Static Channel Assignment Research Articles

Cost‐Efficient Network Design in Multichannel WSNs With Power Control: A Grey Wolf Optimization Approach to Routing and Clustering

Wireless sensor networks (WSNs) require optimized energy consumption and an improved packet delivery ratio (PDR) for optimal performance. Clustering and routing strategies are frequently used to reduce energy usage, while multiradio (MR) multichannel (MC) systems improve PDR levels. Transmission power control (TPC) features in both energy consumption reduction and PDR improvement. While the mentioned techniques are used in previous studies, they were investigated separately and without a holistic approach. This study discusses the challenge of obtaining high‐PDR, energy‐efficient, and cost‐effective clustering and routing in WSNs. As a means of reducing deployment costs, a heterogeneous setting with energy‐constraint normal sensors for environmental monitoring as well as some high‐energy, TPC‐enabled, MR super nodes is assumed. The super nodes are considered as CHs and are responsible for collecting the sensed data from the normal sensors. Installing additional radios on super nodes enables static channel assignment (CA), which yields high PDR with low imposed overhead on the network. The mentioned TPC‐based MC heterogeneous setting, which yields cost‐effectiveness, high PDR, and energy efficiency, was not investigated in previous studies. The considered problem is decoupled into two phases of configuring the super nodes and normal sensors, which are solved using the grey wolf optimization (GWO) algorithm. The performed simulations show an average improvement of our proposed algorithm in PDR, energy consumption, consumed energy per delivered bit, and network lifetime by 9%, 30%, 65%, and 44%, respectively.

A bonded channel in cognitive wireless body area network based on IEEE 802.15.6 and internet of things

Despite the recent developments in communication technologies for wireless body area networks (WBAN), the reliability of packet transmission, especially for emergency and critical data transfer remains a significant challenge. This may be that most of the existing techniques in WBAN use single-channel for data transmission with no intelligence. The cognitive bonded channel which provides high data rate for emergency and the demanding situation. Existing techniques in WBAN rely on the use of the single-channel for data transmission and do not exploit the use of the bonded channel, which can improve the WBAN capacity of off-body communication. In our research, we propose a traffic load aware bonded channel algorithm (TLA-BCA), which exploits channel bonding to improve the performance of off-body communication between the WBAN sink nodes and gateway. Our proposed algorithm, i.e., TLA-BCA utilizes high-quality channels for channel bonding to maximize the capacity of off-body communication in WBANs. TLA-BCA demonstrates significant performance improvement over Traffic Priority Based Channel Assignment Technique (TP-CAT) and Static Channel Assignment (SCA) in terms of average throughput, average end-to-end delay with comparable energy performance.

Multi-Radio Multi-Channel Assignment Algorithm in Maritime Wireless Mesh Networks

The recent growth in the maritime industry stemming to increase in global commerce as well as searching for hydrocarbons at offshore locations, the high data rate and cost affordable maritime communication is acquired. A mesh network is envisaged for maritime communications because of its expanded coverage, self-healing, and high-capacity. With the development of multi-radio technology, the frequency interference can be decreased sharply with proper channel assignment. The static channel assignment optimization is often applied to decrease the wireless frequency interference which is known as an NP-hard problem. In this paper, we focus on the static channel assignment issue and propose a heuristic algorithm to solve the optimization problem. The problem is addressed by assigning channels to communication links to minimize the interference from overall network. A modified particle swarm optimization (PSO) algorithm is proposed to optimize the problem, and a new merging solution is adopted to reassign channels for nodes, which violate the radio constraints. Multi-radio simulation is performed in NS-3 to validate the effectiveness of the proposed channel assignment algorithm. The results show that the algorithm is able to find an optimized assignment with fewer iterations than the previous work and improve network performance.

