4747results about "Signal channels" patented technology

A pipelined digital data receiver for a cable TV headend which is capable of receiving DOCSIS 1.0 or 1.1 or advanced PHY TDMA or SCDMA bursts having programmable symbol rates and programmable modulation types as well as a host of other burst parameters such at Trellis code modulation on or off, scrambling on or off, various values for Reed-Solomon T number and codeword length. The receiver has an RF section to filter and digitize incoming RF signals. It also has an input section to detect impulse noise and do match filtering and despread SCDMA bursts. A timing recovery section recovers the symbol clock and detects the start of bursts and collisions. A rotational amplifier and equalizer calculate and track gain, phase and frequency offsets and correct symbols and calculates equalization coefficients. A decoder section decodes TCM and non TCM bursts, and a Reed-Solomon decoder section reconstructs RS codewords and uses them to error correct the payload data.

An apparatus and process for allocating carriers in a multi-carrier system is described. In one embodiment, the process comprises determining a location of a subscriber with respect to a base station, selecting carriers from a band of carriers to allocate to the subscriber according to the location of the subscriber with respect to the base station, and allocating selected carriers to the subscriber.

An uplink capacity is increased by a method in which more than two mobile stations simultaneously use a radio resource allocated to one mobile station. A method of allocating a radio resource in an orthogonal frequency division multiplexing system comprises receiving data associated with a radio resource allocation map from a base station, wherein the radio allocation map comprises control parameters for transmitting uplink data to the base station. The control parameters comprises orthogonal pilot pattern indicator for using orthogonal pilot patterns associated with supporting at least concurrent dual transmission by at least one mobile station, and for use in the same frequency band and same time duration. The orthogonal pilot patterns comprises at least a minus pilot being used for an uplink basic allocation unit. The mobile station then transmits uplink data to the base station by using the orthogonal pilot patterns.

A method and apparatus for wireless communication are described. In one embodiment, a method for communicating with a subscriber comprises transmitting orthogonal frequency domain multiplexing (OFDM) signals to the subscriber, and receiving direct-sequence spread spectrum (DSSS) signals from the subscriber.

An adaptation to Carrier Interferometry synthesis and analysis provides for complex coding and decoding in a sliding window transform. Coding and decoding functionality can be extended to spatial processing in systems employing multiple transceiver elements. Poly-amplitude codes permit successive interference cancellation in spatial and frequency-domain processing. Handoffs in cellular systems are facilitated by selecting spectral/base station combinations that optimize link performance.

A facility transport system for transporting high speed Ethernet data over digital subscriber lines. The system, referred to as 100BaseS, is capable of transmitting 100 Mbps Ethernet over existing copper infrastructure up to distances of approximately 400 meters. The system achieves bit rates from 25 to 100 Mbps in increments of 25 Mbps with each 25 Mbps increment utilizing a separate copper wire pair. Each pair used provides a bidirectional 25 Mbps link with four copper wire pair connections providing 4×25 Mbps downstream channels and 4×25 Mbps upstream channels. The system utilizes framing circuitry to adapt the 100BaseT input data signal to up to four separate output signals. A DSL Ethernet Port card couples the modem to each twisted pair used. Each DSL Ethernet Port card comprises modem transmitter and receiver circuitry for sending and receiving 100BaseS signals onto twisted pair wires. The system utilizes QAM in combination with frequency division multiplexing (FDM) to separate downstream channels from upstream channels and to separate both the downstream and the upstream channels from POTS and ISDN signals.

A multi-user MIMO downlink beamforming system with limited feedback (200) is provided to enable preceding for multi-stream transmission, where a channel codeword (u_i) and one or more channel quality indicator values (CQI_A, CQI_B) are computed at the user equipment (201.i) on the basis of maximizing a predetermined SINR performance metric (ρ_i) which estimates the receive signal-to-noise-ratio (SINR) at the user equipment (201.i). The computed codeword (u_i) and CQI values (or differential values related thereto) are quantized and fed back to help the base station (210) which applies a correction to the appropriate CQI value in the course of designing the transmit beamforming vectors w and determining the appropriate modulation and coding level to be used for downlink data transmission.

A digital television (DTV) transmitter and a method of coding data in the DTV transmitter method are disclosed. A pre-processes enhanced data by coding the enhanced data for forward error correction (FEC) and expanding the FEC-coded enhanced data. A data formatter generates enhanced data packets including the pre-processed enhanced data and inserting known data to at least one of the enhanced data packets. A first multiplexer multiplexes main data packets with the enhanced data packets, and a data randomizer randomizes the multiplexed data packets. A Reed-Solomon (RS) encoder RS-codes the randomized data packets by adding first parity data, and a data interleaver interleaves the RS-coded data packets. A trellis encoder trellis-encodes the interleaved data packets, wherein the trellis encoder may be initialized when a known data sequence is inputted thereto.

Techniques for multiplexing and transmitting multiple data streams are described. Transmission of the multiple data streams occurs in “super-frames”. Each super-frame has a predetermined time duration and is further divided into multiple (e.g., four) frames. Each data block for each data stream is outer encoded to generate a corresponding code block. Each code block is partitioned into multiple subblocks, and each data packet in each code block is inner encoded and modulated to generate modulation symbols for the packet. The multiple subblocks for each code block are transmitted in the multiple frames of the same super-frame, one subblock per frame. Each data stream is allocated a number of transmission units in each super-frame and is assigned specific transmission units to achieve efficient packing. A wireless device can select and receive individual data streams.

