集中式无线Mesh网络信道分配策略研究

针对无线Mesh网的部署特点,对其信道分配策略的设计难点进行了阐述,将集中式信道分配策略分为基于图论、基于网络流理论和基于网络分区的三种类型,并对上述各类方法的现状和进展进行了介绍、分析和探讨。最后对集中式信道分配策略的研究进行了总结和展望。     

多信道无线Mesh网络的多播信道分配算法

无线Mesh网络可用信道和节点接口的缺乏限制了多播树链路的可用带宽,致使网络吞吐量下降。针对该问题,提出支持多播的多信道多接口信道分配算法——LAMCA。该算法能最小化无线Mesh网络的干扰程度,并最大化网络吞吐量。仿真结果表明,与层次信道分配算法LCA相比,该算法在吞吐量性能方面较优。     

无线Mesh网络中混合信道分配算法研究

根据多射频多信道无线Mesh网络的特点,提出一种基于节点干扰的混合信道分配算法。将节点间的链路分为正向链路和反向链路,通过概率模型分析链路干扰,计算节点间链路的权重,建立带权重的有向网络连接图。根据链路权重为节点固定接口分配信道,减小可切换接口在信道改变过程中引起的网络干扰。扩展的NS2仿真结果表明,该算法能有效降低链路干扰,提高网络吞吐量。     

多信道无线Mesh网络负载均衡路由算法研究

针对无线网状网的网络容量问题,在多信道无线网状网模型的基础上,利用线性规划公式对无线网状网的路由问题进行描述,在此基础上提出了一个负载均衡的路由算法,在对业务请求的路由跳步数进行约束的前提上,通过减少网络链路上的负载,达到提高网络的吞吐量的目的。仿真结果表明,提出的算法能显著提高网络性能。     

多信道无线网状网自适应路由算法

针对无线网状网的网络容量优化问题,通过建立无线网状网容量优化的数学模型,利用线性规划公式对无线网状网的路由问题进行描述,在此基础上提出了一个自适应路由算法。根据网络的拓扑结构和业务请求特点,自适应地改变路由扩张因子和负载均衡率进行优化路由,达到提高无线网状网的网络容量的目的。仿真结果表明,该算法能明显提高网络容量。     

无线mesh网络中基于拓扑分层的多信道分配算法研究

无线Mesh网络是具有多跳、自组织、自愈合和高健壮性等特点的宽带网络。因为结点信号之间存在干扰及频谱资源的有限性,如何通过频谱分配来提升网络效率成为Mesh网络研究的重要方向。该文给出一种多信道分配算法,目的在于改善无线mesh网络可用信道频率的综合效率,基础在于网络结构按拓扑进行结构分层。该算法首先进行分层设计,然后在拓扑分层的基础上根据信道的优先级分配信道,达到频率资源的有效分配的目标。仿真实验说明该算法能有效地提高无线网络整体性能。     

无线Mesh网络信道分配研究

针对多接口多信道无线Mesh网络,提出了一种基于链路负载和链路“潜在的”干扰度的权值的分布式静态信道分配算法。给出基于链路负载和链路“潜在的”干扰度的权值的定义和基于权值的链表的构建方法;阐述了算法的设计思想和实现步骤。仿真实验测试结果表明,该算法不但能适应业务流量分布均匀或不均匀的状态,而且能相应地提高网络吞吐量,提升网络性能。     

认知无线mesh网中联合路由的分布式信道分配算法*

多信道技术通过对数据流量进行分流,能够减少链路间干扰,从而提升网络容量。首先针对认知无线mesh网络提出一种有效的联合路由的分布式信道分配策略,该信道分配策略主要宗旨是维持邻域内信道差异。仿真结果表明,新的信道分配算法相比于无线多信道网络中基于链接的信道分配算法,平均吞吐量大约提高了50%,平均时延降低了约50%。在信道约束的情况下,进一步引入了信道合并算法。仿真结果表明,执行信道合并算法后,网络平均吞吐量、时延性能得到了进一步改善。     

多信道无线Mesh网络公平带宽分配算法

针对基于IEEE802.11的无线Mesh网络(WMN)在按多跳方式转发数据时存在带宽分配不公平的问题,提出一种改进算法DBAS。通过检测子节点包含的活动终端数量,计算分配指数并发送给子节点,使其能根据分配指数调整介质访问控制层的竞争窗口参数。在子节点向父节点发送数据时,采用加权轮询调度算法进一步保证带宽分配的公平性。NS2实验结果验证该算法的有效性。     

基于分组管理的无线mesh网多信道分配算法*

为了合理利用多信道来提高无线网络吞吐量,针对基于802.11标准无线mesh网的业务特点,提出了基于分组管理的分布式多信道分配算法。该算法将节点接口分为回程接口与转发接口,并使回程接口分配到在干扰区域内干扰值尽可能小的信道。仿真实验结果表明,该算法可以减少区域干扰,并可充分利用信道的多样性和得到较高的网络吞吐量。     

Channel allocation in multi-channel wireless mesh networks

In this article, we survey the latest progress in multi-channel wireless mesh networks, focusing on wireless interference models and channel allocation algorithms with the goal of maximizing the network performance. We present the studies of different interference models and illustrate how they could affect the design of channel assignment. We also summarize channel allocation algorithms with different strategies in both omni-directional and directional antenna networks. We conclude that both static and dynamic channel allocation strategies have advantages and disadvantages, and the design of channel allocation algorithms strongly depends on the interference model and the assumption of network traffic.     

