Abstract: Disclosed are a signal compression apparatus and method for dynamic compressive sensing, including: a signal input unit configured to simultaneously output an input signal, and generate and output a linear measurement reference signal based on the input signal; a linear transform unit configured to receive the linear measurement reference signal and variably generate a linear measurement matrix value according to the linear measurement reference signal; a signal compressor configured to output a compressed signal for the input signal based on the generated linear measurement matrix value; and a signal processor configured to reconstruct the compressed signal and perform spectrum sensing of the input signal.

Abstract: Systems and methods to detect the occurrence of erroneous demodulated bits for decision feedback demodulation are disclosed. In one implementation, an apparatus for detecting demodulation bit errors of a plurality of modulated bits includes a memory component configured to store a first threshold and a second threshold. The apparatus further includes a processor coupled to the memory component, the processor configured to retrieve the first threshold and second threshold from the memory component and to determine a demodulation metric value for each of the plurality of modulated bits, the processor further configured to count the number of demodulation metric values that cross the first threshold and compare the second threshold to the number of demodulation metric values that cross the first threshold.

Abstract: An OFDM transmitter and an OFDM receiver respectively transmit and receive N (N?2, N is an integer) control symbols. For each control symbol, a guard interval time-domain signal is, for example, identical to a signal obtained by frequency-shifting at least a portion of a useful symbol time-domain signal by an amount different from any other symbol, or to a signal obtained by frequency-shifting one or both of a portion and a span of a useful symbol interval time-domain signal different from any other symbol by a predetermined amount.

Abstract: Circuitry for use in a receiver may comprise: a front-end circuit operable to receive an orthogonal frequency division multiplexing (OFDM) symbol on a first number of physical subcarriers. The circuitry may comprise a decoding circuit operable to decode the OFDM symbol using an inter-carrier interference (ICI) model, the decoding resulting in a determination of a sequence of symbols, comprising a second number of symbols, that most-likely correspond to the received OFDM symbol, where the second number is greater than the first number. The sequence of symbols may comprise N-QAM symbols, N being an integer. The ISCI model may be based, at least in part, on non-linearity experienced by the OFDM symbol during transmission by a transmitter, propagation over a channel, and/or reception by the receiver. The ISCI model may be based, at least in part, on phase-noise introduced to the OFDM symbol during transmission by a transmitter, propagation over a channel, and/or reception by the receiver.

Abstract: The present disclosure in some embodiments provides transmission, reception and an apparatus using multiple antennas. A transmission apparatus in an embodiment may include first to M-th transmission antennas, where M is a natural number?2; first to L-th encoders, where L is a natural number?2; and first to M-th transmission signal generators. The I-th encoder (where I=arbitrary natural number between 1 and L) receives an I-th symbol sequence and generates first to M-th encoded symbol sequences by encoding the received I-th symbol sequence according to an I-th multiple antenna transmission scheme. The m-th transmission signal generator (where m=arbitrary natural number between 1 and M) combines m-th encoded symbol sequences generated by the encoders to generate a signal to be transmitted via the m-th transmission antenna.

Abstract: Various embodiments of the present invention provide a method and apparatus for parallel data processing. In one embodiment of the present invention, there is provided a method for parallel data processing, comprising: receiving baseband data corresponding to multiple antennas from uplink data; converting the baseband data from time-domain signals to frequency-domain signals; processing the frequency-domain signals at least partially in parallel by multiple processing units in a general-purpose processor so as to restore transmitted code blocks; and constructing transmission block (TB) based on the transmitted code blocks. In one embodiment of the present invention, there is provided an apparatus for parallel data processing. By means of the method and apparatus of the present invention, the parallel data processing capacity of a general-purpose data processor may be used to process, in parallel as much as possible, data in uplink data transmission and further improve the receiver operation efficiency.

