1177 results about "Constellation" patented technology

A low attenuation surface wave transmission line system for launching surface waves on a bare and unconditioned conductor, such as are found in abundance in the power transmission lines of the existing power grids. The conductors within the power grid typically lack dielectric and special conditioning. Accordingly, the present invention includes a first launcher, preferably including a mode converter and an adapter, for receiving an incident wave of electromagnetic energy and propagating a surface wave longitudinally on the power lines. The system includes at least one other launcher, and more likely a number of other launchers, spaced apart from one another along the constellation of transmission lines. The system and associated electric fields along any given conductor are radially and longitudinally symmetrical.

A method for a combined adaptive digital pre-distorter and pre-equalizer apparatus in single- and/or multiple-link hopping radio systems including hopping among a plurality of radio links to transmit variable-length bursts of radio signals on the plurality of radio links. Further, pre-distorting amplitude and phase of transmitted signal constellations based on the inverse AM-to-AM and AM-to-PM characteristics and the operating conditions of the high-power amplifier, respectively. Further, pre-equalizing amplitude and group-delay variations of the transmit RF radio using the pre-stored estimated complex tap coefficient of the pre-equalizer under different frequency bands.

An interleaving method performed by a transmitter for a communication system with quasi-cyclic low-density parity-check codes, spatial multiplexing, and T transmit antennas is used for applying permutation to N cyclic blocks of a codeword in order to map bits of the permutated cyclic blocks onto T constellation words constituting multiple spatial-multiplexing blocks from the codeword. Each cyclic block consists of Q bits.

A sensor connecting sheet material for inclusion in appropriately structured multiple-axes controllers comprised of a single input member operable in 6 DOF relative to a reference member of the controller. The input member having return-to-center resiliency relative to the reference member on at least the three perpendicular linear axes. The input member can be of a continuously rotatable trackball-type or a limited rotation joystick-type, and the reference member can be a shaft, a base or a housing. The controllers include carriage structuring for influencing sheet connected sensors by hand-applied operation of the input member. The preferred structures provide cooperative interaction with movement or force influenced sensors in primarily a single area. Some, most, or all of the sensors are preferably supported on a generally single plane, such as on a printed flexible membrane sensor sheet or circuit board sheet. In an alternative embodiment, sensors and conductive traces are applied on a generally flat, flexible membrane sensor sheet, which is then bent into a three dimensional configuration which may in some cases reach a widely-spread 3-D constellation of 6 DOF and/or other sensor mountings. The use of sensors connected by a sheet member, whether finally applied in a flat or 3-D configuration, enables efficient circuit and sensor connection and placement during manufacture, resulting in low product costs and high reliability.

A method for automatically creating a database of parameters (e.g., fingerprints/landmarks) used in a media sample recognition system. The user places a media sample in his media player, e.g., a CD or DVD player in his personal computer. A software process installed on the user's personal computer, to which is connected the CD/DVD player, extracts the constellation or “raw parameters” from the CD tracks as the CD plays, or under control of the software process. This extraction process may operate in the background. These raw parameters are then transmitted via the Internet (or other computer network) to a server coupled to a recognition database. The raw parameters are stored in the database. At some point in time, the raw parameters are processed into fingerprint/landmarks (e.g., using linkage) using another software process and then stored either back in the database or in random access memory (RAM) for use during a subsequent recognition process. The media sample can also be simultaneously identified during playback, which identity information is then sent to the server coupled to the recognition database.

A broadcasting base station device transmits broadcast signals modulated by a hierarchical modulation scheme to a mobile terminal device. A hierarchical modulation setup section compares the reception quality of the broadcast signals at the location of the mobile terminal device to predetermined reference quality. Based on the result of the comparison, the hierarchical modulation setup section specifies a hierarchical modulation scheme. For example, the constellation in each quadrant is reduced or enlarged. Accordingly, the broadcasting base station device can transmit optimal broadcast signals that match with actual reception quality to each mobile terminal device.