Fault-tolerant interference-aware topology control in multi-radio multi-channel wireless mesh networks

Wireless Mesh Networks offer an effective technology to establish broadband wireless services. Due to this application, robustness against failures and throughput improvement are the two main objectives in designing such networks. In this paper, we use the “topology control” as a set of tools to reach these objectives. Topology control in wireless mesh networks is an NP-hard problem; therefore, we propose a heuristic method known as Fault-Tolerant Interference-Aware Topology Control (FITC) to solve it in a distributed fashion. In this method, we first guarantee that the network is K-Connected using the graph modification, routing and channel assignment. Then, power control, rate adaptation, channel selection and scheduling is applied to enhance the network throughput. Due to the static channel assignment and the fixed location of the nodes in the network, the first part of the algorithm is conducted using a centralized method, while a distributed cross layer method is applied for the second part. Simulation results validate the efficiency of the proposed method in achieving the main objectives.

Tree‐based channel assignment schemes for multi‐channel wireless sensor networks

AbstractMany sensor node platforms used for establishing wireless sensor networks (WSNs) can support multiple radio channels for wireless communication. Therefore, rather than using a single radio channel for whole network, multiple channels can be utilized in a sensor network simultaneously to decrease overall network interference, which may help increase the aggregate network throughput and decrease packet collisions and delays. This method, however, requires appropriate schemes to be used for assigning channels to nodes for multi‐channel communication in the network. Because data generated by sensor nodes are usually delivered to the sink node using routing trees, a tree‐based channel assignment scheme is a natural approach for assigning channels in a WSN. We present two fast tree‐based channel assignment schemes (called bottom up channel assignment and neighbor count‐based channel assignment) for multi‐channel WSNs. We also propose a new interference metric that is used by our algorithms in making decisions. We validated and evaluated our proposed schemes via extensive simulation experiments. Our simulation results show that our algorithms can decrease interference in a network, thereby increasing performance, and that our algorithms are good alternatives for static channel assignment in WSNs. Copyright © 2015 John Wiley & Sons, Ltd.

Design of logical topology with K‐connected constraints and channel assignment for multi‐radio wireless mesh networks

SummaryIn multi‐radio multi‐channel wireless mesh networks, the design of logical topology is different from that in single channel wireless mesh networks. The same channel assignment algorithm used for various logical topologies will lead to diverse network performance. In this paper, we study the relationship between k‐connected logical topology and the maximum number of assigned channels. Meanwhile, we analyze the issues affecting channel assignment performance, and present the lower and upper bounds of the maximum allowable number of assigned channels for k‐connected logical topology. We then develop a k‐connected logical topology design algorithm based on shortest disjoint paths and minimum interference disjoint paths for each node‐pair. In addition, we propose a static channel assignment algorithm according to minimum spanning tree search. Extensive simulations show that our proposed algorithm achieves higher throughput and lower end‐to‐end delay than fault tolerant topology control algorithms, which validates the involved trade‐off between path length and nodal interference. Moreover, numerical results demonstrate that our proposed channel assignment further improves network performance under the context of limited radio interfaces. Copyright © 2014 John Wiley & Sons, Ltd.

Resource Allocation in City-wide Real-Time Wireless Mesh Networks

To support real-time communication, multi-radio multi-channel city-wide WMNs (Wireless Mesh Networks) are studied in this paper. In the studied WMNs, a WMN router is equipped with two communication interfaces/radios, one is working on 2.4GHz for the client accessing, and the other is working on 5GHz for the backhaul communication. First, a greedy static channel assignment algorithm for access interfaces is proposed to minimize the maximum interference among all the access interfaces. The proposed greedy algorithm has an approximation factor of 2-1/ m , where m is the number of available orthogonal channels of access interfaces. To guarantee interference-free communications for all links, a slot allocation algorithm, combining with the channel assignment for backhaul interfaces, is suggested. The slot allocation algorithm is based on the fixed priorities assigned to real-time flows. After that, the worst-case end-to-end delay analysis of each flow under the slot and channel allocation algorithms is given. Finally, simulation results demonstrate the effectiveness of the delay analysis and the channel assignment and slot allocation algorithms

