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. © 2015, Springer Science+Business Media New York

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. © 2015, Springer Science+Business Media New York

Distributed optimal congestion control and channel assignment in wireless mesh networks

Wireless mesh networks have numerous advantages in terms of connectivity as well as reliability. Traditionally the nodes in wireless mesh networks are equipped with single radio, but the limitations are lower throughput and limited use of the available wireless channel. In order to overcome this, the recent advances in wireless mesh networks are based on multi-channel multi-radio approach. Channel assignment is a technique that selects the best channel for a node or to the entire network just to increase the network capacity. To maximize the throughput and the capacity of the network, multiple channels with multiple radios were introduced in these networks. In the proposed system, algorithms are developed to improve throughput, minimise delay, reduce average energy consumption and increase the residual energy for multi radio multi-channel wireless mesh networks. In literature, the existing channel assignment algorithms fail to consider both interflow and intra flow interferences. The limitations are inaccurate bandwidth estimation, throughput degradation under heavy traffic and unwanted energy consumption during low traffic and increase in delay. In order to improve the performance of the network distributed optimal congestion control and channel assignment algorithm (DOCCA) is proposed. In this algorithm, if congestion is identified, the information is given to previous node. According to the congestion level, the node adjusts itself to minimise congestion

Minimum interference channel assignment for multicast in multi-channel multi-radio wireless mesh networks

Wireless mesh networks (WMNs) have emerged as a key technology for next-generation wireless networking. In a WMN, wireless routers provide multi-hop wireless connectivity between hosts in the network and also allow hosts to access the Internet via the gateway nodes. Wireless routers are typically equipped with multiple radios operating on different channels to increase network throughput. Multicast is a form of communication that delivers data from a source to a set of destinations simultaneously. It is used in a number of applications such as distributed games, distance education, and video conferencing. In this work, we address the channel assignment problem for multicast in multi-radio multi-channel WMNs. In a multi-radio multi-channel WMN, when two nearby nodes transmit on the same channel, they will interfere with each other and cause throughput decrease. Thus, an important goal for multicast channel assignment is to reduce the interference among the tree nodes. We have developed a Minimum Interference Channel Assignment (MICA) algorithm for multicast that accurately models the interference relationship between pairs of multicast tree nodes using the concept of interference factor and assigns channels to tree nodes to minimize interference within the multicast tree. Simulation results show that MICA achieves higher throughout and lower end-to-end packet delay compared with an existing channel assignment algorithm named MCM. In addition, MICA achieves much lower throughput variation among the destination nodes than MCM

Analysis and mitigation of interference in multi-radio multi-channel wireless mesh networks

Ankara : The Department of Computer Engineering and the Graduate School of Engineering and Science of Bilkent Univ., 2013.Thesis (Ph. D.) -- Bilkent University, 2013.Includes bibliographical references leaves 162-170.Wireless mesh networking, which is basically forming a backbone network of mesh routers using wireless links, is becoming increasingly popular for a broad range of applications from last-mile broadband access to disaster networking or P2P communications, because of its easy deployment, self-forming, self-configuration, and self-healing properties. The multi-hop nature of wireless mesh networks (WMNs) aggravates inter-flow interference and causes intra-flow interference and severely limits the network capacity. One technique to mitigate interference and increase network capacity is to equip the mesh routers with multiple radios and use multiple channels. The radios of a mesh router can then simultaneously send or receive packets on different wireless channels. However, careful and intelligent radio resource planning, including flow-radio and channel assignment, is necessary to efficiently make use of multiple radios and channels. This first requires analyzing and modeling the nature of co-channel and adjacent channel interference in a WMN. Through real-world experiments and observations made in an indoor multihop multi-radio 802.11b/g mesh networking testbed we established, BilMesh, we first analyze and model the nature of co-channel and adjacent channel interference. We conduct extensive experiments on this testbed to understand the effects of using multi-radio, multi-channel relay nodes in terms of network and application layer performance metrics. We also report our results on using overlapping in addition to orthogonal channels for the radios of the mesh routers. We then turn our attention to modeling and quantifying adjacent channel interference. Extending BilMesh with IEEE 802.15.4 nodes, we propose computational methods to quantify interference between channels of a wireless communication standard and between channels of two different standards (such as Wi-Fi and ZigBee). Majority of the studies in the literature on channel assignment consider only orthogonal channels for the radios of a multi-radio WMN. Having developed quantitative models of interference, next we propose two optimization models, which use overlapping channels, for the joint flow-radio and channel assignment problems in WMNs. Then we propose efficient centralized and distributed heuristic algorithms for coupling flows and assigning channels to the radios of a WMN. The proposed centralized and distributed schemes make use of overlapping channels to increase spectrum utilization. Using solid interference and capacity metrics, we evaluate the performances of the proposed schemes via extensive simulation experiments, and we observe that our schemes can achieve substantial improvement over single-channel and random flow-radio and channel assignment schemes.Uluçınar, Alper RifatPh.D

