WIA-PA网络中的无冲突资源调度算法

在使用TDMA和FDMA机制的WIA-PA网络中,由于其无线多跳的mesh结构,时隙和信道的调度复杂变得更为复杂.本文归纳分析了多信道无线多跣mesh网络中资源冲突的类型,提出了一种对时隙和信道进行调度的算法.算法利用无线mesh网络中数据传输的路由特征,以网关为根,使用广度优先搜索算法构造uplink路由,对路由图中的节点着色,从而确定每个链接使用的时隙;然后根据链接在路由中的层次,为连续三个层上的链接分配互不相同信道.算法使用至多2倍图的度数减2个时隙,使用不多于三个信道保证了各链接的无冲突传输.最后,分析证明了算法的有效性,并通过仿真验证了算法的性能.     

基于混合干扰模型的多信道Mesh网络调度算法

研究了多信道无线Mesh网络中的调度及信道分配问题,设计了一种综合协议干扰模型与物理干扰模型的混合干扰模型,并在此干扰模型下提出了一种集中式调度算法。该算法在目前普遍使用的协议干扰模型的基础上,考虑了无线链路的物理传输特性：即使存在一定的干扰,也可以成功接收发射端发送的数据。模拟实验表明该算法可以提高Mesh网络中链路的并行性,有效减少总传输时间。     

WiMAXMesh网络路由与调度算法研究

WiMAX Mesh网络引入多跳的方式实现远距离通信,取得覆盖范围和吞吐量的性能优化.在集中式Mesh网络中,路由与调度算法对网络性能有重要影响.针对Mesh模式提出一个新的方案,在基于冲突感知与负载平衡路由的基础上,利用多信道单收发机模式,采用联合调度和信道分配算法提高系统性能.仿真结果表明,该算法在调度长度和归一化...     

WMN中的干扰避免部分重叠信道分配算法

针对无线mesh网络(wireless mesh networks,WMN)中存在的信道干扰问题,提出一种基于部分重叠信道(partially overlapping channels,POC)的负载平衡且干扰避免的信道分配算法。通过基于Huffman树的通信接口分配方法连接邻居节点的接口;根据网络干扰情况,对链路进行迭代信道分配,使用静态链路调度保证网络连接;利用启发式算法优先为重要程度较高的链路分配无干扰时隙,对链路调度进行优化。仿真结果表明,在具有混合流量的WMN中,所提算法可以显著提升网络吞吐量,降低网络干扰与平均丢包率,改善网络性能。     

基于能效的异构无线网络资源分配与切换调度机制研究

【】：为了能够有效提高系统的能效,本文就提出了基于能效的资源分配机切换调度机制。首先通过微基站睡眠集中式的切换调度算法,实现用户关联基站的确定,集中式切换调度算法能够使微基站中的用户到宏基站中切换,从而降低功能消耗,对微基站睡眠准则进行有效的判断。之后基站使用以最优信道质量子载波分配调整算法实现传输功率及子载波的分配,此算法利用最大调整实现最小及最大能效用户子载波的分配,从而使网络能够接近于最优解。通过实验仿真及理论分析可以看出来,和其他的算法相对比,本文所研究的基于能效资源分配及切换调度机制算法具有较高的复杂度,但是能够有效降低网络功能消耗,提高网络速度。通过实验结果表示,基于能效的资源分配及切换调度机制能够实现异构网络能源消耗的有效提高。     

基于优先级分类的工业无线网络确定性调度算法

确定性调度技术对于工业无线网络数据的实时性和确定性传输有着重要意义.本文针对工业无线网络数据流本身存在优先级分类属性的情况,基于多信道时分多址接入(TDMA)技术,在分析高优先级数据流对低优先级数据流造成的链路冲突延时和信道竞争延时基础上,对网络进行调度预处理,进而排除参数不合理的网络,并向网络管理者反馈.对于通过预处理的网络,调度算法优先为高优先级数据流的链路分配时隙和信道资源,而对属于同一类优先级的数据流,提出一种基于比例冲突空余时间的调度方案,在满足可调度性条件的前提下,根据各链路的比例冲突空余时间值从小到大依次分配时隙和信道资源.实验结果表明,所提出的调度算法可以取得较高的网络调度成功率.     

一种多射频多信道分配算法的研究与仿真

随着无线Mesh网络的发展,在网络中配置节点多射频多信道,提高信道资源的利用率和降低无线干扰,成为扩大网络容量的有效手段.采用了一种基于网络拓扑信息的集中式的多射频多信道分配算法.实现包括信道分配计算、信道分配切换及网络恢复三个阶段.三个阶段依次实现网络的信道干扰最小、确保网络的连通以及节点失败后网络的恢复,并提高网络的容量.仿真结果表明,信道分配算法可以有效地提升网络性能.     

