Showing papers on "Data transmission published in 2005"

Chaos-based communications at high bit rates using commercial fibre-optic links

Abstract: Chaos is good, if you are looking to send encrypted information across a broadband optical network. The idea that the transmission of light-based signals embedded in chaos can provide privacy in data transmission has been demonstrated over short distances in the laboratory. Now it has been shown to work for real, across a commercial fibre-optic channel in the metropolitan area network of Athens, Greece. The results show that the technology is robust to perturbations and channel disturbances unavoidable under real-world conditions. Chaotic signals have been proposed as broadband information carriers with the potential of providing a high level of robustness and privacy in data transmission1,2. Laboratory demonstrations of chaos-based optical communications have already shown the potential of this technology3,4,5, but a field experiment using commercial optical networks has not been undertaken so far. Here we demonstrate high-speed long-distance communication based on chaos synchronization over a commercial fibre-optic channel. An optical carrier wave generated by a chaotic laser is used to encode a message for transmission over 120 km of optical fibre in the metropolitan area network of Athens, Greece. The message is decoded using an appropriate second laser which, by synchronizing with the chaotic carrier, allows for the separation of the carrier and the message. Transmission rates in the gigabit per second range are achieved, with corresponding bit-error rates below 10-7. The system uses matched pairs of semiconductor lasers as chaotic emitters and receivers, and off-the-shelf fibre-optic telecommunication components. Our results show that information can be transmitted at high bit rates using deterministic chaos in a manner that is robust to perturbations and channel disturbances unavoidable under real-world conditions.

Monitoring volcanic eruptions with a wireless sensor network

Abstract: This paper describes our experiences using a wireless sensor network to monitor volcanic eruptions with low-frequency acoustic sensors. We developed a wireless sensor array and deployed it in July 2004 at Volcan Tingurahua, an active volcano in central Ecuador. The network collected infrasonic (low-frequency acoustic) signals at 102 Hz, transmitting data over a 9 km wireless link to a remote base station. During the deployment, we collected over 54 hours of continuous data which included at least 9 large explosions. Nodes were time-synchronized using a separate GPS receiver, and our data was later correlated with that acquired at a nearby wired sensor array. In addition to continuous sampling, we have developed a distributed event detector that automatically triggers data transmission when a well-correlated signal is received by multiple nodes. We evaluate this approach in terms of reduced energy and bandwidth usage, as well as accuracy of infrasonic signal detection.

Efficient aggregation of encrypted data in wireless sensor networks

Abstract: Wireless sensor networks (WSNs) are ad-hoc networks composed of tiny devices with limited computation and energy capacities. For such devices, data transmission is a very energy-consuming operation. It thus becomes essential to the lifetime of a WSN to minimize the number of bits sent by each device. One well-known approach is to aggregate sensor data (e.g., by adding) along the path from sensors to the sink. Aggregation becomes especially challenging if end-to-end privacy between sensors and the sink is required. In this paper, we propose a simple and provably secure additively homomorphic stream cipher that allows efficient aggregation of encrypted data. The new cipher only uses modular additions (with very small moduli) and is therefore very well suited for CPU-constrained devices. We show that aggregation based on this cipher can be used to efficiently compute statistical values such as mean, variance and standard deviation of sensed data, while achieving significant bandwidth gain.

Queuing with adaptive modulation and coding over wireless links: cross-Layer analysis and design

Abstract: Assuming there are always sufficient data waiting to be transmitted, adaptive modulation and coding (AMC) schemes at the physical layer have been traditionally designed separately from higher layers. However, this assumption is not always valid when queuing effects are taken into account at the data link layer. In this paper, we analyze the joint effects of finite-length queuing and AMC for transmissions over wireless links. We present a general analytical procedure, and derive the packet loss rate, the average throughput, and the average spectral efficiency (ASE) of AMC. Guided by our performance analysis, we introduce a cross-layer design, which optimizes the target packet error rate of AMC at the physical layer, to minimize thpacket loss rate and maximize the average throughput, when combined with a finite-length queue at the data link layer. Numerical results illustrate the dependence of system performance on various parameters, and quantify the performance gain due to cross-layer optimization. Our focus is on the single user case, but we also discuss briefly possible applications to multiuser scenarios.

