Topology control for multi-channel multi-radio wireless mesh networks using directional antennas

Directional antennas are widely used technologies for reducing signal interference and increasing spatial reuse. In this paper, we propose a topology control method for multi-channel multi-radio wireless mesh networks that use directional antennas. We are given a set of mesh routers installed in a region and some of them are gateway nodes that are connected to the Internet via wired lines. Each router has a traffic demand (Internet access traffic) generated from the end-users. The problem is how to adjust antenna orientations of radios and assign channels to them to construct a logical network topology, such that the minimum delivery ratio of traffic demands of routers is maximized. We first formulate the problem to an equivalent optimization problem with a clearer measurable metric, which is to minimize the largest interfering traffic of links in the network. We then propose a three-step solution to solve the problem. Firstly, we construct a set of routing trees, with the objective to balance the traffic among tree links. Secondly, we assign the radios of a node to the links it needs to serve, such that the total traffic load of the links that each radio serves is as balanced as possible. Thirdly, we do a fine-grained adjustment of antenna orientations and assign channels to them, such that the transmission area of each antenna will cover all the links it serves and the largest interfering traffic of links is minimized.     

Flow admission control for multi-channel multi-radio wireless networks

Providing Quality of Service (QoS) is a major challenge in wireless networks. In this paper we propose a distributed call admission control protocol (DCAC) to do both bandwidth and delay guaranteed call admission for multihop wireless mesh backbone networks, by exploiting the multi-channel multi-radio (mc-mr) feature. We propose a novel routing metric for route setup, and present an efficient distributed algorithm for link reservation that satisfies the required bandwidth and reduces the delay by a local scheduling that minimizes one hop delay. To the best of our knowledge, this is the first distributed protocol that embeds mc-mr feature in Time Division Medium Access (TDMA) to do QoS call admission in wireless backbone networks. Extensive simulation studies show that our protocol significantly improves network performance on supporting QoS sessions compared with some widely used protocols.     

Cross-layer network planning for multi-radio multi-channel cognitive wireless networks

We propose a general network planning framework for multi-radio multi-channel wireless networks. Under this framework, data routing, resource allocation, and scheduling are jointly designed to maximize a network utility function. We first treat such a cross-layer design problem with fixed radio distributions across the nodes and formulate it as a large-scale convex optimization problem. A primal-dual method together with the column-generation technique is proposed to efficiently solve this problem. We then consider the radio allocation problem, i.e., the optimal placement of radios within the network to maximize the network utility function. This problem is formulated as a large- scale combinatorial optimization problem. We derive the necessary conditions that the optimal solution should satisfy, and then develop a sequential optimization scheme to solve this problem. Simulation studies are carried out to assess the performance of the proposed cross-layer network planning framework. It is seen that the proposed approach can significantly enhance the overall network performance.     

An optimization framework for monitoring multi-channel multi-radio wireless mesh networks

This paper studies an optimal monitoring problem for behavior-based detection in multi-channel multi-radio wireless mesh networks. In behavior-based detection, nodes overhear communications in their neighborhood to determine if the behaviors of their neighbors are legitimate. The objective of this work is to maximize the number of nodes being monitored by judiciously choosing a set of monitoring nodes and also channels for the chosen monitoring nodes. This problem is NP-hard, growing exponentially with the number of monitoring nodes. We develop three approximation algorithms, each of which achieves at least a constant factor of the optimum. Furthermore, one of our algorithms achieves the best possible approximation ratio among all polynomial-time algorithms, unless P = NP. We conduct simulations in random networks and scale-free networks to evaluate the coverage and the execution time of the three algorithms.     

A non-cooperative game-theoretic approach to channel assignment in multi-channel multi-radio wireless networks

