Multi-channel Wireless Mesh Research Articles

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.

Online network coding-based multicast routing in multichannel multiradio wireless mesh networks

In this paper, we consider the problem of online multicast routing in multichannel multiradio wireless mesh networks (WMNs). We propose an efficient online algorithm, namely zone-based multicast routing (ZBMR), which exploits network coding and wireless broadcast advantage. In the proposed algorithm, to investigate the acceptance of an arrived session in polynomial time, the WMN is divided into some zones. The derived zones are processed sequentially, where the zone processing is defined as connecting the receivers in a given zone to the session. The main challenge in this scheme is to enable data transmission to the receivers in each zone. If a zone does not contain the source node, it should obtain data from the previously processed neighboring zones. The problem is that the data transmission fails if there is no receiver on the common border between the considered zone and its processed neighboring zones. Our solution to tackle this challenge is to add some virtual receivers to the borders of the zones. The extensive simulations show that ZBMR increases the acceptance rate by 50% in comparison to the previous approaches.

A dynamic channel assignment method for multichannel multiradio wireless mesh networks

The popularity of wireless communication accelerates research on new technologies that are required to satisfy users' needs. Wireless mesh networks (WMNs), which are additional access technologies instead of being a renewed one, have an important place among next-generation wireless networks. In particular, the capability of working without any infrastructure is the most outstanding advantage of WMNs. There are many studies aimed at WMNs, particularly channel assignment and routing methods for multichannel multiradio structures that provide higher data capacity. Interference, which has a direct effect on the quality of communication, is still a challenge to be addressed. In this study, multichannel multiradio WMNs and various channel assignment schemes are analyzed. Directional mesh (DMesh) architecture, which uses directional antennas to form a multichannel structure, is analyzed in terms of channel assignment procedure. A new interference-aware channel assignment scheme that aims to eliminate DMesh's disadvantages is proposed and performances of both schemes are compared. Several results of experimental analysis prove that the proposed channel assignment scheme improves the performance of DMesh

Q-CAR: an intelligent solution for joint QoS multicast routing and channel assignment in multichannel multiradio wireless mesh networks

Multicast routing improves the efficiency of a network by effectively utilizing the available network bandwidth. In multichannel multiradio wireless mesh networks the channel allocation strategy plays a vital role along with multicast tree construction. However, the multicast routing problem in multichannel multiradio wireless mesh networks is proven to be NP-hard. With this paper, we propose a Quality of Service Channel Assignment and multicast Routing (Q-CAR) algorithm. The proposed algorithm jointly solves the channel assignment and multicast tree construction problem by intelligent computational methods. We use a slightly modified differential evolution approach for assigning channels to links. We design a genetic algorithm based multicast tree construction strategy which determines a delay, jitter bounded low cost multicast tree. Moreover, we define a multi objective fitness function for the tree construction algorithm which optimizes interference as well as tree cost. Finally, we compare the performance of Q-CAR with QoS Multicast Routing and Channel Assignment(QoS-MRCA) and intelligent Quality of service multicast routing and Channel Assignment(i-QCA) algorithm in multichannel multiradio wireless mesh network (simulated) environments. Our experimental results distinctly show the outstanding performance of the proposed algorithm.

A cross-layer optimization framework for joint channel assignment and multicast routing in multi-channel multi-radio wireless mesh networks

ABSTRACTExisting literature on multicast routing protocols in wireless mesh networks (WMNs) from the view point of the links involved in routing are divided into two categories: schemes are aimed at multicast construction with minimal interference which is known as NP hard problem. In contrast, other methods develop network-coding-based solutions with the main objective of throughput maximization, which can effectively reduce the complexity of finding the optimal routing solution from exponential to polynomial time. The proposed framework in this paper is placed in the second category. In multi-channel multi-radio WMNs (MCMR WMNs), each node is equipped with multiple radios, each tuned on a different channel. In this paper, for the first time, we propose a cross-layer convex optimization framework for joint channel assignment and multicast throughput maximization in MCMR WMNs. The proposed method is composed of two phases: in the first phase, using cellular learning automata, channels are assigned to the links established between the radios of the nodes in a distributed fashion such that the minimal interference coefficient for each link is provided. Then, the resultant channel assignment scheme is utilized in the second phase for throughput maximization within an iterative optimization framework based on Lagrange relaxation and primal problem decomposition. We have conducted many experiments to contrast the performance of our solution against many representative approaches.

