Distributed Channel Assignment Research Articles

Distributed Channel Assignment for Ultra-Dense Wireless Networks Using Belief Propagation

An efficient channel assignment plays an important role in mitigating co-channel interference in ultra-dense wireless networks. A simple solution is to separate interfering network nodes into orthogonal channels to reduce the interference among them. However, determining the optimal channel assignment is considered to be a non-linear problem, which may also be associated with practical implementation issues such as high computational complexity and control signaling issues. In an effort to cope with these challenging issues, we propose a distributed channel assignment algorithm that efficiently finds the optimal channel configuration by utilizing the concept of belief propagation. Based on a message-passing framework, the proposed distributed channel assignment algorithm maximizes the overall sum rate of the ultra-dense network with a low computational load for each network node. In addition, we design a network protocol and frame format to implement the proposed message-passing framework to real-world wireless networks. The main advantage of the proposed approach is that network nodes autonomously determine the optimal channel assignment and rapidly adapt to dynamic changes of the network. Simulation results confirm that the proposed distributed channel assignment algorithm outperforms conventional algorithms in terms of various network performance aspects, such as the sum rate, scalability, latency, and user mobility.

Throughput-Guaranteed Distributed Channel Assignment and Scheduling Algorithms with Low Complexity for Multichannel Wireless Sensor Networks

In wireless sensor networks, an improved throughput capacity region can be achieved by equipping multiple channels. However, such approach inevitably brings the issue of solving the coupled channel assignment and scheduling problem. This paper put forward a low-complexity distributed channel assignment and scheduling policy for multichannel wireless sensor networks with single-hop traffic flows, named LDCS, as well as its multihop multipath extension. Under the proposed algorithms, random access and backoff time techniques are introduced to keep the complexity low and independent of the number of links and channels. Through theoretical analysis and simulation experiments, it is proved that the proposed algorithms are throughput guaranteed, and in some network scenarios, the achieved capacity region can be larger than that of other comparable distributed algorithms.

Traffic-predictive QoS on-demand routing for multi-channel mobile ad hoc networks

Mobile multimedia applications have recently attracted numerous interests in mobile ad hoc networks (MANETs) supporting quality-of-service (QoS) communications. Multiple non-interfering channels are available in 802.11- and 802.15-based wireless networks. Channel assignment depends on the available bandwidth at involved nodes and the bandwidth consumption required by a new flow. Predicting available bandwidth of a node in wireless networks is challenging due to the shared and open nature of the wireless channel. This paper proposes a traffic-predictive QoS on-demand routing(TPQOR) protocol to support QoS bandwidth and delay requirements. A distributed channel assignment scheme and routing discovery process are presented to support multimedia communication and to satisfy QoS bandwidth requirement. The proposed channel assignment and reuse schemes can reduce the channel interference and enhance channel reuse rate. The proposed bandwidth prediction scheme can estimate the bandwidth requirement of each node for future traffic by the history information of its channel usage. Unlike many existing routing protocols, we take the traffic prediction as an important factor in route selection. The simulation results show that TPQOR protocol can effectively increase throughput, reduce loss ratio as well as delay, and avoid the influences of future interference flows, as compared to AODV protocol for a different number of channels.

Distributed Resource Allocation for IBFD-Enabled NOMA Systems

A joint power control and channel assignment problem for an in-band full duplex (IBFD)-enabled non-orthogonal multiple access (NOMA) system is investigated. To strike a balance between performance and complexity, a matching-based distributed channel assignment mechanism is proposed based on the optimal design of power control, and it achieves a stable Pareto-optimal solution to the resulting combinatorial optimization problem in polynomial time. Simulations are conducted to show the efficiency of the proposed mechanism and the benefits when IBFD and NOMA are integrated.

