Patent application number | Description | Published |
20090175398 | I/Q IMBALANCE ESTIMATION AND CORRECTION IN A COMMUNICATION SYSTEM - Certain aspects and embodiments provide for accurate measurement and estimation of imbalances between in-phase (I) and quadrature (Q) components of a complex baseband signal. The accuracy of I/Q phase imbalance estimates may be enhanced by conducting them on a transmitter and a receiver that are connected via a local, loopback connection and by removing cross-spectrum interference in transferred packets. Once these accurate I/Q phase imbalances are determined, they may be used to adjust a signal processed by the transmitter or the receiver to increase the performance and data throughput of communications using the signal. | 07-09-2009 |
20090322621 | ANTENNA ARRAY CONFIGURATIONS FOR HIGH THROUGHPUT MIMO WLAN SYSTEMS - The present disclosure provides techniques for configuring multi-element antenna arrays. Such antenna arrays may be designed with slot pairs separated by λ/2 along perpendicular axes (e.g., x and y-directions). One such array may have four or more co-located antenna element pairs formed with cross slots having the same rotational orientation. Another such array may have four or more co-located antenna element pairs formed with some cross slots having the same rotational orientation and other cross slots having a different rotational orientation. | 12-31-2009 |
20100183088 | CALIBRATION OF TRANSMIT AND RECEIVE CHAINS IN A MIMO COMMUNICATION SYSTEM - Techniques for calibrating the transmit and receive chains at a wireless entity are described. For a pre-calibration, N first overall gains for a receiver unit and N transmitter units in the transmit chain are obtained, where N>1. Each first overall gain is for a combined response for the receiver unit and the associated transmitter unit. N second overall gains for a transmitter unit and N receiver units in the receive chain are also obtained. Each second overall gain is for a combined response for the transmitter unit and the associated receiver unit. The gain of each transmitter unit and the gain of each receiver unit are determined based on the first and second overall gains. At least one correction matrix is then derived based on the gains of the transmitter and receiver units and is used to account for the responses of these units. | 07-22-2010 |
20100285733 | WIDEBAND ECHO CANCELLATION IN A REPEATER - A wireless repeater having a receiving antenna for receiving an input signal and a transmitting antenna for transmitting an amplified signal includes first and second front-end circuits and a repeater baseband block coupled between the first and second front-end circuits. The repeater baseband block includes a channel estimation block, an echo canceller implementing time domain echo cancellation, a variable gain stage controlled by a gain control block implementing digital gain control, a first variable delay element introducing a first delay before or after the echo canceller, a second variable delay element introducing a second delay to the output signal. The delayed output signal is coupled to the channel estimation block as a reference signal for estimating the feedback channel, to the echo canceller as a reference signal for estimating the feedback signal, and to the gain control block for monitoring the stability of the repeater. | 11-11-2010 |
20110013724 | I/Q IMBALANCE ESTIMATION AND COMPENSATION FOR A TRANSMITTER AND A RECEIVER - Techniques for performing inphase/quadrature (I/Q) imbalance estimation and compensation are described. In one exemplary design, I/Q imbalances in a receiver may be estimated by (i) applying a continuous wave signal at different frequencies to the receiver and (ii) processing I and Q input samples from the receiver to determine I/Q imbalances at different frequencies. In another exemplary design, I/Q imbalances may be estimated by (i) downconverting an input RF signal with an LO signal that is offset in frequency from the input RF signal, (ii) transforming I and Q input samples from the receiver to the frequency domain to obtain I and Q symbols, and (iii) determining I/Q imbalances based on the I and Q symbols. In one exemplary design, I/Q imbalances may be corrected by compensating for frequency-dependent and frequency-independent I/Q imbalances separately. I/Q imbalances in a transmitter may also be estimated and compensated. | 01-20-2011 |
20120015603 | METHOD IN A WIRELESS REPEATER EMPLOYING AN ANTENNA ARRAY INCLUDING VERTICAL AND HORIZONTAL FEEDS FOR INTERFERENCE REDUCTION - An echo cancellation wireless repeater with first and second antenna arrays having vertical and horizontal feed antenna elements selects a combination of antenna elements for reception and transmission to reduce interference and improve the quality of signal reception. In one embodiment, the antenna elements are switchably connected to transceiver circuits and a combination of antenna elements is selected based on the best desired performance result. In another embodiment, the antenna elements are each connected to its own transceiver circuit and the echo cancellation repeater performs beamforming in baseband to select a combination of antenna elements. | 01-19-2012 |
20120015608 | METHOD IN A WIRELESS REPEATER EMPLOYING AN ANTENNA ARRAY FOR INTERFERENCE REDUCTION - A wireless repeater with an antenna array determines the antenna weights to modify the spatial selectivity of the antenna array to reduce interference and improve the quality of signal reception. The antenna weights are determined using an error minimizing algorithm to minimize the error between a desired receive signal and a reference signal or an adaptive metric optimization algorithm to calculate adaptively antenna weights to minimize the signal-to-noise ratio of a desired receive signal. | 01-19-2012 |
20120300818 | SELF-CALIBRATION I/Q IMBALANCE REDUCTION - A method for a self-calibrating reduction in inphase/quadrature imbalance is described. An inphase/quadrature amplitude imbalance is calculated. A correction to the inphase/quadrature amplitude imbalance is applied. An estimated inphase/quadrature phase imbalance is calculated. Calculating an estimated inphase/quadrature phase imbalance includes calculating a loopback phase. A correction to the estimated inphase/quadrature amplitude imbalance is applied. | 11-29-2012 |