基于网络编码技术的水声网络路由协议研究

针对水声通信传输速率低、时延大的缺点,提出在水声环境下将随机网络编码方法应用于节点之间广播通信,利用NS-2仿真软件对网络编码路由协议NCR(Network Coding Routing)进行仿真,并分别从投递率、投递时延、协议开销和冲突率4个网络性能评价指标进行了分析。发现在节点数量为50的随机网络拓扑结构中,与传统的泛洪(Flooding)方式相比,NCR协议的数据包投递率大约提高了20%~50%,网络时延降低了大约50%~60%,NCR协议改善了水声通信网络传输效率,提高投递率,提高能量利用效率和传输可靠性,时延和数据冲突率有效降低,网络性能获得明显改善。     

水声传感器网络实时路由算法研究

水下声信道的传输特点,使得在水声传感器网络中实现实时传输非常困难。文章在SPEED协议的基础上提出了一种水下传感器网络的实时路由算法LQRT。该算法通过节点的链路感知能力,来达到实时传输的要求,同时还能延长网络的生存期。仿真结果表明,该算法在水声传感器网络实时应用环境中具有很好的性能。     

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。     

无线Ad hoc网络机会路由的实现与仿真

在无线自组织网络中,路由协议对网络的性能起着关键性作用。然而由于无线信道的不稳定性经常造成通信中断而需重建路由,使自组织网传统路由协议的效率大大降低。提出了一种应用于无线自组织网络的机会路由协议（WAOR）,利用无线信道的广播特性和多径传输来增强链路的可靠性。采用网络仿真器NS2的仿真结果表明,WAOR的性能优于传统的动态源路由协议（DSR）和自组织网按需平面距离矢量路由协议（AODV）。     

机动突击中的自组网多路径路由技术

随着作战样式的变化和武器装备的变革,装甲车辆机动突击作战中协同控制的重要性不断增强,对网络通信的各项性能指标提出了更高要求,而自组织网络所具备的一些优良特性能够较好地适应这一需求。在网络通信中,稳定性是衡量网络路由性能的重要因素。机动突击作战中,车辆移动、障碍物阻挡等因素将导致网络拓扑变化迅速,给路由稳定性带来严重影响,极大地降低了网络通信质量。基于AODV协议,设计并仿真了一种链路不相交的多路径被动式路由协议,以路由回复消息中携带的路由信息为基础,实现两条不相交链路作为通信路由并互为备份。仿真结果表明,该协议在数据包到达率及平均时延方面较AODV协议均有一定提高。     

短波Ad Hoc路由协议仿真与性能分析

为找到一种适合短波Ad hoc网络使用的路由协议,通过OPNET仿真软件对短波信道进行建模,在该模型的基础上对无线Ad Hoc常用的3种路由协议:优化链路状态路由(Optimized Link State Routing,OLSR)、反应式路由中的动态源路由(Dynamic Source Routing,DSR)和按需距离矢量(Ad hoc On Demand Distance Vector,AODV)进行仿真分析。仿真结果表明,OLSR路由协议网络时延最小、吞吐量最高和数据丢失率最低,其整体性能优于AODV及DSR路由协议,更适合于短波信道,但是OLSR路由协议也存在着开销高的不足,下一步可以针对降低路由开销进行研究。     

高动态Ad Hoc路由协议性能分析

Ad Hoc网络是一种没有固定设施的无线移动自组织网络,动态变化的拓扑结构对路由协议的性能有着重要影响。研究了动态源路由(DSR)协议、Ad Hoc按需距离矢量(AODV)路由协议和最优链路状态路由(OLSR)协议3种传统路由协议,利用OPNET软件作为仿真工具,设计了2种不同网络规模条件下空中飞行平台网络拓扑结构背景的高动态仿真方案,通过比较网络时延、归一化网络吞吐量、路由负载和数据传送成功率,分析了它们的性能。仿真结果表明,OLSR协议的综合性能优于其它协议,更适合于节点高速移动且网络拓扑结构频繁变化的Ad hoc网络,并为下一步研究打下基础。     

基于802.11 MAC的移动Ad Hoc网络AODV路由协议改进算法

基于802.11的Ad Hoc网络AODV路由协议会引入通信盲区问题,使路由发现信息建立的路由不能很好地满足高速数据分组的传输,本文在传统通信盲区解决方案的基础上提出一种AODV路由协议改进算法.Opnet仿真表明,改进算法能有效地提高Ad-hoc网络性能.     

