Showing papers on "Data transmission published in 1999"

Channel estimation for OFDM systems with transmitter diversity in mobile wireless channels

Abstract: Transmitter diversity is an effective technique to improve wireless communication performance. In this paper, we investigate transmitter diversity using space-time coding for orthogonal frequency division multiplexing (OFDM) systems in high-speed wireless data applications. We develop channel parameter estimation approaches, which are crucial for the decoding of the space-time codes, and we derive the MSE bounds of the estimators. The overall receiver performance using such a transmitter diversity scheme is demonstrated by extensive computer simulations. For an OFDM system with two transmitter antennas and two receiver antennas with transmission efficiency as high as 1.475 bits/s/Hz, the required signal-to-noise ratio is only about 7 dB for a 1% bit error rate and 9 dB for a 10% word error rate assuming channels with two-ray, typical urban, and hilly terrain delay profiles, and a 40-Hz Doppler frequency. In summary, with the proposed channel estimator, combining OPDM with transmitter diversity using space-time coding is a promising technique for highly efficient data transmission over mobile wireless channels.

Principles of Digital Transmission: With Wireless Applications

Abstract: From the Publisher: Principles of Digital Transmission is designed for advanced undergraduate and graduate level students and professions in telecommunications. Teachers and learners can mix and match chapters to create four distinct courses: (1) a one-term basic course in digital communications; (2) a one-term course in advanced digital communications; (3) a one-term course in information theory and coding; (4) a two-term course sequence in digital communications and coding. The book provides rigorous mathematical tools for the analysis and design of digital transmission systems. The authors emphasize methodology in their aim to teach the reader how to do it rather than how it is done. They apply the fundamental tools of the discipline onto a number of systems, such as wireless data transmission systems.

Method and apparatus for media data transmission

Abstract: Methods and apparatuses for processing media data transmitted in a data communication medium. A digital processing system is provided with a time related sequence of media data provided to the digital processing system based on a set of data, wherein the set of data indicates a method to transmit the time related sequence of media data according to a transmission protocol. The set of data, itself, is a time related sequence of data associated with the time related sequence of media data. The time related sequence of media data may be presented and/or stored by the digital processing system.

Copy protection for DVD video

Abstract: The prospect of consumer digital versatile disk (DVD) recorders highlights the challenge of protecting copyrighted video content from piracy. We describe the copy-protection system currently under consideration for DVD. The copy-protection system broadly tries to prevent illicit copies from being made from either the analog or digital I/O channels of DVD recorders. An analog copy-protection system is utilized to protect the NTSC/PAL output channel by preventing copies to VHS. The digital transmission of content is protected by a robust encryption protocol between two communicating devices. Watermarking is used to encode copy-control information retrievable from both digital and analog signals. Hence, such embedded signals avoid the need for metadata to be carried in either the digital or analog domains. Finally, the copy-protection system provides the capability for one-generation copying. We discuss some proposed solutions and some of the implementation issues that are being addressed.

Method and apparatus for establishing a secure connection over a one-way data path

Abstract: Improved techniques for facilitating secure data transfer over one-way data channels or narrowband channels are disclosed Often, these channels are wireless channels provided by wireless data networks The techniques enable cryptographic handshake operations for a one-way data channel to be performed over a companion two-way data channel so that the one-way data channel is able to effectively satisfy security protocols that require two-way communications for the cryptographic handshake operations Once the cryptographic handshake operations are complete, data can be transmitted over the one-way data channel in a secure manner Additionally, the techniques also enable the cryptographic handshake operations to be performed more rapidly because the two-way channel is typically a wideband channel In which case, the use of a wideband channel instead of a narrowband channel for the cryptographic handshake operations results in latency reductions, regardless of whether the narrowband channel is a one-way channel or a two-way channel

System and method for powering, controlling, and communicating with multiple inductively-powered devices

Abstract: Magnetic Vector Steering (MVS) and Half-Cycle Amplitude Modulation (HCAM) are novel techniques which enhance the powering and control of multiple arbitrarily oriented implant devices. Together, these techniques enable arbitrarily oriented implants to receive power and command, programming, and control information in an efficient manner that preserves battery life and transmission time while reducing overall implant device bulk. By steering the aggregate magnetic field from a near-orthogonal set of AC-energized coils, selected implants can be powered or communicated with at desired times. Communication with individual implants can also be enhanced through half-cycle amplitude modulation —a technique that allows bit rates up to twice the energizing frequency. Unlike prior art systems, power and data transfer can be realized over the same frequency channel.