High speed silicon Mach-Zehnder modulator

Abstract: We demonstrate a silicon modulator with an intrinsic bandwidth of 10 GHz and data transmission from 6 Gbps to 10 Gbps Such unprecedented bandwidth performance in silicon is achieved through improvements in material quality, device design, and driver circuitry

Precoding and Signal Shaping for Digital Transmission: Fischer/Precoding and Signal Shaping

Abstract: Preface. Introduction. Digital Communications via Linear, Distorting Channels. Precoding Schemes. Signal Shaping. Combined Precoding and Signal Shaping. Appendix A: Wirtinger Calculus. Appendix B: Parameters of the Numerical Examples. Appendix C: Introduction to Lattices. Appendix D: Calculation of Shell Frequency Distribution. Appendix E: Precoding for MIMO Channels. Appendix F: List of Symbols, Variables, and Acronyms. Index.

Theory and Applications of OFDM and CDMA: Wideband Wireless Communications

Abstract: Preface. 1 Basics of Digital Communications. 1.1 Orthogonal Signals and Vectors. 1.2 Baseband and Passband Transmission. 1.3 The AWGN Channel. 1.4 Detection of Signals in Noise. 1.5 Linear Modulation Schemes. 1.6 Bibliographical Notes. 1.7 Problems. 2 Mobile Radio Channels. 2.1 Multipath Propagation. 2.2 Characterization of Fading Channels. 2.3 Channel Simulation. 2.4 Digital Transmission over Fading Channels. 2.5 Bibliographical Notes. 2.6 Problems. 3 Channel Coding. 3.1 General Principles. 3.2 Convolutional Codes. 3.3 Reed-Solomon Codes. 3.4 Bibliographical Notes. 3.5 Problems. 4 OFDM. 4.1 General Principles. 4.2 Implementation and Signal Processing Aspects for OFDM. 4.3 Synchronization and Channel Estimation Aspects for OFDM Systems. 4.4 Interleaving and Channel Diversity for OFDM Systems. 4.5 Modulation and Channel Coding for OFDM Systems. 4.6 OFDM System Examples. 4.7 Bibliographical Notes. 4.8 Problems. 5 CDMA. 5.1 General Principles of CDMA. 5.2 CDMA Transmission Channel Models. 5.3 Receiver Structures for Synchronous Transmission. 5.4 Receiver Structures for MC-CDMA and Asynchronous Wideband CDMA Transmission. 5.5 Examples for CDMA Systems. 5.6 Bibliographical Notes. 5.7 Problems. Bibliography. Index.

Satellite based data transfer and delivery system

Abstract: A high speed data transfer system includes a WAU ( 201 ) which is utilized to provide high speed data access to satellite transferred data. The system is configured such that a plurality of data utilization devices ( 205 ) may access the high speed data via wireless links to the WAU ( 201 ). Advantageously, high speed data services may be provided to users without the users requiring individual satellite antennas.

Method and apparatus for closed loop data transmission

Abstract: A method for communicating a plurality of data streams between a transmitting device with multiple transmit antennas and a receiving device, is disclosed. The method comprises determining a set of power weightings, efficiently quantizing the power weightings, and providing the set of power weightings the transmitting device. Another aspect of the invention comprises the transmitter implicitly signaling the number of data streams which the receiver should feedback information for through the amount of feedback requested. An additional aspect of the invention is a means of determining the best codebook weights by combining the maximum power and maximum capacity criteria.

