WSNs中基于转发区域调整的能效地理路由

针对无线传感网络(WSNs)的数据传输问题,提出基于转发区域调整的能效地理位置路由(FAEG)。FAEG限定了数据包的转发区域,构建候选转发节点集,并从节点集中选择权重大的节点传递数据包;通过节点剩余能量和离目的节点距离信息计算节点权重,使剩余能量大和离目的节点近的节点具有优先传递数据包的资格,提高了路由稳定性。节点遭遇路由空洞时,则调整转发区域,在更广范围内选择传输数据包的节点。仿真结果表明,提出的FAEG降低了能耗,并提高了数据包传递率。     

基于地理-机会的水下无线传感网的混合路由

水下无线传感网络UWSNs被认为是监测海洋最有前景的技术。然而,声信道特性给UWSNs的数据采集提出了挑战。提高UWSNs数据采集效率的有效方式就是融合水下声通信和高动态网络拓扑的特性,设计高性能的路由协议。为此,提出基于地理-机会的水下无线传感网的混合路由,记为GOHR。在GOHR协议中,源节点先计算候选转发节点集,并计算集内每个节点的归一化权重值,再依据归一化权重值对集内节点进行排序,并形成转发节点簇。然后,计算每个簇的期望权重值,最后,选择期望权重值最大的簇内节点作为数据包转发节点。为了避免簇内节点转发数据包时发生碰撞,设置定时延时转发机制。仿真结果表明,提出的GOHR协议提高了数据包传递率,降低了数据包的传输时延。     

基于拓扑感知的水下传感网络路由

由于水下传感网络的高时延、低带宽和高能耗等特性,建立路由协议仍存在挑战。为此,提出基于拓扑感知的水下传感网络路由(TAR)。TAR路由先通过交互Beacon包,使每个节点获取网络拓扑信息,并建立邻居信息表。再依据节点剩余能量和链路的可靠性,择优选择下一跳转发节点,进而提高路由的稳定性,平衡节点间能耗。仿真结果表明,提出的TAR路由增强了路由稳定性,并减少了节点的能耗。     

接触时间感知的移动WSNs路由

多数无线传感网络应用中需要处理节点移动性,为此,面向移动无线传感网络(M-WSNs),提出基于接触时间的区路由(CTAR)。CTAR路由先利用源节点和目的节点的相对位置信息形成活动区,只有区内的节点才能参与路由;然后,利用节点的移动矢量信息选择能够最大化接触时间的邻居节点作为下一跳转发节点。仿真数据表明,与RoF协议相比,CTAR协议的数据包传递率得到有效提高。     

基于博弈的协作路由算法

协作虚拟多输入多输出（VMIMO）传输是一种有效的无线传输性能优化技术。将物理层协作VMIMO技术和网络层路由选择技术相结合,设计跨层VMIMO路由选择方案可以利用VMIMO的分集增益,显著地降低网络传输能耗。如何设计VMIMO协作路由协议抵抗无线网络的自私节点和欺骗行为,保证高数据转发率和低传输能耗成为路由设计中的重大挑战。为了提高自私网络的VMIMO路由性能,提出了一种基于重复路由博弈的VMIMO协作路由算法。该算法将网络划分成多个Group、Group间使用VMIMO传输数据。将Group间路由选择过程建模为重复路由博弈过程。为了提高数据转发的成功率,提出适用度函数评估节点参与数据分组转发的信誉。以此为基础,提出基于适用度的路由选择子算法和路由转发子算法。理论证明所提重复路由博弈可达到帕累托最优。仿真实验结果表明本算法可以促进自私节点相互合作,可获得较高的数据转发率,较好地减少数据传输时延以及能量消耗。     

基于智能天线的定向传播路由协议在WSAN中的应用

在无线传感器及执行器网络(WSAN)中,节点的协作需要通过路由协议进行大量的信息转发。传统使用全方向天线的节点存在能耗高、传输延迟高、数据包传递率低的问题。文中基于智能天线,将定向传播路由协议(ADA)应用于WSAN网络中,通过定向的转发信息减小节点能耗,降低传输延迟,提高数据包传递率。最后,通过Matlab对ADA协议和其他使用全方向天线的节点通信协议的性能进行仿真对比。实验结果表明,在节点能耗、数据包传送延迟和数据包传递率方面,基于智能天线的ADA协议优于其他使用全方向天线的节点通信协议。     

