Showing papers on "Data transmission published in 2004"

An active-set approach for OFDM PAR reduction via tone reservation

Abstract: Common to all orthogonal frequency division multiplexing (OFDM) systems is a large peak-to-average-power ratio (PAR), which can lead to low power efficiency and nonlinear distortion at the transmit power amplifier. Tone reservation uses other unused or reserved tones to design a peak-cancelling signal that lowers the PAR of a transmit OFDM block. In contrast to previous methods, the new active-set method proposed here converges very quickly toward a minimum-PAR solution at a lower computational cost. An efficient real-baseband algorithm is well suited for discrete multitone (DMT) modulation over twisted-pair copper wiring, where some subchannels may have an insufficient SNR to reliably send data. The real PAR problem occurs in the analog signal before the power amplifier, and results focus on this figure of merit. The performance of oversampling before applying PAR reduction is analyzed, and results show that this is necessary to sufficiently handle the analog PAR problem. An extension of the real-baseband technique can be applied to complex-baseband signals to help reduce PAR in wireless and broadcast systems. By sacrificing 11 out of 256 OFDM tones (4.3%) for tone reservation, over 3 dB of analog PAR reduction can be obtained for a wireless system.

Power line communications

Abstract: This article overviews the power line communication, which is originally devised to transmit electric power from a small number of sources to a large number of sinks. Initially the first data transmission were over power lines were primarily done only to protect sections of the power distribution system in case of faults. This paper also studies the performance of power lines for high bit rate applications. DMT technology is adopted by the homeplug standard can theoretically provide data rates of 100Mb/s. However, products based on the standard only have achieved data rates up to 14 Mb/s. To protect against the severe noisy conditions and fading in the powerline channel, very high levels of error control coding need to be provided. The efforts of the homeplug alliance and home networking technology's growth in the US portend a very bright future for DMT-based PLC home networking.

Apparatus and method for mobile personal computing and communications

Abstract: A hand-held mobile personal computing and communications device offers full operating system functionality and performance of modern laptops and desktop personal computers, along with seamless networking and session and application persistence for supporting voice, video and data communications. The device uses an ultra low voltage processor and ample low power mass storage for effectively running complete versions of modern operating systems and associated applications with extended battery life. The device also utilizes modular peripherals to extend battery life and increase the effectiveness of the overall system. The device includes multiple broadband wireless communications technologies along with integrated cellular communication technologies for supporting real-time voice, video and data transmission. Various processes are provided for managing connectivity and communications.

Pilot transmission schemes for wireless multi-carrier communication systems

Abstract: Pilot transmission schemes suitable for use in wireless multi-carrier (e.g., OFDM) communication systems. These pilot transmission schemes may utilize frequency, time, or both frequency and time orthogonality to achieve orthogonality among the pilots transmitted by multiple base stations on the downlink. Frequency orthogonality is achieved by transmitting pilots on disjoint sets of subbands. Time orthogonality is achieved by transmitting pilots using different orthogonal codes (e.g., Walsh codes). The pilots may also be scrambled with different scrambling codes, which are used to randomize pilot interference and to enable identification of the transmitters of these pilots. Pilot interference cancellation may be performed to improve performance since subbands used for data transmission by one transmitter may also be used for pilot transmission by another transmitter. Pilot interference is estimated and then subtracted from received symbols to obtain pilot-canceled symbols having improved quality.

DVB: The Family of International Standards for Digital Video Broadcasting

Abstract: This paper presents an overview of the fields of technology addressed by technical specifications created by the DVB Project (DVB). It serves as an introduction to the section of the special issue of the Proceedings of the IEEE in which a number of very recent DVB technologies will be explained in detail. The overview starts with an explanation of the wide field of application which the members of the DVB Project decided to address over the years. It then discusses the base band processing required for DVB services and looks into the specifications provided for the broadcasting over cable, satellite, and terrestrial transmitters. The concept of broadcasting generic data is explained and the interaction channels supported by DVB will be introduced. Multimedia Home Platform (MHP) facilitates a horizontal market of receivers able to run software programs (applications in DVB terminology)in a well defined way. After a short introduction into the specifications addressing the delivery of broadcast-type content over broad-band IP networks,the concept of broadcasting to handheld devices is introduced. The paper closes with a description of the newest areas of development DVB has decided to tackle.

Communication protocol over power line communication network

Abstract: A communication apparatus for high-speed data transmission over power line networks comprises a head-end unit (1) which provides a single logical entry point into the communications network (2), an infrastructure of physical power line cables, one or more client-end units (3) which communicate with the head-end unit (1), and one or more hybrid units which simultaneously acts as a head-end unit for another physical sub-network of the power-line communication network (2) and functions as a client-end unit (3) of another physical sub-network of the power line communication network.

