面向应用的车载自组织网络跨层多信道MAC协议

提出了一种面向应用的车载网络跨层多信道MAC协议。对来自应用层不同类型的消息进行实时统计,预测出最优控制信道周期,确保控制信道上安全消息的及时、可靠传输,同时采用预约机制实现消息在服务信道上的无竞争传输,提高服务信道的吞吐量。本协议适合饱和与非饱和的一般VANET环境,具有较低的计算复杂度,扩展性较好。与现存的其他协议相比较,仿真结果证实了所提协议的优越性。     

Ad Hoc网络中的多信道多接口技术研究

无线自组织网络是一种不依赖基础设施的无线网络,网络中节点均是由移动主机构成.文中通过修改NS2中的移动节点结构引入多信道多接口,可以使得路由协议能够灵活调用多信道功能,并根据AODVPlus协议的实现机制,提出一种对应的信道分配策略.通过仿真模拟与单信道进行比较分析得出,多信道多接口在传输率与传输时延方面比单信道都有所改善,但有效的多信道分配策略显得尤为重要.     

Ad-hoc网络中一种低控制开销的多信道MAC协议

针对Ad-hoc网络中多信道MAC机制引起的控制信道瓶颈问题和隐终端问题,该文提出一种低控制开销MAC协议(LCO-MAC)。与基于信道使用表一类的MAC机制不同,LCO-MAC参考Meshhadany提出的RTS/CTS (Request To Send/Clear To Send)信道分配机制,将数据信道映射为帧中时隙,但不同的是LCO-MAC不限制RTS的发送时间,且一旦申请信道后即可发送数据。仿真结果表明,LCO-MAC无需传输太多的控制信息用于预约信道,有效缓解了控制信道瓶颈问题和多信道隐终端问题,网络吞吐量也得到明显提升。     

无线MESH网络中的多信道MAC协议概述

分析了无线mesh网络多信道应用的必要性;介绍了多信道应用的现状,列出了几种典型的多信道协议;对各种多信道协议进行了分析,总结了其优缺点;提出对多信道未来改进方向的看法.     

移动代理WSN网络中信道Sift MAC协议

介绍了一种采用移动代理的无线传感器(WSN)网络,该网络系统由移动代理节点负责复杂数据处理、接入处理、数据转发传输、路由维护等工作,与一般WSN网络相比具有节能优势。该网络系统MAC层采用S-ALOHA协议,不仅网络吞吐量低而且能耗大,依据网络结构特点提出了采用基于信噪比(SNR)的信道Sift协议。仿真验证该协议大大提高了网络吞吐量和降低了网络系统能耗。     

无线传感器网络和移动自组织网络的MAC协议

首先对移动自组织网络与无线传感器网络进行介绍;接着指出了在多跳和自组织要求下．MAC需要解决的两个基本问题．即网络形成和公平有效地在节点之间共享通信资源;然后对现有的MAC协议进行了分类与回顾．阐述了MAC协议的最新进展;最后指出了MAC协议需要解决的问题。     

Ad Hoc网络支持QoS保障的多信道MAC协议

提出一种基于多信道的QoS保障方案,结合业务区分和资源预留两种QoS保障策略,保证优先级高的业务及时接入信道;并且建立节点发送链表,给数据通信预留一段时间,实现数据信道上连续的帧交换,有效地使用了数据信道资源。     

Ad Hoc网络支持QoS保障的多信道MAC协议

提出一种基于多信道的Qo S保障方案,结合业务区分和资源预留两种Qo S保障策略,保证优先级高的业务及时接入信道;并且建立节点发送链表,给数据通信预留一段时间,实现数据信道上连续的帧交换,有效地使用了数据信道资源。     

无线Mesh网络多信道MAC协议

分析了WMN多信道MAC协议设计所面临的问题;介绍了几种现有典型的多信道MAC协议,并对其进行了分析;对多信道MAC协议未来的发展作了简要的总结。期望文章使读者对WMN多信道MAC协议的关键技术,特别是协议的设计有一个概括性的了解。     