In transmitter apparatus for a digital television (DTV) broadcasting system, internet-protocol (IP) packets of digital television information are subjected to multilevel concatenated Bose-Chaudhuri-Hocquenghem (BCH) coding and low-density parity-check convolutional coding (LDPCCC) before being bit-interleaved and mapped to quadrature-amplitude-modulation (QAM) constellations. The QAM constellations are used in coded orthogonal frequency-division modulation (COFDM) of plural carrier waves up-converted to a radio-frequency broadcast television channel. In receiver apparatus for the DTV broadcasting system the results of de-mapping QAM constellations recovered from demodulating the COFDM carrier waves are de-interleaved, and the constituent LDPCCC codewords are decoded to recover constituent BCH codewords of the multilevel BCH coding. The constituent BCH codewords are decoded to correct remnant bit errors in them. Then, IP packets of digital television information are reconstituted from the systematic data bits in those BCH codewords.

According to embodiments of the invention, a communications system includes an error correction encoder that error correction encodes a bitstream according to an error correction code. The system also includes a variable symbol generator that generates a symbol according to a selected one of a plurality of selectable signal constellations from a group of bits of the error correction encoded bitstream. The system further includes a spreader that spreads the symbol according to a spreading code, and a transmitter that transmits the spread symbol in a communications medium. Preferably, the plurality of selectable signal constellations includes at least two signal constellations of different order. In other embodiments, the error correction encoder includes a variable error-correction encoder that encodes the bitstream according to a selected error correction code of a plurality of selectable error correction codes. In still other embodiments, the spreader includes a variable spreader that spreads the symbol according to a selected spreading code of a plurality of selectable orthogonal spreading codes including at least two spreading codes of different lengths. A controller may select the error correction code used by the variable error correction encoder, the signal constellation used by the variable symbol generator, and the spreading code used by the variable spreader to provide a desired information transmission rate for the bitstream. Related methods are also described.

A waterpouring system and method for use with a multiple-input, multiple-output (MIMO) transmitter. In one embodiment, the waterpouring system includes an encoding decision subsystem that selects a constellation combination based on gains in channels of the MIMO transmitter, and a vector modulator subsystem, coupled to the encoding decision system, that modulates a fixed number of bits in a bitstream with the constellation combination to generate a symbol vector. The waterpouring system also includes a normalization and precoding subsystem, coupled to the vector modulator subsystem, that weights the symbol vector based on the gains to yield a weighted symbol vector and distributes the weighted symbol vector among the channels.

In one embodiment, a method for generating an adaptive air interface waveform includes generating a waveform that includes a variable carrier frequency and variable bandwidth signal. The variable bandwidth signal includes one or more subcarriers that are dynamically placeable over a range of frequencies, and each subcarrier is separately modulated according to a direct sequence (DS) spread spectrum (SS) technique. The waveform has an embedded pilot usable to optimize one or more spectrum efficiencies of the waveform. A modulation constellation, a code rate, and a code length of the generated waveform are adapted according to an available spectrum and one or more sub-carrier conditions.

An RF device including a control loop for maximizing output power for each of several data rates or constellation types. The RF device includes a power detector, a power amplifier and a MAC that includes input and output adjust circuits. A power level value is generated from measured output power. The MAC compares an adjusted power level value with a set point value and generates an error value. The MAC adjusts a power control value based on the error value for controlling the gain of the power amplifier. The MAC uses a data rate signal indicative of a selected constellation type or data rate. The input adjust circuit stores one or more input adjustment values selected by the data select signal for adjusting the power level value. The output adjust circuit stores one or more output adjustment values selected by the data select signal for adjusting the power control value.

A wireless system (e.g., Bluetooth, WCDMA, etc.) with multiple antenna communication channel eigenvector weighted transmissions including possibly differing order symbol constellations for differing eigenvectors. Comparison of maximizations of minimum received symbol distances provides for selection of eigenvector combinations and symbol constellations.

