Showing papers on "Data transmission published in 1993"

A clustering technique for digital communications channel equalization using radial basis function networks

Abstract: The application of a radial basis function network to digital communications channel equalization is examined. It is shown that the radial basis function network has an identical structure to the optimal Bayesian symbol-decision equalizer solution and, therefore, can be employed to implement the Bayesian equalizer. The training of a radial basis function network to realize the Bayesian equalization solution can be achieved efficiently using a simple and robust supervised clustering algorithm. During data transmission a decision-directed version of the clustering algorithm enables the radial basis function network to track a slowly time-varying environment. Moreover, the clustering scheme provides an automatic compensation for nonlinear channel and equipment distortion. Computer simulations are included to illustrate the analytical results. >

Method and apparatus for adaptive, variable bandwidth, high-speed data transmission of a multicarrier signal over digital subscriber lines

Abstract: A method and apparatus for adaptive, variable bandwidth, high-speed data transmission of a multicarrier signal over digital subscriber lines wherein the initial optimal transmission bandwidth is identified based on initial signal-to-noise ratio (SNR) estimates of the orthogonal carriers of the multicarrier system. Maximum data throughput, or system performance margin, is achieved by assigning the total amount of information, or number of bits, to be transmitted in each multicarrier symbol to particular carriers through an initial bit allocation procedure, which is possibly subject to variable target bit error rates among the carriers. A transmit power mask, of any shape and level, is imposed upon the system by an initial energy allocation procedure that limits the maximum amount of power to be transmitted in each of the several carriers. Lastly, run-time adaptivity is achieved by monitoring the mean-squared-errors (MSE) of the orthogonal carriers, and the transmission bandwidth, as well as the bit allocation within the multicarrier symbol, is caused to change in real-time corresponding to changes in the channel characteristics in order to maintain optimal system performance.

Data transfer system for an infusion pump

Abstract: A data transfer system (10) is provided for communication with an infusion pump (12) of the type used for programmable delivery of medication such as insulin to a patient. The data transfer system (10) includes a communication station (14) having a shaped pocket (16) formed therein for seated reception of the infusion pump (12). Optical communication members including light emitting (42) and detecting devices (44) mounted on the pump and station are aligned for two-way data transmission when the pump (12) is seated within the station pocket (16). The communication station can be used directly to monitor data received from the pump, and to transmit reprogrammed data to the pump, as desired. Alternately, the communication station can provide a data relay link to a remote site such as to a computer via a computer data cable, or a modem.

Diversity coding for transparent self-healing and fault-tolerant communication networks

Abstract: A channel coding approach called diversity coding is introduced for self-healing and fault-tolerance in digital communication networks for nearly instantaneous recovery from link failures. To achieve this goal, the problem of link failures is treated as an erasure channel problem. Implementation details of this technique in existing and future communication networks are discussed. >

Subband coded digital transmission system using some composite signals

Abstract: Reproduction accuracy of, for example a digital stereo audio signal, is improved by transmitting sample data as sub-signals such as frequency subband signals. In one or more subbands, corresponding components such as left and right stereo channels are combined so that only one composite signal is transmitted per subband. An indicator signal is transmitted, indicating which subbands are combined. Scale factor signals for all subbands, and for the relative intensity of the respective subband signals which were combined, may also be transmitted. In the receiver a subband signal is derived for each channel from the composite signal, before synthesis of the full channel signals which will be reproduced.

High speed data transfer over twisted pair cabling

Abstract: A method provides for a first network node in a plurality of network nodes to transmit a data packet to a hub. The hub and the network nodes are interconnected within a local network system. Control signals are exchanged between the first network node and the hub. The exchange of control signals is done in a first signal frequency range. A data packet is sent from the first network node to the hub. The data packet is sent using data signals within a second signal frequency range. The first signal frequency range and the second signal frequency range do not overlap.

