Showing papers on "Data transmission published in 1998"

Efficient use of side information in multiple-antenna data transmission over fading channels

Abstract: We derive performance limits for two closely related communication scenarios involving a wireless system with multiple-element transmitter antenna arrays: a point-to-point system with partial side information at the transmitter, and a broadcast system with multiple receivers. In both cases, ideal beamforming is impossible, leading to an inherently lower achievable performance as the quality of the side information degrades or as the number of receivers increases. Expected signal-to-noise ratio (SNR) and mutual information are both considered as performance measures. In the point-to-point case, we determine when the transmission strategy should use some form of beamforming and when it should not. We also show that, when properly chosen, even a small amount of side information can be quite valuable. For the broadcast scenario with an SNR criterion, we find the efficient frontier of operating points and show that even when the number of receivers is larger than the number of antenna array elements, significant performance improvements can be obtained by tailoring the transmission strategy to the realized channel.

Method and apparatus for high-rate packet data transmission

Abstract: In a data communication system capable of variable rate transmission, high rate packet data transmission improves utilization of the forward link and decreases the transmission delay. Data transmission on the forward link is time multiplexed and the base station transmits at the highest data rate supported by the forward link at each time slot to one mobile station. The data rate is determined by the largest C/I measurement of the forward link signals as measured at the mobile station. Upon determination of a data packet received in error, the mobile station transmits a NACK message back to the base station. The NACK message results in retransmission of the data packet received in error. The data packets can be transmitted out of sequence by the use of sequence number to identify each data unit within the data packets.

Understanding Digital Subscriber Line Technology

Abstract: 1. DSL Fundamentals. Alternatives to DSLs: Fiber, Wireless, and Coax. Worldwide Extent. Voice-Band Modems and DSLs. Transmission Modes. DSL Terminology. Rate Versus Reach. Crosstalk. Enabling and Disabling Forces. Applications. Evolution of Digital Transmission. 2. Types of DSLs. DSL Design Margin. DSL Precursors. Basic Rate ISDN. HDSL. ADSL. VDSL. 3. Twisted-Pair Transmission. Twisted-Wire-Pair Origins. Telephone Network and Loop Plant Characteristics. Line Powering. Sealing Current. Transmission Line Characterization. Noises. Spectral Compatibility. More Two-Port Networks. Three-Port Networks for DSLs. References. 4. Comparison with Other Media. Fiber-to-the-Home. Coax and Hybrid Fiber Coax. Wireless Alternatives. Satellite Services. References. 5. Transmission Duplexing Methods. Four-Wire Duplexing. Echo Cancellation. Time-Division Duplexing. Frequency-Division Multiplexing. References. 6. Basic Digital Transmission Methods. Basic Modulation and Demodulation. Baseband Codes. Passband Codes. References. 7. Loop Impairments, Solutions, and DMT. Intersymbol Interference. Multichannel Line Codes. Trellis Coding. Error Control. References. 8. Initialization, Timing and Performance. Initialization Methods. Adaptation of Receiver and Transmitter. Measurement of Performance. Timing Recovery Methods. References. 9. Operations, Administration Maintenance, and Provisioning. OAM&P Features. Loop Qualification. 10. DSL in the Context of the ISO Reference Model. The ISO Model. Theory and Reality. The Internet Protocol Suite. ATM in the Seven-Layer Model. 11. ADSL: The Bit Pump. ADSL System Reference Model. ATU-C Reference Model. ATU-R Reference Model. Specific Configurations to Support ATM. Framing. Operations and Maintenance. Initialization. Reference. 12. ATM Transmission Convergence on ADSL. Functions of ATM Transmission Convergence. Transmission Convergence in an ADSL Environment. Reference. 13. Frame-Based Protocols over ADSL. PPP over a Frame-Based ADSL. FUNI over ADSL. Reference. 14. ADSL in the Context of End-to-End Systems. An Overview of a Generic DSL Architecture. Potential ADSL Services and the Service Requirements. Specific Architectures for Deploying ADSL in Different Business Models. Several ADSL Architectures. References. 15. Network Architecture and Regulation. Private Line. Circuit Switched. Packet Switched. ATM. Remote Terminal. Competitive Data Access Alternatives. Regulation. 16. Standards. ITU. Committee T1. ETSI. ADSL Forum. ATM Forum. DAVIC. IETF. EIA/TIA. IEEE. The Value of Standards and Participation in Their Development. Standards Process. Appendix A: Glossary. Appendix B: Selected Standards and Specifications. Appendix C: Selected T1E1.4 Contributions and ADSL Forum Technical Reports (found on website). Index.

