Showing papers on "Communications system published in 2003"

Cryptographic requirements for chaotic secure communications

Abstract: In recent years, a great amount of secure communications systems based on chaotic synchronization have been published. Most of the proposed schemes fail to explain a number of features of fundamental importance to all cryptosystems, such as key definition, characterization, and generation. As a consequence, the proposed ciphers are difficult to realize in practice with a reasonable degree of security. Likewise, they are seldom accompanied by a security analysis. Thus, it is hard for the reader to have a hint about their security. In this work we provide a set of guidelines that every new cryptosystems would benefit from adhering to. The proposed guidelines address these two main gaps, i.e., correct key management and security analysis, to help new cryptosystems be presented in a more rigorous cryptographic way. Also some recommendations are offered regarding some practical aspects of communications, such as channel noise, limited bandwith, and attenuation.

To code, or not to code: lossy source-channel communication revisited

Abstract: What makes a source-channel communication system optimal? It is shown that in order to achieve an optimal cost-distortion tradeoff, the source and the channel have to be matched in a probabilistic sense. The match (or lack of it) involves the source distribution, the distortion measure, the channel conditional distribution, and the channel input cost function. Closed-form necessary and sufficient expressions relating the above entities are given. This generalizes both the separation-based approach as well as the two well-known examples of optimal uncoded communication. The condition of probabilistic matching is extended to certain nonergodic and multiuser scenarios. This leads to a result on optimal single-source broadcast communication.

Optimization of the split-step Fourier method in modeling optical-fiber communications systems

Abstract: We studied the efficiency of different implementations of the split-step Fourier method for solving the nonlinear Schro/spl uml/dinger equation that employ different step-size selection criteria. We compared the performance of the different implementations for a variety of pulse formats and systems, including higher order solitons, collisions of soliton pulses, a single-channel periodically stationary dispersion-managed soliton system, and chirped return to zero systems with single and multiple channels. We introduce a globally third-order accurate split-step scheme, in which a bound on the local error is used to select the step size. In many cases, this method is the most efficient when compared with commonly used step-size selection criteria, and it is robust for a wide range of systems providing a system-independent rule for choosing the step sizes. We find that a step-size selection method based on limiting the nonlinear phase rotation of each step is not efficient for many optical-fiber transmission systems, although it works well for solitons. We also tested a method that uses a logarithmic step-size distribution to bound the amount of spurious four-wave mixing. This method is as efficient as other second-order schemes in the single-channel dispersion-managed soliton system, while it is not efficient in other cases including multichannel simulations. We find that in most cases, the simple approach in which the step size is held constant is the least efficient of all the methods. Finally, we implemented a method in which the step size is inversely proportional to the largest group velocity difference between channels. This scheme performs best in multichannel optical communications systems for the values of accuracy typically required in most transmission simulations.

Ultra-wideband communications: an idea whose time has come

Abstract: Summary form only given. In February 2002, a law-and-order of the federal communications commission (FCC) gave the "green light" (spectral mask in the range 3.1-10.6 GHz) for commercial applications of ultra wideband (UWB) systems. Since this recent FCC release, UWB has emerged as an exciting technology whose "time has come" for wireless communications, and local area networking. Conveying information over ultra-short waveforms, UWB technology allows for very accurate delay estimates providing position and localization capabilities within a few centimeters. The scarcity of bandwidth resources coupled with the capability of IR to overlay existing systems, welcomes UWB connectivity in the workplace, and at home for indoor and especially short range wireless links. However, to realize these attractive features, UWB research and development has to cope with formidable challenges. This plenary will provide the fundamentals of UWB communication systems, driving applications, recent developments, and open problems.

Multicarrier techniques for 4G mobile communications

Abstract: From the Publisher: As research for future fourth generation (4G) mobile communication systems is underway worldwide in major companies and academic institutions, forward-thinking professionals are striving to gain a thorough understanding of the cutting-edge technologies and design techniques that will make these systems work. This book helps readers do just that by: providing a comprehensive introduction to multicarrier techniques for 4G mobile communications with a special focus on the analytical aspects; explaining radio channel characteristics and phenomena and discussing the advantages and disadvantages of the OFDM scheme; featuring new multicarrier-related techniques, MC-CDMA, research on several 4G systems, and a look at several problems to be overcome with these systems; examining the concept and detail of the ODFM scheme and how to carry out theoretical analysis on the performance of transmission systems in radio channels; showing how ODFM has been successfully adopted as a modulation scheme in communications systems and broadcasting systems such as ADSL, wireless LANs, and DVB-T.

