Software defined P2P architecture for reliable vehicular communications

Vehicular networking is considered a promising and enabling technology that helps in the realization and diversification of vehicle related applications such as road traffic safety, emergency management, and infotainment. For applications such as the road traffic safety, the system has to respond in certain bounded time and ensure higher reliability. A major bottleneck of the existing architectures is the reliability and scalability that results in a considerable performance degradation. Therefore, in this paper, we proposed a software defined peer to peer (P2P) architecture for reliable vehicular communications solution that scales out overall network intelligence into the system components (Road side units, on-board units, Gateways, Control centre) and offer an unprecedented reliability, adaptability and scalability. The reliability of the communication is achieved by using redundant system components such as multiple switches and GWs links that are deployed to achieve lower communication latencies and higher packet success rates. Furthermore, higher reliability is achieved by the application of fast-failover and fast recovery techniques. The proposed architecture is implemented using Docker, and containerized ONOS and Cassandra. The obtained results show that the proposed architecture offer higher reliability by offering higher packet success rate (PSR) and smaller round trip time (RTT).     

A survey on routing techniques in underwater wireless sensor networks

Underwater Wireless Sensor Networks (UWSNs) are finding different applications for offshore exploration and ocean monitoring. In most of these applications, the network consists of significant number of sensor nodes deployed at different depths throughout the area of interest. The sensor nodes located at the sea bed cannot communicate directly with the nodes near the surface level; they require multi-hop communication assisted by appropriate routing scheme. However, this appropriateness depends not only on network resources and application requirements but also on environmental constraints. All these factors provide a platform where a resource-aware routing strategy plays a vital role to fulfill the different application requirements with dynamic environmental conditions. Realizing the fact, significant attention has been given to construct a reliable scheme, and many routing protocols have been proposed in order to provide an efficient route discovery between the sources and the sink. In this paper, we present a review and comparison of different algorithms, proposed recently in order to fulfill this requirement. The main purpose of this study is to address the issues like data forwarding, deployment and localization in UWSNs under different conditions. Later on, all of these are classified into different groups according to their characteristics and functionalities.     

Decentralized key generation scheme for cellular-based heterogeneous wireless ad hoc networks

With the support of cellular system a cellular-based mobile ad hoc network (MANET) offers promising communication scenarios while entails secure data exchange as other wireless systems. In this paper, we propose a novel decentralized key generation mechanism using shared symmetric polynomials in which the base stations (BSs) carry out an initial key generation by a symmetric polynomial in a distributed manner and then pass on the key material to mobile stations (MSs). Thereafter, our proposed key generation scheme enables each pair of MSs to establish a pairwise key without any intervention from the BS, thus reducing the management cost for the BS. The shared key between two MSs is computed without any interaction between them. In addition, the trust among MSs is derived from the cellular infrastructure, thus enjoying an equal security level as provided in the underlying cellular network. Simulations are done to observe the system performance and the results are very encouraging.     

天河-1A互连系统的接口设计

NIC是高性能互连网络THNet的网络接口芯片,基于自主研发的通信协议,它高效地实现了无连接、零拷贝、用户级通信的RDMA传输机制,基于该机制的MPI实现具有极高的系统可扩展性。实现了基于控制报文触发的描述符队列处理机制,以支持卸载的聚合通信,包括广播和栅栏同步。使用NIC芯片的网络接口卡在测试中获得了1.57μs的最小单边延迟和6.34GB/s的带宽。NIC已成功应用于2010年TOP500排名世界第一的天河-1A超级计算机。     

Promondia: a Java-based framework for real-time group communication in the Web

The World Wide Web has evolved from a distributed hypertext system to a platform-independent graphical user interface that integrates many network services. So far, its technology has restricted it mainly to applications for information retrieval.As networks become ubiquitious and more and more users have a permanent connection, there is an increasing demand for other network services, such as real-time data feeds, group communication, and teleconferencing. So far, these services have been provided by various proprietary software systems, which were hard to set up and use, and thus not very successful.Integrating real-time group communication services into the World Wide Web is a natural way to make them more accessible and will take the Web a step further on its way to becoming the universal network application.In this paper, we describe functionalities required for these services and present an implementation based on Sun Microsystem's Java² programming language. We focus on the high-level functionalities and abstractions, but also describe an object-oriented programming model for group communication systems.     