The role of synchronization in digital communications using chaos. II. Chaotic modulation and chaotic synchronization

Abstract: For pt. I see ibid., vol. 44, p. 927-36 (1997). In a digital communications system, data are transmitted from one location to another by mapping bit sequences to symbols, and symbols to sample functions of analog waveforms. The analog waveform passes through a bandlimited (possibly time-varying) analog channel, where the signal is distorted and noise is added. In a conventional system the analog sample functions sent through the channel are weighted sums of one or more sinusoids; in a chaotic communications system the sample functions are segments of chaotic waveforms. At the receiver, the symbol may be recovered by means of coherent detection, where all possible sample functions are known, or by noncoherent detection, where one or more characteristics of the sample functions are estimated. In a coherent receiver, synchronization is the most commonly used technique for recovering the sample functions from the received waveform. These sample functions are then used as reference signals for a correlator. Synchronization-based coherent receivers have advantages over noncoherent receivers in terms of noise performance, bandwidth efficiency (in narrow-band systems) and/or data rate (in chaotic systems). These advantages are lost if synchronization cannot be maintained, for example, under poor propagation conditions. In these circumstances, communication without synchronization may be preferable. The theory of conventional telecommunications is extended to chaotic communications, chaotic modulation techniques and receiver configurations are surveyed, and chaotic synchronization schemes are described.

Applications of error-control coding

Abstract: An overview of the many practical applications of channel coding theory in the past 50 years is presented. The following application areas are included: deep space communication, satellite communication, data transmission, data storage, mobile communication, file transfer, and digital audio/video transmission. Examples, both historical and current, are given that typify the different approaches used in each application area. Although no attempt is made to be comprehensive in the coverage, the examples chosen clearly illustrate the richness, variety, and importance of error-control coding methods in modern digital applications.

Method of supporting unknown addresses in an interface for data transmission in an asynchronous transfer mode

Abstract: Data received in the form of data packets which include destination addresses is transmitted over virtual channels in an asynchronous transfer mode to emulate the operation of a plurality of emulated local area networks. A plurality of bus channels are provided, each specified for the broadcast transmission of data packets to members of a respective one of the emulated local area networks. An address look-up data-base is used to receive the destination address of a data packet and data defining the respective bus channel for the broadcast transmission of that packet in the respective emulated local area network. The data packet is then transmitted over the respective bus channel. The content addressable memory provides a data field which indicates whether a request for the resolution of the destination address into a specific virtual channel number has been made.

Method and apparatus for forward link rate scheduling

Abstract: In a communication system capable of variable rate transmission, scheduling of high speed data transmission improves utilization of the forward link and decreases the transmission delay in data communication. Each remote station is assigned one primary code channel for the duration of the communication with a cell. Secondary code channels of various types and transmission capabilities can be assigned by a channel scheduler for scheduled transmission of data traffic at high rates. Secondary code channels are assigned in accordance with a set of system goals, a list of parameters, and collected information on the status of the communication network. Secondary code channels can be grouped into sets of secondary code channels. Data is partitioned in data frames and transmitted over the primary and secondary code channels which have been assigned to the scheduled user.

Intelligent network interface device and system for accelerated communication

Abstract: An intelligent network interface card (INIC) or communication processing device (CPD) works with a host computer for data communication. The device provides a fast-path that avoids protocol processing for most messages, greatly accelerating data transfer and offloading time-intensive processing tasks from the host CPU. The host retains a fallback processing capability for messages that do not fit fast-path criteria, with the device providing assistance such as validation even for slow-path messages, and messages being selected for either fast-path or slow-path processing. A context for a connection is defined that allows the device to move data, free of headers, directly to or from a destination or source in the host. The context can be passed back to the host for message processing by the host. The device contains specialized hardware circuits that are much faster at their specific tasks than a general purpose CPU. A preferred embodiment includes a trio of pipelined processors devoted to transmit, receive and utility processing, providing full duplex communication for four Fast Ethernet nodes.