Channel assignment in multi-channel multi-radio wireless networks poses a significant challenge due to scarcity of number of channels available in the wireless spectrum. Further, additional care has to be taken to consider the interference characteristics of the nodes in the network especially when nodes are in different collision domains. This work views the problem of channel assignment in multi-channel multi-radio networks with multiple collision domains as a non-cooperative game where the objective of the players is to maximize their individual utility by minimizing its interference. Necessary and sufficient conditions are derived for the channel assignment to be a Nash Equilibrium (NE) and efficiency of the NE is analyzed by deriving the lower bound of the price of anarchy of this game. A new fairness measure in multiple collision domain context is proposed and necessary and sufficient conditions for NE outcomes to be fair are derived. The equilibrium conditions are then applied to solve the channel assignment problem by proposing three algorithms, based on perfect/imperfect information, which rely on explicit communication between the players for arriving at an NE. A no-regret learning algorithm known as Freund and Schapire Informed algorithm, which has an additional advantage of low overhead in terms of information exchange, is proposed and its convergence to the stabilizing outcomes is studied. New performance metrics are proposed and extensive simulations are done using Matlab to obtain a thorough understanding of the performance of these algorithms on various topologies with respect to these metrics. It was observed that the algorithms proposed were able to achieve good convergence to NE resulting in efficient channel assignment strategies.     

多接口多信道无线Mesh网中一种基于信号干扰监测的路由度量机制

多接口多信道无线Mesh网中,提出了一种基于信号干扰监测的路由度量机制(ISB)。现有的路由度量机制如WCETT、iAWARE等均存在各自的不足。通过对iAWARE深入分析,发现其并不能正确地反映背景噪声这一重要因素。为此改进了该度量机制,使其更加正确地反映背景噪声,并且具有了等分性,即可以在路由协议中使用如Bellman-Ford或Dijkstra路径计算方法。理论分析和网络仿真表明,新度量机制下的网络性能如网络吞吐量和端到端延迟均优于HopCount、ETT、WCETT和iAWARE。     

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.     

Distributed channel assignment combined with routing over multi-radio multi-channel wireless mesh networks

In order to realize the reduction of equipment cost and the demand of higher capacity,wireless mesh network(WMN) router devices usually have several interfaces and work on multi-channels.Jointing channel allocation,interface assignment and routing can efficiently improve the network capacity.This paper presents an efficient channel assignment scheme combined with the multi-radio link quality source routing(MR-LQSR) protocol,which is called channel assignment with MR-LQSR(CA-LQSR).In this scheme,a physical interference model is established:calculated transmission time(CTT) is proposed as the metric of channel assignment,which can reflect the real network environment and channel interference best,and enhanced weighted cumulative expected transmission time(EWCETT) is proposed as the routing metric,which preserves load balancing and bandwidth of links.Meantime,the expression of EWCETT contains the value of CTT,thus the total cost time of channel assignment and routing can be reduced.Simulation results show that our method has advantage of higher throughput,lower end-to-end time delay,and less network cost over some other existing methods.     

Modeling throughput gain of network coding in multi-channel multi-radio wireless ad hoc networks

In this paper, we model the network throughput gains of two types of wireless network coding (NC) schemes, including the conventional NC and the analog NC schemes, over the traditional non-NC transmission scheduling schemes in multihop, multi-channel, and multi-radio wireless ad hoc networks. In particular, we first show that the network throughput gains of the conventional NC and analog NC are (2n)/(2n-1) and n/(n-1), respectively, for the n-way relay networks where n ges 2. Second, we propose an analytical framework for deriving the network throughput gain of the wireless NC schemes over general wireless network topologies. By solving the problem of maximizing the network throughput subject to the fairness requirements under our proposed framework, we quantitatively analyze the network throughput gains of these two types of wireless NC schemes for a variety of wireless ad hoc network topologies with different routing strategies. Finally, we develop a heuristic joint link scheduling, channel assignment, and routing algorithm that aims at approaching the optimal solution to the optimization problem under our proposed framework.     

Joint multi-radio multi-channel assignment, scheduling, and routing in wireless mesh networks

The IEEE 802.11 DCF and EDCA mechanisms based on CSMA/CA are the most widely used random channel access mechanisms in wireless mesh networks (WMNs), but unfortunately these cannot effectively eliminate hidden terminal and exposed terminal problems in multi-hop scenarios. In this paper, we propose a set of efficient multi-radio multi-channel (MRMC) assignment, scheduling and routing protocols based on Latin squares for WMNs with MRMC communication capabilities, called “M4”, i.e., the Multiple access scheduling in Multi-radio Multi-channel Mesh networking. M4 uses nodal interference information to form cliques for inter-cluster and intra-cluster inWMNs, and then applies Latin squares to map the clique-based clustering structure to radios and channels for communication purposes. Then, M4 again applies Latin squares to schedule the channel access among nodes within each cluster in a collision-free manner. From a systematic view, we also design the corresponding MRMC routing to support M4 communication. Extensive simulation results show that M4 achieves much better performance than IEEE 802.11 standards and other channel access control protocols.     