Prediction and congestion control algorithm for networked motion tracking

In this paper a novel prediction method and a communication protocol is proposed for distributed motion tracking systems, for example robot control system over the Internet based on on-line visual information. It is assumed that the trajectory generator part of the control system is connected to the low level controller through wide area network (WAN). In this case the variable network delay, packet losses, irregular packet arrival can severely influence the control characteristics (transient behavior and tracking performance) in a negative sense. The proposed prediction method is based on dynamic filters and it generates the trajectory on the control system side in the control periods when no new information on the time varying reference trajectory arrives through the network. The developed application level communication protocol is meant to keep the packet loss under a predefined limit even if the network bandwidth varies below the value required by the control application. Simulations and real-time experiments show that the prediction algorithm applied jointly with the proposed communication protocol can effectively compensate the effect of networked communication on control characteristics.     

Network protection codes: Providing self-healing in autonomic networks using network coding

Agile recovery from link failures in autonomic communication networks is essential to increase robustness, accessibility, and reliability of data transmission. However, this must be done with the least amount of protection resources, while using simple management plane functionalities. Recently, network coding has been proposed as a solution to provide agile and cost efficient self-healing against link failures, in a manner that does not require data rerouting, packet retransmission, or failure localization, hence leading to simple control and management planes. To achieve this, separate paths have to be provisioned to carry encoded packets, hence requiring either the addition of extra links, or reserving some of the resources for this purpose.In this paper we introduce self-healing strategies for autonomic networks in order to protect against link failures. The strategies are based on network coding and reduced capacity, which is a technique that we call network protection codes (NPC). In these strategies, an autonomic network is able to provide self-healing from various network failures affecting network operation. Also, network protection codes are extended to provide self-healing from multiple link failures in autonomic networks. Although this leads to reducing the network capacity, the network capacity reduction is asymptotically small in most cases of practical interest. We provide implementation aspects of the proposed strategies, derive bounds and show how to construct network protection code. The paper also develops an Integer Linear Program formulation to evaluate the cost of provisioning connections using the proposed strategies, and uses results from this formulation to show that it is more resource efficient than 1 + 1 protection. A simulation study to evaluate the recovery times, and the buffering requirements due to network coding is also conducted using the OPNET simulator.     

Detecting criminal organizations in mobile phone networks

The study of criminal networks using traces from heterogeneous communication media is acquiring increasing importance in nowadays society. The usage of communication media such as mobile phones and online social networks leaves digital traces in the form of metadata that can be used for this type of analysis. The goal of this work is twofold: first we provide a theoretical framework for the problem of detecting and characterizing criminal organizations in networks reconstructed from phone call records. Then, we introduce an expert system to support law enforcement agencies in the task of unveiling the underlying structure of criminal networks hidden in communication data. This platform allows for statistical network analysis, community detection and visual exploration of mobile phone network data. It enables forensic investigators to deeply understand hierarchies within criminal organizations, discovering members who play central role and provide connection among sub-groups. Our work concludes illustrating the adoption of our computational framework for a real-word criminal investigation.     

