基于SINR的动态无线网络分布式链路调度

无线信号之间的干扰阻碍了信号的并发传输,降低了无线网络的吞吐量.链路调度是提高无线网络吞吐量、减少信号传输延迟的一种有效方法.因为SINR (signal to interference plus noise ratio)模型准确地描述了无线信号传播的固有特性,能够真实反映无线信号之间的干扰,提出一种在动态无线网络中基于SINR模型的常数近似因子的在线分布式链路调度算法(OLD＿LS).在线的意思是指,在算法执行的过程中任意节点可以随时加入网络,也可以随时离开网络.节点任意加入网络或者从网络中离开体现了无线网络的动态变化的特性. OLD＿LS算法把网络区域划分为多个正六边形,局部化SINR模型的全局干扰.设计动态网络下的领导者选举算法(LE),只要网络节点的动态变化速率小于1/ε, LE就可以在O(log n+log R)ε≤5(1-2^1-α/2)/6,α表示路径损耗指数, n是网络节点的规模, R是最长链路的长度.根据文献调研,所提算法是第1个用于动态无线网络的在线分布式链路调度算法.     

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。     

可变频宽无线网络中信道频谱分配与链路调度

考虑信道频宽对链路传输距离和链路间干扰的影响,对可变频宽无线网络现有的累积干扰模型进行了改进,并基于改进的干扰模型对可变频宽无线网络的信道频谱分配和链路调度问题进行了建模分析。设计了一种两层优化算法对信道频谱分配和链路调度问题进行解耦,提出了一种考虑链路负载需求满足程度的链路优先级指标,启发式地构建并发传输信道分配矩阵的方法。仿真结果表明,两层优化算法能够在合理时间内收敛,启发式方法能够高效地构建并发传输信道分配矩阵。     

相继干扰消除的无线网络中的调度算法

相继干扰消除(successive interference cancellation,简称SIC)是一种多包接收技术,它从冲突信号中解码报文.SIC可有效减轻无线网络中的干扰.SIC的顺序解码特性给链路调度带来了新的挑战.提出并发图以刻画SIC导致的链路相关性.基于并发图,定义链路的干扰数并据此设计有效的调度机制.证明了基于并发图的链路调度是NP-hard的、而最大干扰数提供了极大贪婪算法的性能下界.在讨论了一类基于独立集的贪婪算法之后,结合干扰数对链路排序,给出了一种理论上性能更好的算法.仿真结果表明,仅需略高于现有模型的开销,与IEEE 802.11相比,新调度算法的性能提高可达110％.     

无线多跳网络基于位势博弈的传输调度方法*

为了进一步提高无线多跳网络的吞吐量,采用物理干扰模型,考虑链路速率可以随信干噪比(signal tointerference plus noise ratio,SINR)动态可调,提出了基于位势博弈的传输调度算法。通过设计合适的位势函数,使得纳什均衡点的存在性和收敛性都得到保证。同时,每个参与者在最小化自己支付的同时,使全局函数达到最优。仿真结果表明,该算法具有较好的吞吐量性能,而且有较快的收敛速度。     

LTE-A Relay下行静态系统仿真方法

Relay(无线中继)技术是 LTE-Advanced R10(4G移动通信标准)中引入的一项无线多跳技术.在LTE-A的Relay系统性仿真中,需要考虑到宏基站和RN(中继节点)之间的回程链路对系统性能的影响.提出一种针对Relay系统下行性能评估的静态系统仿真的建模方法.模型考虑了Relay 回程链路的信道传播和干扰模型,回程链路的无线资源分配,以及回程链路容量对UE(用户设备)调度的影响.对LTE-A relay进行了仿真,仿真结果表明,Relay提高了用户的平均吞吐率和小区边缘用户的吞吐率,不同的回程链路资源配置方案对Relay的性能有很大影响.     