Error statistics in data transmission over fading channels

Abstract: We investigate the behavior of block errors which arise in data transmission on fading channels. Our approach takes into account the details of the specific coding/modulation scheme and tracks the fading process symbol by symbol. It is shown that a Markov approximation for the block error process (possibly degenerating into an identically distributed (i.i.d.) process for sufficiently fast fading) is a good model for a broad range of parameters. Also, it is observed that the relationship between the marginal error rate and the transition probability is largely insensitive to parameters such as block length, degree of forward error correction and modulation format, and depends essentially on an appropriately normalized version of the Doppler frequency. This relationship can therefore be computed in the simple case of a threshold model and then used more generally as an accurate approximation. This observation leads to a unified approach for the channel modeling, and to a simplified performance analysis of upper layer protocols.

A multi-user communication system architecture with distributed transmitters

Abstract: A new signal processing architecture for base stations and gateways (124, 126) used in spread spectrum communication systems (100) that simplifies data transfer, reduces required bus capacity, and does not require special synchronization of signals that are to be combined. A series of transmission modules (5081-508M) are used to transfer data to corresponding ones of a series of analog transmitters (4121-412M) used to form communication circuits for each system user. Each transmission module (5081-508M) employs a series of encoders (502MR) and modulators (504MS) to form spread communication signals, using appropriate PN spreading codes. Spread spectrum communication signals from each module (508) for each system user (D), are summed together (5101-510M) and transferred to a single analog transmitter (412) associated with that module. The signals being combined are automatically synchronized by common timing signals used for elements within each module. The number of processing elements within each module is such that at least one processing path is available for each user or user channel over which it is desired to transmit information through the connected analog transmitter (4121-412M). Data is output from the modules (5081-508M) at a greatly reduced transfer rate which can be more easily accommodated using current technology. This is very useful for satellite based communication systems, or high capacity cellular systems, and this system architecture can be accomplished cost effectively using a series of easily manufactured circuit modules.

File transfer system using dynamically assigned ports

Abstract: A computer data signal embodied in a propagation medium is provided. The signal enables a variable number of data transfers and includes an initial connection source code segment and a data transfer source code segment. The initial connection source code segment establishes a connection between at least two devices via predetermined listening ports, with at least one predetermined listening port residing within each device. The initial connection source code segment also dynamically assigns a first data port within a first device, and transmits the address of the first data port to a remaining device via the predetermined listening ports. The data transfer source code segment is for each of the variable number of data transfer operations. The data transfer source code segment dynamically assigns a corresponding second data port within the remaining device and transfers data between the connected devices via the data ports so that the data is substantially simultaneously transferred between a variable number of devices via the data ports. Each pair of first and second data ports is established in response to each listening port connection.

Controller area network

Abstract: This paper focuses on data transmission in automotive applications that employ a controller area network. Issues regarding transmission errors and electromagnetic interference are addressed. A flexible error-model is proposed for assessing the transmission's reliability and for designing message scheduling policies.

Feedforward frequency estimation for PSK: A tutorial review

Abstract: This paper considers feedforward carrier frequency estimation methods in burst-mode digital transmission, with tutorial objectives foremost. Assuming PSK modulation, two scenarios are envisaged in which frequency estimates are derived either from a preamble appended to the data block, or directly from the modulated signal. Several estimation algorithms are considered with different and somewhat contrasting characteristics. The characteristics we focus on are: estimation accuracy, estimation range, minimum operating signal-to-noise ratio (threshold), and implementation complexity. They provide a framework within which current estimation methods can be evaluated. The paper reviews and compares some prominent algorithms proposed in literature, trying to single out the best ones for a given application.