An apparatus and method for wireless transmission of uncompressed HDTV video overcomes the challenges of sending vast amounts of information over a wireless link. This is achieved by direct mapping of transformation coefficients of the video components to communication symbols, such as OFDM symbols. A main portion of the important transform coefficients, for example the MSBs of the coefficients representing lower frequencies of each of the video components, and in particular the quantized values of the lower frequencies components, are sent in a coarse representation using, for example, QPSK or QAM. The coefficients representing higher frequencies of the video components, and the quantization error values of the lower frequencies components, or some, non-linear transformation thereof, are sent as pairs of real and imaginary portions of a complex number that comprises a point in a fine constellation. The invention further provides a delay-less and buffer-less implementation of transmitter and receiver pairs.

Methods and apparatuses for decoding codewords received over a MIMO channel are provided. According to one aspect of the disclosure, a cost function is computed for each constellation point of an Mth rank or spatial layer, and N_cand of those constellation points having minimum cost are preserved as candidate points, where N_cand is a parameter specified to the decoding algorithm. In addition, a cost function may be computed for all possible transitions from the N_cand candidate points of the Mth rank to all possible constellation points of the (M-1)th spatial layer, and N_cand of those transitions having minimum cost are preserved as candidate points. The process is repeated for all spatial layers, resulting in the identification of N_cand candidate codewords and their associated cost functions.

The invention relates generally to the field of wireless communications and more particularly to a method of and device for detecting the presence of a received data packet in a digital receiver. The present invention proposes a simplified method of correlation by removing dependency on the amplitude fluctuations while at the same time maintaining phase relevancy. The key advancement involves mapping the complex quadrature amplitude modulation (QAM) preamble to a quantized phase shift keying (PSK) constellation before application to a matched complex correlator. The proposed process essentially “amplitude normalizes” the input signal without the use or complexity associated with a divider. This simplified normalization scheme makes the packet detection algorithm robust against amplitude variations in the input signal, while still allowing for good correlation output. In applications where interference is superimposed on the I/Q input signals, the invention improves the detection capability over automatic gain control (AGC) normalization methods.

Provided is a detector system for detecting a plurality of items each having at least one RFID tag attached thereto. The detector system may include a presence detector and/or a message detector. The presence detector may include a signal reader which receives modulated carrier frequencies from the RFID tags during a predetermined response time period for comparison to a reference level. The signal reader may be configured as a power integrator or a constellation discriminator. The power integrator sums the power contained in signals transmitted by the RFID tags by integration for comparison to an environmental noise level measurement taken during a quiet period. For the constellation discriminator, bits contained in the modulating message are compared to the bit pattern of a predetermined reference constellation. The detector system may be configured as a 3-state detector which combines the presence detector with a message detector that indicates the identification code of the RFID tags.

Soft symbol decoder algorithms for multiple input, multiple output (MIMO) receivers reduce the search complexity by searching over fewer than all possible combinations of transmitted symbols to compute log metrics for each transmitted bit from each transmit antenna. In one algorithm, a sub-optimal set of transmitted symbols is computed and the transmitted symbols are restricted to neighboring constellation points of the sub-optimal set. In another algorithm, all constellation points are searched for every antenna except one. In yet another algorithm, constellation points are searched excluding more than one antenna. The non-searched antenna(s) can be handled by either a bit stuffing or a soft slicing technique.

Methods and systems provide an efficient power save mode for multi carrier modems, such as DMT based ADSL and VDSL modems. Fast transitions from power save mode to full operational mode occur, without the overhead of transmitting large quantities of configuration information between the transmitter and receiver. Signal constellation size changes occurring while operating in power save mode to continue to apply once full operational mode is resumed. Multiple power save modes are enabled, each having a different level of power dissipation and crosstalk, both far end crosstalk and near end crosstalk. Power dissipation and crosstalk can thus be graduated on a line, according to a user-requested bit rate.

A transmitter includes a plurality of encoders configured to receive source bit streams from m information sources, each of the plurality encoders including identical (n,k) low-density parity check (LDPC) codes of code rate r=k/n, where k is a number of information bits and n is codeword length. An interleaver is configured to collect m row-wise codewords from the plurality of encoders, and a mapper is configured to receive m bits at a time column-wise from the interleaver and to determine an M-ary signal constellation point. A modulator is configured to modulate a light source in accordance with the output of the mapper at a transmission rate R_s/r (R_s—the symbol rate, r—the code rate). A receiver and transmission and receiving methods are also disclosed.