A hierarchical modulation for upgrading digital broadcast systems

Abstract: A hierarchical modulation scheme is proposed to upgrade an existing digital broadcast system, such as satellite TV, or satellite radio, by adding more data in its transmission. The hierarchical modulation consists of a basic constellation, which is the same as in the original system, and a secondary constellation, which carries the additional data for the upgraded system. The upgraded system with the hierarchical modulation is backward compatible in the sense that receivers that have been deployed in the original system can continue receiving data in the basic constellation. New receivers can be designed to receive data carried in the secondary constellation, as well as those in the basic constellation. Analysis will be performed to show the tradeoff between bit rate of the data in secondary constellation and the penalty to the performance of receiving the basic constellation.

High data rate interface apparatus and method

Abstract: A data interface for transferring digital data between a host and a client over a communication path using packet structures linked together to form a communication protocol for communicating a pre-selected set of digital control and presentation data. The signal protocol is used by link controllers configured to generate, transmit, and receive packets forming the communications protocol, and to form digital data into one or more types of data packets, with at least one residing in the host device and being coupled to the client through the communications path. The interface provides a cost-effective, low power, bi-directional, high-speed data transfer mechanism over a short-range “serial” type data link, which lends itself to implementation with miniature connectors and thin flexible cables which are especially useful in connecting display elements such as wearable micro-displays to portable computers and wireless communication devices.

Exploiting partially overlapping channels in wireless networks: turning a peril into an advantage

Abstract: Interference has always been considered as an unavoidable peril in wireless networks. A single data transmission is useful to some nodes and becomes interference to others. Based on channel of origin, interference can be categorized into co-channel (from transmissions on the same channel as the receiver) and adjacent-channel (transmissions on adjacent and overlapping channels).In this paper, we define specific mechanisms that can transform partially overlapped channels into an advantage, instead of a peril. We construct simple analytical and empirical models of such interference occurring in IEEE 802.11 networks, and illustrate two scenarios where such interference can be exploited. First, we apply partially overlapping channels to improve spatial channel re-use in Wireless LANs (WLANs). Second, we leverage such channels to enable nodes with a single radio interface to communicate more efficiently with their peers in 802.11 ad-hoc mode potentially using multi-hop paths. We evaluate both capabilities through testbed measurements.

Data transfer control device and electronic instrument

Abstract: A data transfer control device includes an OUT-transfer transmitter circuit which transmits OUT data by driving a serial signal line, a clock-transfer transmitter circuit which transmits a clock signal CLK by driving a serial signal line, a PLL circuit which generates the clock signal CLK, and a power-down setting circuit which sets a power-down mode. In a first power-down mode, the OUT-transfer transmitter circuit is set to the power-down mode, and the clock-transfer transmitter circuit is set to the power-down mode to stop a system clock signal of a target-side data transfer control device. In a second power-down mode, the OUT-transfer transmitter circuit is set to the power-down mode without setting the clock-transfer transmitter circuit to the power-down mode.

Method and apparatus for reducing interference associated with wireless communication

Abstract: The present invention provides for a method and apparatus for reducing interference associated with wireless communication in an area having sensitive electronic equipment. A wireless communications device receives, from an access point, a signal having a signal strength above a predetermined threshold. The wireless communications device determines a transmission power level maximum based on the received signal and then transmits a signal to the access point at a transmission power level at or below the transmission power level maximum. The wireless communications device disables the transmission when the signal strength falls below the predetermined threshold.

System and method for remote optical digital networking of computing devices

Abstract: This invention extends the range of optical data of mobile device by trading speed for distance as well as integrating a plurality of pulses over time to define a single bit of information. The present invention uses a number of integrated pulses to represent a single bit instead of utilizing a one to one correspondence between pulses and bits. The present invention executes a range extender application which executes on the mobile device without any hardware modification to the mobile device. The range extender application causes the optical transmitter to “stutter” or repetitively emanate the identical pulse representing a bit of information. Sufficient photons are thereby gathered at a receiver to reach a predetermined threshold. A tradeoff of the data transmission frequency in this invention is that a signal intensity drops by a factor of 100 when distance increases by a factor of 10 yielding a distance/intensity ratio of {fraction (1/10)}.