System for short range wireless data communication to inexpensive endpoints

Abstract: A system provides short range wireless data communication from a central control point (e.g., interrogator) to inexpensive endpoints (e.g., tags). The endpoints utilize the technology of modulated backscatter for transmission from the tags to the interrogator. The system uses a new downlink protocol for data transmission from the interrogator to the tags and a new uplink protocol for data transmission from the tags to the interrogator. Both protocols use a backoff/retry algorithm to randomly retransmit any non-acknowledged messages. System capacity from the tags to the interrogator is further enhanced by the use of uplink subcarrier frequency division multiplexing.

Contemporary Communication Systems Using MATLAB

Abstract: Signals and linear systems random processes analog communications analog-to-digital conversion baseband digital transmission channel equalization carrier modulation systems channel capacity and coding spread spectrum communications.

Multimedia delivery system

Abstract: A computerized multimedia delivery system designed to simultaneously display multiple streams of multimedia content is disclosed. The interactive delivery system is capable of (1) providing multiple streams of content to users of the system, (2) allowing users to interact with the system, (3) providing information concerning such users to a centralized computer for processing, (4) providing users with the ability to perform financial transactions, and (5) provide a printed receipt or redemption coupon. Content is digitally stored on a medium suitable for storage and retrieval by the computer system such as large capacity hard disk drives. The content to be displayed is selected either using a scheduling device or by user interaction. A user can interact with the system through a touch-screen graphical user interface on a video display. Once the content is selected, the system reads the configuration information for that particular content. The digital data representing the selected content is sent to a series of suitable digital to analog converters capable of converting the digital representation of the content into an analog signal which can be transferred to analog devices capable of audio and video reproduction. A device capable of financial transactions such as a magnetic stripe reader, smartcard reader, or currency validator is connected to the computer through input/output interfaces allowing the user to perform financial transactions through the system. An attached printer has the ability to provide the user with printed material related to the selected content. Two-way communication between the user and the system allows the system to collect user information directly related to specific content and transmit such information to a centralized data management center through a modem connected to the system. The system's multimedia content can be upgraded through an optical disk or data transmission by satellite.

An adaptive modulation scheme for simultaneous voice and data transmission over fading channels

Abstract: We propose a new adaptive modulation technique for simultaneous voice and data transmission over fading channels and study its performance. The proposed scheme takes advantage of the time-varying nature of fading to dynamically allocate the transmitted power between the inphase (I) and quadrature (Q) channels. It uses fixed-rate binary phase shift keying (BPSK) modulation on the Q channel for voice, and variable-rate M-ary amplitude modulation (M-AM) on the I channel for data. For favorable channel conditions, most of the power is allocated to high rate data transmission on the I channel. The remaining power is used to support the variable-power voice transmission on the Q channel. As the channel degrades, the modulation gradually reduces its data throughput and reallocates most of its available power to ensure a continuous and satisfactory voice transmission. The scheme is intended to provide a high average spectral efficiency for data communications while meeting the stringent delay requirements imposed by voice. We present closed-form expressions as well as numerical and simulation results for the outage probability, average allocated power, achievable spectral efficiency, and average bit error rate (BER) for both voice and data transmission over Nakagami-m fading channels. We also discuss the features and advantages of the proposed scheme. For example, in Rayleigh fading with an average signal-to-noise ratio (SNR) of 20 dB, our scheme is able to transmit about 2 bits/s/Hz of data at an average BER of 10/sup -5/ while sending about 1 bit/s/Hz of voice at an average BER of 10/sup -2/.

Practical study on wireless transmission of power and information for autonomous decentralized manufacturing system

Abstract: In previous papers, the authors have already introduced the idea of an autonomous decentralized manufacturing system (ADMS), in which machines receive electrical energy through wireless power transmission and also are decentrally controlled through wireless transmission of the control and feedback data. With this idea, the degree of freedom in motion control is enlarged, and the system has the capability of adaptive reconfiguration to product variation as a result. In this paper, the practical problems for realization of wireless transmission of power and information (WTPI) needed for the proposed ADMS are clarified, and the practical solutions to these problems are presented. Several industrial applications of the WTPI are also introduced.

