Showing papers on "Communications protocol published in 2006"

Slotted FAMA: a MAC protocol for underwater acoustic networks

Abstract: Long propagation delays and low bit rates of underwater acoustic networks make these systems fundamentally different from the packet radio networks. As a consequence, many of the network protocols designed for radio channels are either not applicable, or have extremely low efficiency over underwater acoustic channels. These facts necessitate a dedicated design of protocols for an underwater acoustic network. A medium access control (MAC) protocol suitable for an underwater acoustic network is proposed and analyzed. The protocol is based on a channel access discipline called floor acquisition multiple access (FAMA) which combines both carrier sensing (CS) and a dialogue between the source and receiver prior to data transmission. During the initial dialogue, control packets are exchanged between the source node and the intended destination node to avoid multiple transmissions at the same time. Special attention is paid to the networks that are not fully connected, in which nodes can be hidden from each other. The new protocol uses time slotting and is thus called slotted FAMA. Time slotting eliminates the need for excessively long control packets, thus providing savings in energy. Protocol performance in throughput and delay is assessed through simulation of a mobile ad hoc underwater network, showing the existence of optimal power level to be used for a given user density.

Controllably mobile infrastructure for low energy embedded networks

Abstract: We discuss the use of mobility to enhance network performance for a certain class of applications in sensor networks. A major performance bottleneck in sensor networks is energy since it is impractical to replace the batteries in embedded sensor nodes post-deployment. A significant portion of the energy expenditure is attributed to communications and, in particular, the nodes close to the sensor network gateways used for data collection typically suffer a large overhead as these nodes must relay data from the remaining network. Even with compression and in-network processing to reduce the amount of communicated data, all the processed data must still traverse these nodes to reach the gateway. We discuss a network infrastructure based on the use of controllably mobile elements to reduce the communication energy consumption at the energy constrained nodes and, thus, increase useful network lifetime. In addition, our approach yields advantages in delay-tolerant networks and sparsely deployed networks. We first show how our approach helps reduce energy consumption at battery constrained nodes. Second, we describe our system prototype, which utilizes our proposed approach to improve the energy performance. As part of the prototyping effort, we experienced several interesting design choices and trade-offs that affect system capabilities and performance. We describe many of these design challenges and discuss the algorithms developed for addressing these. In particular, we focus on network protocols and motion control strategies. Our methods are tested using a practical system and do not assume idealistic radio range models or operation in unobstructed environments

Sift: a MAC protocol for event-driven wireless sensor networks

Abstract: Nodes in sensor networks often encounter spatially-correlated contention, where multiple nodes in the same neighborhood all sense an event they need to transmit information about. Furthermore, in many sensor network applications, it is sufficient if a subset of the nodes that observe the same event report it. We show that traditional carrier-sense multiple access (CSMA) protocols for sensor networks do not handle the first constraint adequately, and do not take advantage of the second property, leading to degraded latency as the network scales in size. We present Sift, a medium access control (MAC) protocol for wireless sensor networks designed with the above observations in mind. We show using simulations that as the size of the sensor network scales up to 500 nodes, Sift can offer up to a 7-fold latency reduction compared to other protocols, while maintaining competitive throughput.

PEDAMACS: power efficient and delay aware medium access protocol for sensor networks

Abstract: PEDAMACS is a Time Division Multiple Access (TDMA) scheme that extends the common single hop TDMA to a multihop sensor network, using a high-powered access point to synchronize the nodes and to schedule their transmissions and receptions. The protocol first enables the access point to gather topology (connectivity) information. A scheduling algorithm then determines when each node should transmit and receive data, and the access point announces the transmission schedule to the other nodes. The performance of PEDAMACS is compared to existing protocols based on simulations in TOSSIM, a simulation environment for TinyOS, the operating system for the Berkeley sensor nodes. For the traffic application we consider, the PEDAMACS network provides a lifetime of several years compared to several months and days based on random access schemes with and without sleep cycles, respectively, making sensor network technology economically viable.

Toward Distributed service discovery in pervasive computing environments

Abstract: The paper proposes a novel distributed service discovery protocol for pervasive environments. The protocol is based on the concepts of peer-to-peer caching of service advertisements and group-based intelligent forwarding of service requests. It does not require a service to be registered with a registry or lookup server. Services are described using the Web Ontology Language (OWL). We exploit the semantic class/subClass hierarchy of OWL to describe service groups and use this semantic information to selectively forward service requests. OWL-based service description also enables increased flexibility in service matching. We present simulation results that show that our protocol achieves increased efficiency in discovering services (compared to traditional broadcast-based mechanisms) by efficiently utilizing bandwidth via controlled forwarding of service requests.