Process, transmitter and receiver for data transmission with variable traffic volume and a control station for coordinating several such transmitters and receivers

Abstract: During data transmission or transmission of redundancy-reduced signals, the traffic volume and, hence, the necessary transmission capacity are not constant. Instead of the prior art approach of more or less intensive use of the total capacity, the basic idea of the invention is coded transmission and simultaneous use of more or less many, mutually orthogonal codes. An embodiment shows the use of a mixed code-division multiplex (CDMA)-time division multiplex (TDMA) radio system. The number of channels assigned to a signal station (CDMA) is determined anew frame-by-frame (TDMA) in response to requests in preceding frames.

Experimental demonstration of soliton data transmission over unlimited distances with soliton control in time and frequency domains

Abstract: A 29 – 1 pseudorandom-binary-sequence soliton signal has been transmitted experimentally over one million km for the first time with no degradation in the bit error rates. The synchronous modulator was driven by a timing clock signal extracted from the transmitting data signal. These results mean that it is possible to send soliton data signals over unlimited distances through the use of soliton control in the time and frequency domains.

System for transmission of digital data using orthogonal frequency division multiplexing

Abstract: A system is disclosed which provides a significantly enhanced transmission rate for digital data transmitted over a channel, while also providing immunity to signal interference caused by multipath reception. One embodiment of the system transmits a signal containing digital data in the vertical blanking interval of a television signal. Before being transmitted, the digital data is modulated by a process called orthogonal frequency division multiplexing, or OFDM. A guard interval is optionally prefixed to the front end of the data signal to provide additional immunity to multipath interference. A further feature of the present system is the optional inclusion in the transmitted signal of an error correcting code which allows detection and correction of multiple sequential data transmission errors.

Low-complexity multiple access protocols for wavelength-division multiplexed photonic networks

Abstract: Media access control protocols for an optically interconnected star-coupled system with preallocated wavelength-division multiple-access channels are discussed. The photonic network is based on a passive star-coupled configuration in which high topological connectivity is achieved with low complexity and excellent fault tolerance. The channels are preallocated to the nodes with the proposed approach, and each node has a home channel it uses either for data packet transmission or data packet reception. The performance of a generalized random access protocol is compared to an approach based on interleaved time multiplexing. Semi-Markov analytic models are developed to investigate the performance of the two protocols. The analytic models are validated through extensive simulation. The performance is evaluated in terms of network throughput and packet delay with variations in the number of nodes, data channels, and packet generation rate. >

Method and apparatus for device control by data transmission in TV lines

Abstract: A video signal processing system, such as a pay TV system, that includes a smart card access control feature decodes control information from data included in groups of video line intervals that represent data channels. Each channel includes data arranged in packets of data. Each packet includes both descriptor data and application data. The packets of data are extracted from the video lines by a data dispatcher. After receiving a packet from a data channel, the data dispatcher analyses the descriptor data to determine the target for the application data. The data dispatcher transmits the application data contained in the packet, without analyzing the data, to the correct target processor unit, e.g. either a control access processor or a decoder intelligent processor. Information that may be transferred to the decoder processor includes, a specific channel allocation table, data related to the VTR of the customer, and information related to a geographic location.

Cellular data overlay system for storing data identifying selected data allocated channels

Abstract: A cellular telephone system includes a packet-switched digital data communication subsystem overlaying a circuit-switched (e.g., voice) communication subsystem, with voice and data services sharing the same voice channels. The voice communication subsystem provides voice services independently of the operation of the data communication subsystem. On the other hand, the data communication subsystem monitors use of the voice channels for voice communication, and, in response thereto, temporarily allocates one or more of the available voice channels for data service. In a preferred embodiment, each data basestation transmits, from time to time, an available-channel signature to identify those, if any, of the data-allocated channels that are not then being used to transmit voice or data. For data communication, a remote unit monitors selected voice channels in the coverage area of the cellular telephone system for available-channel signatures, selects one of the channels (if any) identified by the signature thereon as being available for data transmission, and transmits or receives digital information over that channel.

