Patent application number | Description | Published |
20120250790 | FREQUENCY SELECTIVE IQ CORRECTION - In conventional radio frequency (RF) systems, transmitters will usually convert baseband signals to RF so as to be transmitted. As part of the conversion process, the transmitters will perform digital preditortion (DPD), which uses feedback from a power amplifier. However, there are usually mismatches between the in-phase (I) and quadrature (Q) paths within with feedback loop. Traditional IQ correction filters were ineffective at providing adequate compensation for these mismatches, but here a filter is provided that provides adequate out-of-band compensation by use of frequency selectivity. | 10-04-2012 |
20130083834 | Power-Indexed Look-Up Table Design of Digital Pre-Distortion for Power Amplifiers with Dynamic Nonlinearities - This invention is a method of power amplifier digital pre-distortion which measures a current power level of the power amplifier, stores in a look up table entries consisting of a power level and a corresponding set of digital pre-distortion coefficients, selects a set of digital pre-distortion coefficients corresponding to the measured power level. If the measured current power level is near a power level index, the digital pre-distortion coefficients correspond to the power level index. If the measured current power level is greater than the maximum power level entry, the digital pre-distortion coefficients is of the maximum power level entry. If the measured current power level is less than the minimum power level entry, the digital pre-distortion is of the minimum power level entry. If the measured current power level is not near a power level index, the digital pre-distortion coefficients are an interpolation. | 04-04-2013 |
20140140452 | CREST FACTOR REDUCTION FOR SIGNALS WITH DYNAMIC POWER AND FREQUENCY DISTRIBUTION - A method to form a CFR cancellation filter for signals with dynamic power and frequency distribution by estimating the filter at the rate required by the input signal's dynamics. For mixed mode systems (for example CDMA and LTE) the CFR is computed for each stream, and combined to form the final filter. | 05-22-2014 |
20140169496 | Crest Factor Reduction for Multi-Band System - Systems and methods for crest factor reduction (CFR) are described. A multi-band CFR architecture achieves significant hardware savings without sacrificing CFR performance by applying peak cancellation to each band individually. However, peak detection is calculated based on a combined input signal. | 06-19-2014 |
20140177740 | HEXAGONAL CONSTELLATIONS AND DECODING SAME IN DIGITAL COMMUNICATION SYSTEMS - Embodiments of the invention provide a method of decoding of hexagonal constellations. The decoding methods exploit the inherent structure of the hexagonal grid to eliminate/minimize the requirements for distance computations. A constellation which has unused constellation points is received. A plurality of lookup tables is used for indicating whether a particular constellation point is used. The lookup tables are indexed using the two integers u and v. An initial estimate ū and | 06-26-2014 |
20140294120 | DUAL LOOP DIGITAL PREDISTORTION FOR POWER AMPLIFIERS - A method of predistorting an input signal ( | 10-02-2014 |
20150085748 | SYSTEM AND METHOD FOR CONTROLLING PEAK TO AVERAGE POWER RATIO - A system and method for reducing peak to average power ratio in a wireless communication system. A wireless communication system includes a radio frequency wireless transmitter that includes signal peak reduction circuitry configured to reduce peak to average power ratio of a signal to be transmitted by reducing amplitude of the signal to be transmitted that is greater than a predetermined amplitude. The signal peak reduction circuitry includes a bit inverter configured to invert a bit of a symbol identified as causing the amplitude of the signal to exceed the predetermined amplitude. The bit inverter is also configured to select the bit to invert such that inversion of the bit reduces the amplitude of the signal, and such that forward error correction in a receiver wirelessly coupled to the transmitter restores the bit to a pre-inversion value. | 03-26-2015 |
20150092879 | APPARATUS AND METHOD FOR MULTILEVEL CODING IN COMMUNICATION SYSTEMS - A method includes receiving input blocks each having multiple bits to be transmitted. The method also includes applying a first encoding scheme to a first subset of the bits in the input blocks to generate first encoded bits and applying a second encoding scheme to a second subset of the bits in the input blocks to generate second encoded bits. The second encoding scheme has lower overhead than the first encoding scheme. The method further includes generating symbols using the first and second encoded bits. The first encoded bits include two or more first bits per symbol of each output block, and the second encoded bits include one or more second bits per symbol of each output block. | 04-02-2015 |