一种基于AODV路由协议的分簇算法研究

基于距离向量的按需路由协议AODV是AdHoc网络研究的热点之一。该协议有效减少了建立和维护路由所需要的开支,但是随着网络节点发送数据量的增加,网络性能会迅速下降。为了提高AdHoc网络的路由效率和可靠性,文章提出了一种基于AODV路由协议的分簇算法。经仿真研究分析表明,该算法提高了网络节点的平均每跳吞吐率,减少了节点的平均每跳时延。     

定向接收低冲突率水声网络媒体接入控制协议

在全向水声通信网络场景中,较大的传播时延和较高的数据包碰撞率严重影响了网络性能。相比全向接收技术,声矢量传感器的声压和振速通过线性加权组合可以形成单边指向性,实现定向接收某个方向上的信号,进而提高网络的空间复用率。该文首先分析了声矢量传感器定向接收模式下的网络中断概率,验证定向接收技术网络应用的可行性。然后,提出了定向接收低冲突概率媒体接入控制协议(DRLCP-MAC)。该协议利用指向性接收波束握手机制建立稳定的数据传输链路,通过状态转移策略构建多对并行通信链路,缩小虚拟载波监听范围,提高网络的空间复用度。仿真结果表明,与水下冲突避免多址接入协议(MACA-U)和时隙地面多址接入协议(Slotted-FAMA)相比,DRLCP-MAC协议使信道接入成本降低了约50%和60%,网络吞吐量提升了约60%和400%,端到端时延降低了约50%和85%。     

A highly topology adaptable ad hoc routing protocol with complementary preemptive link breaking avoidance and path shortening mechanisms

Ad-hoc on-demand distance vector routing (AODV) is a well-known routing protocol for mobile ad hoc networks. The original AODV protocol works in a semi-dynamic fashion, by establishing a route on demand and using that route until it breaks. However, to suit the changing network topology of ad hoc networks, more aggressive and adaptable routing strategies are required. A number of researches have proposed improving AODV performance by locally repairing broken links, predicting and replacing potentially vulnerable links, or shortening a link through removing redundant nodes from the transmission path. Although local repair may relieve some problems, it usually results in longer paths and thus a considerable performance drop in heavy traffic conditions. There are also issues regarding packet loss and communication delay due to route rebuilding once the link is broken. Predicting and replacing potentially vulnerable links may require special hardware, additional tables to maintain, or other extra overhead. Finally, path shortening may result in shorter and more efficient routes, but there is no guarantee that the new paths will be robust. This paper proposes integrating preemptive link breaking avoidance and path shortening mechanisms into a modified AODV protocol. However, the difficult issue lies in determining the right timing to initiate the two independent mechanisms so that the two dynamically and complementarily operating mechanisms can work together to improve the routing performance. Through numerical analysis and simulation, we have arranged a simple parameter setting for controlling the activation of each mechanism at the appropriate time. The proposed combination is a highly dynamic ad hoc routing protocol that is capable of adapting itself to the changing network topology and achieving extremely good performance in various routing performance metrics. Extensive simulations show that each of the two schemes alone improves AODV performance. More importantly, the integrated protocol performs even better in terms of data delivery rate, average delay time, and network overhead. To be more specific, in the best cases our protocol can reduce up to 82% in control overhead and 66% in delay time, while achieving 12% more in data delivery rate comparing to AODV.     

移动自组网路由恢复算法的研究

移动自组网是由一组带有无线收发装置的移动终端组成的自治通信系统.煤矿井下移动自组网可应用于矿井的监控管理系统、数据采集系统或者应急通信系统.移动自组网的路由方案主要包括表驱动(Proactive)和按需驱动(Reactive)两种,AODV是一种代表性的按需驱动算法.文中介绍了利用辅助路径基于AODV的一种矿井移动自组网的路由恢复算法,给出了辅助路由算法的性能测评方案.     

水声通信网络介质访问控制协议的设计与仿真

采用OPNET平台对水声通信网络节点模型与介质访问控制协议进行了设计与实现,并重点研究建立了基于忙时间改进网络分配向量帧冲突处理机制的水声通信网络协议——UMACAW。同时建立并测试了包含1个主节点与4个传感器节点的水声通信网络。仿真结果表明,MAC层采用UMACAW协议能更好地克服冲突,减少节点间端对端传输延时,从而获得更高水声通信网络的吞吐量。     

Transmission Power Control Aware Routing in Cognitive Radio Ad Hoc Networks

Abstract—Cognitive radio technology has drawn much attention since it is a promising candidate to efficiently utilize the scarce radio resources. However, cognitive radio introduces new challenges in the protocol stacks in wireless networks. This paper proposes a routing protocol for Cognitive Radio Ad Hoc Networks (CRAHNs), called Transmission Power Control aware AODV (TPC-AODV). TPC-AODV is based on Ad hoc On Demand Distance Vector (AODV) routing protocol. The main objectives of TPC-AODV are to avoid interruption of primary users’ communication and to support basic Quality of Service for secondary users. TPC-AODV takes inputs from both secondary users’ application requirements and the channel condition after spectrum sensing. These inputs enable secondary users’ communication with specific transmission power on the selected channel. Our simulation results show that TPC-AODV improves network performance in terms of throughput and delay compared to AODV in CRAHNs.     

