Abstract: The present invention relates to a method for allowing a terminal to transmit CSI for downlink transmission from a base station through an uplink comprises the steps of: receiving a downlink signal through a downlink channel; generating CSI that contains one or more indicators among an RI, a PMI, and CQI for the downlink channel; and transmitting the CSI through an uplink channel, wherein the CSI can contain one or more pieces of information among a first type of CSI which is determined on the basis of a rank N that is determined by the terminal and a second type of CSI which is determined on the basis of a rank that is restricted by a reference value M.

Abstract: A receiver receives multipath signals in a W-CDMA system. Channel estimates and timing reference signals are generated utilizing the received multipath signals. Timing correction signals indicating a location of the received multipath signals may be generated and the received multipath signals may be combined based on the computed channel estimates and/or the generated timing reference signals. The multipath signals may be combined as a signal cluster. Circuitry may be provided that computes channel estimates based on at least one of a plurality of received multipath signals, and generates timing reference signals indicating a location of at least one of the plurality of received multipath signals. Circuitry may also be provided that combines at least a portion of the plurality of received multipath signals based on at least a portion of the computed channel estimates and/or the generated timing reference signals.

Abstract: A codebook C is provided in a MIMO transmitter as well as a MIMO receiver. The codebook C will include M codewords ci, where i is a unique codeword index for each codeword ci. Each codeword defines weighting factors to apply to the MIMO signals, and may correspond to channel matrices or vectors to apply to the MIMO signals prior to transmission from the respective antennas of the MIMO transmitter. The present invention creates codeword subsets Si for each codeword ci of the codebook C. Each codeword subset Si defines L codewords cj, which are selected from all the codewords ci in the codebook C. The codewords cj in a codeword subset Si are the L codewords in the entire codebook that best correlate with the corresponding codeword ci.

Abstract: A phased array antenna for providing a radiation pattern having at least one communication beam, includes a plurality of antenna elements, each with an antenna element signal having a phase relationship and an amplitude relationship to the other element signals; a digital signal processing arrangement providing a digital beamforming network; and an analog beamforming network arranged to reduce exposure of the digital signal processing arrangement to an interfering signal. Analog beamforming weights are selected to generate a null in the radiation pattern in a direction corresponding to the interfering signal.

Abstract: A diversity receiver comprises a plurality of receiving paths connected to a receiver circuit. Each of the receiving paths comprises an antenna receiving a signal, connected to a matching network connected to a receive amplifier. The receiver circuit is connected to a signal level comparison circuit for providing a relative comparison value indicating one of the receiving paths receiving the signal with a relative maximum strength. The signal level comparison circuit comprises a comparator circuit connected to the receiver circuit receiving a currently received signal level, and to a logic control unit being arranged to select one of the receive paths to provide the currently received signal to the receiver circuit.

Abstract: Disclosed is a self-correlation receiver of a transceiver in which a transmitter shares an antenna with a receiver. The self-correlation receiver includes: a clamper which receives a received signal, limits the magnitude of the received signal within a predetermined range and outputs a clamping signal; and a mixer which receives the received signal and the clamping signal and outputs a signal having a difference frequency between the received signal and the clamping signal.

Abstract: A method of estimating the Doppler spread of a communication channel includes computing a first sum defined by a difference between the pilot tones of a first group of N symbols and a corresponding pilot tones of a second group of N symbols preceding the first group of N symbols, computing a second sum defined by the pilot tones of the second group of N symbols, and computing a ratio of the first sum and the second sum for each of the N symbols of the first and second group of symbols to generate N ratios representative of the Doppler spread of the channel. The first sum is further defined by the square of the difference between the pilot tones of the first group of N symbols and the corresponding pilot tones of the second group of N symbols.