Contactless proximity automated data collection system and method

Abstract: A fast data transfer collection system using message authentication and contactless RF proximity card technology in non-contact storage and retrieval applications. The system is generally comprised of Host computers (application computer systems), Target radio frequency (RF) terminals, and a plurality of portable Tags ('smart' or 'proximity' cards). A Host provides specific application functionality to a Tag holder, with a high degree of protection from fraudulent use. A Target provides control of the RF antenna and resolves collisions between multiple Tags in the RF field. A Tag provides reliable, high speed, and well authenticated secure exchanges of data/information with the Host resulting from the use of a custom ASIC design incorporating unique analog and digital circuits, nonvolatile memory, and state logic. Each Tag engages in a transaction with the Target in which a sequence of message exchanges allow data to be read (written) from (to) the Tag. These exchanges establish the RF communication link, resolve communication collisions with other Tags, authenticate both parties in the transaction, rapidly and robustly relay information through the link, and ensure the integrity and incorruptibility of the transaction. The system architecture provides capabilities to ensure the integrity of the data transferred thus eliminating the major problem of corrupting data on the card and in the system. The architecture and protocol are designed to allow simple and efficient integration of the transaction product system into data/information processing installations.

Method for establishment of the power level for uplink data transmission in a multiple access system for communications networks

Abstract: The power level for uplink data transmission in a wireless communications network utilizing an on-demand multiple access method with a fair queuing service discipline (ODMAFQ) for efficient utilization of the limited bandwidth available in the wireless network is established curing the initial access request message. The power level in a wireless network having a base station and several remote hosts is established by first transmitting a short connection request message to the base station from one of the remote hosts at an initial power level that is set relative to the nominal open loop power level. If the first remote host's transmission is unsuccessful, the power level is incremented by a power increment amount that may be predetermined, and the steps of transmitting and incrementing are repeated until the transmission from remote host to base station is successful. Finally, the power level at which transmission is successful is stored and used for further data transmission between that particular remote host and the wireless network base station.

Data transmission over a power line communications system

Abstract: A power line communications system comprises a power line (120) for distributing electricity to a plurality of premises (S1, S2...) and communication stations (TRX) coupled to the power line at the premises. Data is transmitted to/from stations over the power line using a packet data communications protocol. Apparatus at premises can convert signals between a first protocol, used on the power line, and a second protocol e.g. Ethernet for transferring data to a communications station.

Maximum-likelihood synchronization of a single user for code-division multiple-access communication systems

Abstract: Code-division multiple access (CDMA) has emerged as an access protocol well-suited for voice and data transmission. One significant limitation of the conventional CDMA system is the near-far problem where strong signals interfere with the detection of a weak signal. Multiuser detectors assume knowledge of all of the modulation waveforms and channel parameters, and exploit this information to eliminate multiple-access interference (MAI) and to achieve near-far resistance. A major problem in practical application of multiuser detection is the estimation of the signal and channel parameters in a near-far limited system. We consider maximum-likelihood estimation of users delay, amplitude, and phase in a CDMA communication system. We present an approach for decomposing this multiuser estimation problem into a series of single-user problems. In this method the interfering users are treated as colored non-Gaussian noise. The observation vectors are preprocessed to be able to apply a Gaussian model for the MAI. The maximum-likelihood estimate (MLE) of each user's parameters based on the processed observation vectors becomes tractable. The estimator includes a whitening filter derived from the sample covariance matrix which is used to suppress the MAI, thus yielding a near-far resistant estimator.

Symbol rate and modulation level-controlled adaptive modulation/TDMA/TDD system for high-bit-rate wireless data transmission

Abstract: This paper proposes a time-division multiple-access/time-division duplex (TDMA/TDD)-based symbol rate and modulation level-controlled adaptive modulation system for high-bit-rate data transmission. The proposed system controls both the symbol rate and modulation level for the next transmission time slot according to the estimated carrier power to noise spectral density ratio (C/N/sub 0/) and delay spread for the time slot to achieve higher bit rate and higher transmission quality as well as higher delay-spread immunity. It is demonstrated by computer simulation and laboratory experiments that the proposed system can achieve a higher average bit rate with higher transmission quality in comparison with the fixed-rate quaternary phase-shift keying (QPSK) system and modulation level-controlled adaptive modulation system in both flat Rayleigh and frequency-selective fading environments. The simulated and experimental results also show that the proposed adaptive modulation techniques can be applied to 1-2-Mb/s indoor and outdoor microcellular systems with its delay spread of up to 250 ns and its terminal mobility of up to pedestrian speed without employing any special antifrequency-selective fading techniques, such as the adaptive equalizer and space diversity.

