An overlapping communication protocol using improved time-slot leasing for Bluetooth WPANs

In this paper, we propose an overlapping communication protocol using improved time-slot leasing in the Bluetooth WPANS. One or many slave–master–slave communications usually exist in a piconet of the Bluetooth network. A fatal communication bottleneck is incurred in the master node if many slave–master–slave communications are required at the same time. To alleviate the problem, an overlapping communication scheme is presented to allow slave node directly and simultaneously communicates with another slave node to replace with the original slave–master–slave communication works in a piconet. This overlapping communication scheme is based on the improved time-slot leasing (TSL) scheme which modified from the original TSL, while the original TSL scheme only provides the slave-to-slave communication capability. The key contribution of our improved TSL scheme is to offer the overlapping communication capability. With the overlapping communication scheme, we developed an overlapping communication protocol in a Bluetooth WPANs. Finally, simulation results demonstrate that our developed communication protocol achieves the performance improvements on bandwidth utilization, transmission delay time, network congestion, and energy consumption.     

Toward integrating IP multicasting in internet network management protocols

Supporting multi-point group communications in network management platforms is essential for improving scalability and responsiveness of management applications. With the deployment of IP multicasting as the standard infrastructure for multi-point group communications in the Internet, the integration of IP multicasting in SNMP becomes significantly important to achieve these goals. This paper presents a highly flexible, efficient and easy-to-integrate framework for integrating IP Multicast in standard SNMP agents. The proposed framework enables managers to re-configure the agents’ group membership and the communication model (e.g. one-to-many, many-to-one and many-to-many) dynamically based on the application requirements. This framework exploits the advantages of IP multicasting without requiring any significant changes or performance overhead in the protocol or the agent architecture. The resulting framework can be easily adopted by exiting SNMP agents of various network management platforms. Although the other approaches provide group communications through broker agents in the management platform, integrating IP multicasting in SNMP agents is more efficient and a simpler approach. Our ultimate goal is to promote the integration of IP multicasting as a standard service in SNMP agents.     

全自主足球机器人通信子系统的设计与实现

全自主足球机器人系统涉及到在未知的动态环境中多机器人的协同工作,如何实现各足球机器人之间的高效实时通信是一个关键的问题。通信需要解决对话管理、对话协议和通信平台三个问题。其中,对话管理为机器人之间的信息交换提供各种连接方式;对话协议是机器人之间对协作信息内容和格式的约定;通信平台则是实现信息交互的物理硬件。该文采用基于CSMA/CA的无线局域网,建立了全自主足球机器人通信子系统的通信平台;建立了基于C/S模式的对话管理;并为多机器人系统的协作问题求解提出了一套可行的对话协议。实验证明该设计可行。     

Capability-Passing Processes

Capability-passing processes model global applications in a way that decouples the global agreement aspects of protocols from the details of how the communications are actually made. It relies on a restricted API or programming language and on the exchange of digital certificates representing capabilities to ensure that participants are faithful to a protocol and that outsiders cannot interfere. At the specification level, protocols are reasoned about independently of the underlying communication, using a process calculus with an abstraction of logs to isolate the remote state required for such protocols. At the implementation level, protocol steps no longer perform global communication; instead capabilities are used to transmit evidence of remote state, which in turn are used to authorize local log changes (corresponding to protocol steps). In this way, an API for global agreement protocols is defined independently of the underlying communication system.     

Leader-following consensus for a class of second-order nonlinear multi-agent systems

This paper deals with the leader-following consensus problem for a class of multi-agent systems with nonlinear dynamics and directed communication topology. The control input of the leader agent is assumed to be unknown to all follower agents. A distributed adaptive nonlinear control law is constructed using the relative state information between neighboring agents, which achieves leader-following consensus for any directed communication graph that contains a spanning tree with the root node being the leader agent. Compared with previous results, the nonlinear functions are not required to satisfy the globally Lipschitz or Lipschitz-like condition and the adaptive consensus protocol is in a distributed fashion. A numerical example is given to verify our proposed protocol.     