Market segmentation using service levels in data networks

The objective of this paper is to study a communication system based on aM ^(x)/ D/1 queueing system representing a cell-switch network like Asynchronous Transfer Mode (ATM) network. Network structure consists of a single link modeled as a batch arrival markovian queue with non-preemptive head of the line priority service. Network manager (NM) is assumed to be a decision maker at a Management Information System (MIS) department. This paper establishes the incentive compatible pricing which maximizes the net value of the overall corporation, while the delays have to satisfy the Quality of Service (QoS) guarantees. We obtain structural results for the two priority case in the short run. In equilibrium, we find that the network manager maximizes the price spread between the two priority class services. We prove that as the capacity level increases indefinitely, the market is equally divided among the priority classes. In the first part of the paper, we assume that the users do not respond to network manager’s prices. In the second part, we relax this assumption and look at a leader follower game. Users choose their willingness to pay by deciding on how much value they assign to timely transmission of messages after seeing the prices set by the network manager. Our results indicate that unless there is high enough capacity set upex ante, monopoly network provider cannot price discriminate by offering different quality of service via priority classes. This trade-off between ex ante capacity level choice and ex post price discrimination decision is eliminated if the capacity is set high. It is shown in the network literature that best effort services lead to lower quality of service, in general, for a single service. We show that this holds in multiple priority services as well. We prove that when the capacity is also considered as a decision variable, simultaneous capacity and price setting yields the same optimal level with sequential capacity and price choices.     

Designing communication strategies for heterogeneous parallel systems

This paper explores the suitability of the emerging passive star-coupled optical interconnection using wavelength division multiplexing as the system interconnect to provide high bandwidth (Gbits/sec) communication demanded by heterogeneous systems. Several different communication strategies (combinations of communication topologies and protocols) are investigated under a representative master-slave computational model. The interplay between system speed, network speed, task granularity, and degree of parallelism is studied using both analytical modeling and simulations. It is shown that a hierarchical ALOHA-based communication strategy between the master and the slaves, implemented on top of the passive star-coupled network, leads to a considerable reduction in channel contention and provides 50–80% reduction in task completion time for applications with medium to high degrees of coarse grain parallelism. Comparable reduction in channel contention is also shown to be achieved by using tunable acoustooptic filters at master nodes.     

Framework of a flexible computer communication network

With the increasing speed of computers and communication links, and the successful convergence of both fields, computers connected by high speed links now represent an enormously large distributed computing system. At the same time, communication between man and machine is also becoming more diverse and personalized. Networking issues such as evolution of user services, seamless communication between hosts, failure recovery and integration of new technologies arise daily. Problem-specific approaches and corresponding solutions are available at considerable cost. However, a common requirement is adaptability of the computer network to a variety of changes. In this paper, we propose Flexible Computer Communication Networks (FN) as a uniform solution to most of these networking problems. The framework of Flexible Networks can be considered as an intelligent shell enclosing existing networking architectures. An agent-oriented implementation of a flexible network is outlined. The conversion of existing networks to flexible networks is shown to be incremental, and therefore practicable.     

An efficient utilization of intermittent surface–satellite optical links by using mass storage device embedded in satellites

Recently, earth observation system by using satellite network has attracted much attention due to its wide coverage and disaster resistance. Although the system is useful for collecting various data, which have an effect on a natural disaster, ecology and so forth, earth observation satellite hardly send the collected observation data to the ground station. This is because that the earth observation satellite needs to orbit near surface of the earth to get high-precision data, and it limited the time that can be used to send the observed data traffic to the ground station. Additionally, the amount of the observed data drastically increase in these days. Thus, we focus on the data relay satellite using optical communication in this network. By relaying observed data to traffic to the relay satellite, which has geostationary orbit, it is possible to increase the chance of sending data for the observation satellite due to the wide coverage of the relay satellite. In addition, laser light that is used in optical communication in satellite network has high frequency and it can deliver large data compared with radio wave. However, laser light is greatly influenced by atmosphere, and optical link capacity between satellite and ground station drastically changes according to weather condition. Therefore, we propose a new data traffic control method to use the network constructed by satellites which has mass storage device effectively according to the condition of optical downlink between satellite and optical ground station. The effectiveness of the proposed method is evaluated with numerical result.     