A fully integrated low-power BPSK demodulator for implantable medical devices

Abstract: During the past decades, research has progressed on the biomedical implantable electronic devices that require power and data communication through wireless inductive links. In this paper, we present a fully integrated binary phase-shift keying (BPSK) demodulator, which is based on a hard-limited COSTAS loop topology, dedicated to such implantable medical devices. The experimental results of the proposed demodulator show a data transmission rate of 1.12 Mbps, less than 0.7 mW consumption under a supply voltage of 1.8 V, and silicon area of 0.2 mm/sup 2/ in the Taiwan Semiconductor Manufacturing Company (TSMC) CMOS 0.18-/spl mu/m technology. The transmitter satisfies the requirement of applications relative to high forward-transferring data rate, such as cortical stimulation. Moreover, the employment of BPSK demodulation along with a passive modulation method allows full-duplex data communication between an external controller and the implantable device, which may improve the controllability and observability of the overall implanted system.

A generalized framework for distributed power control in wireless networks

Abstract: Most power control algorithms that aim at hitting a signal-to-interference ratio (SIR) target fall within Yates' framework. However, for delay-tolerable applications, it is unnecessary to maintain the SIR at a certain level all the time. To maximize throughput, one should increase one's power when the interference level is low, and the information transmission rate is adjusted accordingly by adaptive modulation and coding techniques. This approach is called opportunistic communications. In this paper, we generalize Yates' result and establish a new framework, which is applicable to systems supporting opportunistic communications and with heterogeneous service requirements. Simulation results show that our proposed algorithm yields significant improvement in throughput when compared with the conventional target tracking approach.

Method and system for data transmission in a wireless network

Abstract: A method and system for data transmission by computational devices in a wireless network ( 100 ) are disclosed. A computational device ( 102 ) organizes the wireless network in a hierarchical topology having at least one root node and updates a list of interferers and a list of descendents. Then, the computational device allocates a Contention Free Period (CFP) slot to each computational device in the wireless network based on at least one of the list of interferers and the list of descendents and transmits data during the allocated CFP slot.

Improving the Data Transmission Throughput over the Home Electrical Wiring

Abstract: Powerline communications (PLC) are receiving special attention since they use an already available and ubiquitous infrastructure. The main standard for PLC home networks is HomePlug. This work improves the throughput of HomePlug by modifying the medium access control sub-layer. The key idea is to define a fast collision avoidance mechanism where every station that wants to access the medium increments its contention window after sensing another ongoing transmission. The proposal reduces the number of collisions in the network improving the achievable throughput. We compared our mechanism to the original HomePlug standard through simulation and mathematical analysis. We verified that the improvement is independent from the packet size, the transmission rate and the number of nodes when the network is high loaded

Wireless packet scheduling based on the cumulative distribution function of user transmission rates

Abstract: In this paper, we present a new wireless scheduling algorithm based on the cumulative distribution function (cdf) and its simple modification that limits the maximum starving time. This cdf-based scheduling (CS) algorithm selects the user for transmission based on the cdf of user rates, in such a way that the user whose rate is high enough, but least probable to become higher, is selected first. We prove that the CS algorithm is equivalent to a scheduling algorithm that regards the user rates as independent and identically distributed, and the average throughput of a user is independent of the probability distribution of other users. So, we can evaluate the exact user throughput only if we know the user's own distribution, which is a distinctive feature of this proposed algorithm. In addition, we try a modification on the CS algorithm to limit the maximum starving time, and prove that the modification does not affect the average interservice time. This CS with starving-time limitation (CS-STL) algorithm turns out to limit the maximum starving time at the cost of a negligible throughput loss.