Abstract: The present invention provides a method of providing feedback information in a user equipment of a communication system based on MIMO, comprising: determining a first latest measured long-term covariance matrix according to a downlink channel matrix model; transmitting the quantization of a first latest estimated long-term covariance matrix corresponding to the first latest measured long-term covariance matrix to the base station; determining a second latest measured long-term covariance matrix according to a downlink channel matrix model; determining the variation information of a second latest estimated long-term covariance matrix with respect to an estimated long-term covariance matrix of the last-time reset point; and transmitting the quantization of the variation information to the base station. With such a solution, overhead during the feedback of long-term covariance matrix is greatly reduced in MIMO scenario.

Abstract: A receiver receives, using a plurality of antennas, a multiplexed signal that includes (i) a first OFDM modulation signal with a subcarrier carrying a symbol including multiplex information and a subcarrier carrying a pilot symbol and a subcarrier carrying a data symbol and (ii) a second OFDM modulation signal with a subcarrier carrying a symbol including multiplex information and a subcarrier carrying the pilot symbol and a subcarrier carrying the data symbol. A decoder uses the symbol including multiplex information and decodes the data symbol.

Abstract: A wireless device that operates in accordance with the IEEE 802.11 standard receives the preamble of a packet with the highest number of receive chains enabled, thereby obtaining the highest gain, detection sensitivity and range. The wireless device determines a signal-to-noise ratio (SNR) in response to two different short training fields (STFs) in the preamble. The wireless device also determines a modulation and coding scheme (MCS) and a number of spatial streams (Nss) used to transmit the received packet in response to a signal field of the preamble. The wireless device uses these determined parameters to identify a minimum number of the receive chains required to reliably receive the packet. The wireless device uses only the identified minimum number of receive chains to perform channel estimation and receive the data portion of the packet.

Abstract: Provided is a data transmission apparatus to transmit a reference orthogonal frequency division multiplexing (OFDM) symbol generated by frequency division multiplexing a reference symbol and a data symbol, and a data reception apparatus to estimate a channel using the reference OFDM symbol. Since the reference symbol and the data symbol are frequency division multiplexed, a Peak to Average Power Ratio (PAPR) may not increase greatly, and the transmission apparatus may transmit the reference OFDM symbol to the data reception apparatus more frequently. Accordingly, the data reception apparatus may estimate a channel accurately.

Abstract: An apparatus and method reduce power consumption in a broadband wireless communication system. A transmitting end apparatus that includes a plurality of transmit (Tx) antennas includes a control block, a Processor (DSP) block, a modem block, and at least one power controller. The control block determines a traffic amount based on an amount of used resources. The Digital Signal Processor (DSP) block performs scheduling by using a subset of Tx antennas and a subset of resources on a frequency axis if the traffic amount is less than a threshold. The modem block applies boosting to a signal transmitted using the subset of resources. And at least one controller turns off an operation of at least one power amplifier that corresponds to at least one Tx antenna that is not included in the subset of Tx antennas.

Abstract: In a wireless communication system where communication devices exchange information utilizing physical layer (PHY) data units that conform to a first format, where the first format includes a short training field (STF) that includes exactly N repetitions of a spreading sequence, a method for generating a PHY data unit that conforms to a second format, where the second format has a longer STF than the first format, includes generating an STF of the PHY data unit that includes M instances of the spreading sequence, where M is greater than N, and generating a channel estimation field (CEF).

Abstract: A receive only smart antenna with a command pointing option for communicating with geostationary satellites that autonomously detects the directions from which desired signal are received, and steer the multiple beams accordingly. An array feed is used to illuminate a parabolic reflector. Each feed element of the receive only smart antenna is associated with a unique beam pointing direction. As a receiver is switched to different feed elements, the far-field beam is scanned, making it possible to track a geostationary satellite in a slightly inclined orbit. This eliminates the need for mechanical tracking and maintains high antenna gain in the direction of the geostationary satellite. The receive only smart antenna also features capabilities to form multiple simultaneous beams supporting operations of multiple geo-satellites in closely spaced slightly inclined orbits. The designs can support orthogonal beams for enhanced bandwidth capacity via multiple beams with excellent spatial isolation.