A novel approach for multicast call acceptance in multi-channel multi-radio wireless mesh networks

Multicasting is an efficient data transmission approach for group communication applications in multi-channel multi-radio wireless mesh networks. In this paper we have studied the problem of accepting on-line multicast requests, which is quite important for supporting multimedia applications. Our proposed algorithm investigates the acceptance of an arrived call in two phases. In the first phase, a loop-free mesh backbone is constructed. In this mesh, the set of possible parents of each node is limited to the neighbors that are one hop closer to the source node. The neighbors with the same distance from the source node are also acceptable under the circumstance that two neighboring nodes cannot be the possible parents of each other. Next, a sub-optimal mathematical model has been proposed for tree construction over the obtained mesh. The derived multicast trees utilize the minimum amount of bandwidth; are load-balanced; and exploit wireless broadcast advantage. The results show that the proposed algorithm improves the rate of multicast call acceptance by 40% on average compared to previous algorithms in a short running time.

Performance Analysis of Large Multi-Interface Wireless Mesh Networks with Multi-Different Bandwidth Channel

In this paper, we study the asymptotic throughput capacity of a static multi-channel multi-interface infrastructure wireless mesh network (InfWMN) wherein each infrastructure node has m interfaces and c channels of unequal bandwidth are available. First, an upper bound on the InfWMN per-user capacity is established. Then, the feasible lower bound is derived by construction. We prove that both lower and upper bounds are tight. We limit our analysis for more practical case of $\mathrm{m} \le \mathrm{c}$ . However, for the asymptotic upper bound, our analysis can be used for the general case in which there is no constraint on m and c. Our study shows that in such a network with Nc randomly distributed mesh clients, Nr regularly placed mesh routers, and Ng gateways, the asymptotic per-client throughput capacity has different bounds, which depend on the ratio between the total available bandwidth for the network and the sum of m first greatest data rates of c available channels, i.e., $\sum \limits_{\mathrm{j} = 1}^\mathrm{C} \mathrm{w}_\mathrm{j} / \sum \limits_{\mathrm{j} = 1}^\mathrm{m} \mathrm{w}_\mathrm{j}$ . The results of this paper are more general compared to the existing published researches. In addition, in the case that $\mathrm{w}_\mathrm{i} = \mathrm{W}/\mathrm{c} \forall \mathrm{i},\mathrm{}1 \le \mathrm{i} \le \mathrm{c}$ , our results reduce to the previously reported studies. This implies that our study is comprehensive compared to the formerly published researches.

On Demand Stable Routing with Channel Allocation and Backoff Countdown Optimization in Wireless Mesh Networks

The multi-channel and multi-interface wireless mesh networks (WMNs) allow multiple orthogonal channels simultaneously to facilitate increased broadband connectivity to the end-users. Many efforts have been devoted to allocate the channels to the interfaces in a multi-channel multi-interface setting. Recently, the hybrid channel allocation mechanism jointly optimizes the routing and channel assignment, by utilizing the queuing traffic. It is essential to map the optimization of traffic distribution on each channel along with channel switching in such an order that it adapts to the changing traffic. However, the contention in medium access and channel switching delay are the key issues in a multi-channel hidden terminal problem. The proposed optimized stable path- channel allocation and routing (OSCAR) protocol is a hybrid multi-channel protocol that reduces the communication delay without degrading the network performance. The proposed work, OSCAR determines a highly stable path that increases mesh routers to improve the routing efficiency. The channel allocation mechanism mainly promotes queue dynamics based probabilistic channel selection (QDPCS), and backoff countdown optimization (BCO). An essential component of the QDPCS scheme is the factor of queuing utilization, and this strategy selects a least congested channel. The BCO mechanism creates the logical order among contending nodes based on the remaining backoff value. It reduces the medium access delay and enables the feasibility of scheduled transmissions without degrading the network throughput. Finally, the performance evaluation results show that the OSCAR protocol outperforms the existing protocol over WMNs.