Understanding and measuring circular polarization

Abstract: Many modern satellite and terrestrial point-to-point communications systems use circular polarization (CP) wave propagation in order to maximize the polarization efficiency component of the link budget. Therefore, in an undergraduate electromagnetics syllabus, an introduction to the topic of circular polarization is necessary to promote an understanding of the propagation aspects of modern communications system design. Students new to the antennas and propagation discipline often have difficulty in grasping the concept of CP; therefore, in this paper, the essential aspects of this topic are reinforced by a tutorial description of CP in terms of wave propagation, antenna properties, and measurement techniques. A simple laboratory-based project is described that requires the design, fabrication, and measurement of a crossed dipole antenna. The measured input impedance and radiation patterns are correlated with theory to highlight the conditions necessary to support CP wave propagation. By combining basic electromagnetic concepts with a series of simple intuitive laboratory experiments, the students can more easily visualize, and hence understand, CP wave propagation and its use in communications systems design.

Network supporting roaming, sleeping terminals

Abstract: Improved apparatus for a radio communication system having a multiplicity of mobile transceiver units selectively in communication with a plurality of base transceiver units which, in turn, communicate with one or more host computers for storage and manipulation of data collected by bar code scanners or other collection means associated with the mobile transceiver units. A network controller and an adapter which has a simulcast and sequential mode provide selective interface between host computers and base transceivers. A scheme for routing data through the communication system is also disclosed wherein the intermediate base stations are organized into an optimal spanning-tree network to control the routing of data to and from the RF terminals and the host computer efficiently and dynamically. Additionally, redundant network and communication protocol is disclosed wherein the network utilizes a polling communication protocol which, under heavy loaded conditions, requires that a roaming terminal wishing to initiate communication must first determine that the channel is truly clear by listing for an entire interpoll gap time. In a further embodiment, a criterion used by the roaming terminals for attaching to a given base station reduces conflicts in the overlapping RF regions of adjacent base stations.

Principles of Communication Systems Simulation with Wireless Applications

Abstract: The hands-on, example-rich guide to modeling and simulating advanced communications systemsSimulation is an important tool used by engineers to design and implement advanced communication systems that deliver optimal performance This book is a hands-on, example-rich guide to modeling and simulating advanced communications systems The authors take a systems-level approach, integrating digital communications, channel modeling, coding, elementary statistical estimation techniques, and other essential facets of modeling and simulation This is the first book to present complete simulation models built with MATLAB that can serve as virtual laboratories for predicting the impact of system design changes Coverage includes: Role of simulation in communication systems engineering Simulation approaches and methodologies Signal and system representations, filter models, noise generation, Monte Carlo simulation, and postprocessing Advanced techniques for modeling and simulating nonlinear and time-varying systems Waveform level and discrete channel models Performance estimation via Monte Carlo simulation Semianalytic simulation techniques Variance reduction techniques Co-channel interference in wireless communication systems, and more The authors also present detailed case studies covering phase-locked loops, CDMA systems, multichannel nonlinear systems, as well as a start-to-finish simulation of an advanced cellular radio systemPrentice Hall Series in Communications Engineering & Emerging Technologies, Theodore S Rappaport, Editor

Power line communication system and method of operating the same

Abstract: The present invention provides a system for operating a power line communications system that is comprised of a plurality of network elements, which may take the form of repeaters, bypass devices, backhaul devices, wireless backhaul devices, enhanced bypass device, communication interface devices and others. In one embodiment, two groups of network elements in the same electrical distribution system are isolated except selected communication link.

First responder communications system

Abstract: A First Responder Communications System (FRCS), also referred to as an Automated Incident Control System, is provided that supports inter-agency and intra-agency communications among first responders including fire, police, border patrol, emergency medical service, safety, and/or other agencies. The FRCS also supports communication among multiple on-scene agencies and various command and control personnel and increases situational awareness by automatically providing position information as well as other sensor information. Components of the FRCS integrate multiple communications channels including High Frequency (HF), Very High Frequency (VHF), Ultra High Frequency (UHF)/microwave, cellular, satellite, and Public Switched Telephone Network (PSTN). The FRCS also provides position and time information via Global Positioning System (GPS) and/or other positioning systems, and data from deployed and/or personal sensors to provide enhanced communications, command and control capabilities to the first responders and incident command.