Abstract: A device is provided for use of an antennal base formed of two antennas which pick up the emissions present and produce two radioelectric signals S1 and S2. These two signals are used to produce at least one intermediate-frequency signal Fl by demodulation of one of the two signals by the other (autotransposition). The demodulation is carried out by firstly transposing one of the signals, S1 for example, around a given frequency F1, the signal S2 being preserved around its initial central frequency F0. Thus, whatever the central frequency F0 of the emission picked up by the antennas, the demodulation produces a signal of central frequency F1, thereafter demodulated into a given intermediate frequency Fl by a local oscillator of constant frequency F2=F1+Fl. The device is applied to the production of a device for detecting emissions and for characterizing the emissions picked up.

Abstract: A transmitter includes first generator to generate pilot source signal by modulating pilot sequence, second generator to generate data source signal with time length longer than that of pilot source signal by modulating data sequence, first cyclic shifter to perform cyclic shift of first shift amount to pilot source signal to generate first pilot signal, second cyclic shifter to performs cyclic shift of second shift amount to data source signal to generate first data signal, third cyclic shifter to perform cyclic shift of third shift amount to pilot source signal to generate second pilot signal, fourth cyclic shifter to perform cyclic shift of fourth shift amount to data source signal to generate second data signal, first transmit antenna to transmit first pilot signal and first data signal, and second transmit antenna to transmit second pilot signal and second data signal.

Abstract: Systems, methods, and devices enable spectrum management by identifying, classifying, and cataloging signals of interest based on radio frequency measurements. In an embodiment, signals and the parameters of the signals may be identified and indications of available frequencies may be presented to a user. In another embodiment, the protocols of signals may also be identified. In a further embodiment, the modulation of signals, data types carried by the signals, and estimated signal origins may be identified.

Abstract: A video transmission system includes a transceiver module that transmits a video signal to a remote device over at least one communications channel wherein the video signal is transmitted as at least one separate video layer stream chosen from, an independent video layer stream and at least one dependent video layer streams that require the independent video layer for decoding. A control module determines at least one channel characteristic of the at least one channel and chooses the at least one separate video layer stream based on the at least one channel characteristic of the at least one channel.

Abstract: An unrolled decision feedback equalizer (DFE) as disclosed herein has a reduced number of compensation factors while keeping a suitable performance level for a given application. The KN possible DFE correction levels are reduced or compressed into fewer levels (R), merging together the levels that are the closest together where K represents the number of possible symbols in each baud, or the number of bits encoded into each baud, and N represents the DFE depth in number of bauds. A mapping function is then provided to convert the KN combinations of previous history bits into R sampler selections.

Abstract: The description herein relates to pilot designs for an Orthogonal Frequency Division Multiplexing (OFDM) based communication system. In at least one embodiment, the communication system is one operating according to the IEEE 802.16m, or WiMax, standard. In general, an OFDM transmitter operates to insert pilot symbols into a resource of a transmit frame according to a predetermined staggered pilot symbol pattern defining pilot symbol locations within the resource of the transmit frame. The predetermined pilot symbol pattern is defined such that pilot symbols are located at or near time boundaries of the resource, at or near frequency boundaries of the resource, or both. By doing so, when generating a channel estimate for the communication channel between the OFDM transmitter and an OFDM receiver based on the pilot symbols, extrapolations needed to estimate the channel near the boundaries of the resource are optimized, thereby improving overall channel estimation accuracy.

Abstract: Disclosed is a device and method to automate the process of measuring RF noise, correlating measured noise with known sources, and making adjustments to the noise-measuring and reporting process. A wireless communication device is coupled to equipment at a fixed location, and transmits data about the operation of the equipment back to an operator, via a provider's network. Examples include fixed wireless terminals. A management entity aboard the wireless communication device performs the measurements via a transceiver and performs remedial actions when required, without requiring an onsite technician or remote assistance. The management entity may include a spectrum analyzer.