Partial Bit Strings Pruning Channel Assignment in Multi-Rate Multi-Channel Wireless Networks

IEEE 802.11 based wireless networks are extensively used in mesh, ad hoc, and sensor networks due to less expense and easier deployment. IEEE 802.11a/b/g standard supports multi-rate and multi-channel settings to facilitate network transmissions. Many researchers focus on maximizing network throughput and propose channel assignment algorithms in IEEE based multi-rate multi-channel (M2) wireless networks. Less works are devoted to the study of network capacity in M2 wireless networks. In our observation, static channel assignment algorithms for maximizing network throughput may limit network capacity, and the improvement on network capacity comes mainly from higher data rate communication links. Therefore, we model the optimization problem and derive the optimization formula in detail. Subsequently, we propose an efficient channel assignment algorithm, Partial Bit Strings Pruning (PBSP) channel assignment to maximize network capacity. The results of associated simulations show that the performance of our PBSP channel assignment algorithm is superior to the algorithm based on the well-know minimum-interference approach.

A dynamic channel assignment strategy based on cross‐layer design for wireless mesh networks

SUMMARYIn wireless mesh networks (WMNs), if nonoverlapped channels or partially overlapped channels are used properly, the throughput can be improved drastically. However, the number of nonoverlapped channels is limited in wireless communication standards. An effective channel assignment algorithm for a WMN is necessary to increase the utilization rate of space and nonoverlapped channels. Static channel assignment algorithms can improve network throughput, but their accuracies are not satisfactory in common scenarios. Dynamic channel assignment algorithms can allocate channels according to the status of adjacent links in WMNs. A dynamic channel assignment algorithm needs cross‐layer design to get the information of routing. A routing‐information‐aware channel assignment algorithm based on a cross‐layer design is proposed, which is named R‐CA. The proposed method can dynamically allocate channels for wireless nodes when they need communication and release channels after data transmission. In R‐CA, limited channel resources can be used efficiently by more wireless nodes, and hence the communication throughput can be improved. Simulation results show that our channel allocation strategy can effectively ensure and enhance the network throughput and packet delivery rate in WMNs. Copyright © 2012 John Wiley & Sons, Ltd.

Online reconfiguration of channel assignment in Multi-Channel Multi-Radio wireless mesh networks

Efficient utilization of Multi Channel–Multi Radio (MC–MR) wireless mesh networks (WMNs) can be achieved only by intelligent channel assignment (CA) and Link Scheduling (LS). Due to the dynamic nature of traffic demand in WMNs, the CA has to be reconfigured whenever traffic demand changes, in order to achieve maximum throughput in the network. The reconfiguration of CA requires channel switching at radios which leads to disruption of ongoing traffic in the network. So, we have to consider this traffic disruption overhead while reconfiguring the network for traffic adaptation. The existing CA algorithms for MC–MR WMNs in the literature do not consider the reconfiguration overhead caused by the channel switching. In this paper, we propose a novel reconfiguration model that considers both network throughput and reconfiguration overhead to quantitatively evaluate a reconfiguration algorithm. Based on the reconfiguration model, we formulate the problem of reconfiguration of CA as a Mixed Integer Linear Program (MILP). We also propose an on-line heuristic algorithm for CA called Demand based State Aware channel Reconfiguration Algorithm (DeSARA) that finds the CA for the current traffic demand by considering the existing CA of the network to minimize the reconfiguration overhead. Through extensive simulations, we show the importance of considering the overhead in reconfiguration of CA, by comparing the performance of DeSARA with a static CA and a fully dynamic CA that does not consider the reconfiguration overhead. We also study the performance of the proposed algorithm with real network traces collected in a campus network to show its practicality.