Error correction and channel restoration apparatus for T1 digital links

Abstract: Apparatus, operating in a digital communication system, for interconnecting a primary or a secondary network to an output port. The primary and secondary networks are redundant networks having point-to-point topologies (125, 130) or point-to-multi-point topologies (210, 215). When connected in a point-to-point network topology that supports extended superframe format (ESF), the apparatus functions as an error correction switch and; when connected in a point-to-multi-point network topology, the apparatus functions as a DS1/0 protection switch. In its receiver aspect, the apparatus stores frames of digital data received from each of two redundant networks, inspects certain error codes contained in the received data and, in response to these error codes, selects the digital data originating from one of the networks that does not exhibit an error code. The data selection process uses a time-slot interchanging (TSI) technique. The selected data is subsequently transferred to downstream digital signal processing equipment. In its transmitter aspect, the apparatus transmits replicated versions of digital data supplied by digital transmission equipment onto both redundant networks.

Clipping distortion in DMT ADSL systems

Abstract: A model to analyse the effects of clipping for a Gaussian signal with an arbitrary spectrum is presented The model provides a complete description of the signal and noise spectrum The method is applied to an asymmetric digital subscriber line (ADSL) system using discrete multitone (DMT) modulation Calculations exhibit a 5dB improvement in the SNR compared to an approximate analysis

A distributed queueing random access protocol for a broadcast channel

Abstract: For decades there has been a search for a multiple access protocol for a broadcast channel that would provide a performance that approached that of the ideal M/D/1 queue. This ideal performance would provide immediate access at light loads and then seamlessly move to a reservation system at high offered loads. DQRAP (distributed queueing random access protocol) provides a performance which approaches this ideal. Furthermore it is accomplished using as few as three control minislots which suggests that, aside from establishing new theoretical bounds, DQRAP will be of great practical value.DQRAP requires that channel time be divided into slots each of which consists of one data slot and m control minislots, and that each station maintain two common distributed queues. One queue is called the data transmission queue, or simply TQ, used to organize the order of data transmission, the other queue is the collision resolution queue, or simply RQ, which is used to resolve the collisions and to prevent collisions by new arrivals. The protocol includes data transmission rules, request transmission rules and queuing discipline rules. Modelling and simulation indicate that DQRAP, using as few as 3 minislots, achieves a performance level which approaches that of a hypothetical perfect scheduling protocol, i.e., the M/D/1 system, with respect to throughput and delay. DQRAP could prove useful in packet radio, satellite, broadband cable, cellular voice, WAN, and passive optical networks.

Bit error simulation for pi /4 DQPSK mobile radio communications using two-ray and measurement-based impulse response models

Abstract: An accurate software/hardware bit-by-bit error simulator for mobile radio communications is described. Simulation results in indoor and outdoor channels are compared with theoretical results. Bit error rate (BER) results in simulated frequency-selective fading channels generated by several channel models such as two-ray, constant amplitude, and simulated indoor radio channel impulse models (SIRCIMs) are presented. It is shown that BER is not only dependent on the RMS delay spread, but also on the distribution of temporal and spatial multipath components in local areas. An important result is that a two-ray Rayleigh fading model is a poor fit for indoor wireless channels and, if used, can underestimate the BER by orders of magnitude. A real-time bit error simulation of video transmission using the bit-by-bit error simulator is described. The simulator, called BERSIM, is shown to be a useful tool for evaluating emerging data transmission products for digital mobile communications. >

Impulse noise mitigation strategies for multicarrier modulation

Abstract: Short time-duration and high magnitude noise, taking on the form of time-domain impulse noise over copper twisted-pairs or multipath fading in wireless communication, can potentially be the limiting impairment on performance in many high-speed data transmission applications. Coding techniques are presented, designed specifically for multicarrier modulated systems to mitigate the effects of such impairment. Several coding combinations, involving soft error protection, in addition to hard forward error correction, are considered. The techniques can be applied with minor variation to a number of possible applications employing multicarrier modulation, including wireless digital audio broadcasting (DAB) systems and high-speed data/video transmission over coaxial cables. >

Multicarrier modem for digital HDTV terrestrial broadcasting

Abstract: A digital modulation system using orthogonal frequency division and multiplexing (OFDM) is addressed in this paper. Such a system presents the advantage of coping with echoes more easily than classical single-carrier modems, thanks to the insertion of a guard interval between two symbols. The signal equalization is then achieved in the frequency domain. This OFDM modem is improved by using dual polarizations. In this configuration, it can convey a 70 Mbits/s (HDTV) bit stream in an 8 MHz UHF channel. Some experimental results relate field trials carried out in several countries with such equipment.