Tampering with motes: real-world physical attacks on wireless sensor networks

Abstract: Most security protocols for wireless sensor networks (WSN) assume that the adversary can gain full control over a sensor node through direct physical access (node capture attack). But so far the amount of effort an attacker has to undertake in a node capture attack is unknown. In our project we evaluate different physical attacks against sensor node hardware. Detailed knowledge about the effort needed for physical attacks allows to fine tune security protocols in WSNs so they provide optimal protection at minimal cost.

Apparatus and methods to communicatively couple field devices to controllers in a process control system

Abstract: Example apparatus and methods to communicatively couple field devices to controllers in a process control system are disclosed. An example method of changing a communication protocol of a first field device in a process control system includes decoupling from the first field device a first removable communication module configured to communicate using a first communication protocol. The example method also includes coupling to the first field device a second removable communication module configured to communicate using a second communication protocol. After coupling the second removable communication module, the first field device is configured to communicate using the second communication protocol. In addition, the first field device is coupled to a first communication channel on an input/output card when communicating using the first communication protocol and the first field device is coupled to the first communication channel on the input/output card when communicating using the second communication protocol.

Supporting concurrent applications in wireless sensor networks

Abstract: It is vital to support concurrent applications sharing a wireless sensor network in order to reduce the deployment and administrative costs, thus increasing the usability and efficiency of the network. We describe Melete 1 , a system that supports concurrent applications with efficiency, reliability, flexibility, programmability, and scalability. Our work is based on the Mate virtual machine [1] with significant modifications and enhancements. Melete enables reliable storage and execution of concurrent applications on a single sensor node. Dynamic grouping is used for flexible, on-the-fly deployment of applications based on contemporary status of the sensor nodes. The grouping procedure itself is programmed with the TinyScript language. A group-keyed code dissemination mechanism is also developed for reliable and efficient code distribution among sensor nodes. Both analytical and simulation results are presented to study the impact of several key parameters and optimization techniques on the code dissemination mechanism. Simulation results indicate satisfactory scalability of our techniques to both application code size and node density. The usefulness and effectiveness of Melete is also validated by empirical study.

System and method for sharing network resources between hearing devices

Abstract: A system for enabling a hearing device wireless access to a communication network includes a first transceiver unit in the hearing device communicating according to a first communication protocol. The system also includes a server device including an input/output unit connected to the communication network and configured to communicate according to a second communication protocol. A second transceiver unit is connected wirelessly to the first transceiver unit and configured to communicate according to the first communication protocol. A translator unit interconnects the second transceiver unit and the input/output unit and is configured to translate between the first and second communication protocol. The hearing device is configured to upload and download data to and from the communication network through the server device, and the server device is incorporated in a mobile or cellular telephone.

Virtual MIMO-based cross-layer design for wireless sensor networks

Abstract: In this paper, a novel multihop virtual multiple-input-multiple-output (MIMO) communication protocol is proposed by the cross-layer design to jointly improve the energy efficiency, reliability, and end-to-end (ETE) QoS provisioning in wireless sensor network (WSN). In the protocol, the traditional low-energy adaptive clustering hierarchy protocol is extended by incorporating the cooperative MIMO communication, multihop routing, and hop-by-hop recovery schemes. Based on the protocol, the overall energy consumption per packet transmission is modeled and the optimal set of transmission parameters is found. Then, the issues of ETE QoS provisioning of the protocol are considered. The ETE latency and throughput of the protocol are modeled in terms of the bit-error-rate (BER) performance of each link. Then, a nonlinear constrained programming model is developed to find the optimal BER performance of each link to meet the ETE QoS requirements with a minimum energy consumption. The particle swarm optimization (PSO) algorithm is employed to solve the problem. Simulation results show the effectiveness of the proposed protocol in energy saving and QoS provisioning