Abstract: A method and an apparatus for transmitting and receiving data in a filter bank based multicarrier communication system are provided. The method includes receiving a plurality of data blocks and performing an Inverse Fast Fourier Transform (IFFT) operation on the plurality of data blocks, multiplying the plurality of data blocks on which IFFT has been performed and time axis filter coefficients, and transmitting a result obtained by adding the plurality of multiplied data blocks as a multi carrier signal.

Abstract: A data transmission method includes, in the mobile station apparatus, selecting a PMI and an RI corresponding to an Hermitian transpose of a channel matrix indicative of channel characteristics and calculating a CQI from the PMI. The method further includes transmitting the PMI, the RI, and the CQI to the base station apparatus as feedback information. The method further includes, in the base station apparatus, calculating a first data rate of a case of performing SU-MIMO transmission based on the PMI transmitted from the mobile station apparatus as feedback and calculating a second data rate of a case of performing ZF MU-MIMO transmission based on the PMI. The method further includes selecting a transmission scheme corresponding to a higher data rate between the first and second data rates.

Abstract: An apparatus and method for mitigation of receive power imbalance including estimating input power levels on two diversity receive branches in a receiver; computing a power imbalance between the two diversity receive branches and determining a weaker receive branch; setting a weakRX parameter based on the weaker receive branch; computing an intercept parameter c0 for a switching curve based on the weakRX parameter; computing a threshold T based on the intercept parameter; and determining a switching decision for the receiver based on the threshold T.

Abstract: The present invention provides a method of transmitting broadcast signals. The method includes, formatting input streams into Data Pipe, DP, data; Low-Density Parity-Check, LDPC, encoding the DP data according to a code rate; bit interleaving the LDPC encoded DP data; mapping the bit interleaved DP data onto constellations according to one of QAM (Quadrature Amplitude Modulation), NUQ (Non-Uniform QAM) or NUC (Non-Uniform Constellation); Multi-Input Multi-Output, MIMO, encoding the mapped DP data by using a MIMO encoding matrix having a MIMO encoding parameter; building at least one signal frame by mapping the MIMO encoded DP data; and modulating data in the built signal frame by an Orthogonal Frequency Division Multiplexing, OFDM, method and transmitting the broadcast signals having the modulated data.

Abstract: Provided are an apparatus and method for transmitting data using multiple antennas and beamforming. The apparatus of the present invention comprises: a modulation unit which performs constellation mapping on input bits to generate modulated symbols; a pre-coding unit which multiplies a pre-coding matrix and the modulated symbols to generate pre-coded symbols; and a plurality of transmitting antennas for transmitting the pre-coded symbols. According to the present invention, a beam width is maintained constant, regardless of a radiation angle, thus preventing a loss of power caused by an angular spread and preventing the generation of shadow zone at a large radiation angle.

Abstract: A method for determining a phase of each of a plurality of transmitting antennas in a multiple input and multiple output (MIMO) communication system includes: calculating, for first and second ones of the plurality of transmitting antennas, a value based on first and second groups of channel gains, the first group including channel gains between the first transmitting antenna and each of a plurality of receiving antennas, the second group including channel gains between the second transmitting antenna and each of the plurality of receiving antennas; and determining the phase of each of the plurality of transmitting antennas based on at least the value.

Abstract: The present application discloses a method for reporting channel status information in a multi antenna wireless communication system. In more detail, the method includes: receiving a reference signal from a base station; calculating the optimum precoding matrix index (PMI), at which the intensity of a signal from the base station is maximized, on the basis of the reference signal: determining at least one interference PMI from the base station on the assumption that a plurality of interference PMIs corresponding to the optimum PIM are applied; and transmitting information on at least one determined interference PMI to the base station. Beams corresponding to the plurality of interference PMIs are orthogonal to the beams corresponding to the optimum PMI.