Congestion-aware channel assignment for multi-channel wireless mesh networks

In this paper, we propose a distributed congestion-aware channel assignment (DCACA) algorithm for multi-channel wireless mesh networks (MC–WMNs). The frequency channels are assigned according to the congestion measures which indicate the congestion status at each link. Depending on the selected congestion measure (e.g., queueing delay, packet loss probability, and differential backlog), various design objectives can be achieved. Our proposed distributed algorithm is simple to implement as it only requires each node to perform a local search. Unlike most of the previous channel assignment schemes, our proposed algorithm assigns not only the non-overlapped (i.e., orthogonal) frequency channels, but also the partially-overlapped channels. In this regard, we introduce the channel overlapping and mutual interference matrices which model the frequency overlapping among different channels. Simulation results show that in the presence of elastic traffic (e.g., TCP Vegas or TCP Reno) sources, our proposed DCACA algorithm increases the aggregate throughput and also decreases the average packet round-trip compared with the previously proposed Load-Aware channel assignment algorithm. Furthermore, in a congested IEEE 802.11b network setting, compared with the use of three non-overlapped channels, the aggregate network throughput can further be increased by 25% and the average round-trip time can be reduced by more than one half when all the 11 partially-overlapped channels are used.     

On-line joint QoS routing and channel assignment in multi-channel multi-radio wireless mesh networks

We study the problem of on-line joint QoS routing and channel assignment for performance optimization in multi-channel multi-radio wireless mesh networks, which is a fundamental issue in supporting quality of service for emerging multimedia applications. To our best knowledge, this is the first time that the problem is addressed. Our proposed solution is composed of a routing algorithm that finds up to k but not necessarily feasible paths for each demand and an on-demand channel (re)assignment algorithm that adapts network resources to maintain feasibility of one of the paths. We also study the problem of obtaining an upper bound on the network performance. First, we consider an artificial version of the problem, in which all demands arrive at the same time, and formulate it as a mixed integer linear programming model. To tackle the complexity of the model, it is relaxed that provides a tight upper bound while improves solution time up to 3.0e+5 times. Then, we model the original problem by extending the relaxed model to consider dynamic demands, it leads to a huge model; thus, we develop another model, which is equivalent to the first one and is decomposable. It is broken down by a decomposition algorithm into subproblems, which are solved sequentially. Our extensive simulations show that the proposed solution has comparable performance to the bound obtained from the decomposition algorithm; it efficiently exploits available channels, and needs very few radios per node to achieve high network performance.     

多信道无线Mesh网络的路由协议

针对单径路由协议不能充分利用多信道无线Mesh网络的信道资源的问题,提出了一种基于拥塞控制的并行多径路由协议PMRP。该协议将一个数据流分配到多条路径同时传输,当所有路径都发生中断时,才重新寻找路由;并采取相应的拥塞感知技术,避免拥塞节点再转发新的数据流。仿真结果证明：与无线自组网按需平面距离矢量路由协议（AODV）协议相比,PMRP在网络负载较大时,能有效地减小端到端延迟,提高数据包的成功投递率,增加网络的整体吞吐量。     

An overview of Channel Assignment methods for multi-radio multi-channel wireless mesh networks

Channel Assignment (CA) is an active research area due to the proliferating deployments of multi-radio multi-channel wireless mesh networks. This paper presents an in-depth survey of some of the CA approaches in the literature. First, the key design issues for these approaches are identified, laying down the basis for discussion. Second, a classification that captures their essentials is proposed. Third, the different CA approaches are examined individually, with their advantages and limitations highlighted; furthermore, categorical and overall comparisons for them are given in detail, clarifying their sameness and differences. Finally, the future research directions for CA are discussed at length.     

Channel assignment in heterogeneous multi-radio multi-channel wireless networks: A game theoretic approach

Channel assignment is a challenging issue for multi-radio multi-channel wireless networks, especially in a competing environment. This paper investigates channel assignment for selfish nodes in a heterogeneous scenario, in which nodes may have different QoS requirements and thus compete for different channels with unequal bandwidth. The interaction among nodes is formulated as a non-cooperative Multi-radio Channel Assignment Game (MCAG), where Nash Equilibrium (NE) corresponds to a stable channel assignment outcome from which no individual node has the incentive to deviate. The NEs in MCAG are characterized in this paper. Since multiple NEs may exist in this game, it is natural to choose the NE that maximizes the network utility, i.e., the sum of node utilities. It is shown that the optimal NE outcome can be derived by solving an integer non-linear programming problem. Based on some observations on the radio number distribution of NE, we propose a two-stage optimization algorithm to achieve an optimal channel assignment. Finally, computer simulations validate the effectiveness of the proposed algorithm.     

多射频无线网络中多信道分配方法的研究

针对多射频多信道无线网络信道分配中用户收益不均衡和网络资源利用率低的问题,给出了一种基于博弈论的信道分配策略,该策略在考虑信道分配有效性、公平性的同时,基于不完美信息博弈,给出了一种使网络负载更均衡的算法,并通过实验仿真验证了算法的鲁棒性和有效性。     

A weight-aware channel assignment algorithm for mobile multicast in wireless mesh networks

Wireless mesh networks (WMNs) are one of key technologies for next generation wireless networks. In this paper, we propose a heuristic channel assignment algorithm with weight awareness to support mobile multicast in WMNs. To enhance network throughput, our algorithm is based on the path forwarding weight to perform channel assignment. In addition to non-overlapping channels, partially-overlapping channels are also used in channel assignment. To fully exploit all available channels in channel assignment, we devise a new channel selection metric to consider the channel separation and the distance between nodes. In mobile multicast, the multicast tree structure cannot be fixed due to receiver (multicast member) mobility. The change of the multicast tree structure will result in channel re-assignment. The proposed algorithm is based on a critical-event driven manner to reduce the times of channel re-assignment as much as possible. Finally, we perform simulation experiments to show the effectiveness of the proposed channel assignment algorithm.