The multi-copy diversity for routing in sparse vehicular ad hoc networks

The need for routing based on store-and-carry forwarding has been motivated in sparse vehicular ad hoc networks (VANETs), since the traditional end-to-end unicast routing is infeasible due to the network disconnection problem. In store-and-carry based routing, the end-to-end message delivery delay is dominated by the store-and-carry procedure rather than the wireless transmission. Therefore, the end-to-end delay in such sparse VANETs can be further reduced by replicating multiple copies of the message to other nodes when possible, i.e., multi-copy routing, to increase the chance of finally finding the destination, which we call this gain as multi-copy diversity. In this paper, we present an analytic framework to evaluate the performance of routing by assessing the multi-copy diversity gain in sparse VANETs. By using this model, we first derive an upper and lower-bound of end-to-end routing delay in sparse VANETs. Our analytic results show that a high level of multi-copy diversity gain is achieved when the network is partially connected, which is in contrast to the conventional expectation that multi-copy routing performs better in severely disconnected networks. Second, we propose a new adaptive multi-copy VANET routing scheme called AMR by exploiting these analytic results. AMR adapts to the local network connectivity and increases the level of multi-copy diversity at significantly reduced routing overhead compared to the well known epidemic routing. We validate the accuracy of our analytic model and the performance of AMR via simulation studies.     

Boundary Mapping and Boundary-State Routing (BSR) in Ad Hoc Networks

This paper presents a geographic routing protocol, boundary state routing (BSR), which consists of two components. The first is an improved forwarding strategy, greedy-bounded compass, which can forward packets around concave boundaries, where the packet moves away from the destination without looping. The second component is a boundary mapping protocol (BMP), which is used to maintain link state information for boundaries containing concave vertices. The proposed forwarding strategy greedy-bounded compass is shown to produce a higher rate of path completion than Greedy forwarding and significantly improves the performance of greedy perimeter state routing (GPSR) in sparse networks when used in place of greedy forwarding. The proposed geographic routing protocol BSR is shown to produce significant improvements in performance in comparison to GPSR in sparse networks due to informed decisions regarding the direction of boundary traversal at local minima.     

Noncooperative Dynamic Routing with Bandwidth Constraint in Intermittently Connected Deep Space Information Networks Under Scheduled Contacts

The increasing world-wide demands in deep space scientific missions, such as Lunar, Mars and other Planetary Exploration, along with the rapidly growing advances in space communication technologies have triggered the vision of so called future Deep Space Information Networks (DSINs). The coined DSIN paradigm is envisioned to be an integrated high speed self-organizing hypernetwork consisting of the terrestrial ground-based information networks and the outer space-based entities to provide maximum network capacity. In this paper, we address the challenges of dynamic routing with bandwidth constraint over intermittently connected Deep Space Backbone Layer (DSBL) of DSINs under scheduled contacts. Firstly, we build up hypergraph model to represent DSBL aiming to improve network connectivity. Taking into account the continuous and random changes of selfish traffic along backbone links as well as the selfish forwarding of joint nodes, we propose a noncooperative dynamic routing model with bandwidth constraint, in which routing decision is related to the continuous-time resource usage. Our routing model includes two effective sub-models: stochastic differential game based noncooperative forwarding model with bandwidth constraints and contact schedule model. In addition, we provide a polynomial time algorithm to describe the procedure of our routing model. This algorithm covers three sub-algorithms considering three different cases based on hypergraph model, i.e., internal forwarding, cross-IS forwarding, cross-island forwarding. Theoretical analysis and numerical results demonstrate the effectiveness and feasibility of our routing model.     

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.     

A path selection based routing protocol for urban vehicular ad hoc network (UVAN) environment

Routing in urban environment is a challenging task due to high mobility of vehicles in the network. Many existing routing protocols only consider density, link connectivity, delay, and shortest path information to send the data to the destination. In this paper, a routing protocol is proposed which uses the urban road network information such as multi-lane and flyover to send the data to the destination with a minimum packet forwarding delay. The next path for data forwarding is selected based on a path value calculated by the Road Side Unit for each path connected to a junction. This protocol uses Ground Vehicle to Ground Vehicle (GV2GV) communication, Flyover Vehicle to Flyover Vehicle (FV2FV) communication, and Flyover Vehicle to Ground Vehicle/Ground Vehicle to Flyover Vehicle (FV2GV/GV2FV) communication to enhance the routing performance. Simulation results show that proposed protocol performs better than P-GEDIR, GyTAR, A-STAR, and GSR routing protocols in terms of end-to-end delay, number of network gaps, and number of hops.     

