Showing papers on "Communications protocol published in 2004"

A vehicle-to-vehicle communication protocol for cooperative collision warning

Abstract: This paper proposes a vehicle-to-vehicle communication protocol for cooperative collision warning Emerging wireless technologies for vehicle-to-vehicle (V2V) and vehicle-to-roadside (V2R) communications such as DSRC are promising to dramatically reduce the number of fatal roadway accidents by providing early warnings One major technical challenge addressed in this paper is to achieve low-latency in delivering emergency warnings in various road situations Based on a careful analysis of application requirements, we design an effective protocol, comprising congestion control policies, service differentiation mechanisms and methods for emergency warning dissemination Simulation results demonstrate that the proposed protocol achieves low latency in delivering emergency warnings and efficient bandwidth usage in stressful road scenarios

Input-output stability properties of networked control systems

Abstract: Results on input-output L/sub p/ stability of networked control systems (NCS) are presented for a large class of network scheduling protocols. It is shown that static protocols and a recently considered dynamical protocol called try-once-discard belong to this class. Our results provide a unifying framework for generating new scheduling protocols that preserve L/sub p/ stability properties of the system if a design parameter is chosen sufficiently small. The most general version of our results can be used to treat NCS with data packet dropouts. The model of NCS and, in particular, of the scheduling protocol that we use appears to be novel and we believe that it will be useful in further study of these systems. The proof technique we use is based on the small gain theorem and it lends itself to an easy interpretation. We prove that our results are guaranteed to be better than existing results in the literature and we illustrate this via an example of a batch reactor.

Quantum cryptography without switching.

Abstract: We propose a new coherent state quantum key distribution protocol that eliminates the need to randomly switch between measurement bases. This protocol provides significantly higher secret key rates with increased bandwidths than previous schemes that only make single quadrature measurements. It also offers the further advantage of simplicity compared to all previous protocols which, to date, have relied on switching.

Intelligent Fluid Infrastructure for Embedded Networking

Abstract: Computer networks have historically considered support for mobile devices as an extra overhead to be borne by the system. Recently however, researchers have proposed methods by which the network can take advantage of mobile components. We exploit mobility to develop a fluid infrastructure: mobile components are deliberately built into the system infrastructure for enabling specific functionality that is very hard to achieve using other methods. Built-in intelligence helps our system adapt to run time dynamics when pursuing pre-defined performance objectives. Our approach yields significant advantages for energy constrained systems, sparsely deployed networks, delay tolerant networks, and in security sensitive situations. We first show why our approach is advantageous in terms of network lifetime and data fidelity. Second, we present adaptive algorithms that are used to control mobility. Third, we design the communication protocol supporting a fluid infrastructure and long sleep durations on energy-constrained devices. Our algorithms are not based on abstract radio range models or idealized unobstructed environments but founded on real world behavior of wireless devices. We implement a prototype system in which infrastructure components move autonomously to carry out important networking tasks. The prototype is used to validate and evaluate our suggested mobility control methods.

Intelligent fluid infrastructure for embedded networks

Abstract: Computer networks have historically considered support for mobile devices as an extra overhead to be borne by the system. Recently however, researchers have proposed methods by which the network can take advantage of mobile components. We exploit mobility to develop a fluid infrastructure: mobile components are deliberately built into the system infrastructure for enabling specific functionality that is very hard to achieve using other methods. Built-in intelligence helps our system adapt to run time dynamics when pursuing pre-defined performance objectives. Our approach yields significant advantages for energy constrained systems, sparsely deployed networks, delay tolerant networks, and in security sensitive situations. We first show why our approach is advantageous in terms of network lifetime and data fidelity. Second, we present adaptive algorithms that are used to control mobility. Third, we design the communication protocol supporting a fluid infrastructure and long sleep durations on energy-constrained devices. Our algorithms are not based on abstract radio range models or idealized unobstructed environments but founded on real world behavior of wireless devices. We implement a prototype system in which infrastructure components move autonomously to carry out important networking tasks. The prototype is used to validate and evaluate our suggested mobility control methods.