Performance comparison of trust-based reactive routing protocols

Abstract: Ad hoc networks, due to their improvised nature, are frequently established in insecure environments and hence become susceptible to attacks. These attacks are launched by participating malicious nodes against different network services. Routing protocols, which act as the binding force in these networks, are a common target of these nodes. A number of secure routing protocols have recently been proposed, which make use of cryptographic algorithms to secure the routes. However, in doing so, these protocols entail a number of prerequisites during both the network establishment and operation phases. In contrast, trust-based routing protocols locate trusted rather than secure routes in the network by observing the sincerity in participation by other nodes. These protocols thus permit rapid deployment along with a dynamically adaptive operation, which conforms with the current network situation. In this paper, we evaluate the performance of three trust-based reactive routing protocols in a network with varying number of malicious nodes. With the help of exhaustive simulations, we demonstrate that the performance of the three protocols varies significantly even under similar attack, traffic, and mobility conditions. However, each trust-based routing protocol has its own peculiar advantage making it suitable for application in a particular extemporized environment.

So near and yet so far: distance-bounding attacks in wireless networks

Abstract: Distance-bounding protocols aim to prevent an adversary from pretending that two parties are physically closer than they really are. We show that proposed distance-bounding protocols of Hu, Perrig and Johnson (2003), Sastry, Shankar and Wagner (2003), and Capkun and Hubaux (2005, 2006) are vulnerable to a guessing attack where the malicious prover preemptively transmits guessed values for a number of response bits. We also show that communication channels not optimized for minimal latency imperil the security of distance-bounding protocols. The attacker can exploit this to appear closer himself or to perform a relaying attack against other nodes. We describe attack strategies to achieve this, including optimizing the communication protocol stack, taking early decisions as to the value of received bits and modifying the waveform of transmitted bits. We consider applying distance-bounding protocols to constrained devices and evaluate existing proposals for distance bounding in ad hoc networks.

Variable-Rate Two-Phase Collaborative Communication Protocols for Wireless Networks

Abstract: The performance of two-phase collaborative communication protocols is studied for wireless networks. All the communication nodes in the cluster are assumed to share the same channel and transmit or receive collaboratively in a quasi-static Rayleigh flat-fading environment. In addition to small-scale fading, the effect of large-scale path loss is also considered. Based on a decode-and-forward approach, we consider various variable-rate two-phase protocols that can achieve full diversity order and analyze the effect of node geometry on their performance in terms of the outage probability of mutual information. For the single-relay node case, it is shown that if the collaborator node is close to the source node, a protocol based on space-time coding (STC) can achieve good diversity gain. Otherwise, a protocol based on receiver diversity performs better. These protocols are also compared with one based on fixed-rate repetition coding and their performance tradeoffs with node geometry are studied. The second part deals with multiple relays. It is known that with N relays an asymptotic diversity order of N+1 is achievable with STC-based protocols in the two-phase framework. However, in the framework of collaborative STC, those relay nodes which fail to decode remain silent (this event is referred to as a node erasure). We show that this node erasure has the potential to considerably reduce the diversity order and point out the importance of designing the STC to be robust against such node erasure

Creating secure interactive connections with remote resources

Abstract: Implementations of the present invention efficiently establish secure connections between a client and server, at least in part by authenticating the client and server early on in the connection setup phases. A client initiating a connection with a server identifies the secure communication protocols enabled at the client, and identifies these protocols in a connection request it sends to the server. The server processes the message and responds with a communication protocol it deems appropriate for the connection. The client and server then exchange appropriate authentication information, and then establish a connection session that implements the chosen communication protocol, and encrypts messages using the negotiated communication protocol. Additional implementations relate to reestablishing dropped connections behind virtual Internet Protocol addresses, without necessarily having to recommit much connection resource overhead.

When TCP Breaks: Delay- and Disruption- Tolerant Networking

Abstract: The authors give an overview of current work on delay- and disruption-tolerant networking and review the overall architecture proposed by the Internet Research Task Force's Delay Tolerant Networking Research Group. Their approach to networking makes no assumption that nodes will have end-to-end connectivity, which could be missing with extremely high-latency connections, if the nodes are only in contact with one another infrequently or if contacts are being continually disrupted. They also describe the main protocols the group is developing and give examples of some pilot networks that use these protocols