一种无线传感器网络链路调度模型与算法

研究无线传感器网络最小空间重用链路调度（MSRLS）模型,提出一种求解一般网络下MSRLS问题的分步式近似算法MSRLS-D。该算法同时考虑无线传感器网络带宽需求分布和通信过程中的无线信道干扰,更适用于真实网络。通过理论分析和仿真实验,对该算法的性能进行论证和比较。     

面向MIMO多跳无线网络的多用户视频传输优化方法

MIMO(multi-input multi-output)作为一种有效提高无线信道可靠性和带宽的新兴技术,已在无线网络中得到广泛应用.但是,如何利用MIMO在多跳无线网络中为多用户提供高质量视频服务,尚未得到广泛关注.多跳无线链路之间的共信道干扰是需要解决的关键问题.提出一种面向多跳无线网络的多用户视频传输方法,利用链路选择、MIMO的空间复用和空间分集等特点,减少链路间的共信道干扰,最大化多用户的平均视频传输质量.通过对链路选择和天线分组进行建模,将上述传输策略抽象成一个最优化问题,该问题是一个NP-hard问题.为了降低求解复杂度,引入遗传算法来求解链路选择问题.该算法采用基因遗传“优胜劣汰”的特性,在保证性能的同时,大幅度降低了求解复杂度.另外,由于遗传算法中每条“染色体”的“优劣”与天线分组策略有关,因此结合可伸缩视频的失真模型,将天线分组问题转化为一个标准的0/1背包问题,并在搜索时采用深度优先和分支限界技术,进一步降低算法复杂度.实验结果表明,所提出的链路选择算法和天线分组算法均能显著提高用户接收视频的质量.     

一种无线传感器网络空间重用TDMA链路调度算法

本文研究了无线传感器网络最小空间重用链路调度(MSRLS)模型,给出了该模型的形式化描述,并在此基础上提出一种求解一般网络下MSRLS问题的集中式近似算法MSRLS-C。该算法同时考虑了无线传感器网络带宽需求分布和通信过程中的无线信道干扰,更适合真实网络。通过理论分析和实验对该算法的性能进行了论证和比较。     

无线Ad hoc网络中分布式极大吞吐率调度算法研究*

针对无线Ad hoc网络广播链路的特点,在更一般的链路干扰约束模型下,设计了一种分布式、贪婪的极大吞吐率调度算法。通过运用Laypunov定理,证明了该调度算法的稳定区域是网络最大稳定区域的γ倍（0<γ<1）。通过仿真验证了该算法性能接近集中式的GMM（贪婪极大匹配）调度算法。     

无线网络中隐藏终端的干扰特性研究

无线网络中,隐藏终端对分组接收的干扰是造成网络性能下降的主要原因之一.因此,对其进行深入细致的研究具有重要意义.在仿真工具OMNeT 4++中,对IEEE 802.11a标准所规定的物理层变速率传输机制进行了精确的仿真建模,并在此基础上进一步研究了不同传输模式与分组冲突情况下的隐藏终端干扰特性.研究表明,隐藏终端干扰特...     

一个可感知干扰的无线自组网MAC协议

在分析无线自组织网中隐终端和暴露终端问题的基础上,指出在802.11MAC协议中,造成这两类问题的根本原因是其采用了简化的干扰模型,并提出一个基于busy tone的、可以感知干扰的MAC协议(IABT)用来提高无线自组织网的性能.通过在busy tone中编码当前的干扰信息,busy tone可以有效的为将要进行的通信预留信道.IABT协议可同时解决隐终端和暴露终端的问题.通过NS2的模拟仿真,显示出IABT协议可以有效的减少MAC层的冲突,从而提高了无线自组织网的性能.     

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.     