Abstract: Described herein are one or more apparatus, that at least partially synchronise with a first radio-frequency signal from a first antenna element, of an array of spatially distributed antenna elements in a multi-antenna array receiver, to determine the position of at least one of a repeated guard interval in the first radio-frequency signal from the first antenna element, the repeat occurring at a particular defined characteristic interval. The apparatus then use the determined position of the at least one guard interval in the first radio-frequency signal to switch to a second radio-frequency signal from a second antenna element, of the array of spatially distributed antenna elements in a multi-antenna receiver, and further determine a relative orientation of the multi-antenna receiver from a transmitter of the radio-frequency signals using characteristics determined for the first and second radio-frequency signals following the at least respective partial synchronisations.

Abstract: A demapping scheme, having a low computational cost, suitable for any transmission in which only exhaustive demapping can guarantee good performance. The scheme, proposed in this document, can be used in any transmission based on no differential modulation. For example the proposed scheme can be directly applied to a transmission on flat fading AWGN channels or to a transmission on frequency selective channels after equalization or on each sub-carrier of an OFDM System. The proposed solution can be applied for the demapping of any communication system. The proposed scheme can be used for rotated and un-rotated constellation.

Abstract: Disclosed herein is a reception apparatus, including: a reception section configured to receive an OFDM (Orthogonal Frequency Division Multiplexed) signal obtained by modulating a common packet sequence configured from a packet common to streams and a data packet sequence configured from packets individually unique to the streams; a time counting section configured to count, using predetermined time indicated by additional information added to particular packets of the common and data packet sequences obtained by demodulating the received OFDM signal as a reference, elapsed time after the predetermined time; a detection section configured to compare the counted time and time indicated by the additional information added to the particular packets of the common and data packet sequences to detect a displacement in the time direction between the packets; and a correction section configured to correct the displacement between the packets of the common and data packet sequences in the time direction.

Abstract: Self-monitoring reset circuitry is presented for use in analog-to-digital converters and other modulator circuitry with capacitively coupled isolation barriers in which the modulator output data is monitored for inactivity by a reset circuit synchronized to the modulator clock, and extra pulses are selectively introduced into the data prior to transmission across the isolation barrier if no modulator state changes occur within a predetermined number of clock cycles to provide a predictable data output value for each end of the analog input range and to reset the output to the correct state in situations where transient noise toggles the output and the modulator output is static.

Abstract: A method is provided for improving synchronization and information transmission in a communication system, including: generating a signal with a centrally symmetric part s(k) exploitable for synchronization; and sending the signal over a communication channel. The signal is based on a uniquely identifiable sequence c(l) from a set of sequences exploitable for information transmission. The centrally symmetric part s(k) is centrally symmetric in the shape of absolute value thereof. The centrally symmetric part s(k) is of arbitrary length N.

Abstract: Systems, methods, and other embodiments associated with a single stream wireless communication with a greenfield preamble that uses a short guard interval are described. According to one embodiment, a wireless communication device includes a receiver configured to receive an orthogonal frequency-division multiplexing (OFDM) signal. The OFDM signal includes a greenfield preamble. The wireless communication device includes an interval select logic configured to determine a type of guard intervals in the OFDM signal based, at least in part, on the greenfield preamble. The wireless communication device includes a signal processor configured to process the OFDM signal based, at least in part, on the type of the guard intervals as determined by the interval select logic.

Abstract: Process for canceling Intercarrier Interference in a OFDM receiver receiving OFDM blocks in presence of Doppler, comprising the steps of: receiving a OFDM block comprising N samples; applying a FFT for the purpose of generating N frequency domain representations composing the received signal (R); multiplying said received signal (R) by the hermitian value of the channel (HH), with H being the channel estimate; applying on said received signal a preconditioned conjugate gradient algorithm based on a N×N P preconditioner matrix; Characterized in that said preconditioner matrix is computed at follows: Formula (19) and formula (20), where formula (I) is a LFIR×PN selection matrix obtained by extracting a predetermined number (LFIR) of rows from the identity matrix IPN, LFIR being a predetermined integer inferior to PN, with p corresponding to the basis expansion order chosen and N is the FFT size; formula (II) is equal to HFH, with H being the frequency-domain channel matrix and F being the N×N discrete-Fourier t

Abstract: An OFDM system embeds sequence information in the transmitted signal that reduces peak average power ratio (PAP) with minimal impact on the overall system efficiency. A marker is embedded onto the transmitted information that is used to identify the combining (inversion) sequence at the receiver. In one embodiment, selected tones in a cluster are rotated when the corresponding phase factor rotates the cluster.