On the end-to-end flow allocation and channel assignment in multi-channel multi-radio wireless mesh networks with partially overlapped channels

The performance of wireless mesh networks (WMNs) can be improved significantly with the increase in number of channels and radios. Despite the availability of multiple channels in several of the current wireless standards, only a small fraction of them are non-overlapping and many channels are partially overlapped. In this paper, we formulate the joint channel assignment and flow allocation problem for multi-channel multi-radio WMNs as a Mixed Integer Linear Program (MILP). Unlike most of the previous studies, we consider the case when both non-overlapped and partially overlapped channels are being used. We consider an objective of maximizing aggregate end-to-end throughput and minimizing queueing delay in the network, instead of the sum of link capacities, since the traffic characteristics of a multi-hop WMN are quite different from a single hop wireless network. Our static channel assignment algorithm incorporates network traffic information, i.e., it is load aware. Our formulation takes into consideration several important network parameters such as the transmission power of each node, path loss information, the signal to interference plus noise ratio at a node, and the frequency response of the filters used in the transmitter and receiver. We show by simulations that our MILP formulation makes efficient use of the spectrum, by providing superior channel assignments and flow allocations with the addition of partially overlapped channels, without the use of any additional spectrum. We also justify the need to consider alternative objective functions such as, minimizing average queueing in the network. We also propose a polynomially bounded heuristic algorithm to scale the proposed algorithm to bigger network topologies.

Lattice routing: A 4D routing scheme for multiradio multichannel ad hoc networks

An efficient channel assignment strategy ensures capacity maximization in a multiradio, multichannel ad hoc network. Existing mechanisms either use a static channel assignment or a centralized process intensive system that assigns channels to individual nodes. These are not effective in a dynamic environment with multiple flows that are active at different time instants. The protocol proposed in this work (Lattice routing) manages channels of the radios for the different nodes in the network using information about current channel conditions and adapts itself to varying traffic patterns in order to efficiently use the multiple channels. Further the protocol uses multipathing, a key mechanism that is found to alleviate bottlenecks present in single path routes in such an environment. Results indicate that Lattice routing consistently outperforms it closest competitor ((MCR) Kyasanur and Vaidya (2006) [1]) across a large number of experiments.

Cognitive Radio for aeronautical air-ground communications

The system of air-ground communications is one of the most fundamental elements of air traffic control in the National Airspace System (NAS). The current air-ground voice communications systems are using the more than 50-year-old analog voice transmission technology in the licensed air traffic management VHF spectrum band. The limited spectrum is allocated statically based on air traffic control organization and geographic locations. With the increasing use of data applications for air-ground communications, the demand to effectively use the limited spectrum has increased. There are several proposed approaches to solve the projected saturated spectrum in the future. However, these approaches do not address the current practice of static spectrum allocation, which this author anticipates will be a major bottleneck for effective use of the limited spectrum. The current static channel assignment creates inefficient use of the limited spectrum. Regardless of whether a channel is used, it is permanently assigned to the particular geographical areas and organizations. This prevents other users from using the channels when the channels are idle. Also, this static allocation of the spectrum constrains the reassignment of channels and creates a long transition period for moving the existing analog system to a new digital system. The emerging Cognitive Radio (CR) technology provides the opportunity to address the static allocation of spectrum issue and offer a more flexible transition approach for updating the legacy air-ground radio system. The emerging CR technology provides the sensing of surrounding environment, allowing the radio to adapt to the environment accordingly. Built on software-defined radio (SDR) technology, CR is able to employ these features with the cognitive engine and the aid of several sensors. The cognitive engine carries out these tasks by obtaining all available information from sources such as sensors, protocol layers, a policy engine, and its own hardware, and then interprets, reasons, and makes the optimum decision to adapt. Integrated with ground radio stations and centralized management systems, the CR can dynamically use the available channels based on its actual location, environment condition, and, therefore, maximize the use of the limited spectrum.

