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1349results about How to "Improve transfer rate" patented technology

Adaptive modulation for multi-antenna transmissions with partial channel knowledge

InactiveUS20050047517A1Transmission rate be increase and maximizeImprove transmission rateSpatial transmit diversityChannel estimationSubcarrierConstellation
Adaptive modulation techniques for multi-antenna transmissions with partial channel knowledge are described. Initially, a transmitter is described that includes a two-dimensional beamformer where coded data streams are power loaded and transmitted along two orthogonal basis beams. The transmitter optimally adjusts the basis beams, the power allocation between two beams, and the signal constellation. A partial CSI model for orthogonal frequency division multiplexed (OFDM) transmissions over multi-input multi-output (MIMO) frequency selective fading channels is then described. In particular, an adaptive MIMO-OFDM transmitter is described in which the adaptive two-dimensional coder-beamformer is applied on each OFDM subcarrier, along with an adaptive power and bit loading scheme across the OFDM subcarriers.
Owner:RGT UNIV OF MINNESOTA

Apparatus for adaptable/variable type modulation and demodulation in digital tx/rx system

Disclosed is an adaptable / variable type modulation / demodulation apparatus. A physical layer transmission apparatus for adaptable / variable type modulation, the transmission apparatus including a classification unit to classify a bit stream according to a standard that is determined in advance after receiving the bit stream, an uncoded bit group unit to group the bit stream not to be LDPC-coded by a predetermined number of bits, an LDPC encoder to perform LDPC-coding of the bit stream, a coded bit group unit to group the coded bit stream by the predetermined number of bits, a quadrature amplitude modulation (QAM) unit to select a symbol coset using the coded bit groups; and a convolutional interleaver to perform convolutional interleaving of the symbol.
Owner:ELECTRONICS & TELECOMM RES INST

Quantum cryptography

A method of establishing a shared secret random cryptographic key between a sender and a recipient using a quantum communications channel is described. The method comprises: generating a plurality of random quantum states of a quantum entity, each random state being defined by a randomly selected one of a first plurality of bases in Hilbert space, transmitting the plurality of random quantum states of the quantum entity via the quantum channel to a recipient, measuring the quantum state of each of the received quantum states of the quantum entity with respect to a randomly selected one of a second plurality of bases in Hilbert space, transmitting to the recipient composition information describing a subset of the plurality of random quantum states, analysing the received composition information and the measured quantum states corresponding to the subset to derive a first statistical distribution describing the subset of transmitted quantum states and a second statistical distribution describing the corresponding measured quantum states, establishing the level of confidence in the validity of the plurality of transmitted random quantum states by verifying that the first and second statistical distributions are sufficiently similar, deriving a first binary sting and a second binary string, correlated to the first binary string, respectively from the transmitted and received plurality of quantum states not in the subset, and carrying out a reconciliation of the second binary string to the first binary string by using error correction techniques to establish the shared secret random cryptographic key from the first and second binary strings.
Owner:HEWLETT-PACKARD ENTERPRISE DEV LP +1

Dynamic sub-carrier assignment in OFDM systems

A method and apparatus are provided for selecting and signalling the identity of sub-carriers to be used for transmission of data in a radio communication system, and for using other sub-carriers. A remote unit determines which sub-carriers are acceptable for use in data transmission by comparing the signal to interference ratio of each sub-carrier with a threshold. A sequence of numbers is generated using one set of values to identify acceptable sub-carriers and another set of values to identify unacceptable sub-carriers. The sequence of numbers is transmitted to a base station. The average signal to interference ratio of sub-carriers whose signal to interference ratio was above the threshold can also be transmitted to the base station, thereby allowing the base station to determine an optimum set of transmission parameters for use only in the acceptable sub-carriers. Alternatively, the remote unit can determine the optimum set of transmission parameters itself for transmission to the base station. As yet another alternative, the remote unit can determine an optimum Link Mode for each acceptable sub-carrier, and use a reference to the Link Modes as the set of values identifying acceptable sub-carriers. The base station transmits data over the acceptable sub-carriers at the optimum Link Mode or Link Modes. The base station may use some of the unacceptable sub-carriers for transmission of low sensitivity data at the optimum Link Mode, and may use some of the unacceptable sub-carriers for transmission of data at a lower Link Mode. The transmission power of any unused unacceptable sub-carriers can be diverted to other sub-carriers.
Owner:BLACKBERRY LTD