Space-time code, and methods for constructing space-time codes are provided. The space-time coder performs a respective linear transformation on each of P sets of K modulated symbols of a modulated symbol stream to produce P sets of T linearly transformed symbols, applies a respective phase rotation to each set of T linearly transformed symbols to produce a respective set of T phase rotated symbols, and performs a threading operation on the sets of T phase rotated symbols to produce P threaded sequences that define M output sequences; the threading operation being such that each threaded sequence is an allocation of output sequences over time of a respective one of the P sets of T phase rotated symbols in which all of the output sequences are used by each threaded sequence; during each of T symbol periods, a respective one of the P threaded sequences includes a symbol from one of the P sets of phase rotated symbols; and at least one symbol from each set of phase rotated symbols appears in each output sequence; where M>=2, 2<=P<=M, and T>=M and M>=K.

An apparatus and method for changing a signal mapping rule in an hybrid automatic repeat request (HARQ) system are provided. In a transmitter in an automatic repeat request (ARQ) system according to the present invention, a memory stores different signal constellations for a predetermined modulation scheme according to retransmission numbers (k). A modulator reads a signal constellation according to a current retransmission number from the memory, upon receipt of a retransmission request signal from a receiver, and modulates transmission data to complex symbols on the signal constellation.

The invention discloses a route exchange method suitable for a GEO/LEO double layered constellation network. According to the method, a system period is divided into equal-duration time sections based on a dynamic boundary value; a GEO layer satellite high in on-board processing capacity is used for calculating the best route and the second best route for each LEO satellite; in the processes of information transmission and exchange, when loads of the LED satellites are large, the GEO satellite shares part of low priority services in time for the LED satellites, and it is guaranteed that important information is reliably transmitted in real time; when link congestion, node ineffectiveness and other emergency conditions happen in the satellite network, in order to avoid rerouting of the whole network, and the GEO satellite only calculates rerouting for affected routes; after link congestion is eliminated, the LED satellites recover route information in time before congestion in order to avoid link resource waste in the network. In the network that topology time varying happens, links are prone to congestion, on-board resources are limited, continuous high-load flows are prone to being generated, and nodes are prone to being ineffective at the special period, the method can reduce constellation system cost, shorten convergence time, save the on-board resources, increase the utilization rate of the link resources, guarantee that important information is reliably transmitted in real time and improve invulnerability and robustness of the satellite network.

The present invention discloses a method for channel coding and modulation mapping in HARQ of the LDPC code, comprising: performing structural LDPC encoding of an information bit sequence with a length of K input by a channel encoder, and sending a generated codeword to a HARQ buffer; rearranging codeword bits of a LDPC HARQ mother code in the HARQ buffer, and sequentially selecting codeword bits to generate a binary sequence of a HARQ packet; mapping codeword bits of the HARQ packet to a constellation, and high-order bits in encoding blocks of the HARQ packet being mapped to high reliability bits in the constellation. The present invention provides the LDPC codeword with the maximal constellation gain, so that the LDPC HARQ channel encoding has the optimal performance.

A method for enhancing the bit rate and/or margin at which quadrature amplitude modulation (QAM) communication is performed over multiple bands of a communication link includes the steps of varying a spectral allocation and constellation size with which communication is performed, so as to define a combination of spectral allocation and constellation size at which the bit rate and/or margin are enhanced. The rate adaptation method identifies the spectral allocation and constellation size to use on each of the multiple bands that results in a total bit rate greater than or equal to the target bit rate, subject to specified constraints on SNR margin and/or BER limits. If more than one parameter set has this property, the rate adaptation method may for example select the spectral allocation and constellation size combination that maximizes the minimum SNR margin across the multiple bands.