Modern Communications Jamming Principles and Techniques

Abstract: This newly revised and greatly expanded edition of the popular Artech House book, Modern Communications Jamming Principles and Techniques, provides an up-to-date, exhaustive treatment of the techniques and methods available to create countermeasures against anti-jam, over-the-air communications. The Second Edition features a wealth of new material on urban warfare, including a computer simulation of EW architecture alternatives for land-based forces based on urban constraints. The new edition also includes an expanded section on time-hopped spread spectrum communications, more details on modern communication system technologies such as CDMA and OFDM, and an in-depth discussion on sources of urban noise. This practical resource is focused on showing you how to design and build jammers specifically targeted at spread spectrum, anti-jam communications. Moreover, you find assistance in evaluating the expected performance of jamming systems against modern communications systems, and discover the best waveform to use to counter communication systems designed to be effective in jamming environments. While mathematical derivations in general are avoided, the book presents error rate performance equations for most modern digital anti-jam communication systems.

Integrated system of white LED visible-light communication and power-line communication

Abstract: White LED offers advantageous properties such as high brightness, reliability, lower power consumption and long lifetime. Indoor optical wireless communication systems employing white LED lighting have been proposed. This system will enable high quality of service by the high radiation power from this lighting equipment. And, this system does not cause or suffer from radio or electromagnetic interference. But, it is difficult for existing offices and households to install the communication cable to the ceiling. In this paper, an easy wiring system for optical communication using the existing power-line is proposed. This system is emitted as visible-light from LED lighting according to the transmitted signal waveform without demodulating the signal from the power-line. This system is expected to be applicable from the existing illuminant easily like exchanging electric bulbs. This integrated system will surely have a big impact as a new signal transmission system and its economical effect will be great. The basic performance of this system is analyzed. The actual system is built and its feasibility is shown through experiments.

Communication application server for converged communication services

Abstract: A communication application server for supporting converged communications in a communication system. The communication application server is responsive to communication service requests from external endpoints, applications or other requesting entities, and in one embodiment comprises at least first and second components. The first component is operative: (i) to process a given one of the communication service requests to identify at least one corresponding communication service supported by the communication application server; (ii) to determine one or more executable communication tasks associated with the identified communication service; and (iii) to establish communication with one or more external servers to carry out execution of at least a subset of the one or more executable communication taks associated with the communication service. The second component is coupled between the first component and the one or more external servers, and provides, for each of the external servers, a corresponding interface for connecting the communication application server to the external server.

Communications system for providing broadband communications using a medium voltage cable of a power system

Abstract: A broadband service communication system using an MV cable for conveying RF signals in a network segment, which includes a distribution center (PLT controller) and a plurality of power line telecommunication (PLT) stations. The PLT controller has a distribution modem for conveying downstream and upstream RF signals to and from the PLT stations through the MV cable via couplers. Each PLT station has a modem for conveying the downstream and upstream RF signals via couplers and for conveying media signals to one or more customer premises equipment (CPE) via, e.g. wireless links. The PLT controller controls each PLT station regarding upstream communications transfer of all downstream communications and also controls. The PLT controller can be connected via a router to a WAN to convey media signals to and from the WAN. Repeaters and interlinks are used to join multiple network segments.

Open architecture communications in a gaming network

Abstract: Open architecture communication systems and methods are provided that allow flexible data transmission between gaming machines and other devices and nodes within a gaming machine network. The gaming machine and other devices employ a communication interface that sends and receives data via a common communication protocol and via common communication hardware. The communication interface and common communication protocol allow data transfer between gaming machines and other network nodes such as gaming service servers, despite the presence of different proprietary gaming machine functions and proprietary communication protocols and despite the presence of various proprietary hardware and proprietary communication protocols relied on by the servers.

Diversity transmission modes for mimo ofdm communication systems

Abstract: Techniques for transmitting data using a number of diversity transmission modes to improve reliability. At a transmitter, for each of one or more data streams, a particular diversity transmission mode is selected for use from among a number of possible transmission modes. These transmission modes may include a frequency diversity transmission mode, a Walsh diversity transmission mode, a space time transmit diversity (STTD) transmission mode, and a Walsh-STTD transmission mode. Each diversity transmission mode redundantly transmits data over time, frequency, space, or a combination thereof. Each data stream is coded and modulated to provide modulation symbols, which are further processed based on the selected diversity transmission mode to provide transmit symbols. For OFDM, the transmit symbols for all data streams are further OFDM modulated to provide a stream of transmission symbols for each transmit antenna used for data transmission.