Layering As Optimization Decomposition

Abstract: Network protocols in layered architectures have historically been obtained on an ad hoc basis, and many of the recent cross-layer designs are conducted through piecemeal approaches. They may instead be holistically analyzed and systematically designed as distributed solutions to some global optimization problems. This paper presents a survey of the recent efforts towards a systematic understanding of “layering” as “optimization decomposition”, where the overall communication network is modeled by a generalized Network Utility Maximization (NUM) problem, each layer corresponds to a decomposed subproblem, and the interfaces among layers are quantified as functions of the optimization variables coordinating the subproblems. There can be many alternative decompositions, each leading to a different layering architecture. This paper summarizes the current status of horizontal decomposition into distributed computation and vertical decomposition into functional modules such as congestion control, routing, scheduling, random access, power control, and channel coding. Key messages and methods arising from many recent work are listed, and open issues discussed. Through case studies, it is illustrated how “Layering as Optimization Decomposition” provides a common language to think about layered network architecture and a unifying approach to holistically design protocol stacks.

VoIP Intrusion Detection Through Interacting Protocol State Machines

Abstract: Being a fast-growing Internet application, voice over Internet protocol (VoIP) shares the network resources with the regular Internet traffic, and is susceptible to the existing security holes of the Internet. Moreover, given that voice communication is time sensitive and uses a suite of interacting protocols, VoIP exposes new forms of vulnerabilities to malicious attacks. In this paper, we propose a highly-needed VoIP intrusion detection system. Our approach is novel in that, it utilizes not only the state machines of network protocols but also the interaction among them for intrusion detection. This detection approach is particularly suited for protecting VoIP applications, in which a melange of protocols are involved to provide IP telephony services. Based on tracking deviations from interacting protocol state machines, our solution shows promising detection characteristics and low runtime impact on the perceived quality of voice streams

Method and System for Minimizing Power Consumption in a Communication System

Abstract: Certain embodiments of the invention may be found in a method and system for minimizing power consumption in a communication system. Exemplary aspects of the invention may comprise configuring a supply voltage of an amplifier to enable communication of data using a first communication protocol during a first timeslot in a TDM frame, reconfiguring the supply voltage of the amplifier to enable communication of data using a different communication protocol, and adjusting the supply voltage of the amplifier in proportion to the envelope of a baseband signal conforming to one of the communication protocols. The first and second communication protocols may conform to various communication protocols, such as WCDMA, HSDPA, HSUDPA, GSM, GPRS, EDGE, WiMAX, OFDM, UWB, ZigBee, and Bluetooth. The baseband signal may be delayed by a number of samples before being input into the amplifier.

System monitor for networks of nodes

Abstract: Systems and methods are described that provide a system monitor component, e.g., for a sensor network, which may include, e.g., a server component that is continuously running and monitoring zero or more networks consisting of (possibly wireless) devices, where each network may be executing a different communications protocol, such as a proprietary, platform-dependent protocol. The system monitor may maintain a system model of the networks. The system monitor may be connected with the networks through a message transport system that routes any occurring messages in a common or standard communications protocol, as well as message handlers that access either platform-abstracting gateways or the proprietary messages that the devices of one or more of the networks may use.

Path Computation Element (PCE) Communication Protocol Generic Requirements

Abstract: The PCE model is described in the "PCE Architecture" document and facilitates path computation requests from Path Computation Clients (PCCs) to Path Computation Elements (PCEs). This document specifies generic requirements for a communication protocol between PCCs and PCEs, and also between PCEs where cooperation between PCEs is desirable. Subsequent documents will specify application-specific requirements for the PCE communication protocol. This memo provides information for the Internet community.

Timing analysis of the FlexRay communication protocol

Abstract: FlexRay will very likely become the de-facto standard for in-vehicle communications. However, before it can be successfully used for safety-critical applications that require predictability, timing analysis techniques are necessary for providing bounds for the message communication times. In this paper, we propose techniques for determining the timing properties of messages transmitted in both the static (ST) and the dynamic (DYN) segments of a FlexRay communication cycle. The analysis techniques for messages are integrated in the context of a holistic schedulability analysis that computes the worst-case response times of all the tasks and messages in the system. We have evaluated the proposed analysis techniques using extensive experiments.