Abstract: Methods and systems are provided for loop-through for multi-chip communication systems. Receiver circuitry, that is operable to receive one or more input feeds, may comprise a plurality of chips, each of which may be configurable to generate a corresponding output comprising one or more feed elements (e.g., channels) extracted from the input feed(s). However, only a first chip may be operable to handle reception and/or initial processing of the one or more input feeds, with each one of the remaining chips processing a loop-through feed generated by the first chip, in order to generate the corresponding output of that chip. The first chip generates the loop-through feed based on the one or more input feeds, such as after the initial processing thereof in the first chip. Generating the loop-through feed may comprise applying channelization (e.g., separately for each remaining chip), switching based processing, and/or interfacing based processing.

Abstract: A first transmitter transmits symbols. The leading edge of each symbol has the form Djexp{?jt}, where Dj is real, where ?j is selected from N possible values based on a current group of bits. The receiver has N filters whose transfer functions correspond respectively to the N possible values. The filter outputs are used to recover the group of bits. A second transmitter transmits an exponential symbol or a zero symbol depending on a current bit to be transmitted. The zero symbol has zero amplitude over the symbol period. The corresponding receiver applies threshold detection to estimate the transmitted bits. A third transmitter transmits a sequence of analog pulses with known interpulse time separation(s). The pulse sequence reflects from a moving object. A receiver captures the reflected pulse sequence. The interpulse separation(s) of the reflect pulse sequence is used to determine the radial velocity of the object.

Abstract: According to one embodiment, a method of transmitting a broadcasting signal includes: encoding data; encoding signaling data by an LDPC (Low Density Parity Check) scheme; building a signal frame based on at least one preamble data symbol having the encoded signaling data and a data slice having the encoded data; inserting at least one pilot into the signal frame with a specific pattern and modulating the signal frame by an OFDM (Orthogonal Frequency Division Multiplexing) method; and transmitting the modulated signal frame. A signaling block having the signaling data is repeated in the at least one preamble data symbol in a frequency domain by a bandwidth. The bandwidth of the signaling block corresponds to a number of active subcarriers assigned to a single channel.

Abstract: A conversion circuit (20) for converting a complex analog input signal having an in-phase, I, component and a quadrature-phase, Q, component resulting from frequency down conversion of a radio-frequency, RF, signal (XRF) to a frequency band covering 0 Hz into a digital representation is disclosed. It comprises a channel-selection filter unit (40) arranged to filter the complex analog input signal, thereby generating a channel-filtered I and Q components, and one or more processing units (53, 53a-b). Each processing unit comprises four mixers (60-75) for generating a first and a second frequency-translated I component and a first and a second channel-filtered Q component based on two LO signals with equal LO frequency and a 90° mutual phase shift. Furthermore, each processing unit comprises a combiner unit (85, 120) for generating a first, a second, a third, and a fourth combined signal proportional to sums and differences between said frequency translated I and Q components.

Abstract: In some embodiments, a receiver circuit is configured to receive a modulated signal from a transmitter that is galvanically isolated from the receiver circuit. The receiver circuit is configured to demodulate the modulated signal by using two comparator circuits that respectively detect the presence or absence of first and second signal states of a carrier signal. Based on the detection of the first and second states, the receiver circuit determines whether the carrier signal is present or absent in the modulated signal to determine a demodulated value of the modulated signal.

Abstract: The invention is directed to a system and method of regulating a slicer for a communication receiver. A zero-crossing accumulator receives a slicer output from the slicer and accordingly determines a zero-crossing length of the slicer output. A threshold decision unit regulates at least one threshold value of the slicer according to the zero-crossing length.