Digital media distribution cryptography using media ticket smart cards

Abstract: FIG. 7 of the drawings depicts an overall view of this invention which relates to a new method or process for a system used to do digital media distribution in an architecture of public key cryptography called the digital media distribution cryptography architecture ( 100 ) which is implemented in computer hardware, computer software, and communications protocols, furthermore, the hardware components involved are media ticket smart cards ( 880 ), media ticket smart card readers ( 900 ), local area networks ( 924 ) (LAN's), internet protocol (IP) wide area networks ( 928 ) (WAN's), personal computers ( 820 ) (PC's), world wide web servers ( 824 ) (WWW), cryptographic media players (e.g. crypto-MP 3 players) with built-in media ticket smart card readers ( 880 ), ( 900 ), ( 1004 ), cryptographic digital signal processors ( 932 ) (C-DSP's), furthermore, the software components involved are cryptographic key distribution programs, cryptographic mathematics algorithms, and cryptographic protocols.

High speed media access control with legacy system interoperability

Abstract: Techniques for MAC processing for efficient use of high throughput systems that is backward compatible with various types of legacy systems are disclosed. In one aspect a first signal is transmitted according to a legacy transmission format to reserve a portion of a shared medium, and communication according to a second transmission format transpires during the reserved portion. In another aspect, a communication device may contend for access on a legacy system, and then communicate according to a new class communication protocol with one or more remote communication devices during the access period. In another aspect, a device may request access to a shared medium according to a legacy protocol, and, upon grant of access, the device may communicate with or facilitate communication between one or more remote stations according to a new protocol.

Method, system and apparatus for messaging between wireless mobile terminals and networked computers

Abstract: A system (20) is disclosed for messaging between wireless mobile terminals (22) operating on wireless carrier networks (32) and networked computers (26). The mobile terminals (22) and computers (26) include client applications (28,30) for communicating messages to one another using push-to-talk modality. A server (24), located on a packet network (34) outside the wireless carrier networks (32), forwards messages between the mobile terminals (22) and the computers (26). The messages consist of text or streaming voice. The server (24) can also include gateways for forwarding messages from the mobile terminals (22) and computers (26) to external email and instant messaging (IM) users. By placing the server (24) outside wireless carrier networks (32) and using conventional packet network protocols such as the Internet protocol (IP), the system (20) provides seamless inter-carrier push-to-talk and/or instant messaging between mobile terminals (22), networked computers (26), and users of third-party email (35) and IM (37) services.

Implementing software on resource-constrained mobile sensors: experiences with Impala and ZebraNet

Abstract: ZebraNet is a mobile, wireless sensor network in which nodes move throughout an environment working to gather and process information about their surroundings[10]. As in many sensor or wireless systems, nodes have critical resource constraints such as processing speed, memory size, and energy supply; they also face special hardware issues such as sensing device sample time, data storage/access restrictions, and wireless transceiver capabilities. This paper discusses and evaluates ZebraNet's system design decisions in the face of a range of real-world constraints.Impala---ZebraNet's middleware layer---serves as a light-weight operating system, but also has been designed to encourage application modularity, simplicity, adaptivity, and repairability. Impala is now implemented on ZebraNet hardware nodes, which include a 16-bit microcontroller, a low-power GPS unit, a 900MHz radio, and 4Mbits of non-volatile FLASH memory. This paper discusses Impala's operation scheduling and event handling model, and explains how system constraints and goals led to the interface designs we chose between the application, middleware, and firmware layers. We also describe Impala's network interface which unifies media access control and transport control into an efficient network protocol. With the minimum overhead in communication, buffering, and processing, it supports a range of message models, all inspired by and tailored to ZebraNet's application needs. By discussing design tradeoffs in the context of a real hardware system and a real sensor network application, this paper's design choices and performance measurements offer some concrete experiences with software systems issues for the mobile sensor design space. More generally, we feel that these experiences can guide design choices in a range of related systems.