A merging control algorithm based on inter-vehicle communication

Abstract: Deals with merging control of vehicles with inter-vehicle communication on highways, which would greatly contribute to increased safety and decreased traffic congestion. Algorithms for merging control of vehicles using the concept of a virtual vehicle and for inter-vehicle communication for the control are presented. A virtual vehicle is generated by mapping a vehicle on one lane onto another lane, in order to enable longitudinal control between a vehicle on a main lane and one on a sub lane to make smooth merging. The inter-vehicle communication is essential in the merging control algorithm, because the generation of the virtual vehicle requires the inter-vehicle communication. The data transmission in the communication consists of an intra-platoon algorithm and an inter-platoon one. The former is featured by provision of the interruption detective gaps that allow us to reduce transmission delay caused by collision, and the latter is featured by data transmission only between lead vehicles. Simulation results show the efficiency of the data transmission and the feasibility of merging control using the data transmission algorithm. When a platoon consists of ten vehicles, the transmission rate is three times as efficient as the conventional algorithm and it is sufficient for merging control.

Image pickup device

Abstract: PROBLEM TO BE SOLVED: To simplify a device by eliminating a buffer memory in an image pickup device. SOLUTION: Discharge driving operation of unwanted charges of an imaging device 11 is performed by using an image data requesting signal S2 from an external device 20 as a trigger and a signal S3 to indicate the fact that the unwanted charges are discharged to the external device 20 by this image pickup device 10. A clock signal S1 for data transfer is outputted to a timing generating circuit 14 after the signal S3 is received by the external device 20. A timing signal S4 of the imaging device 11 and a clock signal S5 of an A/D converter 12 are generated upon receipt of the clock signal S1 by the timing generating circuit 14.

Method and apparatus for storing reference codes in a writing instrument and for retrieving information identifed by the reference codes

Abstract: An interactive data transfer system and method is provided. In embodiments of the invention, the data transfer system includes a computing device, and a data well for interfacing with an elongate instrument, the elongate instrument having a data transfer end with a data transfer tip. The data well has a housing with an opening for receiving the data transfer tip of the elongate instrument. The data well also has a communications port operatively coupled to the computing device to provide data to the computing device, and the data well has a data communication device contained in the housing for interfacing with the data transfer tip when the data transfer end of the elongate instrument is received in the opening The computing device is programmed to receive data from the data well. The received data includes data indicative of at least one address on a global communications network. The computer device is also programmed, upon receipt of the at least one address, to launch an application to retrieve information related to the at least one address from the global communications network and transmit such information to the computing device.

Data transmission system for reducing terminal power consumption in a wireless network

Abstract: The system transmits data between terminals of a wireless network In the system, a base station/central controller (“BS/CC”) controls transmission of data from a transmitting terminal to plural receiving terminals, where the data is ordered in slots of a control data frame (“CDF”), and where each slot is reserved for a data transmission between the transmitting terminal and a specific receiving terminal Specifically, the BS/CC divides the plural receiving terminals into a set of power-saving terminals and a set of non-power-saving terminals, and then reserves a set of slots in the CDF for data transmission between the transmitting terminal and the power-saving terminals, and another set of slots in the CDF for data transmission between the transmitting terminal and the non-power-saving terminals The BS/CC then issues a message over the wireless network instructing the power-saving terminals when to switch between a low-power mode and a data-receiving mode based on a location of the set of slots in the frame reserved for data transmission between the transmitter and the power-saving terminals

Method for connecting data flows

Abstract: The invention relates to a method for supporting the quality of service (QoS) in packet data transmission between a wireless terminal (MT), having data communication with a radio access network, and a data network (LN), in which method data transmission between the terminal (MT) and the radio access network ( 2 ) is controlled by at least one mobile IP router ( 5, 5′, 5 ″). Further, in the method data is transmitted in radio flows between the wireless terminal (MT) and the mobile IP router ( 5, 5′, 5 ″). In the method, a flow label is defined for at least one radio flow and the desired quality of service is defined for the radio flow.

Data transmission over a communications link with variable transmission rates

Abstract: An optimal data block size is determined for use in transmitting data at variable rates over a communications link in predetermined time intervals, where each predetermined time interval has the same time duration. Rather than varying data block size according to changes in transmission rates, which adds unnecessary complexity, the data blocks all have the same fixed size, i.e., the same number of data bits in each block. That fixed data block size is determined so that for all of the available data transmission rates, each predetermined time interval is fully occupied with useful information. The fixed data block size is determined based on a maximum frequency at which the transmission rate may change on the communications link and a lowest available transmission rate. Preferably, the fixed size of each date block is limited by predetermined maximum and minimum data block sizes in order to reduce the number of bit errors per data block, maintain a certain data throughput, and limit the amount of overhead bits relative to the number of payload bits for each data block.

Digital signal propagation in dispersive media.