一种基于区域广播的VANET机会路由协议

对VANET网络中现有的路由协议进行了系统的分析和研究,提出了一种基于区域广播的VANET机会路由协议。基于安全消息在网络割裂情况下的传播需求,新协议结合地理信息和机会转发算法,提出了不同于点对点的新的基于区域广播的消息传播模式,以实现安全消息在稀疏车辆环境下的有效传播。理论分析和仿真实验表明,该协议相比传统路由协议具有更优异的网络性能和可靠性。     

Power control based cooperative opportunistic routing in wireless sensor networks

This paper proposes an approach called PC-CORP (Power Control based Cooperative Opportunistic Routing Protocol) for WSN (Wireless Sensor Networks), providing robustness to the random variations in network connectivity while ensuring better data forwarding efficiency in an energy efficient manner. Based on the realistic radio model, we combine the region-based routing, rendezvous scheme, sleep discipline and cooperative communication together to model data forwarding by cross layer design in WSN. At the same time, a lightweight transmission power control algorithm called PC-AIMD (Power Control Additive Increase Multiplicative Decrease) is introduced to utilize the cooperation of relay nodes to improve the forwarding efficiency performance and increase the robustness of the routing protocol. In the simulation, the performance of PC-COPR is investigated in terms of the adaptation of variations in network connectivity and satisfying the QoS requirements of application.     

DTN-Balance: A Forwarding-Capacity and Forwarding-Queue Aware Routing for Self-organizing DTNs

In delay-tolerant networks (DTNs), intermittent network connectivity and lack of global system information pose serious challenges to achieve effective data forwarding. Most state-of-the-art DTN routing algorithms are based on hill-climbing heuristics in order to select the best available next hop to achieve satisfactory network throughput and routing efficiency. An adverse consequence of this approach is that a small subset of good users take on most of the forwarding tasks. This can quickly deplete scarce resources (e.g. storage, battery, etc.) in heavily utilized devices which degrades the network reliability. A system with a significant amount of traffic carried by a small number of users is not robust to denial of service attacks and random failures. To overcome these deficiencies, this paper proposes a new routing algorithm, DTN-Balance, that takes the forwarding capacity and forwarding queue of the relay nodes into account to achieve a better load distribution in the network. For this, we defined a new routing metric called message forwarding utility combining nodal available bandwidth and forwarding workload. Applying small world theory, we impose an upper bound on the end-to-end hop count that results in a sharp increase in routing efficiency. Queued messages in a forwarding node are arranged by DTN-Balance based on message dropping utility metric for a more intelligent decision in the case of a message drop. The performance of our method is compared with that of the existing algorithms by simulations on real DTN traces. The results show that our algorithm provides outstanding forward efficiency at the expense of a small drop in the throughput.

     

Active routing for ad hoc networks

Ad hoc networks are wireless multihop networks whose highly volatile topology makes the design and operation of a standard routing protocol hard. With an active networking approach, one can define and deploy routing logic at runtime in order to adapt to special circumstances and requirements. We have implemented several active ad hoc routing protocols that configure the forwarding behavior of mobile nodes, allowing data packets to be efficiently routed between any two nodes of the wireless network. Isolating a simple forwarding layer in terms of both implementation and performance enables us to stream delay-sensitive audio data over the ad hoc network. In the control plane, active packets permanently monitor the connectivity and setup, and modify the routing state     

BA网络中一种基于节点动态权值的局部路由策略

为适应大规模通信网络的路由需求,提出了一种基于BA网络的局部路由策略。基本思想是在数据包转发过程中,将邻居节点的度和发送能力以一定比例加和得到的值作为权值,根据权值大小选择下一站点。其中,节点的发送能力由节点的数据包队列长度,节点的度及一个调节系数组成,节点的发送能力可根据实时数据包产生率进行调节。仿真结果表明,该路由策略有较好的通讯能力,通过改变加权算法中的比例系数可以调节网络的临界负载量,达到该算法下的最优路由方法,使节点的处理能力得到合理利用,为实际大规模通讯网络中利用局部路由实现数据传输提供了有效可靠的方法。     