State-of-the-art of distributed channel assignment

Channel assignment for Wireless Mesh Networks (WMNs) attempts to increase the network performance by decreasing the interference of simultaneous transmissions. The reduction of interference is achieved by exploiting the availability of fully or partially non-overlapping channels. Although it is still a young research area, many different approaches have already been developed. These approaches can be distinguished into centralized and distributed. Centralized algorithms rely on a central entity, usually called Channel Assignment Server (CAS), which calculates the channel assignment and sends the result to the mesh routers. In distributed approaches, each mesh router calculates its channel assignment decision based on local information. Distributed approaches can react faster to topology changes due to node failures or mobility and usually introduce less protocol overhead since communication with the CAS is not necessary. As a result, distributed approaches are more suitable once the network is operational and running. Distributed approaches can further be classified into static and dynamic, in regard to the modus of channel switching. In dynamic approaches, channels can be switched on a per-packet basis, whereas in static approaches radios stay on a specific channel for a longer period of time. Static assignments have been more in focus, since the channel switching time for current Institute of Electrical and Electronics Engineers (IEEE) 802.11 hardware is in the order of milliseconds which is two orders higher than the packet transmission time. Recently, surveys of channel assignment algorithms have been presented which cover certain aspects of the research field. The survey in [1] introduces the problem and presents a couple of distributed algorithms and [2] gives a broad introduction to centralized and distributed approaches. The survey herein is focused on distributed approaches for peer- to-peer network architectures. This report describes the problem formulation for channel assignment in WMNs and the fundamental concepts and challenges of this research area. We present different distributed channel assignment algorithms and characterize them according to a set of classification keys. Since channel assignment algorithms may change the connectivity and therefore the network topology, they may have a high impact on routing. Therefore, we present routing metrics that consider channel diversity and adapt better to the multi- radio multi-channel scenario than traditional routing metrics designed for single channel networks. The presented algorithms are discussed and compared focusing on practical evaluations in testbed and network environments. The implementation for real networks is a hard and labor-intensive task because the researcher has to deal with the complexity of the hardware, operating system, and wireless network interface drivers. As a result, frameworks emerged in order to simplify the implementation process. We describe these frameworks and the mechanisms used to help researchers implementing their algorithms and show their limitations and restrictions

PUMA: Policy-Based Unified Multi-radio Architecture for Agile Mesh Networking

This paper presents the design and implementation of PUMA, a declarative constraint-solving platform for policy-based routing and channel selection in multi-radio wireless mesh networks. In PUMA, users formulate channel selection policies as optimization goals and constraints that are concisely declared using the PawLog declarative language. To efficiently execute PawLog programs in a distributed setting, PUMA integrates a high performance constraint solver with a declarative networking engine. We demonstrate the capabilities of PUMA in defining distributed protocols that cross-optimize across channel selection and routing. We have developed a prototype of the PUMA system that we extensively evaluated in simulations and on the ORBIT testbed. Our experimental results demonstrate that PUMA can flexibly and efficiently implement a variety of centralized and distributed channel selection protocols that result in significantly higher throughput compared to single channel and identical channel assignment solutions