MANETs中基于节点移动度的虚连接的路由

由于移动自组织网络MANETs中节点的快速移动,使得维持源节点与目的节点间的通信路径成为一项挑战性工作。节点的高速移动导致通信链路频繁断裂。为此,提出基于节点移动度的虚连接的路由(MDVRP)。虚路由为一条动态的逻辑路由,其由一系列的特定地理区域构成。每个区域内的节点依据自己的移动度设置转发数据包的定时器,移动度越小,具有优先转发数据包权。MDVRP通过虚路由策略,在源节点与目的节点间建立了多条传输路通,每个节点能独立选取下一跳转发节点,并利用节点移动度,择优选取转发数据包下一跳节点,从而提高链路的稳定性。仿真结果表明,提出的路由协议在端到端传输时延、路由开销以及数据包传输率性能均得到提高。     

基于中断概率的多跳混合协作地理路由算法

为了减小无线传感器网络中路由的路径长度,该文提出基于中断概率的多跳混合协作地理路由(MHCGR)算法。首先对不同协作机制的链路进行分析,理论分析表明,在一定中断概率要求下,采用译码放大转发混合协作机制可以进一步扩大传输距离,并推导了每跳协作链路的理想最大协作传输距离和理想中继的位置。在无信标地理路由(BLGR)算法的基础上,MHCGR算法结合节点位置信息为每跳选择最佳的中继节点和转发节点,建立从源节点到目的节点的多跳协作路由。仿真表明,与ENBGCR算法和基于DF协作机制的MPCR算法两种协作地理路由算法相比,MHCGR算法可明显减少路由的跳数,改善路由的整体发射功率。     

面向AODV的有效路由选择的研究

按需矢量路由(AODV)是移动自组织网络(MANET)的典型路由,然而AODV路由总是选择最短路径进行通信,这会引起网内流量的不平衡,可能也会引起拥塞问题,最终影响服务质量(QoS)。为此,提出基于AODV的权值路由方案,记为AODV-W。AODV-W路由考虑了路径传输时延、链路稳定性和节点能量,并利用这些信息计算路径权值。再选择权值最低的路径作为数据传输通道。实验数据表明,提出的AODV-W路由提高了数据包传递率和吞吐量。     

无线网络中基于DSDV的最大化吞吐量的协作路由算法

为最大化无线自组织网络的吞吐量,提出一种自适应的协作路由算法。在算法中,协作分集技术与路由选择相结合,通过在路由的每一跳选择最佳的中继节点协作发送节点传输信息来改善网络吞吐量。首先通过目的序列距离矢量路由协议（DSDV）初步建立最短路由路径,在每条链路的发送节点和接收节点根据邻节点表选出公共邻居节点,建立候选中继集合;进一步,每一跳根据链路吞吐量,在候选中继集合中自适应选择最多两个中继来协助发送节点进行传输,并根据选出的中继节点数动态分配节点发射功率。在保证系统发射功率一定的情况下,最大化网络吞吐量。仿真结果表明,在相同的发射功率下,相对于非协作路由DSDV算法,采用固定数量中继的协作路由算法提高了整个网络的吞吐量,而自适应的协作路由算法可进一步提高吞吐量;同时仿真了网络吞吐量与网络规模和节点最大移动速度的变化关系。      

车载自组织网中基于车辆密度的可靠性路由协议

为了降低转发节点在转发范围内直接寻找一个最优或次优节点的复杂度、减少平均跳数和提高链路的可靠性,提出一种车载自组织网络中基于车辆密度的可靠性路由协议,转发节点首先根据道路车辆密度设置最优块的大小,并将转发范围分割成若干大小相等的块,然后选择其中一个距离转发节点最远的块,最后在被选中的块里根据可靠性原则选择连接时间最长的邻居节点作为中继节点进行转发。仿真结果表明,与EG-RAODV 相比,所提路由协议的平均跳数较少,平均每跳前进距离较大,能够使数据分组快速到达目的节点。     