Abstract: A receiver is provided that can receive a first signal transmitted on a first carrier and a second signal transmitted on a second carrier. The receiver includes a channel estimation portion, a multicarrier nonlinear equalizer, a first log likelihood computing portion and a second log likelihood computing portion. The channel estimation portion can output a first estimation. The multicarrier nonlinear equalizer can output a first equalized signal and a second equalized signal. The first log likelihood ratio computing portion can output a first log likelihood ratio signal based on the first equalized signal. The second log likelihood ratio computing portion can output a second log likelihood ratio signal based on the second equalized signal. The multicarrier nonlinear equalizer can further output a third equalized signal and a fourth equalized signal. The third equalized signal is based on the first signal, the second signal and the first estimation.

Abstract: A method is provided for synchronization in a communication system. A receiver receives and processes a signal with a centrally symmetric part s(k) exploitable for synchronization. The signal is based on a uniquely identifiable sequence c(l) from a set of sequences exploitable for information transmission. The centrally symmetric part s(k) is centrally symmetric in the shape of absolute value thereof. The centrally symmetric part s(k) is of arbitrary length N, and the sequence c(l) is a Zadoff-Chu sequence.

Abstract: Systems, methods, and devices to enable monitoring of wireless networks are described herein. In some aspects, a low power receiver or a receiver operating in a low power mode scans for signals with a moderate or low duty cycle. If a signal identifying a device or user of the receiver, or a signal indicating that there will be a subsequent data communication, is received, a high power receiver or a receiver operating in a high power mode is activated to receive data communications.

Abstract: A discrete digital transceiver includes a receiver sample and hold module, a discrete digital receiver conversion module, a transmitter sample and hold module, a discrete digital transmitter conversion module, clock generation module, and a processing module. The receiver sample and hold module samples and holds an inbound wireless signal in accordance with a receiver S&H clock signal. The discrete digital receiver conversion module converts the receiver frequency domain sample pulse train into an inbound baseband signal. The transmitter sample and hold module samples and holds an outbound signal to produce a transmitter frequency domain sample pulse train. The discrete digital transmitter conversion module converts a transmitter frequency domain sample pulse train into the outbound wireless signal. The clock generation module generates S&H clock signals in accordance with a control signal. The processing module generates the control signal such that the S&H clock signals are shifted.

Abstract: A method of generating a reliability indicator for decoding an encoded signal transmitted from a transmitter to a receiver via a wireless channel subject to fading. The method comprises: receiving symbols of the encoded signal; generating a reliability indicator for decoding at least some of the symbols selectively based on one or both of a statistical model representing additive white Gaussian noise (AWGN) in the encoded signal and a statistical model representing fading of the encoded signal; and selecting the statistical model based on signal characteristics of the wireless channel.

Abstract: An apparatus comprising an inter symbol interference (ISI) cancellation circuit and a detector circuit. The inter symbol interference (ISI) cancellation circuit may be configured to minimize ISI at data sampling and crossing sampling points in a symbol interval of an input signal. The detector circuit may be configured to generate data samples and crossing samples at the data sampling and crossing sampling points in the symbol interval of the input signal.

Abstract: Of any one of a transmission method X of transmitting modulated signal A and modulated signal B including the same data from a plurality of antennas and a transmission method Y of transmitting modulated signal A and modulated signal B having different data from the plurality of antennas, a base station apparatus does not change the transmission method during data transmission and changes only the modulation scheme. The base station apparatus transmits modulated signal A and modulated signal B to a communication terminal apparatus using the determined transmission method and modulation scheme. In this way, it is possible to improve data transmission efficiency when transmitting data using the plurality of antennas.