The Nostrum backbone-a communication protocol stack for Networks on Chip

Abstract: We propose a communication protocol stack to be used in Nostrum, our Network on Chip (NoC) architecture. In order to aid the designer in the selection process of what parts of protocols, and their respective facilities, to include, a layered approach to communication is taken. A nomenclature for describing the individual layers' interfaces and service definitions of the layers in the protocol stack is suggested and used. The concept includes support for best effort traffic packet delivery as well as support for guaranteed bandwidth traffic, using virtual circuits. Furthermore an application to NoC adapter is defined, as part of the Resource to Network Interface, and is used to communicate between the Nostrum protocol stack and the application. An industrial example has been implemented, simulated, and the results justifies the suggested layered approach.

Communication protocol over power line communication network

Abstract: A communication apparatus for high-speed data transmission over power line networks comprises a head-end unit (1) which provides a single logical entry point into the communications network (2), an infrastructure of physical power line cables, one or more client-end units (3) which communicate with the head-end unit (1), and one or more hybrid units which simultaneously acts as a head-end unit for another physical sub-network of the power-line communication network (2) and functions as a client-end unit (3) of another physical sub-network of the power line communication network.

Model checking large network protocol implementations

Abstract: Network protocols must work. The effects of protocol specification or implementation errors range from reduced performance, to security breaches, to bringing down entire networks. However, network protocols are difficult to test due to the exponential size of the state space they define. Ideally, a protocol implementation must be validated against all possible events (packet arrivals, packet losses, timeouts, etc.) in all possible protocol states. Conventional means of testing can explore only a minute fraction of these possible combinations. This paper focuses on how to effectively find errors in large network protocol implementations using model checking, a formal verification technique. Model checking involves a systematic exploration of the possible states of a system, and is well-suited to finding intricate errors lurking deep in exponential state spaces. Its primary limitation has been the effort needed to use it on software. The primary contribution of this paper are novel techniques that allow us to model check complex, real-world, well-tested protocol implementations with reasonable effort. We have implemented these techniques in CMC, a C model checker [30] and applied the result to the Linux TCP/IP implementation, finding four errors in the protocol implementation.

On the behavior of communication links of a node in a multi-hop mobile environment

Abstract: In this work, we develop an analytical framework to investigate the behavior of the communication links of a node in a random mobility environment. Analytical expressions characterizing various properties related to the formation, lifetime and expiration of links are derived. The derived framework can be used to design efficient algorithms for medium access, routing and transport control, or to analyze and optimize the performance of existing network protocols. A number of applications of the characteristics investigated, such as selection of stable routes, route cache lifetime optimization, providing Quality-of-Service (QoS) data communication and analysis of route lifetime are discussed. In particular, we focus on designing an efficient updating strategy for proactive routing protocols based on the derived statistics. Using simulations, we show that the proposed strategy can lead to significant performance improvements in terms of reduction in routing overhead, while maintaining high data packet delivery ratio and acceptable latency.

Group key agreement efficient in communication

Abstract: In recent years, collaborative and group-oriented applications and protocols have gained popularity. These applications typically involve communication over open networks; security thus is naturally an important requirement. Group key management is one of the basic building blocks in securing group communication. Most prior research in group key management focused on minimizing computation overhead, in particular minimizing expensive cryptographic operations. However, continued advances in computing power have not been matched by a decrease in network communication delay. Thus, communication latency, especially in high-delay long-haul networks, increasingly dominates the key setup latency, replacing computation delay as the main latency contributor. Hence, there is a need to minimize the size of messages and, especially, the number of rounds in cryptographic protocols. Since most previously proposed group key management techniques optimize computational (cryptographic) overhead, they are particularly impacted by high communication delay. In this work, we discuss and analyze a specific group key agreement technique which supports dynamic group membership and handles network failures, such as group partitions and merges. This technique is very communication-efficient and provably secure against hostile eavesdroppers as well as various other attacks specific to group settings. Furthermore, it is simple, fault-tolerant, and well-suited for high-delay networks.