Abstract: When a determination is made that communication by an SM scheme is suitable, a setting unit performs switching from a communication level by an STC scheme to the communication level by the SM scheme, between the communication level at a first level of MCS by the space-time coding scheme and the communication level at a second level of MCS by the SM scheme. When a determination is made that communication by the SM scheme is unsuitable, the setting unit performs switching from the communication level by the STC scheme to the communication level by the spatial multiplexing scheme, between the communication level at a third level of MCS, which is higher than the first level, by the space-time coding scheme and a fourth level of the modulation scheme and the coding rate, which is higher than the second level, by the SM scheme.

Abstract: A transmitting device and a receiving device wherein, on the transmitting side, a signal creation unit creates, as its output, a signal generated adding up the signals assuming that different data has passed through multiple virtual channels and, on the receiving side, oversampling is performed, the sampled data is distributed, and signals are detected assuming that the distributed data is the output of multiple virtual reception antennas.

Abstract: An apparatus for offset compensation in high-order modulated orthogonal frequency division multiplexing (OFDM) transmission, the apparatus including a transmitter to configure a pilot signal for transmission and reception synchronization and distortion estimation as a frame, and transmit the frame, and a receiver to estimate a channel distortion of a received signal by estimating and compensating for a clock offset and a frequency offset with respect to the received signal.

Abstract: A receiver with Inphase-Quadrature (I-Q) imbalance compensation and an I-Q imbalance compensation method thereof are provided. The receiver chooses a first receiving signal which includes a first data and a first noise, as well as a second receiving signal which includes a second data and a second noise from a plurality of receiving signals. The first data have a first positive frequency data and a first negative frequency data, while the second data have a second positive frequency data and a second negative frequency data. The receiver calculates an I-Q imbalance compensation parameter according to the first receiving signal and the second receiving signal, and compensates for a third receiving signal according to the I-Q imbalance compensation parameter. The I-Q imbalance compensation method is applied to the receiver to implement the aforesaid operations.

Abstract: An interference wave suppressing apparatus includes a digital demultiplexing unit configured to demultiplex a reception signal into demultiplexed signals having predetermined bandwidth, an interference-wave detecting unit configured to determine, for each of the demultiplexed signals, based on a power value, whether an interference wave is present, an interference-wave suppressing unit configured to change a signal value of the demultiplexed signal, in which the interference-wave detecting unit determines that an interference wave is present, to a value equal to or smaller than a predetermined value, output the demultiplexed signal, and output the demultiplexed signal, in which the interference-wave detecting unit determines that an interference wave is absent, and a digital multiplexing unit configured to multiplex the signals output from the interference-wave suppressing unit.

Abstract: A wireless communication terminal according to the embodiment includes a communication module including a circuit board having a plurality of pins; a shield case antenna overlapping with one side of the circuit board, electrically connected to a part of the pins and including a signal receiving unit; and a signal processing unit for processing the received signals. An antenna matching unit for matching impedance between the signal processing unit and an antenna unit, a phase shifter for controlling a phase of the received signal and an amplitude regulator for adjusting amplitude of the received signal are provided between the signal processing unit and the antenna unit.

Abstract: A method for transmitting pilots in a wireless communication system includes generating first two pilots for a first antenna. Second two pilots for a second antenna are generated by multiplying the first two pilots with two weight values respectively. The first two pilots are transmitted over two Orthogonal Frequency Division Multiplexing (OFDM) symbols via the first antenna. The second two pilots are transmitted over the two OFDM symbols via the second antenna, wherein each weight value is determined based on a value used to obtain a symbol index of a corresponding OFDM symbol of the two OFDM symbols within a slot. Symbol indexes for the two OFDM symbols are consecutive, and the two weight values are different with each other.

Abstract: The required bitrate for reporting channel state information from a network transceiver to the network is dramatically reduced, while maintaining fidelity of channel estimates, by exploiting prior channel estimates and the time correlation of channel response. For a selected set of sub-carriers, the transceiver estimates channel frequency response from pilot signals. The transceiver also predicts the frequency response for each selected sub-carrier, by multiplying a state vector comprising prior frequency response estimate and a coefficient vector comprising linear predictive coefficients. The predicted frequency response is subtracted from the estimated frequency response, and the prediction error is quantized and transmitted to the network. The network maintains a corresponding state vector and predictive coefficient vector, and also predicts a frequency response for each selected sub-carrier.