Abstract: A signal transmitting device and a method for transmitting via a signal transmitting device is disclosed. In one embodiment the transmitting device comprises a first resonant circuit with a resonant circuit inductance and a resonant circuit capacitance and a second resonant circuit with a resonant circuit inductance and a resonant circuit capacitance, a coupling element which couples the first resonant circuit to the second resonant circuit, a first excitation circuit, coupled to the first resonant circuit, and at least one further excitation circuit coupled to the second resonant circuit.

Abstract: A process for performing a QR Decomposition of a channel matrix of a wireless communication channel system, said process involving the steps of: performing a full QR Decomposition of one channel matrix for the purpose of deriving a first QR representation of the channel; performing a second iterative QR Decomposition of an adjacent channel matrix, said second iterative QR Decomposition using the results of said first QR representation as well as the difference of the two adjacent channel matrices ?H. More particularly, the process is characterized in that the iterative QR Decomposition is performed in response to the detection of a high level of workload of the processor.

Abstract: In a receiver circuit, a binary signal is generated based on a signal level of a received signal that has been received via a transmission line from a driver of a transmitter circuit. Then, a first stable state and a second stable state are detected based on a reference signal whose signal level changes in accordance with the received signal. In the first stable state, the received signal is stable at a first signal level. In the second stable state, the received signal is stable at a second signal level. When the first stable state is detected and the received signal is changed from the first signal level into the second signal level, the generated binary signal is retained at a signal level corresponding to the second signal level, until the second stable state is detected.

Abstract: Described herein are a technique, method, device and system related to reducing memory requirements and complexity in receivers. According to the present disclosure, the capability to request precoded ACE symbols is added to receivers in a mode under the g.hn MIMO standards that uses precoding to enhance the capacity of links. Using precoded ACE symbols, memory requirements for the receiver can be reduced as it is not necessary for the receiver to save the precoder coefficients. Additionally, the frequency of updates required for the precoding coefficients can be reduced by adapting the MIMO decoder using the precoded ACE symbols as reference symbols.

Abstract: Implementations related to power reduction in physical layer wireless communications are disclosed.

Abstract: A digital front-end circuit is disclosed. In one aspect, the circuit includes a filtering block for filtering received data. The filtering block has a first filter branch for filtering the received data in a first frequency band and a second filter branch for filtering the received data in a selected second frequency band. The second filter branch is in parallel with the first filter branch, is programmable and includes a block for resampling the received data. The front-end circuit also includes a circuit for performing synchronization and spectrum sensing on the received data, which is in connection with the output of the filtering block. The front-end circuit also includes a controller block for controlling the filtering block and the synchronization circuit.

Abstract: A computational processor uses a binary signal, being a set of 1- or 0-valued elements of a same number as a number of elements in an input signal, to generate computational data whose elements are exclusive OR values between each element of the input signal and a corresponding element in the binary signal at a same position. The modulator 13 modulates the input signal and the computational data according to a primary modulation scheme, and generates primary-modulated signals. An IFFT calculator applies an inverse fast Fourier transformation to the primary-modulated signals to generate inverse transformation data. A transmitter generates a baseband signal based on generated inverse transformation data whose peak-to-average power ratio matches a standard, and generates and transmits a transmission signal from the baseband signal and data specifying computations conducted to generate the inverse transformation data that matches the standard.

Abstract: A method for transmitting signals based on dual sensing in a wireless communication system is disclosed. One or more sensor nodes receive Gaussian codes corresponding respectively to the one or more sensor nodes, allocated from a fusion center. The one or more sensor nodes determine whether to operate at a specific time. At least one sensor node that has determined to operate among the one or more sensor nodes multiplies the Gaussian codes by a transmission signal and transmits the multiplied signal to the fusion center.

Abstract: A signal processing method for enhancing the dynamic range of a signal is disclosed. The method comprises: a) forming an attenuated signal from an input signal; b) filtering each of the input and the attenuated signals such that the sum of their bandwidths is less than or equal to the bandwidth of a transmission channel; c) modulating a first one of the filtered input signal and the filtered attenuated signal, whereby the filtered input signal and the filtered attenuated signal occupy respective non-overlapping frequency ranges within the bandwidth of the transmission channel; and d) combining the modulated signal with the second one of the filtered input signal and the filtered attenuated signal to form a composite output signal.