TCP onloading for data center servers

Abstract: To meet the increasing networking needs of server workloads, servers are starting to offload packet processing to peripheral devices to achieve TCP/IP acceleration. Researchers at Intel Labs have experimented with alternative solutions that improve the server's ability to process TCP/IP packets efficiently and at very high rates.

A Distributed TDMA Slot Assignment Algorithm for Wireless Sensor Networks

Abstract: Wireless sensor networks benefit from communication protocols that reduce power requirements by avoiding frame collision. Time Division Media Access methods schedule transmission in slots to avoid collision, however these methods often lack scalability when implemented in ad hoc networks subject to node failures and dynamic topology. This paper reports a distributed algorithm for TDMA slot assignment that is self-stabilizing to transient faults and dynamic topology change. The expected local convergence time is O(1) for any size network satisfying a constant bound on the size of a node neighborhood.

A scalable model for channel access protocols in multihop ad hoc networks

Abstract: A new modeling framework is introduced for the analytical study of medium access control (MAC) protocols operating in multihop ad hoc networks. The model takes into account the effect of physical-layer parameters on the success of transmissions, the MAC protocol on the likelihood that nodes can access the channnel, and the connectivity of nodes in the network. A key feature of the model is that nodes can be modeled individually, i.e., it allows a per-node setup of many layer-specific parameters. Moreover, no spatial probability distribution or a particular arrangement of nodes is assumed; the model allows the computation of individual (per-node) performance metrics for any given network topology and radio channel model. To show the applicability of the modeling framework, we model multihop ad hoc networks using the IEEE 802.11 distributed coordination function and validate the results from the model with discrete-event simulations in Qualnet. The results show that our model predicts results that are very close to those attained by simulations, and requires seconds to complete compared to several hours of simulation time.

System and method for monitoring remote devices with a dual-mode wireless communication protocol

Abstract: The present invention is generally directed to systems and device for monitoring remote device with a wireless, dual-mode communication protocol. As such, a representative embodiment is a system for monitoring and controlling remote devices. The system includes a first- and a second remote device; and a first and a second wireless transceiver integrated with the respective remote devices. The wireless transceivers are configured to communicate with at least one of a spread-spectrum communication protocol and a fixed-frequency communication protocol.

At what layer does mobility belong

Abstract: Internetworking is a complex problem, traditionally tackled by splitting responsibilities between several layers of protocols arranged in a stack. A shortcoming of the current Internet suite's layers is that the responsibilities of individual layers are somewhat ill defined. The result is that frequently a feature may cause problems for higher layers when it unexpectedly exists lower in the stack, or may be unnecessarily and inefficiently implemented in multiple layers. Mobility is one such feature with no well defined place in classical protocol stacks. If a link layer hands over between two distinctly administered networks, a network layer protocol will likely need to acquire a new address. Similarly, if mobility is implemented at the network layer, such as with mobile IP, transport layer protocols must be prepared to deal with a slew of problems (rapid changes in available capacity and delay, the asymmetry of triangle routes, and security policies, to name a few). Code for higher-level protocols (above transport) is less frequently reused, so higher-layer mobility schemes fail to leverage the large base of TCP sockets code. We discuss the various strengths and weaknesses of implementing mobility at three different layers of the protocol stack, concluding that a transport layer mobility scheme is likely to suit today's mobile Internet users best, and that ideally there should be more communication between layers to avoid conflict and inefficiency.

Method and apparatus for identifying problems in computer networks

Abstract: A network appliance for monitoring, diagnosing and documenting problems among a plurality of devices and processes (objects) coupled to a computer network utilizes periodic polling and collection of object-generated trap data to monitor the status of objects on the computer network. The status of a multitude of objects is maintained in memory utilizing virtual state machines which contain a small amount of persistent data but which are modeled after one of a plurality of finite state machines. The memory further maintains dependency data related to each object which identifies parent/child relationships with other objects at the same or different layers of the OSI network protocol model. A decision engine verifies through on-demand polling that a device is down. A root cause analysis module utilizes status and dependency data to locate the highest object in the parent/child relationship tree that is affected to determine the root cause of a problem. Once a problem has been verified, a “case” is opened and notification alerts may be sent out to one or more devices. A user interface allows all objects within the network to be displayed with their respective status and their respective parent/child dependency objects in various formats.