Bandwidth-efficient digital transmission up to 155 Mb/s over unshielded twisted pair wiring

Abstract: Techniques for achieving data rates up to 155 Mb/s over unshielded twisted pair wiring in premises distribution systems are described. These high data rates represent an improvement of about an order of magnitude in speed when compared to presently available data rates for local area networks operating over this communication medium. The transmission scheme proposed for achieving these higher data rates is carrierless AM/PM (CAP), which is a bandwidth-efficient two-dimensional passband line code. It is shown that a 32-CAP line code can be used to provide the fiber distributed data interface (FDDI) rate of 125 Mb/s over 100 m of voicegrade unshielded twisted pair (UTP) wiring in a channel bandwidth of 30 MHz, which results in a robust performance and eliminates potential problems with electromagnetic radiation limits above 30 MHz. >

Coordinated coding for digital transmission

Abstract: Methodology, and associated circuitry, for encoding (e.g., 200) and decoding (e.g., 900) an incoming data stream (201) utilize a coordinated code constellation (e.g., Fig. 3) that effects robust signal detection in the presence of channel interference. The encoder (220) partitions the incoming data stream into contiguous data segments in proportion to the number of levels for a given coordinated code. Each data segment is mapped with reference to the coordinated code to signal levels suitable for transmission over a plurality of channels (e.g., 222, 223). The decoder measures (e.g., 900) the received signals on the channels and estimates noise statistics for the channels. A metric relationship engendered by the coordinated code is evaluated with reference to the received signals, estimates to the received signals, and the noise statistics. An output data stream is then generated based on the evaluation of the metric.

An interpolative bandpass converter on a 1.2- mu m BiCMOS analog/digital array

Abstract: The architecture and performance of an interpolative bandpass A/D converter (ADC) and digital quadrature demodulator dedicated for digital narrowband transmission systems, like the cellular radio mobile receiver, are presented. A prototype version has been implemented on a 1.2- mu m/7-GHz BiCMOS analog/digital array. A bandpass signal centered at 6.5 MHz with 200-kHz bandwidth is demodulated and converted with a 55-dB signal-to-noise ratio giving 9-b performance. >

Data transmission apparatus and a communication path management method therefor

Abstract: A data transmission apparatus and a communication management method for transmitting data from task program devices to peripheral devices over a plurality of communication paths. The apparatus includes a communication path management table for storing management data corresponding to each communication path established between the task program devices and the peripheral devices, a communication path management device for retrieving the management data from the communication path management table to select a communication path in response to a request from a requesting task program device to establish a communication path to a specified peripheral device, and a communication protocol processor for controlling communications between the task program devices and peripheral devices by establishing the selected communication path between the requesting task program device and the specified peripheral device.

Pulse time modulation techniques for optical communications: a review

Abstract: The principal factor in realising a high-performance bandwidth-efficient fibre communication system at an acceptable cost is the choice of modulation format on the optical carrier. In this context, pulse time modulation (PTM) techniques represent an attractive alternative to purely digital or analogue methods. The PTM family is reviewed, a classification system is proposed and their potential for use in high-speed fibre systems intended for the transmission of analogue data is examined.

System for constructing a partitioned queue of DMA data transfer requests for movements of data between a host processor and a digital signal processor

Abstract: A multi-media user task (host) computer is interfaced to a high speed DSP which provides support functions to the host computer via an interprocessor DMA bus master and controller. Support of multiple dynamic hard real-time signal processing task requirements are met by posting signal processor support task requests from the host processor through the interprocessor DMA controller to the signal processor and its operating system. The signal processor builds data transfer packet request execution lists in a partitioned queue in its own memory and executes internal signal processor tasks invoked by users at the host system by extracting signal sample data from incoming data packets presented by the interprocessor DMA controller in response to its execution of the DMA packet transfer request queues built by the signal processor in the partitioned queue. Processed signal values etc. are extracted from signal processor memory by the DMA interprocessor controller executing the partitioned packet request lists and delivered to the host processor. A very large number of packet transfers in support of numerous user tasks and implementing a very large number of DMA channels is thus made possible while avoiding the need for arbitration between the channels on the part of the signal processor or the host processor.