Distributed and Jamming-Resistant Channel Assignment and Routing for Multi-Hop Wireless Networks

We are becoming more reliant on multi-hop wireless networks (MWNs) for public safety, tactical/military, and last mile Internet communications. The architecture of an MWN can be flat , as in ad-hoc networks or hierarchical , as in mesh or sensor networks. Today, the lower cost and smaller size of radios enables multiple radios to exist in a device. Hence, simultaneous transmissions on orthogonal channels are possible, which multiplies the performance of MWNs. However, an efficient communication is only possible if every device has reliable connection. A connected MWN can be created using a meticulous channel assignment (CA) scheme that reduces congestion and interference. In addition, CA needs to handle jamming attacks. The medium access control (MAC) layer is responsible for CA related tasks. However, CA results in topology changes that affect routing decisions taken at the routing layer, which could lead to unreliable network. This strong interrelationship requires a cross-layered approach to ensure reliable connectivity. In this paper, we formulate this cross-layer problem as network-path cost optimization. Because the problem is NP-hard, we propose a dynamic and distributed heuristic CA and routing scheme that is applicable for both flat and hierarchical MWNs and that is also resistant to jamming attacks. We call it distributed jamming resilient channel assignment and routing (DJ-CAR) scheme. The performance of DJ-CAR, with that of existing schemes, is compared using an OPNET simulator.

Distributed Channel Assignment Algorithm Based on Traffic Awareness in Wireless Mesh Networks

Recently, wireless mesh network (WMN) technology recently has been used in various industries. Especially, a number of multi-channel assignment schemes have been presented to improve the throughput of IEEE 802.11-based multi-hop WMN. However, performance of the conventional multi-channel assignment schemes is not enough to satisfy the industry requirements. We, thus, should study more about the multi-channel assignment scheme in order to enhance the performance. This paper proposes a novel channel assignment scheme that employs multi-channel and multi-Interface in the WMN. The proposed scheme obtains the traffic information of the network and does the efficient channel assignment without any message exchanges. We verify the efficiency of the proposed scheme through the mathematical modeling and the real-world experiments. The results show that the proposed scheme improves the throughput of the network compared with the conventional schemes.

Joint channel assignment and routing protocol for cognitive radio ad hoc networks

Conventional single channel wireless ad hoc networks usually suffer from low network throughput owing to the higher number of packet transmissions required for multi-hop communication. Using multiple channels within a single network can improve the network throughput. In multi-channel communication networks, the channels must be assigned appropriately to maximise network performance. Existing channel assignment methods are usually based on the approach of interference reduction/minimisation, for example, by making a link to operate on only one channel and different links to operate on different channels. In this paper, we go in the opposite direction and propose to make links to operate on more channels. A new distributed joint channel assignment and routing protocol for cognitive radio ad hoc networks called cognitive radio-enhanced AOMDV is proposed. Simulation studies showed that our method outperforms other methods.

5G Development in China: From Policy Strategy to User-Oriented Architecture

5G encompasses the development of various key wireless communication technology standards. The development entails both technological advancement and social interaction. This paper analyzes 5G development and its significant shift from a strategy policy to a user-oriented development showing the coplay of technology and society in China. Based on this theory, relevant proposals are recommended for future technical development and industrial regulation. Also, to increase the throughput and spectrum efficiency, channel assignment and load balance are considered. A hybrid routing protocol TOHRP (tree-based and on-demand hybrid routing protocol) and a distributed channel assignment algorithm LBCA (Load Based Channel Assignment) in the multichannel environment are proposed and they solve the traditional problem of (1) waste of spectrum and (2) self-interference. The computer-simulated experiment shows that the algorithm improves the performance.

Sistema de gestión de recursos para mejorar la capacidad de transmisiones en redes malladas inalámbricas

With numerous active nodes in an 802.11-based wireless mesh network, operating on longer multi-hop routes, the total transmission capacity is limited and the overall network becomes unpredictable and less reliable. The presented work describes the next steps towards a more efficient resource management of a multi-radio node, in order to enhance the performance in this kind of networks. If non-overlapping channels are used for communication, the system enables an optimal usage of the available 802.11 spectrum. To manage bundles of multiple WLAN links between mesh neighbors, a modified node architecture and a novel middle-layer software module have been created. Hop-to-hop load balancing in a bundle is included in each node. In parallel, the inclusion of a distributed channel assignment protocol is foreseen. Packet scheduling is performed based on a set of pre-defined load balancing modes. The modes introduce awareness of current network conditions and cover a wide variety of requirements on mesh networks, from improved performance to robustness. Further inspiring technologies, like layer 2 forwarding and hop-to-hop priority queuing, have been tailored in the novel architecture. The achievement is a flexible platform that can be used for different purposes, ranging from a commercially oriented mesh backbone to spontaneously setting up wireless emergency networks. A set of simulator-driven measurements outlines the effectiveness of the multi-interface system.