Abstract: The transmitter and a mobile terminal based on interference alignment use pre-coding and pre-decoding methods. An antenna mapping matrix is computed according to a downlink channel state information, wherein the antenna mapping matrix is used for antenna mapping for the current transmitter to perform interference alignment. A multi-cell pre-coding matrix according to the downlink channel state information and the antenna mapping matrix; a single cell multi-user pre-coding matrix and pre-coding user data using the single cell multi-user pre-coding matrix and the multi-cell pre-decoding matrix and performing an antenna mapping using the antenna mapping matrix are computed. A system which cannot use the interference alignment method directly may be transformed to use the interference alignment method directly. In addition, the interference suppression between cells and the interference management inside cells are two separate processes, in which different linear pre-coding and decoding methods may be used.

Abstract: A method includes receiving reference signals in a mobile communication terminal, which is designed to receive data-carrying signals that are transmitted from a base station using one of multiple predefined Modulation and Coding Schemes (MCSs). One or more pre-calculated mappings between Signal-to-Noise Ratio (SNR) and error rate for one or more of the MCSs are held in the communication terminal. The pre-calculated mappings are adjusted according to one or more transmission parameters of the data-carrying signals. Measures indicative of respective actual spectral efficiencies that are achievable by the MCSs are estimated based on the adjusted mappings using the received reference signals. A preferred MCS is selected based on the estimated measures, and feedback that is indicative of the preferred MCS is sent to the base station.

Abstract: Certain aspects of the present disclosure relate to techniques and apparatus for performing joint demodulation using a Max-Log MAP algorithm in wireless communications systems. An exemplary method generally comprises receiving a signal comprising one or more serving streams and one or more interfering streams; and processing the signal by performing joint demodulation using a max log map (MLM) algorithm for at least one of the one or more serving streams or at least one of the one or more interfering streams.

Abstract: A network node (28) communicates over a radio interface (32) with a wireless terminal (30). Both the network node (28) and the wireless terminal (30) have multiple-input multiple-output (MIMO) capabilities. A MIMO-related order (90) is generated for inclusion in control signaling on a high speed downlink shared channel from the network node (28) to the wireless terminal (30). The MIMO-related order (90) is configured to modify channel quality indication (CQI) communications between the wireless terminal (30) and the base station (28) in view of MIMO capabilities of the wireless terminal (30). The method further comprises providing a channel quality indication (CQI) report (92) the wireless terminal (30) to the base station (28) in accordance with the order.

Abstract: A preamble detector has a correlator outputting for every sample position of the preamble part of an incoming sampled signal stream a score and associated class value; and a multiple cluster unit receiving the class and score output values from the correlator, wherein a first cluster receives output values from the correlator and the following clusters are coupled in series such that each cluster receives output values from the correlator and a preceding cluster and wherein the output values of the correlator and a cluster are processed such that an n-th cluster of the multiple cluster unit, with n>1, accumulates the highest score values of n score values with matching class values.

Abstract: A method of the multiple input multiple output feedback is disclosed. In accordance with an embodiment of the invention, the multiple input multiple output feedback method includes a receiver receiving a reference signal from a base station and calculating a signal to interference and noise ratio from the received reference signal. The method further includes determining a modulation and coding scheme based on the signal to interference and noise ratio and a receiver type.

Abstract: A receiver includes a detector to detect an interfered-with carrier from a received and demodulated signal, a fast Fourier transform computation part to perform fast Fourier transform to convert a time domain signal to a frequency domain signal and adjust an output power level of a desired carrier wave contained in the frequency domain signal based upon the detected interfered-with carrier, and a channel estimation part to estimate a channel characteristic based upon a non-interfered-with pilot signal that is not subject to influence of the interfered-with carrier and an interpolation value interpolated based upon the non-interfered-with pilot signal, the non-interfered-with pilot signal being obtained by removing, based upon the interfered-with carrier, an interfered-with pilot signal that is subject to the influence of the interfered-with carrier and an interpolation value interpolated based upon the interfered-with pilot signal.