Data input management system for wearable electronically enabled interface

Abstract: A data input management system is disclosed, for allowing a user to select one or more data sources, to be placed either simultaneously or one at a time into electrical communication with a single user interface. The user interface may comprise a wearable support, such as an eyeglass frame, adapted to carry one or more of speakers, microphone and video display, depending upon the desired functionality. Source electronics may be carried by the support or carried remotely, and in wireless communication with the support using Bluetooth protocols or other data transmission technology.

Apparatus for OFDMA transmission and reception for coherent detection in uplink of wireless communication system and method thereof

Abstract: In the resource mapping method for data transmission, a time-frequency resource of a slot interval including OFDM symbols is divided into traffic channels and shared among the subscribers, the traffic channel including resource blocks uniformly distributed in the whole transmit frequency band, the resource block including consecutive subcarriers of consecutive received symbols having at least one inserted pilot symbol. The pilot symbols and the channel-encoded and modulated data symbols are processed by time-frequency mapping according to the resource-block-based mapping method to generate received symbols. The receiver separates the received symbols by subscribers according to the resource-block-based mapping method in a frequency domain, and performs iterative channel estimation, demodulation, and decoding by using the pilot and a data reference value after decoding for each traffic channel.

Exploiting medium access diversity in rate adaptive wireless LANs

Abstract: Recent years have seen the growing popularity of multi-rate wireless network devices (e.g., 802.11a cards) that can exploit variations in channel conditions and improve overall network throughput. Concurrently, rate adaptation schemes have been developed that selectively increase data transmissions on a link when it offers good channel quality. In this paper, we propose a Medium Access Diversity (MAD) scheme that leverages the benefits of rate adaptation schemes by aggressively exploiting multiuser diversity. The basic mechanism of MAD is to obtain instantaneous channel condition information from multiple receivers and selectively transmit data to a receiver that improves the overall throughput of the network, while maintaining temporal fairness among multiple data flows. We identify and address the challenges in the design and implementation of MAD's three phases: channel probing, data transmission, and receiver scheduling. We also use analytical models to examine the tradeoff between network performance improvement and overhead of channel probing, and derive an asymptotic performance bound for the receiver scheduling algorithms used by MAD. Results from the analysis and the extensive simulations demonstrate that, on average, MAD can improve the overall throughput of IEEE 802.11 wireless LANs by 50% as compared with the best existing rate adaptation scheme.

An inductive power system with integrated bi-directional data-transmission

Abstract: An inductive powering system is presented, capable of remotely powering implantable monitoring and stimulating devices. The system is capable of delivering at least 50 mW, with an efficiency of 36% over a distance of 3 cm. The power transfer frequency is 700 kHz. Optimisation of the power transfer efficiency and the misalignment tolerance was obtained using a self-developed design tool. Bi-directional data-transmission is integrated in the system: amplitude modulation is applied for the downlink transmission, absorption modulation for the uplink transmission. Our new system is capable of transmitting data at a maximal bit rate of 60,000 bits/s.

Parallel data transfer over multiple channels with data order prioritization

Abstract: A parallel download system is described to download data from a plurality of source servers in parallel The system may include a source scheduler, a prioritization scheduler, and an I/O dispatcher The source scheduler generates a download schedule to control which source servers will be downloaded from at a current point in time The prioritization scheduler tracks the latency and throughput of all channels to the source servers and dynamically adjusts the download schedule to control download performance The I/O dispatcher produces an output stream to present the downloaded data to one or more external applications or a user

On adaptive transmission for energy efficiency in wireless data networks

Abstract: This paper investigates the problem of energy-efficient transmission of data packets in a wireless network by jointly adapting to backlog and channel condition. Specifically, we consider minimum-energy scheduling problems over multiple-access channels, broadcast channels, and channels with fading, when packets of all users need to be transmitted before a deadline T. Earlier work has considered a similar setup and demonstrated significant transmission energy saving by adapting to backlog for channels that are time invariant and when transmission is restricted to time-division. For concreteness, throughout the paper, rates and powers corresponding to optimal coding over discrete-time additive white Gaussian noise (AWGN) channels are assumed. The results, however, hold for more general channels and coding schemes where the total transmitted power is convex in the transmission rates. The offline scheduling problems for all the channels considered are shown to reduce to convex optimization problems with linear constraints. An iterative algorithm, referred to as FlowRight, that finds optimal offline schedules is presented. A heuristic online algorithm that we call look-ahead water-filling, which jointly adapts to both channel fading state and backlog is described. By the use of a small buffer which introduces an almost fixed delay, this algorithm achieves a considerable reduction in energy relative to water filling solely on channel states.

