Patent application number | Description | Published |
20090083352 | METHODS AND APPARATUS FOR PERFORMING REDUCED COMPLEXITY DISCRETE FOURIER TRANSFORMS USING INTERPOLATION - Methods and apparatus arc provided for performing reduced complexity discrete Fourier transforms using interpolation An input sequence of length N is transformed by extending the input sequence to an extended input sequence of length M, where M is greater than N (a power of two greater than N); performing a discrete Fourier Transform (DFT), such as a power-of-two DFT, on the extended input sequence to obtain an interpolated sequence; and applying a conversion matrix to the interpolated sequence to obtain a DFT output for the input sequence of length N. The input sequence of length N can be extended to an extended input sequence of length M, for example, by employing a zero padding technique, a cyclic extension technique, a windowing of a cyclic extended sequence technique or a resampling-based interpolation technique to extend the input sequence The conversion matrix is substantially a spar se matrix. | 03-26-2009 |
20100197264 | UPLINK CHANNEL ESTIMATION - In one embodiment, a receiver is provided for use in a multiple-input system that includes a receiving antenna receiving a time-domain signal corresponding to a plurality of signals transmitted from a plurality of transmitting antennas. The receiver includes: (a) a transform unit adapted to transform the time-domain signal into a frequency-domain signal; (b) a channel estimation unit adapted to estimate, based on the frequency-domain signal and a frequency-domain pilot signal, a combined transfer function corresponding to a plurality of transfer functions of respective channels between the plurality of transmitting antennas and the receiving antenna; and (c) a channel separation unit including a plurality of frequency-domain convolution units that separate the combined transfer function into a plurality of estimated channel transfer functions. | 08-05-2010 |
20100304687 | METHODS AND APPARATUS FOR SIMULTANEOUS ESTIMATION OF FREQUENCY OFFSET AND CHANNEL RESPONSE FOR MU-MIMO OFDMA - Methods and apparatus are provided for simultaneous estimation of frequency offset and channel response for a communication system, such as a MU-MIMO communication system. An iterative method is provided for estimating frequency offset and channel response for a plurality of frequency resources. The channel response is estimated for a set of users sharing a given one of the frequency resources. In addition, the frequency offset is estimated for the users in the set, wherein the channel response and frequency offset of users not in the set are maintained at their latest updated values. Initially, the channel response of a user can be an ideal channel response and the frequency offset can be approximately zero. | 12-02-2010 |
20110026650 | Rapid Sampling Phase Recovery - In a communication receiver, timing recovery circuitry includes a loop filter associated with a timing recovery loop of a first communication device. The first communication device is in communication with a second communication device prior to a temporary power down/power up sequence in the first communication device. The loop filter is configured to: (i) temporarily disable at least a portion of the timing recovery loop after the temporary power down/power up sequence in the first communication device; and (ii) initiate a progression through a set of potential sampling phases to determine a given sampling phase at which the first communication device can recommence communication with the second communication device. | 02-03-2011 |
20110051867 | METHODS AND APPARATUS FOR WIRELESS CHANNEL ESTIMATION USING INTERPOLATION ELIMINATION IN THE EIGEN DOMAIN - Methods and apparatus are provided for wireless channel estimation using interpolation elimination in the Eigen domain. Channel components at known OFDM symbol locations are interpolated to other OFDM symbol locations. Methods and apparatus are provided for interpolating in the Eigen domain between reference signals (i.e., training signals) to estimate the equalizer coefficients with a reduced complexity. In particular, one aspect of the present invention performs the required interpolation before a required matrix inversion in the Eigen domain. | 03-03-2011 |
20130028342 | UPLINK CHANNEL ESTIMATION - In one embodiment, a receiver is provided for use in a multiple-input system that includes a receiving antenna receiving a time-domain signal corresponding to a plurality of signals transmitted from a plurality of transmitting antennas. The receiver includes: (a) a transform unit adapted to transform the time-domain signal into a frequency-domain signal; (b) a channel estimation unit adapted to estimate, based on the frequency-domain signal and a frequency-domain pilot signal, a combined transfer function corresponding to a plurality of transfer functions of respective channels between the plurality of transmitting antennas and the receiving antenna; and (c) a channel separation unit including a plurality of frequency-domain convolution units that separate the combined transfer function into a plurality of estimated channel transfer functions. | 01-31-2013 |
20130336144 | RECEIVER AND METHOD FOR ESTIMATING A PLURALITY OF ESTIMATED TRANSFER FUNCTIONS CORRESPONDING TO WIRELESS CHANNELS IN A MULTIPLE-INPUT SYSTEM - In one embodiment, a receiver is provided for use in a multiple-input system that includes a receiving antenna receiving a time-domain signal corresponding to a plurality of signals transmitted from a plurality of transmitting antennas. The receiver includes: (a) a transform unit adapted to transform the time-domain signal into a frequency-domain signal; (b) a channel estimation unit adapted to estimate, based on the frequency-domain signal and a frequency-domain pilot signal, a combined transfer function corresponding to a plurality of transfer functions of respective channels between the plurality of transmitting antennas and the receiving antenna; and (c) a channel separation unit including a plurality of frequency-domain convolution units that separate the combined transfer function into a plurality of estimated channel transfer functions. | 12-19-2013 |
20150106577 | DE-INTERLEAVING ON AN AS-NEEDED BASIS - One embodiment is an apparatus having a memory, a controller, and a de-interleaving module. The memory is configured to store portions of a set of interleaved values, where the set of interleaved values correspond to a single application of an interleaving mapping to a set of un-interleaved values. The controller is configured to retrieve each portion from an other memory that stores the set of interleaved values by moving the portion from the other memory to the memory. The de-interleaving module is configured to de-interleave the interleaved values in at least one of the portions to generate a de-interleaved portion such that processing downstream of the de-interleaving module can begin processing the de-interleaved portion before all of the interleaved values in the set of interleaved values are de-interleaved by the de-interleaving module. | 04-16-2015 |