基于μclinux 的EPA 通信协议栈

EPA标准是由我国提出的用于提高工业以太网实时通信性能的系统规范。在介绍EPA通信协议模型基础上,对通信协议栈的应用层和通信调度管理实体进行了模块化设计,对协议栈的任务进行了详细划分。在设计过程中,对μ clinux系统的硬实时性和内存利用率进行了重点考虑。经实验测试,该通信协议栈可以正常工作,并取得了较理想的效果。     

Trends in mobile satellite technology

Demand for sophisticated personal communication services has changed communications satellite design. Satellites have moved closer to the Earth to improve communication speed and enable personal communication services. However, in so doing, they require more computing resources and more sophisticated protocols to handle intersatellite communications. This article examines the trends in communications satellite deployment and the resulting requirements for network protocols that are intended to support space communications. It reports the findings of a joint DoD/NASA effort to identify what parts of the seven-layer OSI protocol model can be adapted to support more sophisticated space applications     

Practical voting rules with partial information

Voting is an essential mechanism that allows multiple agents to reach a joint decision. The joint decision, representing a function over the preferences of all agents, is the winner among all possible (candidate) decisions. To compute the winning candidate, previous work has typically assumed that voters send their complete set of preferences for computation, and in fact this has been shown to be required in the worst case. However, in practice, it may be infeasible for all agents to send a complete set of preferences due to communication limitations and willingness to keep as much information private as possible. The goal of this paper is to empirically evaluate algorithms to reduce communication on various sets of experiments. Accordingly, we propose an iterative algorithm that allows the agents to send only part of their preferences, incrementally. Experiments with simulated and real-world data show that this algorithm results in an average of 35% savings in communications, while guaranteeing that the actual winning candidate is revealed. A second algorithm applies a greedy heuristic to save up to 90% of communications. While this heuristic algorithm cannot guarantee that a true winning candidate is found, we show that in practice, close approximations are obtained.     

Some Compartmentalized Secure Task Assignment Models for Distributed Systems

This paper formulates abstract problems of assigning subtasks to agents (processors) in a distributed system with a goal that they can perform its global task efficiently. The paper models the distributed system with a graph that describes the communication capabilities of the constituting agents. This graph is referred to as the "organizational graph.” In addition, the desired task-performing activity is modeled with another graph describing the required communications. Then, a few variants of the task assignment problem are formulated with potentially conflicting objectives (or constraints) of load balancing and communication costs. For some of these variants this paper provides efficient algorithms that solve the assignment problem. Some problems are proven NP-complete, and some others are left open.     

OCI-based group communication support in CORBA

Group communication is a useful mechanism guaranteeing consistency among replicated objects. The existing approaches do not allow transparent plug-in of group communication protocols into CORBA. They either require modification of CORBA or OS, or provide no room for incorporating group communication transport protocols into CORBA. We thus propose a generic group communication framework that allows transparent plug-in of various group communication protocols with no modification of existing CORBA. We extend the open communications interface (OCI) to support interoperability, reusability of existing group communication, and independency on ORB and OS. We also define the group communication inter-ORB protocol (GCIOP) as a group communication instantiation of the general inter-ORB protocol (GIOP) that encapsulates underlying group communication protocols. The proposed scheme can be exploited for fault-tolerant CORBA (FT CORBA).     

COORDINATION DIAGNOSTIC ALGORITHMS FOR TEAMS OF SITUATED AGENTS: SCALING UP

Agents in a team should be in agreement. Unfortunately, they may come to disagree due to sensor uncertainty, intermittent communication failures, etc. Once a disagreement occurs, the agents should detect and diagnose the disagreement. Current diagnostic techniques do not scale well with the number of agents, as they have high communication and computation complexity. We present novel techniques that enable scalability in three ways. First, we use communications early in the diagnostic process to stave off unneeded reasoning, which ultimately leads to unneeded communications. Second, we use light‐weight (and inaccurate) behavior recognition to focus the diagnostic reasoning on beliefs of agents that might be in conflict. Finally, we propose diagnosing only to a limited number of representative agents (instead of all the agents). We examine these techniques in large‐scale teams of situated agents in two domains and show that combining the techniques produces a diagnostic process that is highly scalable in both communication and computation.     

基于基站定位的通信协议设计与实现

为满足移动通信系统信息查找中基站定位的需要,响应手机客户端的请求,设计了一种服务器间的通信协议。该协议确定了手机客户端与前端服务器、前端服务器与中心服务器之间的通信规范。定义了协议的报文格式和通信规程,协议的功能码定义了所要完成的功能,协议内容中包含基站定位信息。测试表明,该协议可以正确地完成服务器间的数据传输,为基站定位及信息返回提供了保证。     

Learning Communication Strategies in Multiagent Systems

In this paper we describe a dynamic, adaptive communication strategy for multiagent systems. We discuss the behavioral parameters of each agent that need to be computed, and provide a quantitative solution to the problem of controlling these parameters. We also describe the testbed we built and the experiments we performed to evaluate the effectiveness of our methodology. Several experiments using varying populations and varying organizations of agents were performed and are reported. A number of performance measurements were collected as each experiment was performed so the effectiveness of the adaptive communications strategy could be measured quantitatively.The adaptive communications strategy proved effective for fully connected networks of agents. The performance of these experiments improved for larger populations of agents and even approached optimal performance levels. Experiments with non-fully connected networks showed that the adaptive communications strategy is extremely effective, but does not approach optimality. Other experiments investigated the ability of the adaptive communications strategy to compensate for distracting agents, for systems where agents are required to assume the role of information routers, and for systems that must decide between routing paths based on cost information.     