SecureDAV: a secure data aggregation and verification protocol for sensor networks

Abstract: Sensor networks include nodes with limited computation and communication capabilities. One of the basic functions of sensor networks is to sense and transmit data to the end users. The resource constraints and security issues pose a challenge to information aggregation in large sensor networks. Bootstrapping keys is another challenge because public key cryptosystems are unsuitable for use in resource-constrained sensor networks. In this paper, we propose a solution by dividing the problem in two domains. First, we present a protocol for establishing cluster keys in sensor networks using verifiable secret sharing. We chose elliptic curve cryptosystems for security because of their smaller key size, faster computations and reductions in processing power. Second, we develop a secure data aggregation and verification (SecureDAV) protocol that ensures that the base station never accepts faulty aggregate readings. An integrity check of the readings is done using Merkle hash trees, avoiding over-reliance on the cluster-heads.

Sensor Networks for Monitoring Traffic

Abstract: Traffic surveillance is currently performed with inductive loop detectors and video cameras for the efficient management of public roads. This paper proposes an alternative traffic monitoring system using wireless sensor networks that offers high accuracy and lower cost compared. The system consists of two parts: wireless sensor network and access point. Traffic information is generated at the sensor nodes and then transferred to the access point over radio. Our prototype called Traffic-Dot achieves vehicle detection accuracy of 97% and accurately measures speed with a node pair. The communication protocol PEDAMACS (Power Efficient and Delay Aware Medium Access Protocol for Sensor Networks) is shown to increase the lifetime of the system up to several years while still guaranteeing the timely arrival of information from the sensor nodes to the access point.

Architecture for mobility and QoS support in all-IP wireless networks

Abstract: Mobility management and quality-of-service (QoS) provisioning are the important tasks on the future development of wireless networks. The high host mobility makes these tasks more challenging. In this paper, we propose an architecture which supports both mobility and QoS management in Internet protocol (IP)-based wireless networks. In mobility management, the fast handoff, which the packets are forwarded in advance to the neighboring locations where a mobile node (MN) may move to, is provided to reduce the service disruption. Also, the fast location lookup, which the routing information about a MN is replicated to some routers, is provided to avoid the triangular routing problem incurred by the protocol of mobile IP. In QoS provisioning, we enable the end-to-end QoS guarantee by using the resource reservation protocol (RSVP) signaling. In particular, the RSVP aggregation technique is used to avoid the scalability problem. Also, the technique of passive resource reservation is used to reduce the influence of host mobility on the resource reservation delay. We emphasize the integration of mobility and QoS management in the architecture design. A performance analysis is given to justify the benefits of our proposed architecture.

Secure group communication using robust contributory key agreement

Abstract: Contributory group key agreement protocols generate group keys based on contributions of all group members. Particularly appropriate for relatively small collaborative peer groups, these protocols are resilient to many types of attacks. Unlike most group key distribution protocols, contributory group key agreement protocols offer strong security properties such as key independence and perfect forward secrecy. We present the first robust contributory key agreement protocol resilient to any sequence of group changes. The protocol, based on the Group Diffie-Hellman contributory key agreement, uses the services of a group communication system supporting virtual synchrony semantics. We prove that it provides both virtual synchrony and the security properties of Group Diffie-Hellman, in the presence of any sequence of (potentially cascading) node failures, recoveries, network partitions, and heals. We implemented a secure group communication service, Secure Spread, based on our robust key agreement protocol and Spread group communication system. To illustrate its practicality, we compare the costs of establishing a secure group with the proposed protocol and a protocol based on centralized group key management, adapted to offer equivalent security properties.