A framework to compare topology algorithms in multi-channel multi-radio wireless mesh networks

Creating an optimal topology for a multi-channel multi-radio wireless mesh network by an algorithm is a balancing act between different metrics such as bandwidth, delay, and redundancy. We propose a framework to quickly evaluate and compare resulting network graphs of different topology algorithms, both distributed and centralized, in wireless mesh networks. This framework complements to graph analysis and network simulation. The metrics presented in this paper, are both data flow (such as bandwidth capacity, delay, and loss) and structural characteristics (such as minimal edge and node cut) related. Each presented metric can be solved using a linear programming with the weighted incidence matrix of the network graph and the protocol interference model. The framework uses matrix operations, which are well established, making the framework unambiguous and easy to implement. We demonstrate the framework by comparing topology algorithms with increasing complexity and by comparing topology algorithms found in literature.

A cross-layer approach for multi-layer multicast routing in multi-channel multi-radio wireless mesh networks

In this paper, we consider multicast applications with bandwidth heterogeneous receivers in multi-channel multi-radio wireless mesh networks MC-MR WMNs. Multi-layering is a well-established approach to handle bandwidth heterogeneity of the receivers. Existing multi-layering schemes have addressed only single-channel settings. In the context of MC-MR WMNs, the channel assignment problem is coupled with multicast routing, thus necessitating a cross-layer solution. In this paper, we propose an optimal cross-layer model, which aims at maximising the total number of obtained layers by the receivers. We include network coding in our design to take advantage of its capacity boosting in multicasting. To alleviate time complexity of the optimal model, we propose grouping-based multi-layer multicast GMLMC algorithm, which yields close to optimal throughput, i.e., nearly 96% of the optimum, in polynomial time. Moreover, the pattern of layer reception to the receivers in the outcomes of GMLMC resembles very much to the optimal results.

A novel adaptive spectrum allocation scheme for multi-channel multi-radio wireless mesh networks

The rapidly developed wireless services and applications have an increasing demand of spectrum resource, which is actually limited. Therefore, how to allocate spectrum resource effectively for network throughput improvement is an urgent issue. Although the utilization of spectrum can be enhanced by link scheduling for spatial reuse, Network Coding (NC) for broadcast transmission, multicast transmission and multi-channel multi-radio techniques, their interactions cannot be ignored. This is because on one hand, the achieved network performance by NC is strongly dependent on the MAC layer, and greedy NC method may in fact reduce network throughput owing to the reduction of spectrum spatial reuse. On the other hand, channel assignment faces more challenges brought by NC and multicast transmission since the broadcast or multicast links are dominated by the link with the worst channel state. In order to utilize the spectrum resource adaptively while not bringing additional constraints, we present a two-phase solution approach. On the first step, we formulate the NC-aware scheduling scheme to an optimization problem, by which the interference-free links are allocated into the same link set and can be activated in the same time slot and channel. Then, we assign different channels to the link sets according to the radio constraints in a heuristic method, which can further increase the utilization of spectrum resource. Finally, simulation results demonstrate that our proposed method can largely increase the utilization of spectrum resource and improve network throughput.

Delay analysis of parallel redundancy transmission in lossy multi-channel multi-radio wireless mesh networks

Delay analysis of parallel redundancy transmission in lossy multi-channel multi-radio wireless mesh networks

I-QCA: An intelligent framework for quality of service multicast routing in multichannel multiradio wireless mesh networks

Multicast routing has brought a revolution by enabling the delivery of the same content to a group of receivers simultaneously. However, multicast routing in multichannel multiradio wireless mesh networks has been proved to be an NP-hard problem. To achieve optimal performance in multichannel multiradio wireless mesh networks the channel assignment strategy plays an important role. In this paper, we present an intelligent Quality of service multicast routing and Channel Assignment (i-QCA) algorithm which solves the multicast tree construction and channel assignment problem conjointly by intelligent computational methods. The multicast tree construction algorithm is based on the differential evolution approach. The channel assignments in prior works are mostly oriented toward heuristic or meta heuristic approaches and hence produce suboptimal results. The proposed algorithm consists of a genetic algorithm based channel assignment strategy and determines a delay, jitter bounded minimal interference lowcost multicast tree. Our experimental results clearly show that the proposed algorithm achieves much better performance as compared to Multi Channel Multicast (MCM) and QoS Multicast Routing and Channel Assignment (QoS-MRCA) algorithm in multichannel multiradio wireless mesh network environments.