Secure web services using two-way authentication and three-party key establishment for service delivery

With the advance of web technologies, a large quantity of transactions have been processed through web services. Service Provider needs encryption via public communication channel in order that web services can be delivered to Service Requester. Such encryptions can be realized using secure session keys. Traditional approaches which can enable such transactions are based on peer-to-peer architecture or hierarchical group architecture. The former method resides on two-party communications while the latter resides on hierarchical group communications. In this paper, we will use three-party key establishment to enable secure communications for Service Requester and Service Provider. The proposed protocol supports Service Requester, Service Broker, and Service Provider with a shared secret key established among them. Compared with peer-to-peer architecture and hierarchical group architecture, our method aims at reducing communication and computation overheads.     

基于IP的空间通信网络设计与仿真

为适应目前空间通信的发展，提出了一种基于IP的空间通信网络模型。详细设计了该通信网络的数据链路结构、数据传输协议、数据包结构等。最后，将该通信网络的通信能力与商业通信系统Teledesic进行了对比。仿真结果表明，该通信网络可以有效减少航天器与接入卫星间的切换频率和通信时延，能够长时间给航天器提供稳定的通信连接，网络的平均吞吐能力强，能够满足未来空间通信的需求。     

Communication between the PC and laboratory instruments

In this paper we describe communications between a personal computer and any instrument with a serial port for the purpose of collecting data or controlling equipment and a program for performing this task. From a user-defined file, the software reads the communication parameters: baud rate, data bits, stop bits and parity. The communication protocol is also read: echo, acknowledge and end-of-transmission characters. The software can be used to determine the protocol, to check the integrity of the communications, and can form the basis of a program for more specific applications.     

移动互联网可信匿名通信模型

针对移动互联网对通信过程的匿名性需求,提出基于签密和可信计算技术设计移动互联网下的匿名通信模型,以实现通信双方间的匿名通信。该模型中,中间节点根据前驱节点的签密信息鉴别转发数据的完整性,验证转发链路的真实性。分析表明该模型在实现通信匿名的同时具有安全性与可信性,满足移动互联网下移动终端匿名通信过程的安全需求。     

An Effective Secure MAC Protocol for Cognitive Radio Networks

The vast revolution in networking is increasing rapidly along with technology advancements, which requires more effort from all cyberspace professionals to cope with the challenges that come with advanced technology privileges and services. Hence, Cognitive Radio Network is one of the promising approaches that permit a dynamic type of smart network for improving the utilization of idle spectrum portions of wireless communications. However, it is vulnerable to security threats and attacks and demands security mechanisms to preserve and protect the cognitive radio networks for ensuring a secure communication environment. This paper presents an effective secure MAC protocol for cognitive radio networks, significantly enhancing the security level of the existing DSMCRN and SSMCRN protocols by eliminating the authentication server’s necessity, which can be a single point of failure to compromise the entire network communication. The proposed protocol has proven to be effective and reliable since it does not rely on a centralized entity for providing the required security for a single pair of cognitive users. The protocol also improves the performance in the context of fast switching to data channels leading to higher throughput is achieved compared to the benchmark protocols.     

基于WebRTC应用层网关在iOS端的设计与实现

随着近年来新媒体技术的快速发展,用户对实时音视频通信的质量要求越来越高.WebRTC技术的出现,以其强大的音视频处理引擎迅速占领市场,对多媒体通信行业产生了巨大的影响.然而WebRTC提供的JSEP仅仅能完成简单的媒体链接功能,在企业级的通信中需要结合其他模块或者信令协议才能胜任完整的应用.本文着重研究了WebRTC与SIP的互通问题,并在iOS端基于WebRTC技术设计实现了一种应用层网关,通过实验验证了该网关的可行性与实用性.     

New efficient communication services for ISO 11898 networks

Fieldbus networks should be able to support several kinds of data exchanges, which are characterised by very different requirements. The most popular solutions available today have been designed with some sets of specific needs in mind and usually, they are not always able to satisfy, equally well, the different kinds of communications which can be found in the industrial and process control environments. Often, system integrators and designers are forced to trade responsiveness (needed in event-driven systems) for efficiency (mostly required in systems which are based on the periodic polling of the controlled devices), or vice-versa. In this paper, a modification of the basic ISO 11898 protocol is described which supports some new transmission services that significantly increase the communication efficiency for periodic exchanges of process data and for messages devoted to high level functions. These services maintain a good degree of compatibility with the original protocol and do not affect its very good responsiveness and flexibility.