End-to-End Delay and Energy Efficient Routing Protocol for Underwater Wireless Sensor Networks

Providing better communication and maximising the communication performance in a Underwater Wireless Sensor Network (UWSN) is always challenging due to the volatile characteristics of the underwater environment. Radio signals cannot properly propagate underwater, so there is a need for acoustic technology that can support better data rates and reliable underwater wireless communications. Node mobility, 3-D spaces and horizontal communication links are some critical challenges to the researcher in designing new routing protocols for UWSNs. In this paper, we have proposed a novel routing protocol called Layer by layer Angle-Based Flooding (L2-ABF) to address the issues of continuous node movements, end-to-end delays and energy consumption. In L2-ABF, every node can calculate its flooding angle to forward data packets toward the sinks without using any explicit configuration or location information. The simulation results show that L2-ABF has some advantages over some existing flooding-based techniques and also can easily manage quick routing changes where node movements are frequent.     

基于AODV改进的水下传感器网络多径路由策略

根据水声信道特性对水声信道的链路传输质量与环路延时等参数进行估值,并在AODV协议的基础上进行改进,提出一种基于环路延时的多径路由传输策略。在初始化阶段根据链路传输质量得到多条路径,并根据定源宿点的环路延时选择主传播路径,从而达到降低网络能量开销与时延的目的。仿真结果表明,该算法相对于传统单径路由策略,能有效节约能量,延长生命周期。     

Shallow water acoustic networks

Underwater acoustic networks are generally formed by acoustically connected ocean bottom sensor nodes, autonomous underwater vehicles (AUVs), and surface stations that serve as gateways and provide radio communication links to on-shore stations. The quality of service of such networks is limited by the low bandwidth of acoustic transmission channels, high latency resulting from the slow propagation of sound, and elevated noise levels in some environments. The long-term goal in the design of underwater acoustic networks is to provide for a self-configuring network of distributed nodes with network links that automatically adapt to the environment through selection of the optimum system parameters. This article considers several aspects in the design of shallow water acoustic networks that maximize throughput and reliability while minimizing power consumption     

Overview of networking protocols for underwater wireless communications

Underwater wireless communications can enable many scientific, environmental, commercial, safety, and military applications. Wireless signal transmission is also crucial to remotely control instruments in ocean observatories and to enable coordination of swarms of autonomous underwater vehicles and robots, which will play the role of mobile nodes in future ocean observation networks by virtue of their flexibility and reconfigurability. To make underwater applications viable, efficient communication protocols among underwater devices, which are based on acoustic wireless technology for distances over one hundred meters, must be enabled because of the high attenuation and scattering that affect radio and optical waves, respectively. The unique characteristics of an underwater acoustic channel -- such as very limited and distance-dependent bandwidth, high propagation delays, and timevarying multipath and fading -- require new, efficient and reliable communication protocols to network multiple devices, either static or mobile, potentially over multiple hops. In this article, we provide an overview of recent medium access control, routing, transport, and crosslayer networking protocols.     

基于WiFi的自组织网络路由协议算法研究

以基于WiFi的自组织网络为应用背景,本文利用仿真平台OPNET对四种经典自组网路由协议的性能进行了仿真比较。实验结果表明,反应式路由协议的性能总体优于先应式路由算法,而AODV协议由于其备份路由的特性,性能更优。为满足战场环境下车载自组织网的大规模组网要求,以及火控数据的时延传输要求,结合AODV算法的优势,本文提出了一种新的分层自组网路由算法CRP,其分簇结构的设计减少了网络拓扑变化对寻由过程的影响和路由发现过程中的洪泛开销,加速了路由的查找过程,仿真结果显示该算法的综合性能优于AODV算法及经典分簇路由协议ZRP算法,端到端传输时延明显减小。     

LRP: Link quality‐aware queue‐based spectral clustering routing protocol for underwater acoustic sensor networks

Recently, underwater acoustic sensor networks (UASNs) have been considered as a promising approach for monitoring and exploring the oceans in lieu of traditional underwater wireline instruments. As a result, a broad range of applications exists ranging from oil industry to aquaculture and includes oceanographic data collection, disaster prevention, offshore exploration, assisted navigation, tactical surveillance, and pollution monitoring. However, the unique characteristics of underwater acoustic communication channels, such as high bit error rate, limited bandwidth, and variable delay, lead to a large number of packet drops, low throughput, and significant waste of energy because of packets retransmission in these applications. Hence, designing an efficient and reliable data communication protocol between sensor nodes and the sink is crucial for successful data transmission in underwater applications. Accordingly, this paper is intended to introduce a novel nature‐inspired evolutionary link quality‐aware queue‐based spectral clustering routing protocol for UASN‐based underwater applications. Because of its distributed nature, link quality‐aware queue‐based spectral clustering routing protocol successfully distributes network data traffic load evenly in harsh underwater environments and avoids hotspot problems that occur near the sink. In addition, because of its double check mechanism for signal to noise ratio and Euclidean distance, it adopts opportunistically and provides reliable dynamic cluster‐based routing architecture in the entire network. To sum up, the proposed approach successfully finds the best forwarding relay node for data transmission and avoids path loops and packet losses in both sparse and densely deployed UASNs. Our experimental results obtained in a set of extensive simulation studies verify that the proposed protocol performs better than the existing routing protocols in terms of data delivery ratio, overall network throughput, end‐to‐end delay, and energy efficiency.