Graph Problems Arising from Wavelength-Routing in All-Optical Networks

Abstract: We survey the theoretical results obtained for wavelength routing in al l-optical networks, present some new results and propose several open problems. In all-optical networks the vast band- width available is utilized through wavelength division multiplexing: a single physical optical link can carry several logical signals, provided that they are transmitted on dif ferent wavelengths. The information, once transmitted as light, reaches its destination withou t being converted to electronic form in between, thus reaching high data transmission rates. We consider both networks with arbi- trary topologies and particular networks of practical interest.

Method and apparatus for channel quality feedback within a communication system

Abstract: A base station (101) will request the transmission of quality information from a particular remote stations (102, 103) only when data is queued to be transmitted to the remote stations. Once a remote station begins the transmission of channel quality information, the transmission of such information continues until the data transmission is successfully delivered to the remote station. The base station receives the channel quality information and adjusts the modulation and coding of the remote stations accordingly. Where data is transmitted simultaneously to a plurality of remote stations, a set of queues (303) for the multiple remote stations is maintained, and based on queue status, a channel quality request messages is sent to a sub-set of remote stations with data queued.

Equalization in high-speed communication systems

Abstract: The article first discusses the major non-ideal issues of low-cost transmission media for over Gbps data transmissions - the frequency dispersion loss and channel noise. The former causes ISI in received signal, which presents difficulty for clock and data recovery at high frequencies and results higher BER. The latter further degrades the received signal quality and further limits the data transmission rate and transmission distance. Then, two equalization approaches - transmitter pre-emphasis and receiver equalization, are reviewed, in addition to various adaptation criteria and algorithms.

System and method for high speed packet transmission implementing dual transmit and receive pipelines

Abstract: The present invention provides systems and methods for providing data transmission speeds at or in excess of 10 gigabits per second between one or more source devices and one or more destination devices. According to one embodiment, the system of the present invention comprises a first and second media access control (MAC) interfaces to facilitate receipt and transmission of packets over an associated set of physical interfaces. The system also contemplates a first and second field programmable gate arrays (FPGA) coupled to the MAC interfaces and an associated first and second memory structures, the first and second FPGAs are configured to perform initial processing of packets received from the first and second MAC interfaces and to schedule the transmission of packets to the first and second MAC interface for transmission to one or more destination devices. The first and second FPGAs are further operative to dispatch and retrieve packets to and from the first and second memory structures. A third FPGA, coupled to the first and second memory structures and a backplane, is operative to retrieve and dispatch packets to and from the first and second memory structures, compute appropriate destinations for packets and organize packets for transmission. The third FPGA is further operative to receive and dispatch packets to and from the backplane.

Iterative layered space-time receivers for single-carrier transmission over severe time-dispersive channels

Abstract: This letter presents an iterative layered space-time (LST) receiver structure for single-carrier (SC)-based transmission in severe time-dispersive channels. The proposed receiver combines LST principles with iterative block decision feedback equalization (IB-DFE) techniques. Our performance results show that the proposed receivers have excellent performance in severe time-dispersive channels, which can be very close to the matched filter bound (MFB) after just a few iterations.

Method and apparatus for efficient power/data transmission

Abstract: A system, method and power/data transmission device comprising a coil having a high Q, a low-voltage driver and a high-voltage driver switchably coupled to the coil. The low-voltage driver and the high-voltage driver are controlled by a microcontroller and switch at about the same time thereby providing a modulated data signal for transmission. Furthermore, the system includes at least one implantable microstimulator coupled to the transmission device.

System for maintaining drug information and communicating with medication delivery devices

Abstract: A system for maintaining drug information and communicating with medication delivery devices includes software designed for use in a hospital, pharmacy or biomedical technical service environments. The software may be provided on a computer readable medium. The software allows a facility to customize a drug library with both hard and soft drug limits and other parameters for use with an infuser having a plug and play module removably inserted into a slot within a housing, or for use with an infuser having a connectivity engine enclosed within the housing. The system supports data transfer to one or more infusers connected to one or more computers. The connection between the computer and the pump can be hard wired or wireless.