双网卡多信道无线MAC协议

多收发器多信道技术能够有效提高无线多跳网络的带宽和吞吐量,成为学术界的研究热点。多收发器多信 道MAC协议研究主要涉及信道资源的分配与管理问题。在现有多信道MAC协议的研究基础上,提出一种基于 IEEE802. 11标准W iFi网卡的双收发器多信道MAC协议—DIM(Dual-Interface Management)。协议采用信道冲 突模型来分配信道资源,以优化网络的信道分布;同时,DIM协议在较少的硬件配置下,充分利用IEEE802. 11标准提 供的信道资源,提高了信道利用率。仿真实验表明,DIM协议具有较大的网络吞吐量和较小的分组传输延迟。     

基于无线传感器网络汇聚传输的两阶段实时调度算法

多对一的汇聚传输是无线传感器网络,特别是工业无线传感器网络中的一个典型的数据传输模式.针对具有星形和网状两层拓扑结构的工业无线传感器网络汇聚传输的实时性要求,分析簇-线型路由下完成汇聚传输所需时隙数和信道数的下限值,并基于理论值提出一种基于紧凑搜索的两阶段实时调度算法.仿真结果表明,存在最优的两阶段实时调度算法,且相比集中式调度算法,时间开销降低了6～8倍.报文开销降低了近2倍.     

WMN中基于链路质量的信道分配算法

针对IEEE 802.11多射频多信道无线Mesh网络,提出一种基于链路质量的分布式信道分配算法,通过信道扫描收集所有信道信息,根据链路质量决定工作信道,同时在网络发生变化时对信道进行动态调整。仿真实验结果表明,与常用的集中式信道分配算法相比,该算法更能有效提升网络容量。     

A cross-layer framework for video-on-demand service in multi-hop WiMax mesh networks

In this work, we introduce a cross-layer framework to favor the video-on-demand service in multi-hop WiMax mesh networks. We first propose a joint solution of admission control and channel scheduling for video streams. The proposed approach guarantees that the required data rate is achieved for video streams, which is crucial for multimedia streaming applications. An efficient and light-weight multicast routing technique is also proposed to minimize the bandwidth cost of joining a multicast tree. Furthermore, we adopt the Patching technique in the application layer to improve the capacity of the video server. Overall, the quality of the video-on-demand service is dramatically improved with the help of the efficient cooperation between the techniques proposed in different layers of the network. Simulation study shows that with the proposed approach, true video-on-demand in WiMax mesh networks can be achieved under high video request arrival rate.     

一种新颖的无线网状网的混合调度策略

提出一种新颖的时分复用与最大调度的混合调度算法,解决了单信道无线网状网中,当同一时刻待传输链路突增时,信道竞争冲突加剧,网络容量显著下降的问题.算法根据链路与系统子时隙染色,使每条链路都有唯一系统子时隙相对应,链路在同色子时隙上实现时分复用调度;在异色子时隙空闲时,实现链路的最大调度.此算法具有时分复用和最大调度两种调度算法的优点.文中利用李雅普诺夫稳定性定理证明了算法的效率比率.仿真结果表明,该算法下的网络容量有明显提升.     

Joint routing, scheduling, and power control for multichannel wireless sensor networks with physical interference

Reliability and real-time requirements bring new challenges to the energy-constrained wireless sensor networks, especially to the industrial wireless sensor networks. Meanwhile, the capacity of wireless sensor networks can be substantially increased by operating on multiple nonoverlapping channels. In this context, new routing, scheduling, and power control algorithms are required to achieve reliable and real-time communications and to fully utilize the increased bandwidth in multichannel wireless sensor networks. In this paper, we develop a distributed and online algorithm that jointly solves multipath routing, link scheduling, and power control problem, which can adapt automatically to the changes in the network topology and offered load. We particularly focus on finding the resource allocation that realizes trade-off among energy consumption, end-to-end delay, and network throughput for multichannel networks with physical interference model. Our algorithm jointly considers 1) delay and energy-aware power control for optimal transmission radius and rate with physical interference model, 2) throughput efficient multipath routing based on the given optimal transmission rate between the given source-destination pairs, and 3) reliable-aware and throughput efficient multichannel maximal link scheduling for time slots and channels based on the designated paths, and the new physical interference model that is updated by the optimal transmission radius. By proving and simulation, we show that our algorithm is provably efficient compared with the optimal centralized and offline algorithm and other comparable algorithms.     

Energy efficient spatial TDMA scheduling in wireless networks

It is now widely acknowledged that packet scheduling can have a significant impact in the overall energy consumption levels of wireless networks. In this paper, a low complexity algorithm based on Local Search (LS) is proposed for spatial-TDMA networks such that the power consumption is minimized without sacrificing throughput or delay. More specifically, given a schedule of a pre-defined frame length we search for a low power schedule with the same length. Numerical investigations reveal that the proposed heuristic has a competitive performance and achieves considerable gains when compared to previously proposed scheduling techniques. Despite the centralized nature of the algorithm, its low complexity and high accuracy make it a very competitive solution for the power efficient scheduling problem.     