A scalable publish/subscribe system for large mobile ad hoc networks

Since nodes that compose mobile ad hoc networks (MANETs) does not have any prior knowledge about other nodes in many cases, the publish/subscribe communication paradigm that has the decoupling and asynchrony properties can be useful to share information between nodes. Existing publish/subscribe services for MANETs can be categorized into document flooding (DF), destination-based routing (DBR), and content-based routing (CBR). Although those approaches may work well when the size of network is small, all of them suffer from the performance decline as the size of the network increases. In this paper, we compare those approaches, and then propose a scalable publish/subscribe communication scheme in large MANETs by combining DF and CBR hierarchically. Our approach is to cluster all nodes in networks and to exploit CBR and DF for the intra- and inter-cluster communication, respectively. By using this approach, we can effectively utilize benefits of both approaches. Then, we present performance evaluation results which validate our idea with respect to system performance and scalability.     

工厂自动化通信发展综述

由局域和广域网以及有线和无线通信系统组成的异构网络将发挥日益重要的作用;然而,需要的不仅只是实时、安全和保密的通信,渴望的情境感知也将通向基于现场的通信服务;因此,这些功能性将越来越多的影响自动化领域通信方法的复杂性;由于目前现场总线系统已在工厂自动化领域达到一个稳定阶段,所以将主要探讨在自动化领域内使用以太网和异构网络的近期发展情况,并指出未来的分布式自动化系统需要使用更多的机制以便于适应自动化功能的地理分布。     

基于多互联网络的并行信号处理系统

在并行处理系统中,处理节点之间的通信开销是制约处理机性能提高的主要瓶颈。该文提出一种以TMS320C641X数字信号处理器为核心的并行处理系统,设计了PCI总线、串口和包交换网络等多种并行互联网络,使得输入、输出、控制等多种数据流分离,在适合的网络上传输,可以提高传输效率,实现高性能DSP与高性能互联系统的结合。     

Optimal conclusive sets for comparator networks

A set of input vectors S$S$ is conclusive for a certain functionality if, for every comparator network, correct functionality for all input vectors is implied by correct functionality for all vectors in S$S$. We consider four functionalities of comparator networks: sorting, merging, sorting of bitonic vectors, and halving. For each of these functionalities, we present two conclusive sets of minimal cardinality. The members of the first set are restricted to be binary, while the members of the second set are unrestricted. For all the above functionalities, except halving, the unrestricted conclusive set is much smaller than the binary one.     

Cooperative security in distributed networks

We consider a distributed network in which faulty nodes can pose serious threats as they can subvert the correct operation of basic functionalities, such as, routing or data aggregation. As a setoff to such nodes, we suggest that trust management between nodes is an essential part of a distributed system. In particular, benign nodes shall communicate with trusted nodes only and misbehaving nodes must be rapidly removed from the system.     

MARP: A Multi-Agent Routing Protocol for Mobile Wireless Ad Hoc Networks

Supporting mobility in a multi hop wireless environment like the MANET still remains a point of research, especially in the context of time-constrained applications. The incapacity of ad hoc networks to offer services of the likes of static or infratructured networks may be attributed to two major reasons. One, unpredictable mobility of hosts cause location-transparent-packet-delivery to be implemented only at the expense of large control overhead. Two, the lack of central control causes connection management and scalability to be major problems in the multi hop environment. In this paper we propose an efficient agent based routing mechanism that not only incurs minimal overhead, but also lays the foundation for additional functionalities as network management and real time applications. In other words, we show that the agent framework makes the MANET robust and survivable under stringent system constraints.     

AD hoc网络中的机会分组调度算法

无线多跳Ad hoc网络中节点在业务发送过程中需要竞争共享信道,容易发生局部拥塞导致网络性能下降,而且节点内部采用的先入先出(FIFO)队列容易使队头阻塞,影响队列中后续分组的发送。本文提出了一种机会分组调度算法CBOS,发送节点采用多播RTS的方式同时指向多个接收节点,可以支持可变长分组,提高了Ad hoc网络的空间重用率,接收节点根据拥塞程度按照一定概率返回CTS,有利于节点网络的拥塞控制。仿真结果表明,该算法提高了网络端到端的饱和吞吐量和信道利用率,并提高了业务流之间的公平性。