WMN中一种基于干扰感知的负载均衡路由协议

无线信道干扰和负载分布的不均衡严重影响无线Mesh网络吞吐量、端到端延时和资源利用率。在已有基于信噪比和邻居节点个数的干扰模型基础上,进一步研究了无线Mesh网络的链路干扰。在综合考虑了无线Mesh网络流间干扰和和流内干扰的基础上,提出路由判据PIL（Path Interfer-ence Level）。在此基础上,提出一种新的基于干扰感知的负载均衡路由协议IA-DSR（Interference-Aware DSR）。IA-DSR考虑无线网络拥塞并选择受到干扰最小的路径。仿真结果表明,在不显著增加开销的情况下,IA-DSR可以有效地提高网络的整体吞吐量,降低网络端到端时延和丢包率。     

基于无线Mesh网络的干扰感知型路由判据

在无线Mesh网络路由判据的研究中,最小跳数、ETX、ETT等路由判据没有考虑到无线网络中的干扰问题,据此选出的一般不是最佳路由。因此,基于它们的路由协议会对整个无线Mesh网络的延时、丢包率、吞吐量等性能产生较大影响。干扰感知型路由判据的提出对无线Mesh网络性能的提升起到了一定的作用。     

无线Mesh网中基于信道感知的多径路由判据

无线Mesh网是一种新型的宽带无线接入网络,其中路由算法的设计是一个非常活跃的研究领域。WCETT路由判据仅适于单径路由协议,但是多路径路由能够提供负载平衡和较高的总带宽。为了提高网络性能,在综合考虑无线链路质量和信道间干扰的基础上,提出了一种新的多径路由判据CAM-WCETT。仿真结果表明,该方案能显著提高网络的吞吐量。     

一种基于信道利用状况的无线Mesh路由判据

无线Mesh网络,又称无线因特网,融合了无线局域网和移动Ad Hoe网络的优势,它已经成为下一代无线网络的关键技术之一.路由技术对Mesh网络性能起着至关重要的作用.现有用于Ad Hoc的路由协议不能充分体现WlVlN的特殊性,在现有WCETT及CCM判据的基础上,提出一种新的用于Mesh网络的多信道路径判据Weighted Cumulative CCM-L(WCCCM-L),该判据主要根据信道利用状况选择干扰低的路径发送消息.     

无线Mesh网路由协议仿真及性能分析

当前对无线网格网络（Mesh网络）主要研究之一是无线路由技术,即针对无线Mesh网络自身的特点进行路由设计。在熟悉基于Linux平台的网络仿真器（NS2）针对Mesh网络路由协议的仿真过程的基础上,利用NS2网络仿真软件分别从端到端平均时延、分组递交率、归一化路由开销三个方面比较了目前三种典型的路由协议——按需平面距离矢量路由（AODV）、动态源路由（DSR）和目的序列距离矢量路由（DSDV）的性能,并详细介绍了整个仿真过程的步骤。最后,通过分析AODV协议的吞吐量,得出网络最佳容纳的节点数,研究成果对协议的实现具有重要的应用价值。     

无线Mesh网络的新型建模方法研究

对无线Mesh网络准确建模是开展Mesh网络各项研究的基础,基于传统802.11协议模型来分析Mesh网络性能会导致较大的偏差。提出了一种适用于无线Mesh网络的新型模型用以计算网络饱和状态下性能参数的理论值,如丢包率、节点发送概率等,性能分析和仿真结果表明,该方法更能精确地评估无线Mesh网性能。同时在此基础上给出了路由判据ETX理论值的计算方法,该方法可用来预测ETX值而无需实测,从而有效的减少了测量误差和带宽消耗。     

一种适用于无线移动Mesh网的路由算法

针对无线移动Mesh网络的特点,以先应式最优链路状态路由协议为基础,整合有限分发路由信息机制与高效分发路由信息机制。结合自适应的检测模块,提出了一种自适应视觉朦胧的链路状态路由协议———自适应视觉的朦胧的链路状态(Adaptive Fuzzy Sighted Link State,AFSLS)路由协议。NS2仿真结果表明,AFSLS路由协议在平均时延、网络吞吐量以及丢包率方面有良好的性能,能够满足无线移动Mesh网络对路由协议的要求。     

基于跨层设计的AODV路由优化机制

以AODV(无线自组网按需平面距离矢量路由)协议为原型,针对WMN(无线Mesh网)中传统AODV协议路由判据单一从而导致路由性能较差的缺陷,采用跨层设计方法为WMN设计了一种新的IAODV(优化的AODV)协议。在路由计算过程中通过跨层操作机制提取节点当前负载和链路投递率这两个影响链路质量的因素,结合路由跳数设计出合理的路由判决函数。理论分析和NS2仿真结果证明,这种路由优化机制提高了吞吐量,降低了网络时延,并且能够达到负载均衡的路由效果。     

