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36
Minimum-interference channel assignment in multi-radio wireless mesh networks
- IN SECON
, 2006
"... In this paper, we consider multi-hop wireless mesh networks, where each router node is equipped with multiple radio interfaces and multiple channels are available for communication. We address the problem of assigning channels to communication links in the network with the objective of minimizing ov ..."
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Cited by 104 (2 self)
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In this paper, we consider multi-hop wireless mesh networks, where each router node is equipped with multiple radio interfaces and multiple channels are available for communication. We address the problem of assigning channels to communication links in the network with the objective of minimizing overall network interference. Since the number of radios on any node can be less than the number of available channels, the channel assignment must obey the constraint that the number of different channels assigned to the links incident on any node is atmost the number of radio interfaces on that node. The above optimization problem is known to be NP-hard. We design centralized and distributed algorithms for the above channel assignment problem. To evaluate the quality of the solutions obtained by our algorithms, we develop a semidefinite program formulation of our optimization problem to obtain a lower bound on overall network interference. Empirical evaluations on randomly generated network graphs show that our algorithms perform close to the above established lower bound, with the difference diminishing rapidly with increase in number of radios. Also, detailed ns-2 simulation studies demonstrate the performance potential of our channel assignment algorithms in 802.11-based multi-radio mesh networks.
CAM-MAC: A Cooperative Asynchronous Multi-Channel MAC Protocol for Ad Hoc Networks
- IEEE BROADNETS
, 2006
"... Medium access control (MAC) protocols have been studied under different contexts for several years now. In all these
MAC protocols, nodes make independent decisions on when to
transmit a packet and when to back-off from transmission. In
this paper, we introduce the notion of node cooperation into MA ..."
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Cited by 20 (8 self)
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Medium access control (MAC) protocols have been studied under different contexts for several years now. In all these
MAC protocols, nodes make independent decisions on when to
transmit a packet and when to back-off from transmission. In
this paper, we introduce the notion of node cooperation into MAC protocols. Cooperation adds a new degree of freedom which has not been explored before. Specifically we study the design of cooperative MAC protocols in an environment where each node is equipped with a single transceiver and has multiple channels to choose from. Nodes cooperate by helping each other select a free channel to use. We show that this simple idea of cooperation has several qualitative and quantitative advantages. Our cooperative asynchronous multi-channel MAC protocol (CAM-MAC) is extremely simple to implement and, unlike other multi-channel MAC protocols, is naturally asynchronous. We conduct extensive simulation experiments. We first compare CAM-MAC with IEEE 802.11b and a version of CAM-MAC with the cooperation element removed. We use this to show the value of cooperation. Our results show significant improvement in terms of number of collisions and throughput for CAM-MAC. We also compare our protocol with MMAC and SSCH and show that CAM-MAC significantly outperforms both of them.
Resource allocation in multi-radio multi-channel multi-hop wireless networks
- IEEE INFOCOM 2008
, 2008
"... Abstract—A joint congestion control, channel allocation and scheduling algorithm for multi-channel multi-interface multi-hop wireless networks is discussed. The goal of maximizing a utility function of the injected traffic, while guaranteeing queues stability, is defined as an optimization problem w ..."
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Cited by 19 (0 self)
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Abstract—A joint congestion control, channel allocation and scheduling algorithm for multi-channel multi-interface multi-hop wireless networks is discussed. The goal of maximizing a utility function of the injected traffic, while guaranteeing queues stability, is defined as an optimization problem where the input traffic intensity, channel loads, interface to channel binding and transmission schedules are jointly optimized by a dynamic algorithm. Due to the inherent NP-Hardness of the scheduling problem, a simple centralized heuristic is used to define a lower bound for the performance of the whole optimization algorithm. The behavior of the algorithm for different numbers of channels, interfaces and traffic flows is shown through simulations. I.
Channel Assignment and Link Scheduling in Multi-Radio Multi-Channel Wireless Mesh Networks
"... Capacity limitation is one of the fundamental issues in wireless mesh networks. This paper addresses capacity improvement issues in multi-radio multi-channel wireless mesh networks. Our objective is to find both dynamic and static channel assignments and corresponding link schedules that maximize th ..."