Sidelobe suppression in OFDM systems by insertion of cancellation carriers

Abstract: Orthogonal frequency-division multiplexing (OFDM) systems exhibit significant out-of-band radiation caused by high sidelobes of the modulated subcarriers. Existing techniques for reducing this undesirable effect have several drawbacks as they waste the scarce spectral resources or expand the signal in time domain. In this paper, we propose a new technique which overcomes these problems. A few so-called cancellation carriers are inserted on the left and right hand side of the used OFDM spectrum. These special subcarriers are not employed for data transmission, but carry complex weighting factors which are determined such that the sidelobes of transmission signal and cancellation carriers cancel each other. Simulation results show that with the proposed method a significant sidelobe suppression is achieved with only a small loss in bit error rate performance. This loss is due to the fact that a certain amount of the transmission power has to be spent on the cancellation carriers and is not available for data transmission.

Multiple description video coding for scalable and robust transmission over IP

Abstract: In this paper, we address the problem of video transmission over unreliable networks, such as the Internet, where packet losses occur. The most recent literature indicates multiple description (MD) as a promising coding approach to handle this issue. Moreover, it has been shown also how important the use of motion compensation prediction is in an MD-coding scheme. This paper proposes two architectures for multiple description video coding, both of them are based on the motion compensation prediction loop. The common characteristic of the two architectures is the use of a polyphase down-sampling technique to create the MDs and to introduce cross-redundancy among the descriptions. The first scheme, that we call drift-compensation multiple description video coder (DC-MDVC) appears very robust when used in an error-prone environment, but it can provide only two descriptions. The second architecture, called independent flow multiple description video coder (IF-MDVC), generates multiple sets of data before the motion compensation loop; in this case, there are no severe limitations in the selection of the number of descriptions used by the coder.

Method and apparatus for scheduling enhanced uplink dedicated channels in a mobile communication system

Abstract: An apparatus and method are provided for performing scheduling in a Node B for data transmission of a user equipment (UE) in a mobile communication system supporting an enhanced uplink dedicated channel (E-DCH). The Node B receives, from a radio network controller (RNC), scheduling assistance information for an uplink service to be provided from the UE. The Node B estimates a data amount for the uplink service on the basis of the scheduling assistance information in each scheduling period. The Node B schedules data transmission for the uplink service according to the estimated data amount.

Implantable device and system and method for wireless communication

Abstract: A wireless communication method and protocol, and wireless devices and systems for stimulation, are provided for communication between a wireless device and a charging device. During active wireless charging, communications (data transmission) from the wireless device to the charging device occurs via pulse loading the receive antenna of the receiving device. Because switching regulation in the receiving device may interfere with the communications, the switching regulation is disabled during a communications window. To further reduce the likelihood of misinterpretation of signals detected in the charging device resulting from the switching regulation or noise, the data bit rate of the pulse loading communications is maintained higher than the switching regulation frequency.

Data transmission with spatial spreading in a MIMO communication system

Abstract: For data transmission with spatial spreading, a transmitting entity (1) encodes and modulates each data packet to obtain a corresponding data symbol block, (2) multiplexes data symbol blocks onto NS data symbol streams for transmission on NS transmission channels of a MIMO channel, (3) spatially spreads the NS data symbol streams with steering matrices, and (4) spatially processes NS spread symbol streams for full-CSI transmission on NS eigenmodes or partial-CSI transmission on NS spatial channels of the MIMO channel. A receiving entity (1) obtains NR received symbol streams via NR receive antennas, (2) performs receiver spatial processing for full-CSI or partial-CSI transmission to obtain NS detected symbol streams, (3) spatially despreads the NS detected symbol streams with the same steering matrices used by the transmitting entity to obtain NS recovered symbol streams, and (4) demodulates and decodes each recovered symbol block to obtain a corresponding decoded data packet.