DFR: an efficient directional flooding‐based routing protocol in underwater sensor networks

Unlike terrestrial sensor networks, underwater sensor networks (UWSNs) have salient features such as a long propagation delay, narrow bandwidth, and high packet loss over links. Hence, path setup‐based routing protocols proposed for terrestrial sensor networks are not applicable because a large latency of the path establishment is observed, and packet delivery is not reliable in UWSNs. Even though routing protocols such as VBF (vector based forwarding) and HHVBF (hop‐by‐hop VBF) were introduced for UWSNs, their performance in terms of reliability deteriorates at high packet loss. In this paper, we therefore propose a directional flooding‐based routing protocol, called DFR, in order to achieve reliable packet delivery. DFR performs a so‐called controlled flooding, where DFR changes the number of nodes which participate in forwarding a packet according to their link quality. When a forwarding node has poor link quality to its neighbor nodes geographically advancing toward the sink, DFR allows more nodes to participate in forwarding the packet. Otherwise, a few nodes are enough to forward the packet reliably. In addition, we identify two types of void problems which can occur during the controlled flooding and introduce their corresponding solutions. Our simulation study using ns‐2 simulator proves that DFR is more suitable for UWSNs, especially when links are prone to packet loss. Copyright © 2011 John Wiley & Sons, Ltd.     

Environment-Driven Opportunity Forwarding Cross-Layer Optimization for Ubiquitous Wireless Networks

In this paper, an environment-driven cross-layer optimization scheme is proposed to maximize packet forwarding efficiency. The proposed algorithm is aimed to improve the performance of location-based routing protocol in respect of greedy forwarding and avoid void regions for ubiquitous wireless networks. In greedy forwarding mode, we use a new routing metric IAPS which can estimate the forwarding distance, link quality and the difficulty of channel access during the process of the next hop node selection. When the packet forwarding comes into a local minimum, the proposed scheme uses an opportunistic forwarding method based on competitive advantage to bypass the void regions. NS2 simulation results indicate that the proposed algorithm can improve network resource utilization and the average throughput, and reduce congestion loss rate of wireless multi-hop network comparison with existing GPSR algorithm.     

车联网中基于动态传输距离的多跳稳定路由

数据传输是车联网(VANETs)实现交通安全的基础。然而,车辆的移动、信号传输的衰减以及彼此间的干扰对链路的可靠性均有影响。为此,提出基于动态传输距离的多跳稳定(DTMS)路由。DTMS路由在选择下一跳转发节点时,考虑到因衰减而导致的传输距离的变小,先估计车辆动态传输距离,再依据动态传输距离估计链路的连通时间以及距离因素,然后,计算邻居节点的权重,最后,基于节点权重值设置定时器,进而竞争产生下一跳转发节点。仿真结果表明,提出的DTMS路由有效地提高了数据包传输成功率。     

On energy efficiency of geographic opportunistic routing in lossy multihop wireless networks

Geographic opportunistic routing (GOR) is an emerging technique that can improve energy efficiency in lossy multihop wireless networks. GOR makes local routing decision by using nodes?? location information, and exploits the broadcast nature and spatial diversity of the wireless medium to improve the packet forwarding reliability. In this paper, our goal is to fully understand the principles and tradeoffs in GOR, thus provide insightful analysis and guidance to the design of more efficient routing protocols in multihop wireless networks. We propose a local metric, one-hop energy efficiency (OEE), to balance the packet advancement, reliability and energy consumption in GOR. We identify and prove important properties about GOR on selecting and prioritizing the forwarding candidates in order to maximize the expected packet advancement. Leveraging the proved properties, we then propose two localized candidate selection algorithms with O(N ³) running time to determine the forwarding candidate set that maximizes OEE, where N is the number of available next-hop neighbors. Through extensive simulations, we show that GOR applying OEE achieves better energy efficiency than the existing geographic routing and blind opportunistic routing schemes under different node densities and packet sizes.     