On selection of forwarding nodes for long opportunistic routes

Opportunistic routing is a promising routing paradigm which increases the network throughput. It forces the sender’s neighbors, who successfully overheard the transmitted packet, to participate in the packet forwarding process as intermediate forwarding nodes. As a seminal opportunistic routing protocol, MORE combines network coding idea with opportunistic routing to eliminate the need for strict coordination among active forwarding nodes. In this paper, we show that MORE performance does not scale well with the route length, especially when the route length goes beyond two hops. Also, we found that MORE fails to establish a working opportunistic route in sparse networks. Clearly, the network throughput is directly influenced by both the quantity and quality of forwarding nodes, and their cooperation order. In this paper, we propose a new forwarder selection mechanism which considers the route length, link qualities, the distance from the source, and nodes density. It eliminates the occasional route disconnectivity happening in MORE and improves the quality of the established opportunistic routes. The simulation result indicates that our proposal always outperforms MORE when dealing with long opportunistic routes.

     

Connectivity-aware minimum-delay geographic routing with vehicle tracking in VANETs

In this paper, we propose the connectivity-aware minimum-delay geographic routing (CMGR) protocol for vehicular ad hoc networks (VANETs), which adapts well to continuously changing network status in such networks. When the network is sparse, CMGR takes the connectivity of routes into consideration in its route selection logic to maximize the chance of packet reception. On the other hand, in situations with dense network nodes, CMGR determines the routes with adequate connectivity and selects among them the route with the minimum delay. The performance limitations of CMGR in special vehicular networking situations are studied and addressed. These situations, which include the case where the target vehicle has moved away from its expected location and the case where traffic in a road junction is so sparse that no next-hop vehicle can be found on the intended out-going road, are also problematic in most routing protocols for VANETs. Finally, the proposed protocol is compared with two plausible geographic connectivity-aware routing protocols for VANETs, A-STAR and VADD. The obtained results show that CMGR outperforms A-STAR and VADD in terms of both packet delivery ratio and ratio of dropped data packets. For example, under the specific conditions considered in the simulations, when the maximum allowable one-way transmission delay is 1 min and one gateway is deployed in the network, the packet delivery ratio of CMGR is approximately 25% better than VADD and A-STAR for high vehicle densities and goes up to 900% better for low vehicle densities.     

消息内容保护的间断连接移动自组织网络转发机制

移动自组织网络资源有限,且节点之间共享无线信道并以协作的方式完成消息转发,导致所传输消息的机密性较为脆弱。为保护消息内容的机密性,该文提出一种间断连接移动自组织网络中的消息转发机制。各节点对原始消息进行切割,并利用多副本消息转发过程的冗余性和节点相似性控制各片段消息在不相交的路径上进行转发,进而由网络中的摆渡节点收集、检验并还原、加密得到仅目的节点能够解密的完整消息,确保转发过程中消息的机密性、完整性。数值分析表明所提机制在保障网络性能前提下,能有效保护消息的机密性。     

一种面向高速路车联网场景的自适应路由方法

车载自组织网络中节点的高速移动性使得网络拓扑频繁变化,造成路由效率低下.本文提出了一种面向高速路车联网场景的自适应路由方法.本方法采用了贪婪机会转发（GOF）算法,在选择下一跳转发节点时,同时考虑到目的节点的距离计算、节点间的链路状态以及下一跳的有效节点度状况来找出最优转发节点,并提出新的计算连通概率的方法.仿真实验和实际道路场景的测试表明,与相关算法相比在路由稳定性方面表现出较好的效果.     

The forwarding index of communication networks

A network is defined as an undirected graph and a routing which consists of a collection of simple paths connecting every pair of vertices in the graph. The forwarding index of a network is the maximum number of paths passing through any vertex in the graph. Thus it corresponds to the maximum amount of forwarding done by any node in a communication network with a fixed routing. For a given number of vertices, each having a given degree constraint, we consider the problem of finding networks that minimize the forwarding index. Forwarding indexes are calculated' for cube networks and generalized de Bruijn networks. General bounds are derived which show that de Bruijn networks are asymptotically optimal. Finally, efficient techniques for building large networks with small forwarding indexes out of given component networks are presented and analyzed.     