Architectures for Digital Signal Processing

Abstract: From the Publisher: Digital Signal Processing is a rapidly expanding area for evaluation and development of efficient measures for representation, transformation and manipulation of signals. This book fuses signal processing algorithms and VLSI circuit design to assist digital signal processing architecture developers. The author also shows how this technique can be used in applications such as: signal transmission and storage, manufacturing process quality control and assurance, autonomous mobile system control and biomedical process analysis.

A novel impulse radio network for tactical military wireless communications

Abstract: Two of the major concerns in tactical military wireless communication networks are covertness and throughput. Impulse radio is an ultra-wideband code division multiple access (UWB-CDMA) technique being considered as the physical layer for future networks. Impulse radio exhibits low power spectral density and relatively high immunity to fading but suffers from relatively long acquisition times. In traditional packet radio networks (PRNs), the physical layer link is terminated while scheduling half-duplex transmissions or in the absence of data packets. To re-establish physical layer links in an impulse radio system, signaling packets containing exceptionally long acquisition headers transmitted at higher powers are required. Hence, to improve covertness in an impulse radio based network, we propose a MAC layer scheme we call sustained link networks (SLN) where the physical layer links are maintained continuously. We develop a full-duplexing scheme which takes advantage of the low duty cycle nature of impulse radio to maintain physical layer links capable of supporting bi-directional data transfer. During the periods between data bursts, the physical layer links are maintained by transmitting supplementary data at low bit rates and low power levels. We quantify the performance of an impulse radio receiver implementing the full-duplex scheme developed. We also present performance comparisons of an SLN based on impulse radio with traditional PRN variations implemented using impulse radio.

Data transmission apparatus, system and method, and image processing apparatus

Abstract: A data transmission system where an image providing device and a printer are directly connected by a 1394 serial bus, a command is sent from the image providing device to the printer, then a response to the command is returned from the printer to the image providing device. Image data is sent from the image providing device to the printer based on information included in the response. The printer converts the image data outputted from the image providing device into print data. Thus, printing can be performed without a host computer by directly connecting the image providing device and the printer by the 1394 serial bus or the like.

System for remote powering and communication with a network of addressable, multichannel sensing modules

Abstract: A multidrop network of multichannel, addressable sensing modules (ASM's), to be embedded within a composite structure, remotely powered, and interrogated by a personal computer through a non-contacting inductive link. Each ASM contains a microprocessor with non-volatile memory, multiplexer, programmable gain and filter instrumentation amplifier, and sigma delta analog to digital converter (all housed in two thin surface mount packages). An embedded mothernode includes circuitry for power and data reception (into the structure), and data transmission (back out of the structure). The external interrogation system communicates into the network of ASM's by modulating the AC waveform that delivers power to the embedded electronics. Once addressed, each ASM powers up its programmable (gain & filter) sensing channels (3 full differential or 5 pseudo differential) and data conversion elements. Sensed data are pulse code modulated, including error checking, which serially modulate an RF carrier for wireless transmission out of the composite to the interrogating computer. These advanced, micro-miniature sensing networks may be applied to a wide variety of military, medical, & civil structures.

System and method for transmitting and receiving data

Abstract: The present invention provides a system and method for transmitting and receiving data that can transmit data over a plurality of data paths simultaneously and that provides a plurality of transmission queues which enable data transmissions to be continuously prioritized and which do not cause bottlenecking of data. In the preferred embodiments, the present invention comprises a data transmission facility, at least one forward data path, at least one data reception facility, and at least one reverse data path. Data is transmitted in response to a request to transmit data which may be locally generated at the data transmission facility, or may be remotely generated at any of the data reception facilities and transmitted to the data transmission facility through the reverse data path. The requested data is then transmitted from the data transmission facility through at least one forward data path to at least one data reception facility. Data is transmitted in the form of at least one header packet and at least one data packet for each data file. In the event that errors are detected in this transmission of data, retransmissions of the corrupted data may then be requested by any of the data reception facilities through the reverse data path. The transmitted data is finally received by at least one data reception facility, where a copy of the requested data file is recovered and the data is used as desired.