Research on node throughput in multi-radio multi-channel multi-rate wireless mesh network

This paper proposes a method to calculate the maximum effectual node throughput in multi-radio multi-channel multi-rate wireless mesh network (M3WMN) under fairness guarantee. The concept of bottle collision domain (BCD) is redefined. When the same traffic originated from each node is transmitted on the scope of each link's collision domain, the transmission time of BCD is the maximum one. After the maximum transmission time of BCD is calculated, the maximum node throughput is also derived. The simulation results indicate that the proposed method can analyze the maximum node throughput in M3WMN exactly.     

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.     

Design of scalable and efficient multi-radio wireless networks

A proper design of Wireless Mesh Networks (WMNs) is a fundamental task that should be addressed carefully to allow the deployment of scalable and efficient networks. Specifically, choosing strategic locations to optimally place gateways prior to network deployment can alleviate a number of performance/scalability related problems. In this paper, we first, propose a novel clustering based gateway placement algorithm (CBGPA) to effectively select the locations of gateways. Existing solutions for optimal gateway placement using clustering approaches are tree-based and therefore are inherently less reliable since a tree topology uses a smaller number of links. Independently from the tree structure, CBGPA strategically places the gateways to serve as many routers as possible that are within a bounded number of hops. Next, we devise a new multi-objective optimization approach that models WMN topologies from scratch. The three objectives of deployment cost, network throughput and average congestion of gateways are simultaneously optimized using a nature inspired meta-heuristic algorithm coupled with CBGPA. This provides the network operator with a set of bounded-delay trade-off solutions. Comparative simulation studies with different key parameter settings are conducted to show the effectiveness of CBGPA and to evaluate the performance of the proposed model.     

Design and analysis of cooperative wireless data access algorithms in multi-radio wireless networks

In the future, most mobile nodes will have multiple radio interfaces, and this feature can be exploited to reduce the transmission cost in wireless data access applications. In this work, we propose cooperative poll-each-read (CoopPER) and cooperative callback (CoopCB) wireless data access algorithms with strong consistency in multi-radio wireless networks. In addition, we investigate CoopPER and CoopCB in heterogeneous wireless networks where CoopPER and CoopCB nodes are mixed. Extensive simulations are done to show the effects of access-to-update ratio, data access pattern, cache size, and cooperation range. Simulation results demonstrate that CoopPER and CoopCB can significantly reduce the expensive transmission cost over wireless links.     

Broadcasting with hard deadlines in wireless multihop networks using network coding

Broadcasting with network coding mixes packets to minimize the number of transmissions, which improves the energy efficiency of wireless networks. On the other hand, delaying the transmissions increases coding opportunities at intermediate nodes, but increases the delay of packets. In this paper, we consider these two contradicting factors and study the problem of minimizing the number of transmissions in wireless networks while meeting the deadline constraints. We show that this problem is NP‐complete; therefore, we provide a heuristic to solve it. First, we construct broadcasting trees, each of them rooted at one source. We then specify overlapping conditions based on the constructed trees, to determine the number of transmissions each node has to perform without the deadline constraints. Then, we partition the set of packets such that coding is performed among the packets of the same partition, which does not result in deadline misses. Linear coding may not be applicable in some wireless networks because of its computational complexity. For these networks, we propose three XOR coding approaches, which rely only on local neighborhood information. Simulation results show that our techniques not only reduce the number of transmissions but also allow the majority of nodes to receive the packets on time. Copyright © 2013 John Wiley & Sons, Ltd.     