Advance Reservations and Scheduling for Bulk Transfers in Research Networks

Data-intensive e-science collaborations often require the transfer of large files with predictable performance. To meet this need, we design novel admission control (AC) and scheduling algorithms for bulk data transfer in research networks for e-science. Due to their small sizes, the research networks can afford a centralized resource management platform. In our design, each bulk transfer job request, which can be made in advance to the central network controller, specifies a start time and an end time. If admitted, the network guarantees to complete the transfer before the end time. However, there is flexibility in how the actual transfer is carried out, that is, in the bandwidth assignment on each allowed path of the job on each time interval, and it is up to the scheduling algorithm to decide this. To improve the network resource utilization or lower the job rejection ratio, the network controller solves optimization problems in making AC and scheduling decisions. Our design combines the following elements into a cohesive optimization-based framework: advance reservations, multipath routing, and bandwidth reassignment via periodic reoptimization. We evaluate our algorithm in terms of both network efficiency and the performance level of individual transfer. We also evaluate the feasibility of our scheme by studying the algorithm execution time.     

Links organization for channel assignment in multi-radio wireless mesh networks

It is one key issue in the wireless mesh networks to provide various scenarios such as multimedia and applications. Links in the network can be organized and assigned to orthogonal channels so as to minimize the co-channel interference. In this paper we focus on the channel assignment problem for links in the mesh networks and aim at minimizing the overall network interference. The problem is proved to be NP-hard. We have first formulated an approach based on the Particle Swarm Optimization (PSO) algorithm which can be used to find the approximate optimized solution in small-size networks and as a baseline that other algorithms can be compared with. We also have proposed a centralized heuristic as well as a distributed heuristic algorithm for the channel assignment problem. Extensive simulation results have demonstrated that our schemes have good performance in both dense and sparse networks compared with related works.     

Rematch: a highly reliable scheduling algorithm on heterogeneous wireless mesh network

In highly dynamic and heterogeneous wireless mesh networks (WMN), link quality will seriously affect network performance. Two challenges hinder us from achieving a highly efficient WMN. One is the channel dynamics. As in real network deployment, channel qualities are changing over time, which would seriously affect network bandwidth and reliability. Existing works are limited to the assumption that link quality values are fixed, and optimal scheduling algorithms are working on the fixed values, which would inevitably suffer from the link quality dynamics. Another challenge is the channel diversity. In single channel wireless networks, channel assignment and scheduling are NP\mathcal{NP} -hard. And in multichannel wireless networks, it could be even harder for higher throughput and efficient scheduling. In this study, we firstly characterize the stochastic behavior on wireless communications in a Markov process, which is based on statistical methodology. Secondly, on exploiting the stochastic behavior on wireless channels, we propose a stochastic programming model in achieving maximized network utilization. Considering the NP\mathcal{NP} -hardness, we propose a heuristic solution for it. The key idea in the proposed algorithm is a two-stage matching process named “Rematch.” Indeed, our solution to the stochastic network scheduling is a cross-layer approach. Also, we have proved that it is 2-approximate to the optimal result. Moreover, extensive simulations have been done, showing the efficiency of “Rematch” in highly dynamic and distributed wireless mesh networks.     

REUSE: A combined routing and link scheduling mechanism for wireless mesh networks

Increasing the capacity of wireless mesh networks has motivated numerous studies. In this context, the cross-layer optimization techniques involving joint use of routing and link scheduling are able to provide better capacity improvements. Most works in the literature propose linear programming models to combine both mechanisms. However, this approach has high computational complexity and cannot be extended to large-scale networks. Alternatively, algorithmic solutions are less complex and can obtain capacity values close to the optimal. Thus, we propose the REUSE algorithm, which combines routing and link scheduling and aims to increase throughput capacity in wireless mesh networks. Through simulations, the performance of the proposal is compared to a developed linear programming model, which provides optimal results, and to other proposed mechanisms in the literature that also deal with the problem algorithmically. We observed higher values of capacity in favor of our proposal when compared to the benchmark algorithms.     

Efficient link scheduling for online admission control of real-time traffic in wireless mesh networks

Link scheduling is used in wireless mesh networks (WMNs) to guarantee interference-free transmission on the shared wireless medium in a time division multiple access approach. Several papers in the literature address the problem of link scheduling guaranteeing a minimum throughput to the flows traversing the WMN. However, none of the existing works address the problem of computing a schedule that guarantees that pre-specified end-to-end delay constraints are met. In this paper, we make a first step forward in this direction by defining a link scheduling algorithm that works in sink-tree WMNs, i.e. those whose traffic is routed towards a common sink (i.e. the Internet gateway). Our iterative algorithm exploits a delay-based admission control procedure, devised through Network Calculus, which solves an optimization problem and tests the feasibility of a schedule from the point of view of delay guarantees. Thanks to a clever solution approach for the optimization problem, the iterative algorithm computes feasible solutions in affordable times for networks of several tens of nodes, and is thus amenable to online admission control of real-time traffic.