Digital Transmission Engineering

Abstract: This textbook is a 4th year(Sweden)/5th year (USA) text in digital communication theory and practice. Chapters include baseband pulse transmission, carrier transmission, synchronization, channels, coding and information theory, and advanced topics. Each chapter ends with 25 home exercises. Worked examples and Matlab tools are integrated with the text.

Method for pacing data flow in a packet-based network

Abstract: A method for pacing data flows in packet switched networks by arranging data transmission over a period of time based upon a set of ascertainable factors about the underlying transmission link to derive an intersegment transmission interval. The intersegment transmission interval can be used to pace either data packets or acknowledgment packets. The method is especially useful for pacing the transmission of data in a digital data packet communication environment having a plurality of digital packet transmission stations inter-connectable in a data path and employing the Transmission Control Protocol (TCP) suite.

Dynamic frame size adjustment and selective reject on a multi-link channel to improve effective throughput and bit error rate

Abstract: A technique for implementing a sublayer of a protocol suitable for data transfer in a multichannel environment where each channel is assumed to be prone to a significant bit error rate such as in a wireless communication system. The invention may be used to provide a high speed data transfer such as at 128 kilobits per second or higher with a bit error rate of 10−6 or better using multiple channels. By keeping track of the number of frames received in error, the sender dynamically adjusts the subframe size for each channel to optimize the effective overall throughput. The subframes each carry preferably two types of sequence numbers including a position number related to an index into a larger frame to be transmitted as a single data entity. The second sequence number is related to the subchannel used so that the receiver can detect missing subframes. This then enables the receiver to submit retransmission requests for the missing pieces which can then be transmitted on the same channel or on another channel.

Communication system for electronic messages

Abstract: Communication system for electronic messages with a plurality of data processing devices and a data network for a data transmission of electronic messages between two data processing devices. Data of an electronic message includes an assignment data block, besides, image data, text data, audio data and the like, which includes specific assignments between particular data segments of said image, text or audio data, such that with the assignement data block interrelations between particular segments of the message can be transmitted in a simple manner and can be used for a subsequent display or reproduction of the message.

Providing reliable communication over an unreliable transport layer in a hand-held device using a persistent session

Abstract: The disclosed system provides a UDP+ connection-oriented protocol layer that reliably communicates over the UDP transport layer in a hand-held device. By providing reliable communication over the UDP transport layer instead of using the TCP transport layer, memory requirements are reduced, and applications running on the hand-held device have reliable data transfers performed on their behalf. Additionally, the UDP+ layer is designed to communicate using a 'persistent session'. A persistent session is a mode of communication where, when a connection terminates, the data associated with the connection, including the packets that have not yet been transferred, is not discarded. Instead, in using a persistent session, UDP+ retains the data associated with a connection after it terminates, reestablishes the connection, and completes the data transfer. By performing such a persistent session, application programs using UDP+ do not need to retain a copy of the packets passed to UDP+, and the code of the application programs is simplified, because the application programs do not need to keep track of which packets were successfully transferred when the connection terminates.

Point-to-multipoint mobile radio transmission

Abstract: A method of operating a mobile communication system supporting data transmission between a mobile station (MS) and a network in a number of different packet data protocols (PDPs) including a point-to-multipoint-multicast (PTM-M) protocol. PDP data is formatted and unformatted by a subnetwork dependent convergence protocol (SNDCP) according to the PDP of data. The PDP is identified to the SNDCP by a procotol identifier transmitted between the network and the mobile station. In order to allow a MS to receive a PTM-M in an IDLE state, a unique protocol identifier is permanently assigned to PTM-M transmissions whilst other identifiers are dynamically assigned to other PDPs by the network.

Adaptive-rate coded digital image transmission

Abstract: An adaptive arrangement and method for the coded digital transmission of images includes an adaptive transmitter (101) having an image coder (109) which is operable at multiple image coding rates, a channel coder (111) which is operable at a plurality of channel coding rates, and is further operable to provide a plurality of power outputs, baud rates, and a plurality of image delivery rates. The transmitter (101) further includes a channel status monitor (115) which monitors the communication channel (105) connecting the transmitter (101) to a receiver (103). The channel status monitor (115) responds to changes in the quality of the communications channel by varying one or more of the image coding rate, the channel coding rate, the power, the baud rate, and the image delivery rate.