基于网络分割的无线传感器网络多信道MAC协议

无线传感器网络中,可用正交信道数目较少和噪声干扰问题制约着多信道MAC协议性能的提升,结合数据采集应用的特点,提出一种基于网络分割的多信道MAC协议。在最小化网络总干扰值的基础上,网络分割引入碰撞因子进一步优化子树结构、降低树内干扰。并利用基于图着色理论的分配策略为每棵子树分配一条高质量信道。仿真实验结果表明,该协议显著提高了网络吞吐量,并且大幅降低了传输延迟和分组丢失率。     

Misbehavior analysis of IEEE 802.11 MAC layer in mobile ad hoc network using stochastic reward nets

In this paper, we present a Petri net model for performance evaluation of IEEE 802.11 distributed coordination function as a popular media access control layer protocol in mobile ad hoc network. The goal of this evaluation is to examine this protocol under the existing of misbehavior nodes that selfishly try to grasp common channel in a neighbor area. The presented model consists of 2 separate models based on stochastic reward net (SRN), as a variation of stochastic Petri net. The first model, which is called one node operation model , is supposed for presenting all distributed coordination function operations in a single node such as collision avoidance, request to send/clear to send (RTS/CTS) handshake, and backoff mechanism. The next SRN model, all node operation model , is used for modeling nodes competition for occupying channel in a neighbor area. The models could be adjusted to a dynamic network with any number of nodes, dimension scale, and nodes' speed. For evaluation purpose, 4 distinct attack types implemented by modifying associated transitions in SRN models. The proposed SRN model has been quantified by deriving 2 performances metrics as Throughput and Delay . Both metrics are also compared to the value obtained from NS‐2 in terms of different number of nodes and 3 packet generation rates. Three additional metrics measuring the channel usage are also quantified in terms of different attack strategies using only presented SRN model.     

移动自组织网络中基于QoE的跨层多波束信道接入机制

引入数字多波束技术可以使移动自组织网络的信道容量得到有效提升，然而，时间、频率、空间、用户、功率等多维度资源域的统一调度与跨层联合优化使得信道接入机制的分析与设计变得更加复杂。为此，结合多波束的特性，将波束宽度限制、收发限制、通道限制、功率限制等多种约束条件抽象图论问题，并建立分析模型。基于分析模型，进一步提出了MB-MAC（Multi-beam Medium Access Control）信道接入机制，结合物理层的预编码技术，建立定向链路的队列模型，度量用户的满意度(Quality of Experience,QoE)，设计了适用于自组织网络中多用户并发并收的信道接入机制，兼顾了网络容量和用户满意度。仿真结果表明，MB-MAC机制能在保证各个用户满意度的情况下，有效提升网络吞吐率。     

Research on multi-channel routing threats and defense for cognitive ad hoc network

In the environment of scarce spectrum resources,cognitive ad hoc network which is independent with infrastruc-ture and fixed spectrum allocation policy,has been also developed quickly.Due to the characteristic of multi-channel routing,cognitive ad hoc network is commonly perceived as an environment offering both opportunities and threats.To further un-derstand the multi-channel routing threats,the current research situation and development trend,the types of threats were analyzed in terms of the node routing and the multi-channel selection,and several typical security methods were concluded.Meanwhile,the most important solution to keep the security of cognitive radio network was found to build trust relationship among cognitive users.Trust management was just the basic technology to solve the security problems of multi-channel routing.Finally,the current problems of related works and research trends in this area were discussed.     

CAPACITY EVALUATION OF MULTI-CHANNEL WIRELESS AD HOC NETWORKS

In this paper, the capacity of multi-channel, multi-hop ad hoc network is evaluated.In particular, the performance of multi-hop ad hoc network with single channel IEEE 802.11 MAC utilizing different topologies is shown. Also the scaling laws of throughputs for largescale ad hoc networks and the theoretical guaranteed throughput bounds for multi-channel grid topology systems are proposed. The results presented in this work will help researchers to choose the proper parameter settings in evaluation of protocols for multi-hop ad hoc networks.     

