Qualcomm

About: Qualcomm is a company organization based out in Farnborough, United Kingdom. It is known for research contribution in the topics: Wireless & Signal. The organization has 19408 authors who have published 38405 publications receiving 804693 citations. The organization is also known as: Qualcomm Incorporated & Qualcomm, Inc..

Channel calibration for a time division duplexed communication system

Abstract: Techniques are described to calibrate the downlink and uplink channels to account for differences in the frequency responses of the transmit and receive chains at an access point and a user terminal. In one method, pilots are transmitted on the downlink and uplink channels and used to derive estimates of the downlink and uplink channel responses, respectively. Correction factors for the access point and correction factors for the user terminal are determined based on (e.g., by performing matrix-ratio computation or minimum mean square error (MMSE) computation on) the downlink and uplink channel response estimates. The correction factors for the access point and the correction factors for the user terminal are used to obtain a calibrated downlink channel and a calibrated uplink channel, which are transpose of one another. The calibration may be performed in real time based on over-the-air transmission.

Joint linear and non-linear cancellation of transmit self-jamming interference

Abstract: Certain aspects of the present disclosure propose an adaptive joint linear and non-linear digital filter that can adaptively estimate and reconstruct cascaded effects of linear and non-linear self-jamming distortions introduced by non-linearities in the transmit and/or receive chains. The proposed digital filter may be used to cancel second-order inter-modulation distortion (IM2) generated in the receive chain and/or harmonic distortion generated in the transmit chain, as well as other distortions introduced by the transmit/and or receive chains.

Method for indicating location and direction of a graphical user interface element

Abstract: In a particular embodiment, a method includes receiving a user input at a first display surface of an electronic device to move a graphical user interface element displayed at the first display surface. The electronic device includes a second display surface separated from the first display surface by a gap. The method also includes determining that at least a portion of the graphical user interface element is to be moved beyond an edge of the first display surface into the gap such that the at least a portion of the graphical user element will not be displayed at the first display surface. The method further includes displaying the at least a portion of the graphical user interface element at the second display surface based on a location and a direction of movement of the graphical user interface element at the first display surface.

Varied transmission time intervals for wireless communication system

Abstract: Embodiments describe a varied transmission time interval in wireless communication system. According to some embodiments is a method for assigning a transmission time interval. The method can include measuring a channel condition and/or a data rate of packet communicated by at least one wireless device. Based in part on the data rate and/or channel condition information, a determination can be made whether to schedule a long transmission time interval or a short transmission time interval to the packet. A long transmission time interval can be scheduled if the channel condition is poor and/or there is a low data rate. A short transmission time interval can be scheduled if the channel condition is good and/or the data rate is high or fast. The method can be repeated for multiple wireless devices. Also included is an alternative interlacing structure that supports both long transmission time intervals and short transmission time intervals.

Error performance of transmit beamforming with delayed and limited feedback

Abstract: Feedback delay can severely affect the performance of transmit beamforming (TB) and the analytical quantification of the performance degradation has attracted much research interest recently. In this letter, we study the effect of delayed and limited-rate codebook index feedback on the error rate performance of TB systems over Rayleigh fading channels. We derive closed-form expressions for the moment generating function (MGF) and the probability density function (PDF) of the receiver output signal-to-noise ratio (SNR) including the effects of outdated and finite-rate feedback and further provide accurate analytical error rate expressions, which are verified by simulation results. The coding gain gap between the full-rate and limited-rate feedback and the coding gain advantage of multiple transmit antennas to the single antenna are analyzed, for limited and delayed feedback. These results are simple and concise and provide new analytical insight into the achievable diversity and combining gains and the loss caused by feedback delay for different system parameters and modulation formats.