基于无环替代重路由的无线Mesh网络自愈策略研究

无线Mesh网络的链路不可靠特性容易造成网络的不稳定和转发不连续,前摄性重路由可以解决这一问题。该文对基于无环替代重路由的无线Mesh网络自愈策略进行研究,提出了基于无环替代的AODV路由AODV-LFA,仿真实验表明AODV-LFA比AODV具有更强的自愈性能。     

多电台多信道无线mesh网络路由研究

针对多电台多信道无线mesh网络中AODV-MR路由判据是基于最小跳数,并且缺乏动态的负载均衡机制,不能选择和维护高性能的路由。针对以上不足,考虑无线链路传输速率、包损失率、流干扰以及通信负载,引入多尺度衡量路由判据MOWCETT和动态负载均衡机制,提出一种改进路由协议-OMAR。利用NS2仿真平台,仿真结果表明OMAR路由协议使路由性能得到改善。     

EFT: a high throughput routing metric for IEEE 802.11s wireless mesh networks

In this paper, we present a throughput-maximizing routing metric, referred to as expected forwarding time (EFT), for IEEE 802.11s-based wireless mesh networks. Our study reveals that most of the existing routing metrics select the paths with minimum aggregate transmission time of a packet. However, we show by analyses that, due to the shared nature of the wireless medium, other factors, such as transmission time of the contending nodes and their densities and loads, also affect the performance of routing metrics. We therefore first identify the factors that hinder the forwarding time of a packet. Furthermore, we add a new dimension to our metric by introducing traffic priority into our routing metric design, which, to the best of our knowledge, is completely unaddressed by existing studies. We also show how EFT can be incorporated into the hybrid wireless mesh protocol (HWMP), the path selection protocol used in the IEEE 802.11s draft standard. Finally, we study the performance of EFT through simulations under different network scenarios. Simulation results show that EFT outperforms other routing metrics in terms of average network throughput, end-to-end delay, and packet loss rate.     

无线网状网路由判据研究

无线网状网(WMN)相关技术的研究非常活跃,路由判据的设计是提高其性能的关键。WMN具有同时拥有移动节点和静态节点及每个节点可能配置多信道等特点。对路由判据的设计提出了特别的要求:必须保证网络的稳定性;保证最小权重路由有最佳性能;该路由可以通过多项式复杂度算法得到;得到的路由中无转发环路。研究了几种现有的路由判据,包括HOP、ETX、ETT、WC-ETT、MIC、mETX、ENT。MIC能较好适应WMN,但需要在自由因子的设定及网络中加入移动节点后的性能方面做改进。对路由判据的跨层、多准则设计是以后的研究方向,基于此文中也对几个改进方案进行分析。     

EPTR: expected path throughput based routing protocol for wireless mesh network

For effective routing in wireless mesh networks, we proposed a routing metric, expected path throughput (EPT), and a routing protocol, expected path throughput routing protocol (EPTR), to maximize the network throughput. The routing metric EPT is based on the estimated available bandwidth of the routing path, considering the link quality, the inter- and intra-flow interference and the path length. To calculate the EPT of a routing path, we first calculate the expected bandwidth of the link and the clique, and then consider the decay caused by the path length. Based on EPT, a distributed routing protocol EPTR is proposed, aiming to balance the network load and maximize the network throughput. Extensive simulations are conducted to evaluate the performance of the proposed solution. The results show that the proposed EPTR can effectively balance the network load, achieve high network throughput, and out-perform the existing routing protocols with the routing metrics previously proposed for wireless mesh networks.     

An adaptive load-aware routing algorithm for multi-interface wireless mesh networks

In wireless mesh networks, the number of gateway nodes are limited, when the nodes access to the internet by fixed gateway node, different requirements of nodes lead to the dataflow shows heterogeneity. Many new routing metrics and algorithms existing in traditional wired networks and the Ad Hoc network, can not be directly applied to wireless mesh networks, so how to design a routing metric and algorithm which can dynamically adapt to current networks topology and dataflow changes, avoid bottleneck node, and select the most stable and least congestion link to establish a route is very important. In this paper, we presented a new dynamic adaptive channel load-aware metric (LAM) to solve the link load imbalance caused by inter-flow and inner-flow interference, designed a self-adaptive dynamic load balancing on-demand routing algorithm through extending and improving AODV routing method with the LAM, to achieve flow balance, reduce the high packet loss ratio and latency because congestion and Packet retransmission, and can increase Network Throughput.     