Learning Automata Based Channel Assignment with Power Control in Multi-Radio Multi-Channel Wireless Mesh Networks

Wireless channel assignment is one of the major challenging issues in multi hop wireless mesh networks (WMN) when there is the need to design them in a distributed fashion, specifically for multi-radio multi-channel (MRMC) systems. In this work, a new learning automata based channel and power assignment scheme which adaptively improve network overall throughput by expecting network dynamics was proposed. First, a utility function which reflected the user’s preference for the signal to interference and noise ratio (SINR) was applied, and then the transmitter power. The distributed channel assignment and power control problem is formulated as a multiple payoff stochastic game of automata. In this game, each user evaluates a channel and power selection strategy by computing a utility value. This evaluation is performed using a stochastic iterative procedure. The utility function that potentially reflected a measure of satisfaction of every node was used by every node as an environmental response for the current selected strategy chosen by the nodes. According to dynamics of system, the proposed algorithm assigned channels and powers to radio interface such that it minimized interference in the neighborhood of a node. The stability of the system was analyzed via appropriate Lyapunov-like trajectory; it was shown that the stability and optimum point of the system converged.

QoE-Based Algorithm to Assign Channel usingDistributed Method for IEEE 802.11WLANs

The main issue with deployment of IEEE 802.11WLANs in the same hotspot is assignment of appropriate channels to the Access Points (APs). The number of channels is limited and most of the channels are overlapping in 802.11and hence the proper reuse of these overlapping channels become a complex problem with respect to QoS and traffic load. Therefore over here QoE defined by the user is targeted. QoE defines the overall acceptability of the service perceived by the user which represents the user/service requirements. In this paper a performance index which takes into account both the user level fairness and aggregate QoE , is defined and the channel assignment is formulated as the optimization problem. The objective is to enhance the experience of user by finding the bandwidth used by each and every node connected to the AP. To achieve the objective we consider Distributed channel assignment algorithm for uncoordinated WLAN’s where AP’s will self configure their channels to reduce the interference level with their neighbouring AP’s and find the bandwidth used by each and every node connected to the network.

RC-MAC: A Receiver-Centric MAC Protocol for Event-Driven Wireless Sensor Networks

Event-driven wireless sensor networks (WSNs) usually operate under light traffic load. However, when an event is detected, a large number of packets may be generated. A MAC protocol designed for this kind of WSNs should be able to swiftly adapt to the two conditions. Most WSN MAC protocols are optimized for light traffic for the energy efficiency consideration. In this paper, we propose a novel receiver-centric MAC protocol called RC-MAC that seamlessly integrates duty cycling and receiver-centric scheduling, providing high throughput without sacrificing the energy efficiency. To handle bursty traffic triggered by an event, RC-MAC takes advantage of the underlying data gathering tree structure of WSNs and the multichannel technique supported by current IEEE 802.15.4 RF transceivers to assist scheduling of medium access. The throughput is improved in two phases with receiver-centric medium access scheduling and distributed channel assignment. First, on a data gathering tree, a receiver is able to coordinate the medium access of multiple senders so as to reduce collisions and achieve high throughput. Second, different receivers coordinate their senders in different channels and the throughput is further improved by allowing parallel data gathering. Observing packet processing time on low cost sensor nodes, we design a scheduling pattern that ensures fairness between source nodes without sacrificing the throughput. We evaluate the performance of our RC-MAC through measurements of an implementation in TinyOS on TelosB motes and extensive ns-2 simulations. Compared with contention-based and scheduling-based MAC protocols, we show that the throughput and the fairness under heavy traffic load are significantly improved by the receiver-centric scheduling. Due to the high throughput, the energy efficiency is also improved.

Distributed Channel Assignment in Cognitive Radio Networks: Stable Matching and Walrasian Equilibrium

We consider a set of secondary transmitter-receiver pairs in a cognitive radio setting. Based on channel sensing and access performances, we consider the problem of assigning channels orthogonally to secondary users through distributed coordination and cooperation algorithms. Two economic models are applied for this purpose: matching markets and competitive markets. In the matching market model, secondary users and channels build two agent sets. We implement a stable matching algorithm in which each secondary user, based on his achievable rate, proposes to the coordinator to be matched with desirable channels. The coordinator accepts or rejects the proposals based on the channel preferences which depend on interference from the secondary user. The coordination algorithm is of low complexity and can adapt to network dynamics. In the competitive market model, channels are associated with prices and secondary users are endowed with monetary budget. Each secondary user, based on his utility function and current channel prices, demands a set of channels. A Walrasian equilibrium maximizes the sum utility and equates the channel demand to their supply. We prove the existence of Walrasian equilibrium and propose a cooperative mechanism to reach it. The performance and complexity of the proposed solutions are illustrated by numerical simulations.

