, Channel Switch Operation CSO and Security Alarm Message SAM, are often used to launch attacks by the malicious nodes in order to disturb the normal channel assignment and thus the overall network performance. In this paper, we propose a joint anti-attack scheme JAS against the channel assignment attacks. Our JAS is composed of four key components: CUM, CCM, CSO and SAM defense schemes to protect the channel assignment. The CUM defense scheme verifies the CUM messages and their sender. The CCM defense scheme employs three rounds of CCM verifications. Furthermore, three control messages are exploited by the CSO defense scheme. The SAM defense scheme offers two rounds of verification for the alarm messages. Moreover, we apply our JAS to a popular distributed channel assignment algorithm, that is, Hyacinth. Through extensive simulation, the performance of the proposed scheme is evaluated by comparing with SeCA and SmartC in terms of Goodput and additional overhead. Observed from the simulation results, our scheme is demonstrated to outperform the best-known secure channel assignment algorithms. Copyright © 2014 John Wiley & Sons, Ltd.

On the impact of interference models on channel assignment in multi-radio multi-channel wireless mesh networks

We study the impact of three different interference models on channel assignment in multi-radio multi-channel wireless mesh networks, namely the protocol model, the signal-to-interference ratio (SIR) model and the SIR model with shadowing. The main purpose is to determine the minimum number of non-overlapping frequency channels required to achieve interference-free communication among the mesh nodes based on a realistic interference model. We propose novel, effective, and computationally simple methods for building the conflict graph based on the SIR model with shadowing, and for finding channel assignments from the resulting conflict graph. We find that channel assignment using a realistic interference model (SIR model with shadowing) requires more frequency channels for network throughputs at different node-degree constraints as compared to using simpler interference models.

A Wireless Mesh Network Channel Assignment Method Based on Potential Game

To solve multi-radio multichannel (MRMC) wireless Mesh network channel assignment problems, we propose and study the PGCA (channel assignment based on potential game) method. PGCA takes each link of the network as a player by designing rational potential function. The action strategies between links select resources containing channel and space information. PGCA converts maximum network throughput into minimum network interference by joint game. Simulation results show PGCA algorithm has better performance in terms of convergence speed and the network throughput. The end-to-end delay has connected with the number of links.

Fairness-oriented routing algorithm joint with power control and channel assignment for multi-radio multi-channel wireless mesh networks

The multi-radio multi-channel wireless mesh network (MRMC-WMN) draws general attention because of its excellent throughput performance, robustness and relative low cost. The closed interactions among power control (PC), channel assignment (CA) and routing is contributed to the performance of multi-radio multi-channel wireless mesh networks (MRMC-WMNs). However, the joint PC, CA and routing (JPCR) design, desired to achieve a global optimization, was poor addressed. The authors present a routing algorithm joint with PC and CA (JPCRA) to seek the routing, power and channel scheme for each flow, which can improve the fairness performance. Firstly, considering available channels and power levels, the routing metric, called minimum flow rate, is designed based on the physical interference and Shannon channel models. The JPCRA is presented based on the genetic algorithm (GA) with simulated annealing to maximize the minimum flow rate, an non-deterministic polynomial-time hard (NP-Hard) problem. Simulations show the JPCRA obtains better fairness among different flows and higher network throughput.

Minimum Cost Bandwidth Guaranteed Multicast Routing in Multi-channel Multi-radio Wireless Mesh Networks

Multicast communication is an important service in wireless mesh networks (WMNs). It covers a broad range of applications, including data distribution, video conferencing, and distance learning. In this paper, we discuss the issue of bandwidth guaranteed multicast routing in multi-channel multi-radio WMNs. The problem of our concern is to construct a tree per multicast session such that the cost of the system, which is defined as the amount of total consumed bandwidth, is minimized. In order to solve the problem efficiently, we design Bandwidth Guaranteed Minimum Cost Tree construction (BGMCT) algorithm. Our algorithm yields cost-effective solutions as it exploits the wireless broadcast advantage (WBA) property of the wireless medium. In the proposed algorithm, we have developed two strategies for constructing minimum cost trees. Firstly, the number of the relay nodes in each tree is minimized. Secondly, the amount of overlapping between the shortest paths which connect different destinations of each session to its source node, is taken into account. The simulation results demonstrate that our algorithm outperforms existing solutions. Moreover, BGMCT provides near to optimal outcomes in a reasonable time.