Abstract: According to one or more aspects, the teachings herein improve user equipment (UE) Channel State Information (CSI) feedback, by letting the precoder part of a CSI feedback report comprise factorized precoder feedback. In one or more such embodiments, the factorized precoder feedback corresponds to at least two precoder matrices, including a recommended “conversion” precoder matrix and a recommended “tuning” precoder matrix. The recommended conversion precoder matrix restricts the number of channel dimensions considered by the recommended tuning precoder matrix and, in turn, the recommended tuning precoder matrix matches the recommended precoder matrix to an effective channel that is defined in part by said recommended conversion precoder matrix.

Abstract: A method and apparatus for improving channel estimation within an OFDM communication system. Channel estimation in OFDM is usually performed with the aid of pilot symbols. The pilot symbols are typically spaced in time and frequency. The set of frequencies and times at which pilot symbols are inserted is referred to as a pilot pattern. In some cases, the pilot pattern is a diagonal-shaped lattice, either regular or irregular. The method first interpolates in the direction of larger coherence (time or frequency). Using these measurements, the density of pilot symbols in the direction of faster change will be increased thereby improving channel estimation without increasing overhead. As such, the results of the first interpolating step can then be used to assist the interpolation in the dimension of smaller coherence (time or frequency).

Abstract: A method is for decoding a pulse signal modulated through a transmitted reference modulation scheme. The modulated pulse signal may include, repetitively, a reference pulse followed by an information pulse delayed with a delay. The method may include subtracting or adding from the modulated pulse signal, a version of the modulated pulse signal delayed with the delay for obtaining a processed signal, and performing a non-coherent detection on the processed signal.

Abstract: According to one or more embodiments, multiple transmitters may simultaneously transmit orthogonal acquisition sequences with certain frequencies zeroed out, such that receivers receiving a signal (waveform) may separate the signal into the orthogonal sequences based on which frequencies are zeroed out to perform acquisition processes. For example, each transmitter may simultaneously transmit an orthogonal acquisition sequence with certain tones zeroed out depending upon which transmitter transmits the symbol. A particular receiver may then receive a signal, and filter it to produce a plurality of filtered signals that distinguish orthogonal acquisition sequence symbols based on which tones are zeroed out within the symbols.

Abstract: A method and apparatus for improving channel estimation within an OFDM communication system. Channel estimation in OFDM is usually performed with the aid of pilot symbols. The pilot symbols are typically spaced in time and frequency. The set of frequencies and times at which pilot symbols are inserted is referred to as a pilot pattern. In some cases, the pilot pattern is a diagonal-shaped lattice, either regular or irregular. The method first interpolates in the direction of larger coherence (time or frequency). Using these measurements, the density of pilot symbols in the direction of faster change will be increased thereby improving channel estimation without increasing overhead. As such, the results of the first interpolating step can then be used to assist the interpolation in the dimension of smaller coherence (time or frequency).

Abstract: The MIMO method and apparatus disclosed herein improve throughput conditions limited by multiplicative noise by reducing the gain of the data streams associated with one or more dominant signal paths between MIMO communication nodes. As used herein, multiplicative noise refers to any noise dependent on or proportional to a signal strength at a transmitting node and/or a receiving node of a wireless communication network. An additional method and apparatus are included for determining that multiplicative noise limits the throughput conditions.

Abstract: A wireless communication system which performs data transmission from a first terminal including N antennas to a second terminal including M antennas using spatially multiplexed streams (N and M are integers larger than or equal to 2 and N<M) is disclosed. The system includes training request means, training means, channel matrix preparing means, transmission weight matrix computation means, and beamforming means.