Joint Channel Assignment and Routing Protocol for Cognitive Radio Ad Hoc Networks

Conventional single channel wireless ad hoc networks usually suffer from low network throughput owing to the higher number of packet transmissions required for multi-hop communication. Using multiple channels within a single network can improve the network throughput. In multi-channel communication networks, the channels must be assigned appropriately to maximise network performance. Existing channel assignment methods are usually based on the approach of interference reduction/minimisation, for example, by making a link to operate on only one channel and different links to operate on different channels. In this paper, we go in the opposite direction and propose to make links to operate on more channels. A new distributed joint channel assignment and routing protocol for cognitive radio ad hoc networks called cognitive radio-enhanced AOMDV is proposed. Simulation studies showed that our method outperforms other methods.

Joint anti-attack scheme for channel assignment in multi-radio multi-channel wireless mesh networks

Nowadays, multi-radio multi-channel wireless mesh networks have been widely exploited to provide high-speed Internet access. By assigning different channels, the interference between wireless mesh network nodes can be greatly reduced, leading to a better network performance. However, the channel assignment attacks have imposed a serious security problem, where the diverse messages, that is, Channel Usage Message CUM, Channel Change Message CCM, Channel Switch Operation CSO and Security Alarm Message SAM, are often used to launch attacks by the malicious nodes in order to disturb the normal channel assignment and thus the overall network performance. In this paper, we propose a joint anti-attack scheme JAS against the channel assignment attacks. Our JAS is composed of four key components: CUM, CCM, CSO and SAM defense schemes to protect the channel assignment. The CUM defense scheme verifies the CUM messages and their sender. The CCM defense scheme employs three rounds of CCM verifications. Furthermore, three control messages are exploited by the CSO defense scheme. The SAM defense scheme offers two rounds of verification for the alarm messages. Moreover, we apply our JAS to a popular distributed channel assignment algorithm, that is, Hyacinth. Through extensive simulation, the performance of the proposed scheme is evaluated by comparing with SeCA and SmartC in terms of Goodput and additional overhead. Observed from the simulation results, our scheme is demonstrated to outperform the best-known secure channel assignment algorithms. Copyright © 2014 John Wiley & Sons, Ltd.

Distributed channel assignment for network MIMO: game-theoretic formulation and stochastic learning

The cooperative frequency reuse among base stations (BSs) can improve the system spectral efficiency by reducing the intercell interference through channel assignment and precoding. This paper presents a game-theoretic study of channel assignment for realizing network multiple-input multiple-output (MIMO) operation under time-varying wireless channel. We propose a new joint precoding scheme that carries enhanced interference mitigation and capacity improvement abilities for network MIMO systems. We formulate the channel assignment problem from a game-theoretic perspective with BSs as the players, and show that our game is an exact potential game given the proposed utility function. A distributed, stochastic learning-based algorithm is proposed where each BS progressively moves toward the Nash equilibrium (NE) strategy based on its own action-reward history only. The convergence properties of the proposed learning algorithm toward an NE point are theoretically and numerically verified for different network topologies. The proposed learning algorithm also demonstrates an improved capacity and fairness performance as compared to other schemes through extensive link-level simulations.

Distributed QoE-aware channel assignment algorithms for IEEE 802.11 WLANs

One of the challenging problems with deployment of IEEE 802.11WLANs in the same hotspot is assignment of appropriate channels to the Access Points (APs). As the number of channels in IEEE 802.11 is limited and most of them are partially overlapping, proper reuse of such channels is a complex optimization problem with respect to the traffic load and Quality of Service (QoS) requirements. Previous methods mostly employ the estimated number of interfering clients or the interference level that is measured by the AP as the main decision parameter, without regarding the actual interference imposed to the clients and their QoS requirements. Quality of Experience (QoE) is defined as the overall acceptability of the service as perceived by the user and can be exploited as a new metric which not only reflects the impairments (such as interference) imposed to the traffic, but also represents the user/service requirements. In this paper, a novel performance index, which takes into account both the aggregate QoE and the user-level fairness, is defined and channel assignment is formulated as the optimization problem on maximizing this index. Two novel distributed channel assignment algorithms are presented that exploit the QoE measure of associated clients to locally solve the optimization problem using Learning Automata mechanism. The proposed methods have been analyzed and compared to the famous Least Congested Channel Scan method by simulations where the results have shown superior performance in term of defined performance index.