Comparative analysis of link quality metrics and routing protocols for optimal route construction in wireless mesh networks

We provide a comparative analysis of various routing strategies that affect the end-to-end performance in wireless mesh networks. We first improve well-known link quality metrics and routing algorithms to enhance performance in wireless mesh environments. We then investigate the route optimality, i.e., whether the best end-to-end route with respect to a given link quality metric is established, and its impact on the network performance. Network topologies, number of concurrent flows, and interference types are varied in our evaluation and we find that a non-optimal route is often established because of the routing protocol’s misbehavior, inaccurate link metric design, interflow interference, and their interplay. Through extensive simulation analysis, we present insights on how to design wireless link metrics and routing algorithms to enhance the network capacity and provide reliable connectivity.     

Multi-radio multi-channel routing metrics in IEEE 802.11s based wireless mesh networks

IEEE 802.11s is one of the emerging standards designed to build wireless mesh networks which may serve to extend the coverage of access networks. The default IEEE 802.11s path selection protocol Hybrid Wireless Mesh Protocol (HWMP) is based on the radio-aware airtime link metric (ALM) that outperforms the hop-count metric in single channel multi-hop wireless networks. However, this metric may lead to capacity degradation when multiple channels and/or multi-radio are used. To fully exploit the capacity gain of multiple channels use, new routing metrics have been proposed such as weighted cumulative expected transmission time, metric of interference and channel switching, interference aware routing metric, exclusive expected transmission time, and normalized bottleneck link capacity. These metrics distribute the data traffic load among channels and/or radios to reach the final destination. In this paper, we provide a qualitative comparison study that considers the characteristics of these metrics. Indeed, we substitute ALM by these different metrics, and we evaluate the performance of HWMP through simulation. Obtained results allow us to identify the appropriate use case of each metric.     

Design and Performance Evaluation of IAR: Interference-Aware Routing Metric for Wireless Mesh Networks

Multihop wireless mesh networks are an attractive solution for providing last-mile connectivity. However, the shared nature of the transmission medium makes it challenging to fully exploit these networks. In an attempt to improve the radio resource utilization, several routing metrics have been specifically designed for wireless mesh networks. However none of these routing metrics efficiently tackles interference issues. Moreover, although some evaluations have been conducted to assess the performance of these metrics in some contrived scenarios, no overall comparison has been performed. The contributions of this paper are consequently twofold. First, we propose a new routing metric, Interference-Aware Routing metric (IAR), specifically designed for WMNs. IAR uses MAC-level information to measure the share of the channel that each link is able to utilize effectively. As a result, paths that exhibit the least interference will be selected to route the data traffic. Then we evaluate the performance of IAR against some of the most popular routing metrics currently used in wireless mesh networks: Hop Count, Blocking Metric, Expected Transmission Count (ETX), Expected Transmission Time (ETT), Modified ETX (mETX), Network Allocation Vector Count (NAVC) and Metric of Interference and Channel-Switching (MIC). We show under various simulation scenarios that IAR performs the best in terms of end-to-end delay and packet loss, and provides the fairest resource utilization.     

Routing metric of interference-aware link quality： an improved ETX in wireless mesh networks

This article addresses the problem of route selection in wireless mesh networks （WMNs）. The traditional routing metrics adopt packet delivery ratio （PDR） as a representative metric of wireless link quality assessment. However, PDR measured by the broadcast-based probe method is affected by the size, number and transmission rate of probe packets, which influences the metric accuracy. In this paper, improved expected transmission count （iETX）, a new routing metric of interference-aware link quality, is proposed for WMNs. Dispensing with traditional broadcast-based probing method, the iETX uses regional physical interference model to obtain PDR. Regional physical interference model is built upon the relationship between signal to interference plus noise ratio （SINR） and PDR, which contributes to the improvement of metric accuracy. The iETX comprehensively considers the effects of interference and link quality and minimizes the expected number of packet transmissions required for successful delivery, which helps find a path with minimum interference and high throughput. Simulation shows that the proposed metric can significantly improve the network performance.     

Reinforcement learning based routing in wireless mesh networks

This paper addresses the problem of efficient routing in backbone wireless mesh networks (WMNs) where each mesh router is equipped with multiple radio interfaces and a subset of nodes serve as gateways to the Internet. Most routing schemes have been designed to reduce routing costs by optimizing one metric, e.g., hop count and interference ratio. However, when considering these metrics together, the complexity of the routing problem increases drastically. Thus, an efficient and adaptive routing scheme that takes into account several metrics simultaneously and considers traffic congestion around the gateways is needed. In this paper, we propose an adaptive scheme for routing traffic in WMNs, called Reinforcement Learning-based Distributed Routing (RLBDR), that (1) considers the critical areas around the gateways where mesh routers are much more likely to become congested and (2) adaptively learns an optimal routing policy taking into account multiple metrics, such as loss ratio, interference ratio, load at the gateways and end-to end delay. Simulation results show that RLBDR can significantly improve the overall network performance compared to schemes using either Metric of Interference and Channel switching, Best Path to Best Gateway, Expected Transmission count, nearest gateway (i.e., shortest path to gateway) or load at gateways as a metric for path selection.