Cable-based interactive multimedia workstation network

Abstract: An existing CATV co-axial cable system provides a two-way path between multimedia workstations and a control center and between multimedia workstations connected at nodes along the cable. Each node/workstation organization comprises at least one tuner/demodulator and a notch filter. The system of the present invention is suitable as a multimedia communications system for providing full motion picture transmission, high fidelity audio communications and data transmission, effectively multimedia communication in its true form.

Method and system for modem command processing during data transfer

Abstract: A method and system are disclosed for permitting selected command sequences to be processed by a modem during data transfer operations. A preselected escape character is designated and inserted into a data stream to be applied to a modem in order to identify a selected command sequence which follows. A termination character is inserted into the data stream following the selected command sequence. Upon detection of the preselected escape character, the selected command sequence is coupled to a command processor within the modem and processed. In applications in which the modem is coupled between a data processing system and a cellular telephone communication channel, the selected command sequence may be utilized to transmit communication channel parameter status queries to a cellular telephone associated with the modem. In this manner, the Received Signal Strength Indicator (RSSI), bit error rate, or other indications of communication channel status may be queried. An identical technique may be utilized to transmit a response to each such query to the data processing system, permitting real time display of cellular communication channel status information during data transfer.

Remote controller linkage to an elevator system

Abstract: A remote controller linkage is established to an elevator system consisting of one or more elevators and using a data transmission network comprising at least one serial communication bus for the transmission of control signals between the operating and/or other devices belonging to the system, car calls, landing calls and other information obtained from and/or generated by the devices comprising the elevator system. At least one of the serial communication buses belonging to the data transmission network of the elevator system is connected to a functional unit fitted to receive messages sent to it by a remote controller. On the basis of the message received, the functional unit transmits into the serial communication bus a message containing at least one control, call or other datum and the bus address of the transmitting functional unit.

Method for digital transmission of hierarchical HDTV, EDTV and SDTV television signals

Abstract: For digital transmission of hierarchical HDTV, EDTV and SDTV television signals, on the transmission side after an analog/digital conversion of video and audio input signals and a subsequent removal of redundancy in a source coder, the signal bits are protected in a UEP coder in accordance with their significance. Thereafter, the hierarchically built up television signals (HDTV, EDTV and SDTV) are subjected to a multilevel coding and, combined to form symbols, to a multiresolution modulation and an OFD multiplexing and transmitted after digital/analog conversion. On the receiving side the transmitted signals, after analog/digital reconversion and inverse OED multiplexing (OFDM), are demodulated in a multiresolution demodulator and then decoded in a multistage decoder. Thereupon the data are processed by digital/analog conversion to HDTV, EDTV and SDTV signals in a UEP decoder specific to the respective receiver and a following source decoder.

Digital electronic loop crossconnect and carrier system

Abstract: A digital cross connect device for telephone and data transfer systems includes a plurality of line cards, including line cards connected to a network line and line cards connected to a subscriber line. The network line and the subscriber line carry a signal including a data portion and a status signal portion. Signal separation is provided for separating the data portion from the status signal portion. A coder is provided for coding the status signals to provide status signal bit packets based on received status signals. A status signal time slot interchange is provided for receiving the status signal bit packets and transmitting the status signal bit packets, based on assigned time slots, to another line card. The status signal time slot interchange includes a connection memory having address locations corresponding to time slots, and a dual port memory for receiving the status signal bit packets and writing bit packets based on the address locations of the connection memory.

System and method for controlling buffer transmission of data packets by limiting buffered data packets in a communication session

Abstract: A system and method for controlling data transmission between computer systems is suitable for use at the OSI session level of structured network architectures. A receiving logical unit can dynamically control packet window sizes to optimize its resources. In the sending logical unit, the number of packets which may be sent by a single session, but not yet acknowledged at the data link control level, is limited. This results in all sessions in the system having a relatively fair access to a single communications link. The number of packets allowed for any given session need not have any relationship to the window size in an adaptive session level pacing environment.