Exploiting the Routing Flexibility for Energy/Performance Aware Mapping of Regular NoC Architectures

Abstract: In this paper, we present an algorithm which automatically maps the IPs onto a generic regular Network on Chip (NoC) architecture and constructs a deadlock-free deterministic routing function such that the total communication energy is minimized. At the same time, the performance of the resulting communication system is guaranteed to satisfy the specified constraints through bandwidth reservation. As the main contribution, we first formulate the problem of energy/performance aware mapping, in a topological sense, and show how the routing flexibility can be exploited to expand the solution space and improve the solution quality. An efficient branch-and-bound algorithm is then described to solve this problem. Experimental results show that the proposed algorithm is very fast, and significant energy savings can be achieved. For instance, for a complex video/audio application, 51.7% energy savings have been observed, on average, compared to an ad-hoc implementation.

A communication device for providing multimedia in a group communication network

Abstract: A system and method for providing group communication services is disclosed. Each of a plurality of group communication devices coverts media, such as video, audio, image and/or data into data packets suitable for transmission over a data network, such as the Internet. The data packets are selectively transmitted through the data network to a communications manager. The communications manager acts as a configurable switch, allowing communications from any communication device to be selectively routed to the plurality of communication devices based on the types of the communication devices and/or the requests received from the corresponding users. The communications manager further allows users of other communication systems and devices to participate in group communications with each other.

Method and system for high-speed communication over power line

Abstract: The present invention relates to a communication system (10, 30) for transmission of data signals over a power line (15, 35) comprising at least one data generating arrangement (11, 31), transceivers and line couplers (14, 34) for coupling data to said line power. The system comprises a microwave transmitter between said transceiver and said line coupler, which transceivs said data signal as electrical field on a surface of said power line.

Multiple-input, multiple-output (mimo) systems with multiple transmission modes

Abstract: Techniques to transmit data on a number of transmission channels in a multi-channel communication system using multiple transmission schemes requiring less channel-state information (CSI). These schemes may include a partial-CSI transmission scheme that transmits a single data stream on each transmit antenna selected for use and a “beam-forming” transmission scheme that allocates all transmit power to a single transmission channel having the best performance. Each transmission scheme may provide good or near-optimum performance for a specific range of operating conditions (or operating SNRs). These multiple transmission schemes may then be combined in a piece-wise fashion to form a “multi-mode” transmission scheme that covers the full range of operating conditions supported by the MIMO system. The specific transmission scheme to be used for data transmission at any given moment would then be dependent on the specific operating condition experienced by the system at that moment.

Rate control for multi-channel communication systems

Abstract: Techniques to determine a set of rates for a set of data streams to be transmitted in a multi-channel communication system A group of transmission channels to be used for each data stream is initially identified An equivalent system for each group is then defined to have an AWGN (or flat) channel and a spectral efficiency equal to the average spectral efficiency of the transmission channels in the group (216) A metric for each group is then derived based on the associated equivalent system, eg, set to the SNR needed by the equivalent system to support the average spectral efficiency (218) A rate for each data stream is then determined based on the metric associated with the data stream The rate is deemed to be supported by the communication system if the SNR required to support the data rate by the communication system is less than or equal to the metric (226)

Radio communication system using adaptive array antenna

Abstract: A radio communication system and method having an array antenna and a weighting arrangement that provides a downlink array weight for a downlink on the basis of information about bearings of a plurality of incoming signals received through a plurality of uplinks, and transmission power control information about transmission data to be transmitted through a downlink.

System and apparatus for performing broadcast and localcast communications

Abstract: Described is a communication system including mobile communication devices. In the described system, the mobile devices may be wrist-worn watches such as are in common use today, except that the watches are specially configured to receive data in a “broadcast” mode and transmit and/or receive data in a “localcast” mode. The localcast mode includes the ability to transmit and receive data in a peer-to-peer fashion, allowing mobile devices to communicate directly with each other. The ability to combine two of these communication modes in a small, integrated and hence inexpensive and low-power package provides many advantages over existing personal communication device solutions.