Self-Organized Cognitive Sensor Networks: Distributed Channel Assignment for Pervasive Sensing

We study the channel assignment strategy in multichannel wireless sensor networks (WSNs) where macrocells and sensor nodes are overlaid. The WSNs dynamically access the licensed spectrum owned by the macrocells to provide pervasive sensing services. We formulate the channel assignment problem as a potential game which has at least one pure strategy Nash equilibrium (NE). To achieve the NE, we propose a stochastic learning-based algorithm which does not require the information of other players’ actions and the time-varying channel. Cluster heads as players in the game act as self-organized learning automata and adjust assignment strategies based on their own action-reward history. The convergence property of the proposed algorithm toward pure strategy NE points is shown theoretically and verified numerically. Simulation results demonstrate that the learning algorithm yields a 26% sensor node capacity improvement as compared to the random selection, and incurs less than 10% capacity loss compared to the exhaustive search.

Distributed channel assignment algorithms for 802.11n WLANs with heterogeneous clients

As the latest IEEE 802.11 standard, 802.11n applies several new technologies, such as multiple input multiple output (MIMO), channel bonding, and frame aggregation to greatly improve the rate, range and reliability of wireless local area networks (WLANs). In 802.11n WLANs, access points (APs) are often densely deployed to provide satisfactory coverage. Thus nearby APs should operate at non-overlapping channels to avoid mutual interference. It is challenging to assign channels in legacy 802.11a/b/g WLANs due to the limited number of channels. Channel assignment becomes more complex in 802.11n WLANs, as the channel bonding in 802.11n allows WLAN stations (APs and clients) to combine two adjacent, non-overlapping 20MHz channels together for transmission. On the other hand, IEEE 802.11n is backward compatible, such that 802.11n clients will coexist with legacy clients in 802.11n WLANs. Legacy clients may affect the performance of nearby 802.11n clients, and reduce the effectiveness of channel bonding. Based on these observations, in this paper, we study channel assignment in 802.11n WLANs with heterogeneous clients. We first present the network model, interference model, and throughput estimation model to estimate the throughput of each client. We then formulate the channel assignment problem into an optimization problem, with the objective of maximizing overall network throughput. Since the problem is NP-hard, we give a distributed channel assignment algorithm based on the throughput estimation model. We then present another channel assignment algorithm with lower complexity, and aim at minimizing interference experienced by high-rate, 802.11n clients. We have carried out extensive simulations to evaluate the proposed algorithms. Simulation results show that our algorithms can significantly improve the network throughput of 802.11n WLANs, compared with other channel assignment algorithms.

A QoS Routing Protocol with Bandwidth Allocation in Multichannel Ad Hoc Networks

Mobile multimedia applications have recently generated much interest in mobile ad hoc networks (MANETs) supporting quality-of-service (QoS) communications. Multiple non-interfering channels are available in 802.11 and 802.15 based wireless networks. Capacity of such channels can be combined to achieve higher QoS performance than for single channel networks. The capacity of MANETs can be substantially increased by equipping each network node with multiple interfaces that can operate on multiple non-overlapping channels. However, new scheduling, channel assignment, and routing protocols are required to utilize the increased bandwidth in multichannel MANETs. In this paper, we propose an on-demand routing protocol M-QoS-AODV in multichannel MANETs that incorporates a distributed channel assignment scheme and routing discovery process to support multimedia communication and to satisfy QoS bandwidth requirement. The proposed channel assignment scheme can efficiently express the channel usage and interference information within a certain range, which reduces interference and enhances channel reuse rate. This cross-layer design approach can significantly improve the performance of multichannel MANETs over existing routing algorithms. Simulation results show that the proposed M-QoS-AODV protocol can effectively increase throughput and reduce delay, as compared to AODV and M-AODV-R protocols.