基于多信道的自组织网络功率控制方法

为解决自组网中功率控制引发的碰撞问题,通过引入多信道技术,结合网络层最小功率路由策略,实现了基于多信道功率可控的自组织网络架构MCBPC。该架构控制了拓扑结构的频繁变化,降低了因功率控制带来的碰撞机率,并实现了节省能量的目的。通过NS-2仿真实验验证,相比基于802.11的AODV架构,MCBPC在成功递交分组数、网络生存时间上均提高了90%以上,分组成功递交率也提高达30%以上。     

RSU-coordinated multichannel MAC protocol in vehicular ad hoc network

A road side unit (RSU)-coordinated multichannel media access control (MAC) (RMM) protocol was proposed in vehicular ad hoc network,which aimed to improve the transmission efficiency of non-safety messages.Under the coordination of RSU,nodes had more opportunities to make SCH reservations on control channel,and the contention-free message transmissions were thus realized.The proposed RMM protocol could use the service channel during the whole synchronization interval for non-safety message transmissions,and thus the saturated network throughput and channel utilization were improved,and the transmission delay was reduced.Compared with other existing protocols,extensive analysis and simulation results demonstrate the superiority of the RMM protocol.     

Eventually Byzantine Agreement on CDS-based mobile ad hoc network

Reliability is an important research topic in the study of distributed systems. Under many circumstances, a healthy processor in a distributed system needs to reach a common agreement before performing some special tasks even if the faults exist. In order to achieve fault-tolerance in distributed systems, one must deal with the Byzantine Agreement (BA) problem. Most BA problem require all the healthy processors to obtain an agreement at the same round, this kind of agreement is called an Immediate Byzantine Agreement (IBA). Another kind of agreement, Eventual Byzantine Agreement (EBA), allows its participants to reach a common agreement at different rounds when the f_act < f_p (f_act is the number of actual arbitrary faulty processors; f_p is the number of tolerate arbitrary faulty processors). However, the traditional EBA problem is solved in well-defined networks, but the Mobile Ad hoc NETworks (MANETs) are increasing in popularity. Therefore, EBA problem is revisited under dual failure mode (processors and transmission media) in the MANET. The proposed protocol, Early Dual Agreement Protocol (EDAP), can achieve agreement while tolerating the maximum number of faulty processors and transmission media in a MANET by using the minimum number of message exchanges. Furthermore, our protocol can manage and organize the network efficiently even if the processors move around the network.     

An efficient MAC protocol for cooperative diversity in mobile ad hoc networks

Cooperative diversity is proposed to combat the detrimental effects of channel fading. In this paper, we investigate the effectiveness of cooperative diversity in interference limited ad hoc networks. The negative effects due to relay blocking on the network throughput are investigated. We show that the relay blocking problem is mainly dependent on the relay selection criterion. To overcome this problem, we propose a new cooperative diversity technique based on a modified IEEE 802.11 Medium Access Control (MAC) protocol. The throughput performance of the proposed MAC protocol is analyzed using a random structured network where nodes are assumed to be equipped with multiple antennas. In our simulations, we consider both single‐ and multiple‐relay scenarios over fading channels. Copyright © 2007 John Wiley & Sons, Ltd.     

一种新的基于多包接收的ad hoc网络媒体接入算法

多包接收技术在无线网络中的应用为提高网络吞吐量提供了一种新思路。本文在结合多包接收技术的基础上提出了一种应用于ad hoc网络的新的媒体接入控制算法，并对其吞吐量作了分析，与IEEE802．11MAC接入方式进行了性能比较。仿真结果表明，在业务量大于某一特定值时，新算法可以显著的提高ad hoc网络的吞吐量。     

基于朋友机制的移动ad hoc网络路由入侵检测模型研究

从如何有效检测移动ad hoc网络路由入侵行为、如何准确地响应并将恶意路由节点移除网络,提供可信路由环境的角度进行分析,提出了一种基于朋友机制的轻量级移动ad hoc网络入侵检测模型,并以典型的黑洞攻击为例,通过OPNET网络建模仿真及实验分析,验证了该模型的可行性和有效性。