Disk drive and method for data transfer initiated by optional disk-drive commands on a serial interface that only supports standard disk-drive commands

Abstract: A disk drive and method are disclosed for data transfer initiated by nonstandard disk-drive commands on a serial interface that only supports standard disk-drive commands. In the method, a nonstandard disk-drive command for data transfer is embedded within a first data block accessible using a first standard disk-drive command. The first standard disk-drive command is transmitted through the serial interface causing the first data block to be transferred from the host computer to the disk control system. The embedded command is extracted from the transferred first data block and provided to the disk control system. A status response is transmitted to the host computer based on the extracted command. At least one additional standard disk-drive command is transmitted through the serial interface to the disk control system for transferring the identified data between the host computer and the disk drive.

Communication method, communication device, and computer program

Abstract: In order to solve a problem of an accumulation on the transmission side, a delay on the reception side, and the like at the time of transmission in a communication system such as a wireless LAN system, each communication station in a network transmits a beacon in which information with respect to the network is written and sets a state in which a reception operation is performed during periods of time before and after the transmission of the beacon signal when performing access control not to make communication timing of a packet collide with that of another station by detecting a signal transmitted from another station. With performing such processing, a system can be formed based on minimum level of transmission and reception operation when transmission and reception data does not exist in each communication station in the network, and also a data transfer can be performed with latency as small as possible in a minimum necessary level of transmission and reception operation by making a transition of a transmission and reception state in accordance with a fluctuating volume of transmission and reception data.

Transmission mode selection for data transmission in a multi-channel communication system

Abstract: Techniques to select a suitable transmission mode for a data transmission in a multi-channel communication system with multiple transmission channels having varying SNRs. In one method, an SNR estimate is initially obtained for each of multiple transmission channels used to transmit a data stream. An average SNR and an unbiased variance are then computed for the SNR estimates for the multiple transmission channels. A back-off factor is determined, for example, based on the SNR variance and a scaling factor. An operating SNR for the transmission channels is next computed based on the average SNR and the back-off factor. The transmission mode is then selected for the data stream based on the operating SNR. The selected transmission mode is associated with a highest required SNR that is less than or equal to the operating SNR. The method may be used for any system with multiple transmission channels having varying SNRs.

MOAR: a multi-channel opportunistic auto-rate media access protocol for ad hoc networks

Abstract: The IEEE 802.11 wireless media standard supports multiple frequency channels as well as multiple data rates at the physical (PHY) layer. In this paper, we introduce the multi-channel opportunistic auto rate (MOAR), an enhanced MAC protocol for multi-channel and multi-rate IEEE 802.11 enabled wireless ad hoc networks to opportunistically exploit the presence of frequency diversity (in the form of multiple frequency channels). The key mechanism of MOAR is that if the signal to noise ratio on the current channel is not favorable, mobile nodes can opportunistically skip to better quality frequency channels enabling data transmission at a higher rate. As channel separation for IEEE 802.11 is greater than the coherence bandwidth, different channels experience independent fading and hence there is a high probability that the skipping nodes will find better channel conditions on one of the other frequency channels. Each skip comes at the cost of resources spent in channel measurement since channel quality of different channels is not known a priori. Consequently, we devise an optimal skipping rule for MOAR which maps the channel conditions at the PHY layer to a MAC rule which allows each node to determine its optimum number of skips based on average channel conditions. Finally, we perform an extensive set of ns-2 simulations to evaluate the performance of MOAR and the impact of such factors as location distribution, channel conditions and error in channel measurements on the throughput gains offered by MOAR.

Optical data buses for automotive applications

Abstract: Optical data links and bus systems are becoming increasingly attractive for automobiles. In 1998, a first optical data bus system, based on polymer optical fibers and visible light-emitting diodes was introduced in Mercedes-Benz cars to interconnect information and entertainment devices within the passenger compartment. Since 2002, media-oriented system transport (MOST) is the standard for an optical infotainment data bus system in the automotive industry. However, with increasing demands on network flexibility, robustness, safety-relevant functions, and data rate, the currently used technologies reach their limit. A new physical layer, based on 200-/spl mu/m polymer-cladded silica fibers and infrared-emitting vertical-cavity surface-emitting lasers, is a promising solution. This paper provides an overview about the state-of-the-art physical layer of standard MOST data bus systems, shows its limitations, and presents new optical-physical-layer concepts for next-generation data bus systems in cars.

Data transmission method

Abstract: The invention relates to a method for transmitting data between a transmitter and a receiver via a wireless data channel of a communication network (CN). The transmitter transmits data to the receiver, where the transmission includes at least one transmission parameter which is selected based on a first channel quality that is known to the transmitter. The receiver receives the data, and the receiver determines the first channel quality known to the transmitter from said data via the at least one used transmission parameter as well as a second, current channel quality via the quality of the received data; and the receiver compares the first channel quality with the second channel quality.