Intelligent beaconless geographical forwarding for urban vehicular environments

A Vehicular Ad hoc Network is a type of wireless ad hoc network that facilitates ubiquitous connectivity between vehicles in the absence of fixed infrastructure. Source based geographical routing has been proven to perform well in unstable vehicular networks. However, these routing protocols leverage beacon messages to update the positional information of all direct neighbour nodes. As a result, high channel congestion or problems with outdated neighbour lists may occur. To this end, we propose a street-aware, Intelligent Beaconless (IB) geographical forwarding protocol based on modified 802.11 Request To Send (RTS)/ Clear To Send frames, for urban vehicular networks. That is, at the intersection, each candidate junction node leverage digital road maps as well as distance to destination, power signal strength of the RTS frame and direction routing metrics to determine if it should elect itself as a next relay node. For packet forwarding between Intersections, on the other hand, the candidate node considers the relative direction to the packet carrier node and power signal strength of the RTS frame as routing metrics to elect itself based on intelligently combined metrics. After designing the IB protocol, we implemented it and compared it with standard protocols. The simulation results show that the proposed protocol can improve average delay and successful packet delivery ratio in realistic wireless channel conditions and urban vehicular scenarios.     

Dynamic cache allocation routing strategy of Internet of things satellite node based on traffic prediction

Aiming at the routing problem of low earth orbit (LEO) Internet of things (IoT) satellite systems,a dynamic cache allocation routing strategy based on traffic prediction for IoT satellite nodes was proposed.Firstly,the space-time characteristics of traffic distribution in the LEO coverage area were analyzed,and an end-to-end traffic prediction model was proposed.Then,according to the traffic prediction result,a dynamic cache allocation routing strategy was proposed.The satellite node periodically monitored the traffic load of the inter-satellite link,dynamically allocated the cache resources of each inter-satellite link between the neighboring nodes.The cache allocation process was divided into two phases,initialization and system operation.At the same time,the traffic offload and packet forwarding strategy when the node was congested was proposed.By comparing the queuing delay and the forwarding delay,it was determined whether the data packet needs to be rerouted.The simulation results show that the proposed routing strategy effectively reduces the packet loss rate and average end-to-end delay,and improves the traffic distribution in the whole network.     

Energy‐efficient void avoidance geographic routing protocol for underwater sensor networks

Underwater wireless sensor networks (UWSNs) consist of a group of sensors that send the information to the sonobuoys at the surface level. Void area, however, is one of the challenges faced by UWSNs. When a sensor falls in a void area of communication, it causes problems such as high latency, power consumption, or packet loss. In this paper, an energy‐efficient void avoidance geographic routing protocol (EVAGR) has been proposed to handle the void area with low amount of energy consumption. In this protocol, a suitable set of forwarding nodes is selected using a weight function, and the data packets are forwarded to the nodes inside the set. The weight function includes the consumed energy and the depth of the candidate neighboring nodes, and candidate neighboring node selection is based on the packet advancement of the neighboring nodes toward the sonobuoys. Extensive simulation experiments were performed to evaluate the efficiency of the proposed protocol. Simulation results revealed that the proposed protocol can effectively achieve better performance in terms of energy consumption, packet drop, and routing overhead compared with the similar routing protocol.     

Simulation‐based real‐time routing protocol with load distribution in wireless sensor networks

In wireless sensor networks (WSNs), sensors gather information about the physical world and the base station makes decision and then performs appropriate actions upon the environment. This technology enables a user to effectively sense and monitor from a distance in real‐time. WSNs demand real‐time forwarding which means messages in the network are delivered according to their end‐to‐end deadlines (packet lifetime). This paper proposes a novel real‐time routing protocol with load distribution (RTLD) that ensures high packet throughput with minimized packet overhead and prolongs the lifetime of WSN. The routing depends on optimal forwarding (OF) decision that takes into account of the link quality (LQ), packet delay time and the remaining power of next hop sensor nodes. The proposed mechanism has been successfully studied through simulation work. Copyright © 2009 John Wiley & Sons, Ltd.