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.

Routing, spectrum access, and scheduling in multi-hop multi-channel wireless networks with MIMO links

Software-defined radios (SDRs) are a promising technology to enable dynamic channel access and sharing. Multiple Input Multiple Output (MIMO) is another radio technology breakthrough for increasing wireless network capacity. To obtain the full benefits brought by the SDR and MIMO technologies in wireless mesh networks (WMNs), the higher layer mechanisms should exploit their capabilities in a systematic way. In this paper, we investigate routing, channel assignment, link scheduling, and MIMO transmission mode control in multi-channel multi-antenna wireless mesh networks. We first present a cross-layer framework for network performance optimization. Network traffic routing is established on a relatively long time scale to maintain system stability. We then proposed a stream controlled multiple access (SCMA) scheme, which is responsible for assigning frequency channels and scheduling links for data transmission and controlling MIMO transmission modes. It enables efficient spectrum access and sharing in time, frequency, and space, and adapts to varying network conditions. The evaluation results show that the proposed scheme greatly improves network performance compared to the traditional schemes.

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.

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.

Interference Nomenclature in Wireless Mesh Networks

The Quality of Service of Multi-Channel Multi-Radio Wireless Mesh Networks is adversely affected by the complex behavior of interference patterns present between the sender and receiver of a link. This behavior is usually captured using wireless channel interference models. The accuracy of the interference model is highly dependent on the interaction of the Carrier Sense Multiple Access with Collision Avoidance Medium Access Control (CSMA/CA MAC) protocol based on the geometric location of the sender and receiver of the link. Therefore, this paper presents a nomenclature of interference modeling schemes available in Wireless Mesh Network (WMN) literature with respect to the geometric location of the sender and receiver of a link. The behavior and limitations of each model are analyzed with the help of empirical examples. The results indicate that Garetto’s model of interfering links is the best choice to model wireless channel interference in WMNs. In addition, this study provides an interference analysis of Garetto’s model for the two link case by computing the conditional packet loss probability of each class of interfering link. The probability analysis concluded that the links with disconnected senders are highly interfering compared to sender connected links. Further, the analysis will assist researchers and engineers in relay node placement, capacity analysis, channel assignment, and topology control schemes in the WMN.

Novel power-based routing metrics for multi-channel multi-interface wireless mesh networks

In this paper the problem of selecting optimal paths in a MCMI (Multi-Channel Multi-Interface) WMN (Wireless Mesh Network) is considered. The WMNs are characterized by high dynamic range of the received signal level, especially in the indoor environment. To improve the existing routing metrics and track fast changes that occur in the link state, a corresponding parameter based on the received signal level was assigned to each link. By combining this parameter and known metrics, ETX (Expected Transmission Count), WCETT (Weighted Cumulative ETT) and MIC (Metric of Interference and Channel-switching), three new metrics were formed. All metrics were incorporated in MCR (Multi Channel Routing) protocol and an appropriate propagation model was used for simulations in a real, indoor environment. Proposed metrics, original metrics, MCR protocol, and indoor propagation model were implemented in Glomosim simulator. New metrics were compared against known metrics and also among each other in terms of throughput of user data and average end-to-end delay of the network. The results have shown that proposed metrics significantly outperform original metrics. With this approach, better network performance can be achieved without any additional hardware and with minimal software changes.

On the Relationship between Multicast/Broadcast Throughput and Resource Utilizations in Wireless Mesh Networks

This paper deals with the problem of multicast/broadcast throughput in multi-channel multi-radio wireless mesh networks that suffer from the resource constraints. We provide a formulation to capture the utilization of the network resources and derive analytical relationships for the network's throughput in terms of the node utilization, the channel utilization, and the number of transmissions. Our model relies on the on-demand quality of service multicast/broadcast sessions, where each admitted session creates a unique tree with a specific bandwidth. As an advantage, the derived relationships are independent of the type of tree built for each session and can be used for different protocols. The proposed formulation considers the channel assignment strategy and reflects both the wireless broadcast advantage and the interference constraint. We also offer a comprehensive discussion to evaluate the effects of load-balancing and number of transmissions on the network's throughput. Numerical results confirm the accuracy of the presented analysis.