Abstract: A technique for reducing the dwell time in acquiring a satellite signal is provided. The technique minimizes the dwell time in searching for a satellite signal in cells of a search space by comparing the peak-power-to-average ratio (PAPR) to one or more thresholds at one or more intermediate points during the search in a code phase/Doppler frequency bin. The comparison is then used to determine whether to continue the search in a current code phase/Doppler frequency bin or to continue to the next code phase/Doppler frequency bin.

Abstract: In a particular embodiment, a method includes receiving a first portion of a sync field of a packet at a receiver. The sync field includes the first portion and a second portion. The packet includes the sync field and a payload field. The method includes detecting a sync word associated with the packet. The sync word is detected based on the first portion of the sync field and prior to receiving the second portion of the sync field. The method initiates a demodulation stage of the receiver prior to receiving an initial bit of the payload field. Initiating the demodulation stage prior to receipt of the initial bit of the payload field enables a demodulator to perform initial demodulation activity prior to demodulation of the payload field. Demodulation continues if, after the second portion is received, the entire received sync field matches the detected sync word.

Abstract: An adaptive filtering arrangement for providing bit-synchronous, time-dependent filtering of a time-varying analog input signal taking the form of a time-dependent low pass filter including at least one adaptive resistive element that exhibits a varying resistance value as a function of a time. The time-dependent low pass filter uses as a “control” input a modifying element responsive to a clock signal associated with the received signal for creating a time-varying control signal applied as an input to the adaptive resistive element. The time-varying control signal is created to be synchronous with a baud interval of a created output signal such that the instantaneous bandwidth of the time-dependent low pass filter is synchronous with the baud interval, exhibiting a relatively small bandwidth during a central portion of the baud interval and exhibiting a relatively large bandwidth during a transition from one baud interval to the next.

Abstract: According to one embodiment, a wireless receiving apparatus includes a receiver, a phase rotation module and a demodulator. The receiver receives a first signal, the first signal being processed a bit conversion, a scramble and an M-phase shift keying modulation processes. The phase rotation module multiplies a first symbol obtained from the first signal with an amount of phase rotation determined by a scramble sequence used for the scramble, to obtain a second symbol. The demodulator demodulates the second symbol by referring to signal points of N-PSK replica signal generated based on a data rate and the bit conversion process and calculates a likelihood obtained from demodulation as a soft decision value.

Abstract: The techniques and components described herein may improve the performance for a class of reduced-complexity receiver designs for coded OFDM MIMO systems with bit interleaved coded modulation. The receiver structures described are soft-input soft-output inner/outer decoder receiver structures that include one or more of the following: 1) an inner decoder that includes a linear front-end followed by a limited tree-search based on a soft-output M-algorithm; 2) a conventional near-optimal or optimal decoder for the outer binary code; and 3) iterative decoding (ID), whereby decoding (output) information is passed from one decoder module as input to the other and used to refine and improve the inner/outer decoding module outputs.

Abstract: Channel estimation and data detection in a wireless communication system in the presence of inter-cell interference is provided.

Abstract: An apparatus for decoding GNSS navigation data to generate at least a target string or subframe includes a demodulator and a processing unit. The demodulator is utilized for demodulating a received signal to generate at least a plurality of strings or subframes having a same string index or subframe index. The processing unit is coupled to the demodulator, and is utilized for determining the target string or subframe according to the plurality of strings or subframes.

Abstract: Appropriate reception processing is performed using a CRS-based estimation method for a covariance matrix RI+N. An IRC receiver 10 according to the present invention includes: a covariance matrix estimation unit 12/13 configured to estimate a covariance matrix RI+N based on a CRS; a missing element insertion unit 14 configured to insert a given value into an inestimable element in an interference-signal covariance matrix RI+N (“˜” is on R) of interference signal components contained in the estimated covariance matrix RI+N; an IRC reception weight generation unit 16 configured to generate an IRC reception weight WIRC by using the control signal and the covariance matrix RI+N having the given value inserted thereinto; and a signal separation unit 17 configured to separate the data signal from a received signal by using the generated reception weight and the control signal.

