Dynamic Channel Assignment Scheme Research Articles

Distributed and Dynamic Channel Assignment Schemes for Wireless Mesh Network

Wireless mesh network (WMN) with wireless backhaul technology provides last-mile Internet connectivity to the end-users. In multi-radio multi-channel WMN (MRMC-WMN), routers provide multiple concurrent transmissions among end-users. The existence of interference among concurrent transmissions severely degrades the network performance. A well-organized channel assignment (CA) scheme significantly alleviates the interference effect. But in trying to minimize interference, the CA scheme may affect the network connectivity. So, the CA scheme has to consider both these two conflicting issues. In this paper, as part of the initial configuration of WMNs, we propose a game theory-based load-unaware CA scheme to minimize the co-channel interference and to maximize the network connectivity. To adapt to the varying network traffic, we propose a dynamic channel assignment scheme. This scheme measures the traffic-load condition of the working channels of each node. Whenever a node finds an overloaded channel, it initiates a channel switch. Channel switching based on the fixed threshold may result in a channel over/underutilization. For optimal channel utilization, we propose a fuzzy logic-based approach to compute the channel switch threshold. The contending nodes and their densities and loads dominantly affect the network capacity and hence the performance. In the context of network capacity enhancement, we have addressed these factors and focused on increasing the network capacity. The simulation results indicate that our proposed load-unaware and load-aware CA schemes outperform the other related load-unaware and load-aware CA approaches.

Context-aware radio resource management below 6\xa0GHz for enabling dynamic channel assignment in the 5G era

Heterogeneous networks constitute a promising solution to the emerging challenges of 5G networks. According to the specific network architecture, a macro-cell base station (MBS) shares the same spectral resources with a number of small cell base stations (SBSs), resulting in increased co-channel interference (CCI). The efficient management of CCI has been studied extensively in the literature and various dynamic channel assignment (DCA) schemes have been proposed. However, the majority of these schemes consider a uniform approach for the users without taking into account the different quality requirements of each application. In this work, we propose an algorithm for enabling dynamic channel assignment in the 5G era that receives information about the interference and QoS levels and dynamically assigns the best channel. This algorithm is compared to state-of-the-art channel assignment algorithm. Results show an increase of performance, e.g., in terms of throughput and air interface latency. Finally, potential challenges and way forward are also discussed.

Graph colouring based fractional frequency reuse for enterprise femtocell networks

In this study, the authors propose a novel dynamic channel assignment scheme called graph colouring based fractional frequency reuse (GC-FFR) to improve system performance for the downlink of enterprise femtocell networks based on orthogonal frequency division multiple access with frequency division duplex. In order to mitigate co-tier interference from neighbour femtocell access points, the proposed GC-FFR scheme uses a heuristic method that consists of two steps: multiple femtocell user equipment (FUE) clustering step and dynamic subchannel assignment step. Simulation results show that the proposed GC-FFR scheme outperforms other schemes in terms of the mean FUE capacity and unsatisfied FUE probability.

Effective dynamic channel assignment scheme for on‐board processing satellite platform

Dynamic channel assignment is an effective approach to decrease inter-cell interference and improve link quality. Due to flat beam coverage property, link performance is degraded if conventional dynamic channel assignment schemes are directly employed in satellite network. To solve this problem, this study proposes the beam cooperation based dynamic channel assignment scheme, in which adjacent beams serve edge users cooperatively. Feature of feed sharing, channel model of satellite network, number of cooperative beams and combination method of the receiver are discussed in the proposed scheme. In addition, link quality restriction is applied to avoid drastically performance degradation in case of heavy traffic. Simulation results show that the proposed dynamic channel assignment scheme can effectively improve the average performance of users in the beam. Furthermore, the optimal antenna parameter for the proposed scheme is achieved by simulation.