Cluster-based multi-channel communications protocols in vehicle ad hoc networks

Abstract: The dedicated short range communications (DSRC) standard equipped with seven channels is designated for intelligent transportation system (ITS) applications to improve the driving safety and support networking services among moving vehicles. Making best use of the DSRC multichannel architecture, we propose a cluster-based multichannel communications scheme, which integrates the clustering with contention-free/contention-based MAC protocols. In our proposed scheme, the elected cluster-head (CH) vehicle functions as the coordinator (like WLAN's basestation) to collect/deliver the real-time safety messages within its own cluster and forward the consolidated safety messages to the neighboring CHs. Also, the CH vehicle controls channel-assignments for cluster-member vehicles transmitting/receiving the non-real-time traffics, which makes the wireless channels more efficiently utilized for the non-real-time data transmissions. Our scheme uses the contention-free MAC (TDMA/broadcast) within a cluster and the IEEE 802.11 MAC among CH vehicles such that the real-time delivery of safety messages can be guaranteed. The simulation results show that our proposed scheme can significantly improve the throughputs of vehicle data communications while guaranteeing the real-time delivery of safety messages

Method and system of remote diagnostic, control and information collection using multiple formats and multiple protocols with verification of formats and protocols

Abstract: A system, method and program product for diagnosing, controlling and collecting information from devices. Information regarding events of each one of a plurality of target applications executing in an application unit is collected and formatted into one of multiple data formats for transmission through one of multiple communication protocols at the request of each of the target applications, through an interface. A combination of a data format and communication protocol requested by a target application is verified for validity. If the requested combination is invalid, a valid combination is substituted for more reliable transmission. The formatted data is transmitted through, e.g., e-mail or FTP to a predetermined destination or may be saved to local storage, e.g., a local disk. By sharing resources, code duplication is reduced or eliminated.

Efficient coordination and transmission of data for cooperative vehicular safety applications

Abstract: This paper presents a method for efficient exchanges of Data Elements between vehicles running multiple safety applications. To date, significant efforts have been made in designing lower-layer communication protocols for VANET. Also, industry and government agencies have made progress in identifying and implementing certain vehicular safety applications. However, the specific environment of VANET-enabled safety applications lends itself to significant efficiencies in how information is coordinated within a vehicle and transmitted to neighboring vehicles. These efficiencies are instantiated in what we call the Message Dispatcher. The Message Dispatcher is an interface between multiple safety applications and the lower-layer communication stack. This Message Dispatcher concept was recently contributed to the Society of Automotive Engineers (SAE) and has become an underlying principle in their safety message standardization process. It has also been implemented in vehicle demonstrations at the Toyota Technical Center (TTC) in Ann Arbor, MI.

Intelligent mobile search client

Abstract: A system and method is provided to provide information services to a plurality of mobile clients where the mobile clients can be any networked device including cell-phones, PDAs and other wireless devices. The system utilizes available communications protocols to submit requests and receive responses that can be information services and mobile content, such as ring tones and wallpaper. The system permits a user to conduct unstructured searches and to use hierarchical navigation systems for generating content-specific structured search queries and datasets. Searches can be based on a prior history of searches, geographical location, stated preferences and profile information associated with the user.

Wireless Network Protocol System And Methods

Abstract: A system and method for providing wireless network communications between a plurality of remote devices and a site controller are provided. Each network and the site controller communicates using a communications protocol adapted to allow remote devices and the site controller to independently control the communication path for transmissions sent by each device. In some embodiments, remote devices can collect and store information about other remote devices and available communication paths for optimum data transmission. Also, in some embodiments, remote devices can quickly join a preexisting network by communicating with a site controller and/or other remote devices. Other embodiments are also claimed and described.

Method and apparatus for providing multi-system cellular communications

Abstract: A method and apparatus of communicating with a plurality of cellular communication networks employing different communication protocols using a single mobile endpoint device, e.g., a cellular phone, are disclosed. In one embodiment, a user cellular phone is provided with a communication protocol conversion or switching module that is adapted for interfacing with different cellular networks operating in a region where the cellular phone is presently located. When a request for an incoming call or an outgoing call is received, the present method evaluates at least one performance factor in selecting one of the plurality of different communication protocols to service or process the incoming call or outgoing call.

On the Energy Efficiency of Wireless Transceivers

Abstract: Battery life-time is an important performance metric for many wireless networks and there is a growing need to improve the life-time of these networks. However, system analysis is complicated by the fact that the transceiver electronics energy cost is non-negligible and often has a major impact on the battery life. This paper develops a simple metric to evaluate the energy cost of both communication protocols and circuit electronics. This metric treats the electronics energy as an overhead cost on top of the Eb/No requirement. This enables the joint optimization of system and circuit parameters for energy limited wireless transceivers with arbitrary communication protocols.