A wireless terminal and network terminal are provided for implementing a new uplink OFDM protocol. In the new protocol, the wireless terminal has a first transmit chain for generating and transmitting a low rate mode OFDM transmission in a first frequency band of the OFDM band; and a second transmit chain for generating and transmitting a burst-mode transmission in a second frequency band of the OFDM band, the first frequency band being distinct from the second frequency band. An access channel is provided which is overlaid over the low rate mode transmissions of other users.

A method and apparatus for controlling OFDMA cellular networks is described. In one embodiment, the method comprises receiving channel characteristics and noise-plus-interference information measured at spatially distributed subscribers and assigning traffic channels for an orthogonal frequency-division multiple-access (OFDMA) network.

Provided is a transmission circuit which allows smooth switching of the operation mode when switching the operation mode of the transmission circuit. A power amplifier 14 includes: a first input terminal to which a direct-current voltage or a voltage in accordance with an amplitude signal M is supplied; a second input terminal to which an output signal from a first variable gain amplifier 171 or an output signal from a second variable gain amplifier 172 is inputted; and a third input terminal to which an output signal from a first bias circuit 15 or an output signal from a second bias circuit 16 is inputted. A control section 11 switches the operation mode of the transmission circuit so that at least one of the first input terminal, the second input terminal, and the third input terminal of the power amplifier is prevented from being in a no input state.

The evolution of high rate data services within future wireless networks will call for new RF access technologies to enable substantial increases in overall system spectral efficiency at an acceptably low cost to the user. Space-Time Coding (STC) is an antenna array processing technology currently simulating considerable Interest across the wireless industry. The invention provides a space-time coding apparatus having an input, a trellis encoder, a modulator, a demultiplexer, and a set of signal outputs wherein the input is operable to receive a stream of data. This allows de-multiplexing to take place after coding and modulation has been performed. The trellis encoder comprises a convolutional encoder operable to sequentially group data to provide coded bits to provide QPSK symbols. By the selection of convolutional encoder rates and/or modulation alphabets STCs of any desired dimensionality may be produced including multi-dimensional codes.

Techniques are provided to support fast frequency hopping with a code division multiplexed (CDM) pilot in a multi-carrier communication system (e.g., an OFDMA system). Each transmitter (e.g., each terminal) in the system transmits a wideband pilot on all subbands to allow a receiver (e.g., a base station) to estimate the entire channel response at the same time. The wideband pilot for each transmitter may be generated using direct sequence spread spectrum processing and based on a pseudo-random number (PN) code assigned to that transmitter. This allows the receiver to individually identify and recover multiple wideband pilots transmitted concurrently by multiple transmitters. For a time division multiplexed (TDM)/CDM pilot transmission scheme, each transmitter transmits the wideband pilot in bursts. For a continuous CDM pilot transmission scheme, each transmitter continuously transmits the wideband pilot, albeit at a low transmit power level. Any frequency hopping rate may be supported without impacting pilot overhead.

An enhanced 8-VSB reception system and E8-VSB data demultiplexing method, by which an E8-VSB signal can be stably received as well as a previous ATSC 8VSB signal, is disclosed. Herein, the enhanced data are coded at ½ code rate and ¼ code rate in the new E8-VSB transmission system compatible with the conventional ATSC 8VSB system, respectively. The ½ and ¼ enhanced data are multiplexed by 164-byte packet unit according to the previously determined multiplexing format and further pre-processed to output as the format of the MPEG transport packet. And, the pre-processed enhanced data and the main data are multiplexed again by 188-byte packet unit according to the previously determined multiplexing format. The E8-VSB map information, which was inserted in the field sync section in the E8-VSB transmission system to be transmitted, is extracted to generate the information indicating the attributes of the respective E8-VSB data. The normal data, ½ enhanced data, and ½ enhanced data are separated from each other to be decoded in the channel decoder.

A cellular radio communication system is provided for transmitting data over a plurality of transmission links. The system includes means for generating a modulated signal by applying a constant amplitude envelope modulation scheme to data to be transmitted across poor quality transmission links and amplifier means for non-linearly amplifying the modulated signal. The system can additionally include means for generating a second modulated signal by applying an amplitude dependent modulation scheme to data to be transmitted across higher quality transmission links and amplifier means for linearly amplifying the second modulated signal. Using a constant amplitude envelope modulation scheme, such as GMSK or MLCAM for poorer quality links means that for these links signals can be amplifier non-linearly at higher gains.

A digital broadcast transmitting and receiving system and a signal processing method thereof that improves the receiving performance of the system. A digital broadcast transmitter can include a randomizer to receive and randomize a data stream into a specified position of which stuff bytes are inserted, a stuff-byte exchange unit to generate known data having a predefined pattern and insert the known data into the specified position of the data stream into which the stuff bytes are inserted, an encoder to encode the data stream output from the stuff-byte exchange unit for an error correction, and a modulator and RF converter to modulate the encoded data stream, RF-convert the modulated data stream and transmit the RF-converted data. The digital broadcast receiving performance can be improved even in an inferior multi-path channel by detecting the known data from the received transmission and using the known data for synchronization and equalization in a digital broadcast receiver.