Fuzzy call admission control combined with distributed dynamic channel assignment and reassignment for cellular mobile systems

In a cellular mobile system (CMS), the service area is divided into cells, each of which has numerous channels, which are shared by two types of call - new calls and handoff calls. Giving a higher priority to handoff calls than new calls is common practice. However, giving too much priority to handoff calls will result to excessive blocking of new calls. This work firstly proposes a distributed dynamic channel assignment and reassignment (DDCAR) scheme to satisfy three types of constraint - co-channel constraint (CCC), adjacent channel constraint (ACC), and co-site constraint (CSC), simultaneously. The purpose is to minimize the number of available channels that become unavailable for the assignment to new calls and to maximize the number of unavailable channels that become available for release when calls complete. To provide a higher priority to handoff calls, a fuzzy call admission control (FCAC) scheme, combined with the DDCAR, is proposed herein for implementation at the base station. A 7 × 7 CMS with two traffic patterns is employed as the test example. The test results reveal that the FCAC scheme significantly reduces the dropping probability of handoff calls at the cost of increasing the blocking probability of new calls to an acceptable level.

An Efficient Dynamic Channel Assignment Scheme for OWDM Based Radio-Over-Fiber Optical System

An Efficient Dynamic Channel Assignment Scheme for OWDM Based Radio-Over-Fiber Optical System

A Two-Stage Dynamic Channel Assignment Scheme with Graph Approach for Dense Femtocell Networks

A Two-Stage Dynamic Channel Assignment Scheme with Graph Approach for Dense Femtocell Networks

Graph-Based Dynamic Channel Assignment Scheme for Femtocell Networks

In this letter, we propose a novel dynamic channel assignment scheme considering interference mitigation to improve the downlink system performance for femtocell networks based on OFDMA. The proposed scheme consists of two steps: the first step aims to group femtocell access points (FAPs) using graph coloring algorithm while the second step dynamically assigns channels according to the channel state of femtocell user equipments (FUEs). Through simulation results, we show that the proposed scheme outperforms other schemes in terms of mean FUE capacity and probability of FUEs which have capacities less than a given FUE traffic load.

펨토셀 네트워크에서 그래프 컬러링을 이용한 동적채널할당 방법

In this paper, we proposed a Dynamic Channel Assignment (DCA) scheme called Graph Coloring based DCA (GC-DCA) to improve system performance for downlink femtocell networks with high density femto Access Point (AP) deployments. The proposed scheme consists of two steps: one is a femto AP grouping step considering interference and the other is a DCA step considering Signal to Interference plus Noise Ratio (SINR) for femto User Equipments (UEs). Simulation results show that the proposed GC-DCA outperforms other schemes in terms of the mean femto UE capacity and probability of femto UEs which have capacities less than a given transmit rate.

Analysis of Interference and Chanel Capacity in a CDMA Wireless Network Using Dynamic Channel Assignment (DCA) Strategy

Analysis of Interference and Chanel Capacity in a CDMA Wireless Network Using Dynamic Channel Assignment (DCA) Strategy

Channel switching control policy for wireless mesh networks

Dynamic channel assignment algorithms allow wireless nodes to switch channels when their traffic loads exceed certain thresholds. These thresholds represent estimations of their throughput capacities. Unfortunately, the threshold estimation may not be accurate due to co-channel interference (CCI) and adjacent-channel interference (ACI), especially with high traffic loads in dense networks. When the link capacity is over-estimated, these channel assignment algorithms are not effective. This is because the channel switch is not triggered even with overloaded data traffic and the link quality decreases significantly as the channel is overloaded. When the link capacity is under-estimated, the link is under-utilized. Moreover, when link traffic load increases from time to time, channel switch occurs frequently. Such frequent channel switches increase latency and degrade throughput, and can even cause network wide channel oscillations. In this paper, we propose a novel threshold-based control system, called balanced control system (BCS). The proposed threshold-based control policy consists of deciding, according to the real time traffic load and interference, whether to switch to another channel, which channel should be switched to and how to perform the switch. Our control model is based on a fuzzy logic control. The threshold which assists to make the channel switch decisions, could be deduced dynamically according to the real-time traffic of each node. We also design a novel dynamic channel assignment scheme, which is used for the selection of the new channel. The channel switch scheduler is provided to perform channel-switch processing for sender and receiver over enhanced routing protocols. We implement our system in NS2, and the simulation results show that with our proposed system, the performance improves by 12.3%–72.8% in throughput and reduces 23.2%–52.3% in latency.