Method and apparatus for using switched multibeam antennas in a multiple access communication system

Abstract: In order to increase a capacity, or a number of mobile stations (MSs), or users, that may engage in concurrent communication sessions, a communication system (100) is provided that schedules a different MS, or user, (110-112) in each beam of multiple predetermined, fixed beams (160-165) associated with a coverage area, for example, a sector By simultaneously scheduling a user in each beam of the multiple beams, a performance and throughput of communication system is significantly increased over the prior art In one embodiment of the present invention, a portion of a shared communication channel that is allocated to each MS is concurrently transmitted to each MS via a beam associated with the MS In other embodiments of the present invention, voice channels, data channels, and control channels associated with each MS scheduled in a beam may be concurrently transmitted to each MS via the beam associated with the MS

Intelligent selectively-targeted communications systems and methods

Abstract: There is disclosed a system and method wherein precise geographical location information such as Global Positioning System coordinate data is utilized as a principal criterion for implementing other wireless transmitted instructions and communications advising vehicles, and others, of an approaching emergency vehicle, the proximity of a hazardous condition, or virtually any other situation which is relevant to the intended recipient because of their location. The system and method further can involve intervention and control of a vehicle, such as an aircraft or automobile, which comes into a predetermined location or area, or under other circumstances. The system and method use transmitting units and receiving units, both of which can receive geographical positioning information and which may sound or otherwise output an appropriate advisory, warning or other communication selected based on their positions, heading, and/or speed.

Low cost multi-beam, multi-band and multi-diversity antenna systems and methods for wireless communications

Abstract: Systems and methods for employing switched phase shifters and a feed network to provide a low cost multiple beam antenna system for wireless communications. The present systems and methods may also facilitate multi-band communications and employ multi-diversity. The present systems and methods allow communication systems to achieve enhanced performance for communication or other services such as location tracking. The present systems and methods may employ switched phase shifters, multiple diversity antennas and/or a feed network having a multi-layer construction to provide an antenna system with low losses, low external component count and/or which is thin and compact.

System and method for collecting and transmitting medical data

Abstract: A system and method for collecting and transmitting medical and health-related data over a network are disclosed. A measuring device measures a user's physiological attribute and produces a first signal related thereto, which an integration system coupled to the measuring device receives and converts into a second signal for transmitting over the Internet. In accordance with one aspect of a preferred embodiment, the integration system is adapted to read the first signal as it is sent from the measuring device to its display. A communications system transmits the second signal over the Internet to a remote system using any of a variety of techniques known in the art. The remote system extracts the measured physiological attribute and other associated data from the second signal and populates a database. Preferably, a web-based portal provides access to the data for one or more users.

Modeling and analysis of high-speed links

Abstract: Very low bit error rate (BER) requirements for the operation of a high-speed link system require a very precise analysis of the link performance in order to prevent unrealistic specifications on both IC design and communication algorithm development. This paper presents the analysis of the noise and distortion sources in a high-speed link system, and their impact on the choice and effectiveness of different communication techniques. Phase-locked loop and clock-and-data recovery loop modeling is also described. It is shown that the most dominant noise and distortion sources are colored and bounded, as opposed to standard unbounded Gaussian white noise assumptions, which yield large errors in the estimation of the link performance and comparison of different signaling techniques. With very low BER requirements, shape of probability distribution of noise and distortion sources and their correlations, are much more important than just their total power, which contrasts the standard analysis in communication systems.

Translation of electronically transmitted messages

Abstract: A communication system for human communication comprises a sending computer system (11), a receiving computer system (21a) and a translation web site (31). The sending system (11) is arranged, when sending a communication, to determine a first human perceptible language associated with the sender and a second human perceptible language associated with the recipient and, if the first and second languages are different, to send the communication to the translation system (31) for translation. The address of the receiving system is sent with the communication. The diverted communication is translated, and forwarded by the translation system (31) to the receiving system. If the first and second languages are the same, the communication is sent by the sending system (11) directly to the receiving system (21a). The receiving system checks the language of incoming communications against that of the recipient and, if necessary, sends the communication to the translation site (31) for translation and return.

Method and device for establishing communication links and detecting interference between mobile nodes in a communication system

Abstract: A wireless communication network includes a plurality of mobile nodes each including a transceiver (14), a phased array antenna (16) connected to the transceiver, and a controller (18) connected to the transceiver. The controller schedules respective semi-permanent time slot for each time frame to establish a communication link with each neighboring mobile node and leaves at least one available time slot in each time frame. The controller also schedules the at least one available time slot to also serve the communication link with a neighboring mobile node based upon link communications demand. The phased array antenna is aimed by the controller towards each neighboring mobile node during communication therewith. The controller also detects interference in time slots for communication with neighboring mobile nodes and coordinates the scheduling of time slots based upon detected interference.