相继干扰消除的无线网络中的调度性能分析

研究了支持相继干扰消除(successive interference cancellation,简称SIC)的无线网络中链路调度算法的设计与分析,首先,为刻画SIC的顺序检测特性,提出M-level非累积干扰模型与有序累积干扰模型.然后,由于两种模型下的调度均为NP-hard问题,研究了近似调度的性能:(1)给出了一种工作于有序累积干扰模型的调度机制,其近似比为O(g),其中,g为网络的链路多样性指数;(2)给出了一种工作于M-level非累积干扰模型的调度机制,其近似比为常数.最后,通过仿真实验考察了SIC对调度性能的影响.     

相继干扰消除的无线自组网基于SINR模型的调度

干扰是限制现代无线网络性能的关键因素。相继干扰消除(SIC)是一种简单而强大的多包接收技术,它可在物理层有效地处理干扰。本文研究了支持SIC的Ad Hoc网络中基于累积干扰模型的链路调度。干扰的累积效应与SIC的顺序解码特性相互作用,给干扰刻画与链路调度带来了重要的技术挑战。为刻画多条链路的干扰的累积,对任意链路,定义冲突集以表示一组能干扰它的解码。然后提出冲突集图(CSG)以刻画网络的干扰并定义干扰度以衡量链路的干扰。由于基于CSG的调度为NP-hard问题,设计了基于独立集的贪婪算法以有效地构造近似最优的可行调度。仿真实验表明,与简单的贪婪算法相比[1],本算法吞吐量平均提高30%且最高达60%。     

How many wireless resources are needed to resolve the hidden terminal problem?

A novel wireless resource partition method is proposed to theoretically solve the hidden terminal problem (HTP) for wireless networks with uniform transmission ranges, and known, stationary node locations. A hidden terminal graph (HTG) representation is used to capture the potential hidden terminal interference among wireless nodes. The wireless resource partitioning solution of the HTP problem is cast as a graph-coloring problem on the HTG. Under a unit-disk wireless transmission range model, a novel, efficient, constructive solution to the HTG graph-coloring problem is proposed. Specifically, by spatially grouping wireless nodes into a hexagonal grid coordinate system, it is shown that the supremum of chromatic number of a HTG can be bounded by [6,12], regardless of the number of nodes or how the nodes are distributed spatially. Moreover, 12 is also the maximum number of wireless resource partitions needed to resolve the corresponding HTP problem. Extensive simulation results reveal that the performance of this hex-coloring method is comparable to existing heuristic graph-coloring methods such as DSATUR for problems with moderate size (a few hundreds of nodes). When the problem size scales up to a few thousands of nodes, the hex-coloring solution consistently achieves superior solutions (fewer wireless resources required) while consuming 3 orders of magnitude less computing time.     

Gray physical interference model based link scheduling algorithms

To improve the concurrent data transmission capability of wireless multi-hop networks,this paper proposes adopting a gray physical interference model instead of using the threshold physical interference model.The model allows non-ideal links to be involved in scheduling,under the premise of not affecting the quality of existing transmission links.In addition,we design two greedy algorithms to schedule more links with SINR values located in the transition region.The results show that a gray physical interference model is more accurate than a threshold physical interference one,the concurrent transmission capability of a network based on the gray physical interference model is significantly increased,and network throughput is increased by 20%.     

Exact formulations for the minimum interference problem in k‐connected ad hoc wireless networks

Energy consumption is one of the most critical issues in wireless ad hoc and sensor networks. A considerable amount of energy is dissipated due to radio transmission power and interference (message collisions). A typical topology control technique aims at reducing energy consumption while ensuring specific desired properties to the established wireless network (such as biconnectivity). Energy minimization can be achieved by reducing the transmission power and selecting edges that suffer or cause less interference. We propose four integer programming formulations for the k‐connected minimum wireless ad hoc interference problem, which consists in a topology control technique to find a power assignment to the nodes of an ad hoc wireless network such that the resulting network topology is k‐vertex connected and the radio interference is minimum. Interference is measured by three different models: Boolean, protocol, and physical. We report computational experiments comparing the formulations and interference models. Optimal solutions for moderately sized networks are obtained using a commercial solver.