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.

Multi-Channel Multi-Radio Using 802.11 Based Media Access for Sink Nodes in Wireless Sensor Networks

The next generation surveillance and multimedia systems will become increasingly deployed as wireless sensor networks in order to monitor parks, public places and for business usage. The convergence of data and telecommunication over IP-based networks has paved the way for wireless networks. Functions are becoming more intertwined by the compelling force of innovation and technology. For example, many closed-circuit TV premises surveillance systems now rely on transmitting their images and data over IP networks instead of standalone video circuits. These systems will increase their reliability in the future on wireless networks and on IEEE 802.11 networks. However, due to limited non-overlapping channels, delay, and congestion there will be problems at sink nodes. In this paper we provide necessary conditions to verify the feasibility of round robin technique in these networks at the sink nodes by using a technique to regulate multi-radio multichannel assignment. We demonstrate through simulations that dynamic channel assignment scheme using multi-radio, and multichannel configuration at a single sink node can perform close to optimal on the average while multiple sink node assignment also performs well. The methods proposed in this paper can be a valuable tool for network designers in planning network deployment and for optimizing different performance objectives.

McWiLL—A New Mobile Broadband Access Technology for Supporting Both Voice and Packet Services

As an evolution from Synchronous Code Division Multiple Access (SCDMA), McWiLL (Multi-Carrier Wireless Information Local Loop) mobile broadband access technology was proposed to work with Next Generation Networks (NGNs) to offer various content-rich services. Several core state-of-the-art technologies used in McWiLL mobile broadband access system are introduced in this paper, such as smart antennas, CS-OFDMA (Code Spreading Orthogonal Frequency Division Multiple Access), adaptive modulation, dynamic channel allocation, make-before-break handoff, and fraud protection, etc. These key techniques allow McWiLL to support a large coverage, high spectrum efficiency (up to 3 bit/s/Hz), a homogeneous service quality between high and low rate traffics, low cost terminals, and high mobility applications. McWiLL was designed in particular to suit for its applications in hostile environments due to its superb interference cancellation capability, special frame structure design, and dynamic channel assignment scheme.

Performance analysis of multihop cellular network with fixed channel assignment

Multihop cellular network (MCN) has been proposed to incorporate the flexibility of ad hoc networks into traditional single-hop cellular networks (SCNs). The performance analysis of MCN through analytical models is not trivial because the classic Erlang B formula no longer applies to MCN where multihop transmission is allowed. In this paper, we first propose a clustered MCN (cMCN) architecture with the use of dedicated information ports (DIPs), which are deployed wireless ports functioning as central controllers for multihop users. The proposed cMCN can be considered as a complement of the existing cellular network. Then, we study the feasibility of modeling time division multiple access (TDMA)-based cMCN with fixed channel assignment (FCA) scheme for uplink transmission. An exact multi-dimensional Markov chain model to analyze the performance of cMCN with FCA is developed. Furthermore, an approximated model which results in reduced complexity is also presented. The analytical results from both models are matched with the simulation results closely. The results show that cMCN with the proposed FCA scheme can reduce the call blocking probability significantly as compared to SCNs with either the conventional FCA or a dynamic channel assignment (DCA) scheme.