Abstract: In one example embodiment, a method for reducing an effect of an interference signal on data being transmitted over a communication channel includes determining, by a processor, a code word based on at least an information vector and an interference vector, the information vector representing the data, the interference vector representing the interference signal. The method further includes determining, by the processor, a code vector based on the determined code word. The method further includes generating, by the processor, a transmit vector based on the code vector and the interference vector.

Abstract: A system and method is provided for estimating the channel in OFDM transmission with inter-carrier interference (ICI). A channel in a data subcarrier in a subchannel shared between pilot subcarriers and data subcarriers can be estimated by performing interpolation based on estimated channels in pilot subcarriers in the same OFDM symbol as the subcarrier, such as through spline interpolation. A second estimate of the channel in the subcarrier can be produced by averaging an estimate of the channel in a subcarrier in the subchannel in a previous OFDM symbol and an estimate of the channel in a subcarrier in the subchannel in a succeeding OFDM symbol. A third estimate of the channel in the subcarrier can be produced through a linear combination of the first estimate and the second estimate. The channel in data subcarriers can be estimated through a weighted sum of the channel in nearest subcarriers.

Abstract: Methods and systems are disclosed for transmitting data over a desired frequency tone in the presence of an interference that has an unknown magnitude that is substantially constant. In general, data symbols are transmitted in a null space of the desired frequency tone. The null space of the desired frequency tone is orthogonal to the desired frequency tone. As such, the data symbols transmitted in the null space of the desired frequency tone are not interfered with by the interference at the desired frequency tone regardless of the magnitude of the interference. The data symbols transmitted in the null space of the desired frequency tone can then be recovered by a receiver without estimation of or compensation for the interference at the desired frequency tone.

Abstract: A transmitter transmits payload data using Orthogonal Frequency Division Multiplexed (OFDM) symbols. The first OFDM symbol is a first type having a number of sub-carriers which is less than or equal to the number of sub-carriers of the one or more second OFDM symbols of a second type and a guard interval for the first OFDM symbol is selected in dependence upon the longest possible guard interval of the second OFDM symbol. Accordingly an OFDM communications system can be formed in which data is transmitted using a frame structure in which a guard interval is adapted to allow a mix of different types of OFDM symbols.

Abstract: Embodiments of the present disclosure provide a transmitter, a receiver and methods of operating a transmitter and a receiver. In one embodiment, the transmitter has at least three transmit antennas and includes a feedback decoding portion configured to recover at least one group-based channel quality indicator provided by a feedback signal from a receiver, wherein each group-based channel quality indicator corresponds to one of a set of transmission layer groupings. The transmitter also includes a modulator portion configured to generate at least one symbol stream and a mapping portion configured to multiplex each symbol stream to at least one transmission layer grouping. The transmitter further includes a pre-coder portion configured to couple the transmission layers to the transmit antennas for a transmission. The receiver includes a decoder portion which is configured to use decoded signals from at least one group to decode the other groups.

Abstract: A method and apparatus for providing channel feedback is provided herein. During operation a covariance matrix at time t (R) is calculated as a function of a received downlink signal. Matrix Ct is also calculated and is based on a previous quantized covariance matrix (Rqt?1), the covariance matrix (R) at time t, and a forgetting factor (?) that is applied to Rqt?1. The Ct is then used to create a DERC feedback message (signal or waveform) and may be transmitted with pilots on a proper feedback channel to a base unit. The base unit receives the feedback (Ct) as a DERC waveform on a proper feedback channel. The base unit uses non-coherent or coherent detection to detect the DERC values send by the remote unit and uses the DERC values with a previous quantized covariance matrix estimate, a forgetting factor, and a weighting value to compute a covariance matrix estimate to use for beamforming.