A method and apparatus for transmitting/receiving control information to support High Speed Downlink Packet Access (HSDPA) in a WCDMA communication system are provided. When transmitting new packet data, a Node B sets a New data Indicator (NI) to a specific bit value indicating an initial transmission for the packet data. Upon receipt of a retransmission request for the packet data, the Node B sets the NI as the inverse of a previous NI. If an redundancy version (RV) representing a constellation and a data type for packet data, is set to a specific value indicating an initial transmission, the Node B set the NI to the inverse of the specific bit value regardless of the previous NI. A User Equipment (UE) receives control information including the NI and the redundancy version (RV) and determines that the packet data is initial transmission data or retransmission data, according to the NI and the RV.

Message passing memory and barrel shifter arrangement in LDPC (Low Density Parity Check) decoder supporting multiple LDPC codes. A novel approach is presented by which a barrel shifter may be implemented in conjunction with a single message passing memory within an LDPC decoder. This arrangement also allows for a single bit/check processor to be employed that is operable to perform updating of edge messages with respect to check nodes as well as updating of edge messages with respect to bit nodes. There are a variety of embodiments by which the barrel shifter and the message passing memory may be implemented. By using this approach, a common architecture and design may operate to decode various types of LDPC coded signals including those whose code rate and/or modulation (including constellation shape and mapping) may vary as frequently as on a frame by frame basis or even on a block by block basis.

Method and apparatus for using long FEC codes in a content distribution system is described. One aspect of the invention relates to encoding frames of content. Each frame is partitioned into un-coded bits and bits to be encoded. For each frame, an FEC code is applied to the bits to be encoded to generate a codeword. Groups of bits from the codeword are divided among a plurality of channels. Symbols formed from the groups of bits and the un-coded bits are mapped to a constellation for each of the plurality of channels. The symbols are modulated across a respective plurality of bonded channels for transmission.

A method for transmitting high rate data within a multiple input multiple output (MIMO) wireless local area network (WLAN) begins by determining a data transmission rate. The method continues by, when the data transmission rate is between a first data rate and a second data rate, enabling two transmission paths. The method continues by, for each of the two transmission paths, determining at least one of: level of constellation, number of data subcarriers, rate code, and cyclic prefix duration.

Precoding mitigates or removes interference signals (especially crosstalk) among multiple users with interconnected transmitters in vectored DSL systems and the like. Efficient implementation is provided of the R matrix in RQ factorization that characterizes multi-user downstream vector channels (such as DMT VDSL one-sided or two-sided transmission channels). A set of precoder coefficients can vary with each tone used by each user and depend upon the encoding order of users selected for each tone. In adaptive operation, the coefficients of the R and Q matrices can be updated when changes occur to the transmission environment. Variable modulo arithmetic mitigates the power-enhancement problem, and the base of modular arithmetic also can vary with each user within a single precoder for a single tone. The user order of preceding need not be the same on each tone, and the modular arithmetic progression may thus also be different on each tone because multi-user situations create an unusual situation for precoding in that the modulo arithmetic used for each user can be different (thus imposing a larger power increase) and because digital duplexed or synchronized DMT systems can separately implement a precoder for each tone. Further, the precoding process terminates each DMT symbol, after processing up to the total number of users. An optional dither signal, known to both transmitter and receiver, can be added at the transmit side and removed at the receiver side to smooth the precoding process and ensure that aberrations in the transmitted constellation size and characteristics are consistent despite any unusual variations in the feedback signal that exits the feedback filter matrix G before being subtracted from the user signal of interest. Some embodiments use a “subtraction only” mode while other embodiments use a dither signal and/or modulo arithmetic, though embodiments of the present invention do not require use of identical constellations by both transmitter and receiver.

Systems and methods for transmitting data, including encoding one or more streams of input data using one or more adaptive Low Density Parity Check (LDPC) encoders, wherein the encoders generate one or more signal constellations; modulate one or more signals using hybrid multidimensional coded modulation; apply orthogonal prolate spheroidal wave functions as electrical basis functions; generate one or more spectral band group signals by selecting and combining two or more spectral band groups with center frequencies that are orthogonal to each other; and spectral-mode-multiplex and transmit the one or more adaptive LDPC-coded data streams including the one or more spectral band group signals combined into corresponding spatial modes over a transmission medium.