Cross-layer optimization for end-to-end rate allocation in multi-radio wireless mesh networks

In this paper, we study rate allocation for a set of end-to-end communication sessions in multi-radio wireless mesh networks. We propose cross-layer schemes to solve the joint rate allocation, routing, scheduling, power control and channel assignment problems with the goals of maximizing network throughput and achieving certain fairness. Fairness is addressed using both a simplified max-min fairness model and the well-known proportional fairness model. Our schemes can also offer performance upper bounds such as an upper bound on the maximum throughput. Numerical results show that our proportional fair rate allocation scheme achieves a good tradeoff between throughput and fairness. Jian Tang is an assistant professor in the Department of Computer Science at Montana State University. He received the Ph.D. degree in Computer Science from Arizona State University in 2006. His research interest is in the area of wireless networking and mobile computing. He has served on the technical program committees of multiple international conferences, including ICC, Globecom, IPCCC and QShine. He will also serve as a publicity co-chair of International Conference on Autonomic Computing and Communication Systems (Autonomics’2007). Guoliang Xue is a Full Professor in the Department of Computer Science and Engineering at Arizona State University. He received the Ph.D. degree in Computer Science from the University of Minnesota in 1991 and has held previous positions at the Army High Performance Computing Research Center and the University of Vermont. His research interests include efficient algorithms for optimization problems in networking, with applications to fault tolerance, robustness, and privacy issues in networks ranging from WDM optical networks to wireless ad hoc and sensor networks. He has published over 150 papers in these areas. His research has been continuously supported by federal agencies including NSF and ARO. He is the recipient of an NSF Research Initiation Award in 1994 and an NSF-ITR Award in 2003. He is an Associate Editor of Computer Networks (COMNET), the IEEE Network Magazine, and Journal of Global Optimization. He has served on the executive/program committees of many IEEE conferences, including INFOCOM, SECON, IWQOS, ICC, GLOBECOM and QShine. He is the General Chair of IEEE IPCCC’2005, a TPC co-Chair of IPCCC’2003, HPSR’2004, IEEE Globecom’2006 Symposium on Wireless Ad Hoc and Sensor Networks, IEEE ICC’2007 Symposium on Wireless Ad Hoc and Sensor Networks, and QShine’2007. He is a senior member of IEEE. Weiyi Zhang received the M.E. degree in 1999 from Southeast University, China. Currently he is a Ph.D. student in the Department of Computer Science and Engineering at Arizona State University. His research interests include reliable communication in networking, protection and restoration in WDM networks, and QoS provisioning in communication networks.     

A routing protocol based on interference-aware and channel-load in multi-radio multi-channel ad hoc networks

Improving capacity and reducing delay are the most challenging topics in wireless ad hoc networks. Nodes that equip multiple radios working on different channels simultaneously permit effective utility of frequency spectrum and can also reduce interference. In this paper, after analyzing several current protocols in Multi-Radio Multi-Channel (MR-MC) ad hoc networks, a new multichannel routing metric called Integrative Route Metric (IRM) is designed. It takes channel load, interflow, and intra-flow interference into consideration. In addition, an MR-MC routing protocol based on Interference-Aware and Channel-Load (MR-IACL) is also presented. The MR-IACL can assign channels and routings for nodes according to channel load and interference degree of links, and optimize channel distribution dynamically to satisfy the features of topology changing and traffic frequent fluctuation during network running. The simulation results show that the new protocol outperforms others in terms of network throughput, end-to-end delay, routing overhead, and network lifetime.     

Path diversified multi-QoS optimization in multi-channel wireless mesh networks

Wireless mesh networks (WMNs) have become a promising solution for quick and low-cost spreading of Internet accesses and other network services. Given the mesh topology, multiple paths are often available between node pairs, which thus naturally endorse path-diversified transmission. Unfortunately, like in wired networks, discovering completely disjoint paths in a WMN remains an intractable problem. It indeed becomes more challenging given the interferences across wireless channels in a WMN, not to mention that applications may demand heterogeneous QoS optimizations across different paths. The availability of multiple channels in advanced WMNs however sheds new lights into this problem. In this paper, we show that, as long as the best channels with different QoS metrics are not overlapped between neighboring node pairs, complete disjoint paths with heterogeneous QoS targets are available in a multi-channel WMN. We present efficient solutions to discover such paths, particularly for bandwidth- and delay-optimization. We also develop novel algorithms for accurately estimating path bandwidth and delay in the multi-channel environment. These lead to the design of a practical protocol that extends the classical Ad hoc On-demand Multi-path Distance Vector (AOMDV). Through extensive simulations, we show that our protocol yields significant improvement over state-of-the-art multi-path protocols in terms of both end-to-end throughput and delay.