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Cited by 7 (1 self)
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Capacity limitation is one of the fundamental issues in wireless mesh networks. This paper addresses capacity improvement issues in multi-radio multi-channel wireless mesh networks. Our objective is to find both dynamic and static channel assignments and corresponding link schedules that maximize the network capacity. We focus on determining the highest gain we can achieve from increasing the number of radios and channels under certain traffic demands. We consider two different types of traffic demands. One is expressed in the form of data size vector, and the other is in the form of data rate vector. For the first type of traffic demand, our objective is to minimize the number of time slots to transport all the data. For the second type of traffic demand, our objective is to satisfy the bandwidth requirement as much as possible. We perform a trade-off analysis between network performance and hardware cost based on the number of radios and channels in different topologies. This work provides valuable insights for wireless mesh network designers during network planning and deployment. I.
From theory to practice: Evaluating static channel assignments on a wireless mesh network
- In INFOCOM ’10
"... Abstract—Multi-radio nodes in wireless mesh networks intro-duce extra complexity in utilizing channel resources. Depending on the configuration of the radios, bad mappings between radio to wireless frequencies may result in sub-optimal net-work topologies. Static channel assignments in wireless mesh ..."
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Cited by 5 (1 self)
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Abstract—Multi-radio nodes in wireless mesh networks intro-duce extra complexity in utilizing channel resources. Depending on the configuration of the radios, bad mappings between radio to wireless frequencies may result in sub-optimal net-work topologies. Static channel assignments in wireless mesh networks have been studied in theory and through simulation but very little work has been done through experiments. This paper focuses on evaluating static channel assignments on a live wireless mesh network. We chose three popular types of static channel assignment algorithms for implementation and comparison purposes. The three types are breadth-first search, priority-based selection and integer linear programming. We find that there is no single channel assignment algorithm that does well overall. BFS algorithm can create the shortest paths to the gateway and also generate balanced channel usage topologies. The PBS algorithm can use all the best links in the network but have poor performance from each radio to the gateway. Overall, we find the channel assignments given by the algorithms to be suboptimal when applied to a live mesh network because temporal variations in the link quality metrics are not taken into account. Looking at the interflow and intraflow performance of these channel assignment algorithms in a live mesh network, we can conclude that routing protocols must be modified to take advantage of the underlying channel assignment algorithms. I.
Adjacent Channel Interference Reduction in Multichannel Wireless Networks Using Intelligent Channel Allocation
, 2009
"... The performance of a multichannel, multi-radio wireless network is often limited by interference due to concurrent transmissions on the same and adjacent channels. These interference effects may be either due to simultaneous traffic activity by the multiple radios within a node or due to transmissio ..."
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Cited by 5 (0 self)
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The performance of a multichannel, multi-radio wireless network is often limited by interference due to concurrent transmissions on the same and adjacent channels. These interference effects may be either due to simultaneous traffic activity by the multiple radios within a node or due to transmission by neighboring nodes. In this paper, we discuss simple local-balancing and interference-aware channel allocation algorithms for reducing the overall interference in the network. We evaluate the relative performance of our algo-rithms using actual implementations on a multichannel, multi-radio testbed. Using overall network throughput as a metric, we show through experiments that the channel allocation that is aware of the node’s transmission activity performs better than the simple local-balancing algorithm, irrespective of the number of channels used for allocation. Additionally, we show that the performance bene-fit of a interference-aware allocation over the local-balancing allo-cation improves as the number of flows in the network increases. However, our experiments also reveal that the benefit of using a interference-aware algorithm over the simple local-balancing algo-rithm reduces when we have more number of channels available for allocation when compared to the number of flows in the network. 1.
Asynchronous Multichannel MAC Design With Difference-Set-Based Hopping Sequences
"... Abstract—Most existing multichannel medium access control (MAC) protocols have at least one of the following four performance bottlenecks: 1) global synchronization among users; 2) dedicated control channel for signaling exchange; 3) dedicated control phase for signaling exchange; and 4) complete kn ..."
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Cited by 4 (1 self)
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Abstract—Most existing multichannel medium access control (MAC) protocols have at least one of the following four performance bottlenecks: 1) global synchronization among users; 2) dedicated control channel for signaling exchange; 3) dedicated control phase for signaling exchange; and 4) complete knowledge of all users ’ channel selection strategies. In this paper, we first design a hopping sequence by combining multiple difference sets to ensure a high rendezvous probability of users over multiple channels. Applying the hopping sequence to all users, we then propose a difference-set-based multichannel MAC (DSMMAC) protocol to overcome the performance bottlenecks. Because all users use the same sequence for frequency hopping and channel access, significant signaling overheads can be reduced. The proposed protocol achieves high system throughput and low access delay without the need for global synchronization or a dedicated control channel/phase. Our analytical and simulation results show that the proposed DSMMAC protocol can achieve up to a 100 % improvement in system throughput and a 150 % reduction in channel access delay compared with an existing multichannel MAC protocol. Index Terms—Asynchronous, difference set, medium access control (MAC) , multichannel. I.