Design space exploration for optimizing on-chip communication architectures

Abstract: Rapid growth in the complexity of system-on-chips is being accompanied by increasing volume and diversity of on-chip communication traffic, which in turn, is driving the development of advanced system-level communication architectures. While these architectures have the potential to improve system performance, they pose significant new challenges to the system designer, owing to the complex design space defined by the availability of numerous network topologies, communication protocols, and mapping alternatives for system communications. In this paper, we address the problem of mapping a system's communication requirements to a given communication architecture template. We illustrate the nature of the communication architecture design space, and describe an exploration methodology that uses efficient algorithms to help automate the process of mapping the system communications to the selected template. In addition, we demonstrate the importance of simultaneously optimizing the on-chip communication protocols in order to maximize system performance. Experiments conducted on example systems, including a cell forwarding unit of an ATM switch, indicate that the proposed techniques aid in automatically constructing communication architectures that have high performance. For the systems we considered, the solutions generated using our methodology had 53% superior performance (on average), over those based on conventional architectures and mapping approaches. The algorithms used in the proposed methodology are computationally efficient, and scale well with increasing communication architecture complexity.

Simulating Sensor Networks in NS-2

Abstract: : Optimizing sensor networks involves addressing a wide range of issues. These issues stem from limited energy reserves, computation power, communication capabilities, and self-managing sensor nodes. The NS-2 simulation environment is a flexible tool for network engineers to investigate how various protocols perform with different configurations and topologies. This report describes how we extended the NS-2 framework to include support for sensor networks.

History of the Internet

Abstract: This chapter traces the beginnings of the Internet, focusing on key personalities and technological developments. The history follows the origin of the original ARPANET, including development of TCP/IP protocols, through the emergence of the NSFNET backbone and the development of the World Wide Web. Focus is also placed on the process of discovery, facilitated by open cooperation among scientists through Requests for Comments and the dedication to create a flexible, open-architecture environment. Keywords: ARPANET; circuit switching; NSFNET; packet switching; protocol; TCP/IP protocols; world wide web (WWW)

Real-Time Network Emulation with ns-2

Abstract: The network simulator ns-2 implements both wireless networks and emulation — a feature that allows to simulate a network environment among real stations. However, the real-time requirements of a network emulation introduce an inaccurate timing behavior of the simulator scheduler. These timing errors have a negative impact on the performance of network protocols in ns-2. Even more, they lead to false simulation results in the IEEE 802.11 protocol implementation. In this paper we present performance improvements in ns-2, that increase the accuracy of its virtual clock and the the exactness of the real-time simulation. Then we describe a simple time monitoring and correction technique that ensures a timely correct execution of network protocols and enables wireless network emulation in ns-2.

On the gain scheduling for networked PI controller over IP network

Abstract: The potential use of networks for real-time high-performance control and automation is enormous and appealing. Replacing a widely used proportional-integral (PI) controller by a new networked controller for networked control capability can be costly and time-consuming. This paper proposes a methodology based on gain scheduling with respect to real-time IP traffic conditions to enhance the existing PI controller so it can be used over IP networks with a general network protocol like Ethernet. This paper first describes the gain scheduling approach based on constant network delays using a rational function approach. The formulation is extended to random IP network round-trip time (RTT) delays by using the generalized exponential distribution model. Simulation results show that the PI controller with gain scheduling provides significantly better networked control system performance.

Protocol analysis in intrusion detection using decision tree

Abstract: Network based intrusion detection are the most deployed IDS. They frequently rely on signature matching detection method and focus on the security of low level network protocols. Because of the large number of false positives from one side, and the incapacity to detect some attack types from another side, IDS must allow more interest to the monitoring of application level protocols. We propose in this paper a combination of pattern matching and protocol analysis approaches. While the first method of detection relies on a multipattern matching strategy, the second one benefits from an efficient decision tree adaptive to the network traffic characteristics.