Network moving target defense technique based on optimal forwarding path migration

Moving target defense is a revolutionary technology which changes the situation of attack and defense.How to effectively achieve forwarding path mutation is one of the hotspot in this field.Since existing mechanisms are blindness and lack of constraints in the process of mutation,it is hard to maximize mutation defense benefit under the condition of good network quality of services.A novel of network moving target defense technique based on optimal forwarding path migration was proposed.Satisfiability modulo theory was adopted to formally describe the mutation constraints,so as to prevent transient problem.Optimization combination between routing path and mutation period was chosen by using optimal routing path generation method based on security capacity matrix so as to maximum defense benefit.Theoretical and experimental analysis show the defense cost and benefit in resisting passive sniffing attacks.The capability of achieving maximum defense benefit under the condition of ensuring network quality of service is proved.     

A Connectivity-Based Multi-Lane Routing Optimization Algorithm in Vehicular Communication

This paper proposed a connectivity-based multi-lane geographic routing protocol (CGRP) for vehicular ad hoc networks. The proposed CGRP is based on an effective selection of road intersections through which a package must pass from source to destination. The cooperative connectivity probability and delay are taken into consideration when choosing the most suitable path for delay-sensitive safety traffic. Analytical expressions for cooperative connectivity probability is derived based on a three-lanes path model. Geographical forwarding is used to transfer packets between any two intersections on the path, reducing the path sensitivity to individual node movements. Furthermore, forwarding packets between two adjacent intersections also depend on geographic location information. Neighbor nodes’ priority are assigned according to position, speed, direction and other factors. Node with the highest priority will be selected as the next hop. Numerical and simulation results show that the proposed algorithm outperforms the exsiting routing protocols in terms of the end-to-end delay and the number of hops with a little cost of routing overhead in city environments.     

Clustering routing protocol based on improved PSO algorithm in WSN

Aiming at the problem that the location distribution of cluster head nodes filtered by wireless sensor network clustering routing protocol was unbalanced and the data transmission path of forwarding nodes was unreasonable,which would increase the energy consumption of nodes and shorten the network life cycle,a clustering routing protocol based on improved particle swarm optimization algorithm was proposed.In the process of cluster head election,a new fitness function was established by defining the energy factor and position equalization factor of the node,the better candidate cluster head node was evaluated and selected,the position update speed of the candidate cluster head nodes was adjusted by the optimized update learning factor,the local search and speeded up the convergence of the global search was expanded.According to the distance between the forwarding node and the base station,the single-hop or multi-hop transmission mode was adopted,and a multi-hop method was designed based on the minimum spanning tree to select an optimal multi-hop path for the data transmission of the forwarding node.Simulation results show that the clustering routing protocol based on improved particle swarm optimization algorithm can elect cluster head nodes and forwarding nodes with more balanced energy and location,which shortened the communication distance of the network.The energy consumption of nodes is lower and more balanced,effectively extending the network life cycle.     

A Geography-Intimacy-Based Algorithm for Data Forwarding in Mobile Social Networks

Due to uncertain network connectivity,efficiently data forwarding in Mobile social networks (MSNs) becomes challenging.To conquer the problem,an Efficient data forwarding scheme based on geography intimacy (GIDF) for MSNs to achieve higher delivery ratio is proposed.In GIDF,we firstly propose an Intimacy based dynamic community detection algorithm (IDCD),which divide the MSNs into several communities.We propose a novel metric geography intimacy which can quantify the node's geographical information and the friendships between nodes.Based on geography intimacy,we further propose a routing algorithm to forward data.Compared with the geography intimacy between nodes,the next hop is found,further find the route of data forwarding by doing the similar operations.Extensive simulations on real data with the ONE simulator show that GIDF is more efficient than the existing algorithms.     

具有扩展局部连通性超立方体中的容错路由

在局部连通性的基础上,提出了针对超立方体网络Hn的扩展的局部k-维子立方体连通性概念,证明了具有扩展的局部k-维子立方体连通性的Hn中正确结点问是连通的;提出了超立方体网络Hn中基于扩展局部k-堆子立方体连通性的路由算法。