Optical network security: technical analysis of fiber tapping mechanisms and methods for detection & prevention

Abstract: Increasing emphasis on reliable data transmission for homeland security and network-centric operations makes secure communications a critical component of national security. While fiber optic cables are immune to typical EMI/RFI issues, it is possible to intercept an optical signal successfully if risk areas are not understood and if detection and/or prevention mechanisms are not actively integrated into network management practices. There are several ways to 'tap' into an optical fiber, including fiber bending, splitting, evanescent coupling, scattering, and V-grooves. Many of these techniques require altering the physical characteristics of the fiber with a significant risk of damaging the fiber and having the optical intercept detected by the end user. Of all the techniques, the bent fiber tap is the most easily deployed with minimal risk of damage or detection. The paper quantifies the bend loss required to tap a signal propagating in a single mode fiber and analyzes the properties of the bend that could be used to detect that a tap is occurring. Understanding the mechanisms used for fiber tapping provides greater insight into ways of actively detecting unauthorized optical intercepts or compromised network security. Enhanced monitoring techniques enable the detection and localization of fiber taps. Monitoring techniques are reviewed with detailed analysis of each method's effectiveness in detecting bent fiber taps and their cost-effectiveness for integration into optical networks.

A class of nonlinear signal-processing schemes for bandwidth-efficient OFDM transmission with low envelope fluctuation

Abstract: This work presents a wide class of digital signal-processing schemes for orthogonal frequency-division multiplexing (OFDM) transmission which combine a nonlinear operation in the time domain and a linear filtering operation in the frequency domain. The ultimate goal of these schemes is to reduce the envelope fluctuation of ordinary OFDM, while keeping its high spectral efficiency and allowing a low-cost, power-efficient implementation. An appropriate statistical model concerning the transmitted frequency-domain blocks is developed, which is derived from well-established results on Gaussian stochastic processes distorted by memoryless nonlinearities. This model can be employed for performance evaluation by analytical means, with highly accurate results whenever the corresponding conventional OFDM signals exhibit quasi-Gaussian characteristics. Cases where the signal-processing scheme is repeatedly used, in an iterative way, are treated through an extension of the proposed statistical modeling. A set of numerical results is presented and discussed so as to show the practical interest of both the proposed schemes and the analytical methods for evaluation of their performance. For the sake of comparisons, this paper includes numerical results concerning the partial transmit sequence technique, which is an alternative peak-to-mean envelope power ratio-reducing technique of higher complexity, often recommended due to its distortionless nature. The superior performance/complexity tradeoffs through the proposed class of nonlinear signal-processing schemes is emphasized.

Multi-antenna reception apparatus, multi-antenna reception method, multi-antenna transmission apparatus and multi-antenna communication system

Abstract: Soft decision parts (503,506) perform temporary decisions of modulated signals (502,505) as separated by a separating part (501) using an inverse matrix calculation of a channel scatter matrix Signal point reduction parts (508,510,514,516) use the temporary decision results (504,507) to reduce the number of candidate signal points of multiplexed modulated signals Soft decision parts (512,518) use the candidate signal points as reduced to perform precise decisions, thereby obtaining reception data of the modulated signals (RA,RB) In this way, a smaller number of calculations is used to successfully obtain the reception data (RA,RB) having an improved error rate characteristic without degradation of the data transmission efficiency

Power Control for Reverse Packet Data Channel in CDMA Systems

Abstract: A method of reverse link power control for a reverse packet data channel in a wireless communication system allows a mobile station to autonomously change its data transmission rate The mobile station transmits packet data over a reverse packet data channel having a data rate variant transmit power level that varies based on a transmit data rate on the packet data channel The mobile station further transmits control signals over a reverse control channel associated with the reverse packet data channel The transmit power level of the reverse control channel is such that the transmit power level does not vary with the transmit data rate on the packet data channel The radio base station measures the strength of the received signals on the reverse control channel, compares the measured strength to a power control set point, and generates a power control signal responsive to the comparison of the control signal to the power control set point

Data transmission protocol and visual display for a networked computer system

Abstract: An on-line multi-player virtual reality game is provided. The multi-player game system is capable of handling many simultaneous players connected to a computer system using personal computers or other gaming consoles via the Internet or other telecommunications network. A unique retransmission transport protocol is used for transmitting and retransmitting data of the multi-player game. A visual display is also provided having a network transmission status display bar.