A Novel Multi-Channel MAC Protocol for Wireless Ad Hoc Networks
- IEEE Vehicular Technology Conference (VTC-Spring
, 2007
"... Medium access control (MAC) protocols coordinate channel access between wireless stations, and they significantly affect the network throughput of wireless ad-hoc networks. MAC protocols that are based on a multichannel model can increase the throughput by enabling more simultaneous transmission pai ..."
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Cited by 4 (0 self)
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Medium access control (MAC) protocols coordinate channel access between wireless stations, and they significantly affect the network throughput of wireless ad-hoc networks. MAC protocols that are based on a multichannel model can increase the throughput by enabling more simultaneous transmission pairs in the network. In this paper, we comprehensively compare different design methods for mul-tichannel MAC protocols. We classify existing protocols into different categories according to the chan-nel negotiation strategies they employ. The common problems that may be encountered in multichannel design are discussed. We then propose a hybrid protocol that combines the advantages of the two meth-ods of a common control channel and a common control period. The simulation results show that our proposed protocol can significantly outperform two representative protocols.
Distance-1 Constrained Channel Assignment in Single Radio Wireless Mesh Networks
"... Abstract — This paper addresses channel assignment and random medium access design for single-radio multi-channel mesh networks. Two prior approaches include: (i) designing MAC protocols that dynamically select channels based on local information and (ii) partitioning the mesh into subnetworks with ..."
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Cited by 3 (0 self)
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Abstract — This paper addresses channel assignment and random medium access design for single-radio multi-channel mesh networks. Two prior approaches include: (i) designing MAC protocols that dynamically select channels based on local information and (ii) partitioning the mesh into subnetworks with different channels and using 802.11 as the medium access protocol. Both of these approaches suffer from limited throughput improvement; the first approach due to wrong or incomplete channel state information that inherently arises in a multi-hop wireless environment, while the second approach due to high interference within each subnetwork. In this paper, we first introduce D1C-CA, Distance-1 Constrained Channel Assignment. D1C-CA statically assigns channels to a set of links as a function of physical connectivity, contention, and the unique gateway functionality of mesh networks, i.e, all internet (non-local) traffic has a gateway node as its source or destination. To design D1C-CA, we model the channel assignment problem as a new form of graph edge coloring in which edges at distance one are constrained. We prove that the problem is NP-complete and design an efficient heuristic solution for mesh networks. Second, we design an asynchronous control-channel-based MAC protocol that solves multi-channel coordination problems and employs the proposed channel assignment algorithm. Finally, we investigate the performance of our approach through extensive simulations and show considerable performance improvements compared to alternate schemes. I.
Analyzing DISH for Multi-Channel MAC Protocols in Wireless Networks ABSTRACT
"... For long, node cooperation has been exploited as a data relaying mechanism. However, the wireless channel allows for much richer interaction between nodes. One such scenario is in a multi-channel environment, where transmitter-receiver pairs may make incorrect decisions (e.g., in selecting channels) ..."
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Cited by 2 (2 self)
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For long, node cooperation has been exploited as a data relaying mechanism. However, the wireless channel allows for much richer interaction between nodes. One such scenario is in a multi-channel environment, where transmitter-receiver pairs may make incorrect decisions (e.g., in selecting channels) but idle neighbors could help by sharing information to prevent undesirable consequences (e.g., data collisions). This represents a Distributed Information SHaring (DISH) mechanism for cooperation and suggests new ways of designing cooperative protocols. However, what is lacking is a theoretical understanding of this new notion of cooperation. In this paper, we view cooperation as a network resource and evaluate the availability of cooperation via a metric, pco, the probability of obtaining cooperation. First, we analytically evaluate pco in the context of multi-channel multi-hop wireless networks. Second, we verify our analysis via simulations and the results show that our analysis accurately characterizes the behavior of pco as a function of underlying network parameters. This step also yields important insights into DISH with respect to network dynamics. Third, we investigate the correlation between pco and network performance in terms of collision rate, packet delay, and throughput. The results indicate a near-linear relationship, which may significantly simplify performance analysis for cooperative networks and suggests that pco be used as an appropriate performance indicator itself. Throughout this work, we utilize, as appropriate, three different DISH contexts — model-based DISH, ideal DISH, and real DISH — to explore pco.