Providing survivability against jamming attack for multi-radio multi-channel wireless mesh networks

Built upon a shared wireless medium, wireless mesh network is particularly vulnerable to jamming attacks. The ability to recover from attacks and maintain an acceptable level of service degradation is a crucial aspect in the design of a wireless mesh network. To address this issue, this paper investigates the network restoration solutions via the joint design of traffic rerouting, channel re-assignment, and scheduling over a multi-radio multi-channel wireless mesh network. Efficient routing and channel assignment schemes can relieve the interference caused by both the normal network nodes and the jamming nodes. Therefore, based on the necessary conditions of schedulability, we first formulate the optimal network restoration problem as linear programming problem, which gives an upper bound on the achievable network throughput. After we solve the LP problems, we have a set of flows assigned to edges that have been assigned to different channels. And based on the LP solutions, we provide a greedy scheduling algorithm using dynamic channel assignment, which schedules both the network traffic and the jamming traffic. And we further provide a greedy static edge channel assignment algorithm, where a channel is assigned to an edge at the beginning and will remain fixed over all time slots. In particular, we consider two strategies, namely global restoration and local restoration, which can support a range of tradeoffs between the restoration latency and network throughput after restoration. To quantitatively evaluate the impact of jamming attacks during and after restoration, we define two performance degradation indices, transient disruption index ( TDI) and throughput degradation index ( THI). Finally, extensive performance evaluations are performed to study the impact of various jamming scenarios in an example wireless mesh network.

Throughput Optimization of Cooperative Teleoperated UGV Network

Cooperative communications among group of teleoperated unmanned ground vehicles (UGVs) allows to exploit spatial diversity in wireless fading channels by relaying signals between each other. Due to the high speed of the UGVs, the nature of the channel environments and the possible co-channel interference, the effect of multipath propagation and the Doppler spread are more pronounced. In this article, we proposed a low complexity dynamic channel assignment (DCA) technique with adaptive modulation and coding (AMC) strategy to allocate the available bandwidth over a number of communications links in a cooperative UGV network. In many processing algorithms and transmission protocols reported in the literature, performance improvement in terms of system throughput and reliability has been demonstrated. The proposed DCA with AMC in a cooperative UGV network has two objectives. First, to maximize the overall throughput of the cooperative UGV network and second, to significantly reduce the probability of outage in the system. In this article, the outage is defined as the percentage of time the links are incapable of supporting a minimum required transmission rate which is determined by the application. The DCA approach is formulated in terms of a binary optimization problem that is solved using the branch-and-bound method. The authors assum the links in the network to be Rayleigh faded and we used a finite state Markov chain (FSMC) for their modeling. Using Monte Carlo simulation, we showed that the proposed DCA approach in a cooperative UGVs provides significant gain in the overall throughput and reduction in the outage probability compared to the static channel assignment (SCA).

Particle swarm optimization-based DRWA for wavelength continuous WDM optical networks using a novel fitness function

Greater demand of bandwidth and network usage flexibility from customers along with new automated means for network resource management has led to the concept of dynamic resource provisioning in WDM optical networks where unlike the traditional static channel assignment process, network resources can be assigned dynamically. This paper examines a novel particle swarm optimization (PSO)-based scheme to solve dynamic routing and wavelength assignment (dynamic RWA) process needed to provision optical channels for wavelength continuous Wavelength Division Multiplexed (WDM) optical network without any wavelength conversion capability. The proposed PSO scheme employs a novel fitness function which is used during quantization of solutions represented by respective particles of the swarm. The proposed fitness function takes into account the normalized path length of the chosen route and the normalized number of free wavelengths available over the whole route, enabling the PSO-based scheme to be self-tuning by minimizing the need to have a dynamic algorithmic parameter `?' needed for better performance in terms of blocking probability of the connection requests. Simulation results show better performance of the proposed PSO scheme employing novel fitness function for solving dynamic RWA problem, not only in terms of connection blocking probability but also route computation time as compared to other evolutionary schemes like genetic algorithms.