Channel Aware Opportunistic Routing in Multi-Radio Multi-Channel Wireless Mesh Networks

Opportunistic routing (OR) involves multiple candidate forwarders to relay packets by taking advantage of the broadcast nature and multi-user diversity of the wireless medium. Compared with traditional routing (TR), OR is more suitable for the unreliable wireless link, and can evidently improve the end to end throughput. 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. To demonstrate the benefit of OR in multi-radio multi-channel network, we propose a new route metric — multi-channel expected anypath transmission time (MEATT), which exploits the channel diversity and resource of multiple candidate forwarders for OR. Based on the new metric, a distributed algorithm named Channel Aware Opportunistic Routing (CAOR) is proposed. The simulation results demonstrate that MEATT improves 1.14 and 1.53 times of the average throughput than existing expected anypath transmission time (EATT)and metric of interference and channel switching cost (MIC) respectively. The average delay of MEATT is 17% and 40% lower than those of EATT, MIC, respectively.

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.

Joint channel assignment and routing in multiradio multichannel wireless mesh networks with directional antennas

SummaryThe aggregate capacity of a wireless mesh network (WMN) is severely affected by interflow interference. In this paper, we propose a network architecture that incorporates directional antennas with multiple orthogonal channels to effectively enhance the performance of WMNs. First, a sectored connectivity graph is introduced to model multiradio multichannel WMNs with directional antennas. Next we formulate the topology design, directional interface assignment, channel allocation, and routing mathematically as a mixed integer linear programming problem. This problem is solved using an iterated local search algorithm to obtain optimized network resource allocation. Simulation results indicate that the proposed architecture can achieve higher packet delivery ratio while providing better network fairness. Copyright © 2014 John Wiley & Sons, Ltd.

Routing Metric of Expected Delay in Multi-Radio Multi-Channel Wireless Mesh Networks

Many routing metrics have been proposed to improve the performance of wireless mesh networks (WMNs). Most of these routing metrics describe intra-flow and inter-flow interference respectively, which brings in adjustable parameters or results in non-isotonicity. However, the adjustable parameters, used to balance the intra-flow and inter-flow interference, are difficult to adapt to the network status, and non-isotonicity makes the design of routing metric complicated. In this paper, we propose an isotonic metric of expected delay (MED) in multi-radio multi-channel (MRMC) WMNs. In particular, MED uses the expected available bandwidth (EAB), which can capture the logical intra-flow and inter-flow interference uniformly, to estimate the delay of the path. In MED, both expected packet transmission delay and expected queuing delay are estimated to capture physical interference, logical interference, load and noise comprehensively. Simulation results show that the proposed metric can improve overall network performance effectively.

Interference-aware QoS routing and dynamic channel assignment for multi-radio multi-channel wireless mesh network

QoS routing in multi-channel wireless mesh networks protocols is a very challenging problem. In this paper, we propose an on-demand bandwidth-constrained routing protocol combined with dynamic channel assignment for multi-radio multi-channel wireless mesh networks with the IEEE 802.11 DCF MAC protocol. A multi-channel available bandwidth estimation method is proposed which is based on the exchange of the bandwidth information for neighbour nodes at first, then a new jointing channel assignment and routing algorithm is designed which dynamically assigns the channel through the available bandwidth in the routing process according to the requirement of bandwidth, distributed call admission control is integrated to prevent network overload and the optimal path metric is advised to establish interference-aware QoS routing. Simulation results show that the routing algorithm can reduce co-channel interference and improve network performance and acceptance rate through assigning channels dynamically.

JORCA: joint opportunistic routing and channel assignment

Opportunistic routing (OR) can improve the throughput of wireless mesh networks (WMNs). Most existing studies on OR focus on single-radio WMNs, where the severe interference may largely decrease the performance. Only a few works have studied OR in multi-radio multi-channel WMNs, while they either select opportunistic route with given channel assignment, or assign channel based on selected opportunistic routing, which separate the interdependency of opportunistic routing and channel assignment, and can hardly achieve good performance. This paper formulates the joint problem of opportunistic routing and channel assignment as a mixed integer programming (MIP) problem and proves it to be NP-hard. To solve it, we propose a heuristic iterative algorithm named joint opportunistic routing and channel assignment (JORCA) which exploits multi-user diversity and channel resource. The simulation results demonstrate that, comparing with the two existing solutions, JORCA improves 44% and 15.5% in total throughput.