Transmitter circuit, receiver circuit, clock data recovery phase locked loop circuit, data transfer method and data transfer system

Abstract: [Problems] To realize a reliable and stable transfer of digital data that does not require a reference clock and a handshake operation. [Means for Solving the Problem] The present invention provides a digital data transfer method for alternately and periodically transferring first information and second information respectively in a first period and in a second period, wherein: an amount of information of the first information per unit time in the first period is greater than an amount of information of the second information per unit time in the second period; and the second information in the first period is transferred as pulse-width-modulated serial data.

A 6.25-Gb/s binary transceiver in 0.13-/spl mu/m CMOS for serial data transmission across high loss legacy backplane channels

Abstract: A transceiver capable of 6.25-Gb/s data transmission across legacy communications equipment backplanes is described. To achieve a bit error rate (BER) <10/sup -15/, transmit and receive equalization that can compensate up to 20 dB of channel loss is employed to remove intersymbol interference (ISI) resulting from finite channel bandwidth and reflections. The transmit feed-forward equalizer (FFE) uses a four-tap symbol-spaced programmable finite impulse response (FIR) filter followed by a 4-bit digital-to-analog converter (DAC) that drives a 50-/spl Omega/ transmission line. The receiver uses a half-baud-rate adaptive decision feedback equalizer (DFE) that cancels the first four symbol-spaced taps of postcursor ISI without use of speculative techniques. Both the transmitter and receiver use an LC-oscillator-based phase-locked loop (PLL) to provide low jitter clocks. Techniques to minimize the complexity of the FIR and DFE implementations are described. The transceiver is designed to be integrated in a standard ASIC flow in a 0.13-/spl mu/m digital CMOS technology. System measurements indicate the ability to transmit and recover data eyes that have been fully closed due to crosstalk and signal loss.

Radio communications system, radio communication apparatus and radio communication method for uwb impulse communication

Abstract: Provided is a radio communication system for ultra wideband (UWB) impulse communications and a radio communication apparatus and method thereof . The present patent provides a radio communication system that can minimize power consumption by eliminating a need for carrier detection and sharing transmission/reception time information in UWB impulse communications. The system includes a network coordinator; and one or more devices communicating on a superframe basis in subordination to the network coordinator. The devices perform data transmission/reception in predetermined time slots and then they are inactivated to thereby reduce power consumption.

Recording apparatus and recording method

Abstract: The amount of light reflected from a disk is detected, and it is determined according to the amount of reflected light whether the disk is a recordable disk or a rewritable disk. The disk is controlled according to the result of determination such that it is rotated at a constant angular velocity (CAV) or at a constant linear velocity (CLV) and recording is executed. Further, rotation driving control of the disk is selected according to factors other than the type of the disk, such as according to whether random recording is allowed or not, according to a recording state in the disk, according to whether an alternative area is provided or not, according to a recording start position, or according to whether initialization is required or not. CLV control or CAV control is appropriately selected for a disk at recording to suppress a reduction in accessibility and a reduction in data transmission rate.

Efficiency analysis of burst transmissions with block ACK in contention-based 802.11e WLANs

Abstract: The channel utilization efficiency of the standard 802.11 networks is severely compromised when high data transmission rates are employed, since physical layer headers and control frames are transmitted at low rate, thus wasting more channel time, proportionally. The extensions defined in the emerging 802.11e for quality-of-service (QoS) provisioning include some new mechanisms developed in order to improve the efficiency. Those include data transmission bursting (referred to as TXOP operation) and acknowledgment aggregation (referred to as block ACK). These two features allow it to offer new data transmission services, in which the data delivery and acknowledgment unit is not a single frame, but a block of frames. In this paper, we evaluate the performance of these operations for both basic and RTS/CTS access cases. We quantify how the data bursting and block ACK mechanisms can affect the system efficiency for different environments, and derive the maximum achievable throughput. We also discuss the operating conditions at which the switch from one channel utilization method to another is desired.