Fixed channel assignment algorithm for multi‐radio multi‐channel MESH networks

AbstractRecently, multi‐radio mesh technology in wireless networks has been under extensive research. This is because of its potential of overcoming the inherent wireless multi‐hop throughput, scalability and latency problems caused by the half‐duplex nature of the IEEE 802.11. The concept of deploying multiple radios in wireless network access points (APs) has shown a promising way to enhance the channel selection and the route formation while the MESH topology allows more fine‐grained interference management and topology control. Within this realm, given a set of end‐to‐end objectives, there are multiple issues that need to be identified when we consider the optimization problem for fixed multi‐channel multi‐hop wireless networks with multiple radios. This paper addresses the static channel assignment problem for multichannel multi‐radio static wireless mesh networks. We first discuss its similarities and differences with the channel assignment problem in cellular networks (WMN). Next, we present four metrics based on which mesh channel assignments can be obtained. Three of these metrics attempt to maximize simultaneous transmissions in a mesh network, either directly or indirectly. The fourth metric quantifies the ‘diversity’ of a particular assignment and can be used as a secondary criterion to the other three metrics. Related optimization models have also been developed. Copyright © 2007 John Wiley & Sons, Ltd.

Interference-based channel assignment for DS-CDMA cellular systems

Link capacity is defined as the number of channels available in a link. In direct-sequence code-division multiple-access (DS-CDMA) cellular systems, this is limited by the interference present in the link. The interference is affected by many environmental factors, and, thus, the link capacity of the systems varies with the environment. Due to the varying link capacity, static channel assignment (SCA) based on fixed link capacity is not fully using the link capacity. This paper proposes a more efficient channel assignment based on the interference received at the base station (BS). In the proposed algorithm, a channel is assigned if the corresponding interference margin is less than the allowed interference, and, thus, channels are assigned adaptively to dynamically varying link capacity. Using the proposed algorithm yields more channels than using SCA in such an environment changes with nonhomogeneous traffic load or varying radio path loss. The algorithm also improves service grade by reserving channels for handoff calls.

Static and dynamic channel assignment using neural networks

We examine the problem of assigning calls in a cellular mobile network to channels in the frequency domain. Such assignments must be made so that interference between calls is minimized, while demands for channels are satisfied. A new nonlinear integer programming representation of the static channel assignment (SCA) problem is formulated. We then propose two different neural networks for solving this problem. The first is an improved Hopfield (1982) neural network which resolves the issues of infeasibility and poor solution quality which have plagued the reputation of the Hopfield network. The second approach is a new self-organizing neural network which is able to solve the SCA problem and many other practical optimization problems due to its generalizing ability. A variety of test problems are used to compare the performance of the neural techniques against more traditional heuristic approaches. Finally, extensions to the dynamic channel assignment problem are considered.

Dynamic single-connection channel access in multichannel networks

When conventional CSMA/CD methods are applied in multichannel environments, the total system capacity is often dependent upon the static and dynamic channel assignment of user stations. If this is the case, user performance may suffer drastically since the traffic-handling capability of the system fluctuates with the system traffic (generation) statistics. The CSMA/CD/IC protocol proposed by Marsan and Roffinella (1983) does not have these shortcomings, because channels are selected for use in a dynamic fashion which follows the instantaneous system load. Unfortunately, CSMA/CD/IC requires that all stations possess a separate receiver for each channel. In the paper, the authors investigate the possibility of using a single receiver per station and yet achieve the automatic global load-balancing capability of the CSMA/CD/IC protocol. It is found that although both persistent and nonpersistent versions of MICON performed as well as CSMA/CD/IC in the tests, MICON imposes different restrictions on the system. Specifically, MICON exploits the fact that in typical network environments, complete connectivity between all stations at any time instant is not required. As a result, MICON requires additional station synchronisation and permits full connectivity only between dynamically established sets of user stations.< >