Display device and semiconductor device

A display device of high definition, multiple colors and low power consumption includes a display panel having a pixel section in which pixels are arrayed in the form of a matrix at the cross points of a plurality of data lines and a plurality of scanning lines, a scanning circuit for applying voltage sequentially to the plurality of scanning lines, and a data-line driver, which receives display data supplied by a host device, for applying signals corresponding to the display data to the plurality of data lines. Provided external to the display panel is a controller IC having a display memory for storing display data corresponding to the pixel section, an output buffer for reading data out of the display memory and outputting this data to the display panel, and a controller for controlling the display memory and output buffer and communication with the host device. The display panel is provided with a digital / analog converter, which forms part of the data-line driver, for converting display data represented by a digital signal to an analog signal. The width of a bus for data transfer between the controller IC and data-line driver of the display panel is such that data of a greater number of bits is transferred in parallel by a single transfer than is transferred by the bus between the controller and the host device. This allows the operating frequency of the data-line driver to be reduced.
Owner:HANNSTAR DISPLAY CORPORATION

III-V charge coupled device suitable for visible, near and far infra-red detection

A photon detector is obtained by using the intersubband absorption mechanism in a modulation doped quantum well(s). The modulation doping creates a very high electric field in the well which enables absorption of input TE polarized light and also conducts the carriers emitted from the well into the modulation doped layer from where they may recombine with carriers from the gate contact. Carriers are resupplied to the well by the generation of electrons across the energy gap of the quantum well material. The absorption is enhanced by the use of a resonant cavity in which the quantum well(s) are placed. The absorption and emission from the well creates a deficiency of charge in the quantum well proportional to the intensity of the input photon signal. The quantity of charge in the quantum well of each detector is converted to an output voltage by transferring the charge to the gate of an output amplifier. The detectors are arranged in the form of a 2D array with an output amplifier associated with the entire array or a row of the array as in the known charge coupled devices, or a separate amplifier could be dedicated to each pixel as in the known architecture of the active pixel device. This detector has the unique advantage of near room temperature operation because the dark current is limited to the generation across the semiconductor bandgap and not the emission over the quantum well barrier. The detector also has the advantage that the readout circuitry is implemented monolithically by the HFETs formed in the GaAs substrate simultaneously, with the detecting elements.
Owner:UNIV OF CONNECTICUT

Semiconductor memory device

For decreasing a recording current and suppressing a cross erase simultaneously, a three-dimensional phase-change memory for attaining higher sensitivity and higher reliability by the provision of a chalcogenide type interface layer is provided, in which an electric resistivity, a thermal conductivity, and a melting point of the material of the interface layer are selected appropriately, thereby improving the current concentration to the phase-change material and thermal and material insulation property with Si channel upon writing.
Owner:HITACHI LTD

Switchable touch stereoscopic image device

A switchable touch stereoscopic image device includes a stereoscopic image generating module and a touch sensing module. The stereoscopic image generating module includes a first substrate, a second substrate, a light-path converting layer, driving electrodes and a common electrode. The first and second substrates are disposed corresponding to each other. The first substrate has a top surface. The second substrate has a top surface and a bottom surface facing the top surface of the first substrate. The light-path converting layer is disposed between the first and second substrates. The driving electrodes are disposed on the top surface of the first substrate. The common electrode is disposed on the bottom surface of the second substrate. The touch sensing module is disposed on a side of the second substrate of the stereoscopic image generating module and includes sensing electrodes disposed on a side of the top surface of the second substrate.
Owner:DONGGUAN MASSTOP LIQUID CRYSTAL DISPLAY +1
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