A compact dynamic channel assignment scheme based on Hopfield networks for cellular radio systems

AbstractIn this paper, a new channel assignment strategy named compact dynamic channel assignment (CDCA) is proposed. The CDCA differs from other strategies by consistently keeping the system in the utmost optimal state, and thus the scheme allows to determine a call succeeding or failing by local information instead of that of the whole network. It employs Hopfield neural networks for optimization which avoids the complicated assessment of channel compactness and guarantees optimum solutions for every assignment. A scheme based on Hopfield neural network is considered before; however, unlike others, in this algorithm an energy function is derived in such a way that for a neuron, the more a channel is currently being allocated in other cells, the more excitation the neuron will acquire, so as to guarantee each cluster using channels as few as possible. Performance measures in terms of the blocking probability, convergence rate and convergence time are obtained to assess the viability of the proposed scheme. Results presented show that the approach significantly reduces stringent requirements of searching space and convergence time. The algorithm is simple and straightforward, hence the efficient algorithm makes the real‐time implementation of channel assignment based on neural network feasibility. Copyright © 2008 John Wiley & Sons, Ltd.

A Dynamic Channel Assignment Scheme for TDMA-based Multihop Cellular Networks

In this paper, we propose a multihop dynamic channel assignment (MDCA) scheme for time division multiple access (TDMA)-based multihop cellular networks. The proposed MDCA assigns channels to calls based on interference information in surrounding cells, provided by the interference information table (IIT) in the network. Two different channel searching strategies, Sequential channel searching (SCS) and packing-based channel searching (PCS), for use in MDCA are proposed and studied. A channel reassignment procedure to further enhance the performance is also investigated. Simulation results show that MDCA significantly improves the system capacity. Furthermore, the MDCA can efficiently alleviate the call blocking in hot-spot cells.

Dynamic Channel Assignment for Multihop Cellular Networks with Any Reuse Factor

A clustered multihop cellular network (cMCN) architecture is recently proposed and studied using fixed channel assignment (FCA) with a reuse factor, Nr=7. In this Letter, we propose and develop a multihop dynamic channel assignment (mDCA) scheme applicable with any reuse factor. The mDCA assigns channels with the knowledge of the information about interference in surrounding cells. Simulations show that the capacity improvements at call blocking probability of 1% for mDCA over the conventional FCA are 96% and 210% for Nr=4 and Nr=7, respectively.

A dynamic channel assignment scheme for clustered multihop cellular networks

AbstractWhereas cellular systems have traditionally adopted single‐hop transmissions between the mobile station (MS) and the base station (BS), researchers expect multihop transmission to be utilised in the future. Cellular systems present several challenges, such as channel assignment, which are exacerbated by multimedia service traffic and an increasing number of subscribers. Recently, a clustered multihop cellular network (cMCN) architecture that complements traditional cellular systems has been proposed and studied using fixed channel assignment (FCA). However, the performance of FCA is limited when the traffic pattern varies in a service area. This paper proposes the use of dedicated information ports (DIPs) as clusterheads in cMCN, followed by a multihop dynamic channel assignment (mDCA) scheme. The mDCA works by assigning channels based on information about interference in surrounding cells. Two different channel searching strategies are developed and evaluated. Through computer simulation, we show that the proposed mDCA is able to achieve a significantly improved capacity which is maintained when the number of system channels is increased. Finally, issues regarding the implementation of the mDCA and future work on this topic are discussed. Copyright © 2007 John Wiley & Sons, Ltd.

A Prediction-Based Flexible Channel Assignment in Wireless Networks Using Road Topology Information

In this article, a novel prediction technique is proposed, which uses road topology information for prediction. The proposed scheme uses real-time positioning information and road topology information, which matches with the real environment. The scheme uses flexible channel assignment to maintain a better tradeoff between forced termination and call blocking probabilities. For reservation of resources in advance, the information about future handoffs is obtained from the road topology prediction technique. To show the effectiveness of the prediction scheme and flexible channel assignment scheme, this work aims at simulation of other channel assignment strategies—fixed and dynamic channel assignment strategy with and without incorporating the prediction based on road topology information. It gives accurate prediction results, which helps to maintain a better QoS and resource management.