Abstract: In this article, the propagation of digital and analog signals through media which, in general, are both dissipative and dispersive is modeled using the one-dimensional telegraph equation. Input signals are represented using impulsive, Heaviside unit step, Gaussian, rectangular pulse, and both unmodulated and modulated sinusoidal pulse type boundary data. Applications to coaxial transmission lines and freshwater signal propagation, for both digital and analog signals, are included. The analysis presented here supports the finding that digital transmission in dispersive media is generally superior to that of analog. The boundary data (input signals) give rise to solutions of the telegraph equation which contain propagating discontinuities. It is shown that the magnitudes of these discontinuities, as a function of distance, can be found without the need of solving the governing equation. Thus, for digital signals in particular, signal strength at a given distance from the input source can be easily determined. Furthermore, the magnitudes of these discontinuities are found to be independent of both the dispersion coefficient k and the elastic coefficient b. In addition, it is shown that, depending on the algebraic sign of k, one of two distinct forms of dispersion is possible and that for small-time intervals, solutions are approximately independent of k.

Synchronization with DMT modulation

Abstract: In a digital transmission system, synchronization is an essential receiver function. Accurate timing information must be known to the demodulator in order to produce reliable estimates of the transmitted data sequence. In this article, synchronization for discrete multitone transmission (DMT) is examined. The effect of imperfect timing on the receiver performance is investigated. An overview of timing estimation and correction circuits based on data-aided and non-data-aided algorithms derived from maximum-likelihood estimation theory is given.

An introduction to digital communications

Abstract: Fourier Series and Transforms. Spectral Analysis of Data Signals and Noise. Baseband Data Transmission. Bandpass Data Transmission. Maximum Likelihood Signal Detection and Some Applications. Carrier Phase and Timing Recovery. Channel Models for Communication Systems. Channel Capacity and Coding. Trellis Coding and Multidimensional Signaling. Equalization of Distorted Channels. Adaptive Equalization and Echo Cancellation. Index.

Communication techniques using monopulse waveforms

Abstract: This paper studies wireless communication systems using technology that does not require a carrier signal. The vehicle used for transmission is a monopulse waveform. Such waveforms possess a bandpass nature, having no DC content. The short time duration of these waveforms, typically nanoseconds, provides has an ultrawide bandpass characteristic, with a spectrum in the range of hundreds of megahertz, making them ideally suited for a spread spectrum communication system. The temporal representations of several monopulse signals are illustrated, and the power spectral densities of the Gaussian and Rayleigh monopulse waveshapes are presented. The relationship between effective time duration, peak-to-RMS value, and bandwidth is detailed. The spectral effect of pulse amplitude modulated data and pulse position modulated data is compared. A methodology for efficient data transmission and a technique for rate doubling at no cost in bandwidth is described. Diversity methods to mitigate a harsh environment, such as those encountered in fading channels, jamming, and multipath situations, are introduced.

System for I/O interfacing for semiconductor chip utilizing addition of reference element to each data element in first data stream and interpret to recover data elements of second data stream

Abstract: An I/O interface circuit includes an output buffer circuit and an input buffer circuit. The output buffer circuit can receive a first stream of data elements for output from the semiconductor chip, add a separate reference element for each data element in the first stream, and generate a first data transmission signal representing the data elements of the first stream and the respective reference elements. The input buffer circuit can receive a second data transmission signal representing data elements of a second stream and respective reference elements for the data elements of the second stream, sample the second data transmission signal to obtain voltage values for each data element of the second stream and the respective reference element, and interpret the voltage value for each data element of the second stream against the voltage value for the respective reference element in order to recover the data elements of the second stream.

Method for coupling a wireless terminal to a data transmission network and a wireless terminal

Abstract: The invention relates to a terminal (A), which comprises at least one network interface card (NIC1, NIC2, NIC3) for setting up a data transmission connection to a communication network (NW1, NW2, NW3, MNW) for packet switched data transmission, and means (PD) for forming packets of the information to be transmitted and for unpacking information from the received packets. The terminal (A) is allocated at least one first address identifying the terminal (A), and at least one data network-specific second address. The means (PD) for forming packets comprise means for connecting the first address to the packets, and the terminal (A) also comprises a network interface selection driver (NISD), which contains means for selecting the communication network (NW1, NW2, NW3, MNW) used in data transmission at a given time, means for transmitting packets between the means (PD) for forming packets and the network interface card (NIC1, NIC2, NIC3) corresponding to the data transmission network (NW1, NW2, NW3, MNW) used at a given time, and means for modifying the first address to the second address according to the data transmission network used in the packets at a given time.

Adaptive trellis coded MQAM and power optimization for OFDM transmission

Abstract: We propose an adaptive trellis coded modulation orthogonal frequency division multiplexing (ATCM-OFDM) scheme to provide high rate transmission with high spectral efficiency for an indoor environment Our objective is to minimize the overall transmit power in each OFDM transmission by optimizing the power distribution, the code rate and modulation scheme in each OFDM subchannel so as to maintain a constant data transmission rate and a fixed bit error rate (BER) In the simulation, the ATCM-OFDM scheme can achieve more than 7 dB power reduction compared with the OFDM scheme using fixed TCM

Filtered multitone modulation for VDSL

Abstract: We present a filter-bank modulation technique called filtered multitone (FMT) and describe its application to data transmission for very-high-speed digital subscriber line (VDSL) technology. The proposed scheme leads to significantly lower spectral overlapping between adjacent subchannels than for known multicarrier techniques such as discrete multitone (DMT) or discrete wavelet multitone. This allows mitigating interference due to echo and near-end crosstalk signals, increasing system throughput and reach, and simplifying system operations for VDSL transmission. In the receiver of an FMT system, signal equalization is accomplished in the form of per-subchannel symbol-spaced or fractionally-spaced linear or decision-feedback equalization. We study by simulation the performance that can be achieved by FMT modulation for VDSL systems where upstream and downstream signals are separated by frequency-division duplexing. We also provide comparisons with DMT modulation for a typical transmission scenario.

Data streaming using caching servers with expandable buffers and adjustable rate of data transmission to absorb network congestion

Abstract: A data streaming transmission method and system is disclosed having a network server connected to client device through a communication network with one or more of caching servers. The network server has a data streaming application and a memory for storing data. A series of connections, each using a data streaming arrangement, is formed in the path between the source network and client device by the caching servers. Each caching server can absorb network congestion in its downstream connection by utilizing an expandable buffer for storing additional segments of the streamed data and varying the transmission data rate in the down stream connection.

Principles of digital transmission

Abstract: The first € price and the £ and $ price are net prices, subject to local VAT. Prices indicated with * include VAT for books; the €(D) includes 7% for Germany, the €(A) includes 10% for Austria. Prices indicated with ** include VAT for electronic products; 19% for Germany, 20% for Austria. All prices exclusive of carriage charges. Prices and other details are subject to change without notice. All errors and omissions excepted. S. Benedetto, E. Biglieri Principles of Digital Transmission

Method for formatting signal in mobile communication system

Abstract: A method for formatting a signal in a mobile communication system by appending a plurality of medium access control headers to a plurality of medium access control-service data units for data transfer between a mobile station and network in the mobile communication system. If the service data units have the same characteristics, a medium access control-protocol data unit is formed by successively coupling the service data units to any one of the medium access control headers. If the service data units have different characteristics, the protocol data unit is formed by sequentially coupling each of the service data units and each of the medium access control headers. The formed protocol data unit is then transformed into a transport block with a predetermined size. A medium access control sublayer formats medium access control-protocol data units according to transport channel characteristics in peer-to-peer communication in such a manner that the protocol data units can have different formats with respect to different transport channels. This makes it possible to provide more efficient functions.

Communication method and transmitter with transmission symbols arranged at intervals on a frequency axis

Abstract: When multiplexing channels which conduct communication at various transmission rates, each communication is made capable of conducting communication processing, such as information reception, with a minimum required processing amount needed by itself. A plurality of communication channels are set in a predetermined band, and communication in each of the set channels is performed by using a multi-carrier signal having transmission symbols distributed among a plurality of subcarriers. Transmission symbols of each channel on a frequency axis are arranged at intervals of an Nth power of 2 (where N is an arbitrary positive number) with respect to a reference frequency interval for transmission. From the transmission signal, a signal component of a required channel is received.

Methods of dynamically switching return channel transmissions of time-division multiple-access (TDMA) communication systems between signalling burst transmissions and message transmissions

Abstract: Data transfer efficiencies of a frequency division and/or time division multiple access (FDMA/TDMA) communication systems are improved over prior art systems by distributing signalling and messaging activities over all return channels of a channel group, by varying forward to return channel data rate ratios, and by reducing message transport delays with respect to prior art communication systems, based on message traffic over such channel group. Return channels of a defined channel group are time division controlled and are generic to operate either in a signalling mode or in a messaging mode. Data rates for the forward channel and the return channels may by selected from predefined combinations of forward and return channel data rates. Message transport delays are reduced over prior art delay periods by reducing the frame lengths of data frames transmitted at a specified frame rate over the forward channel and by transmitting network management data other than time-critical data reception results and time slot allocations periodically at a superframe rate which is less than the frame rate.