Patent application number | Description | Published |
20100195518 | SMOOTH EDGE DISTORTION IN BROADBAND CHANNEL INTERPOLATION VIA VIRTUAL PILOT EXTRAPOLATION - In the basic transform domain (linear filtering interpolation) technique for channel estimation at the receiver in a wireless communication system, the improvement of providing channel estimation at the receiver with computational efficiency, comprising:
| 08-05-2010 |
20100202571 | METHODS AND SYSTEMS FOR FREQUENCY DOMAIN GAIN CONTROL IN OFDM MIMO SYSTEMS - Certain embodiments of the present disclosure provide a method for frequency-domain gain control in system utilizing orthogonal frequency division multiplexing (OFDM) multiple input multiple output (MIMO). The proposed method reduces the complexity of the system while maximizing the internal accuracy of the OFDM MIMO decoder and preserving the performance of the system. | 08-12-2010 |
20110149943 | TIME TRACKING LOOPS FOR A COMMUNICATION SYSTEM UTILIZING A CYCLIC PREFIX - Techniques for performing time tracking in a communication system utilizing a cyclic prefix are described. In an aspect, a receiver may detect for large timing errors based on early and late received samples obtained with early and late FFT windows, respectively. The receiver may derive first and second channel impulse response (CIR) estimates based on the early and late received samples, respectively, determine an early channel energy based on the first CIR estimate, determine a late channel energy based on the second CIR estimate, compute an update amount based on the early and late channel energies, and update the FFT window position based on the update amount. In another aspect, the receiver may perform time tracking with an inner time tracking loop (TTL) and an outer TTL. The receiver may update the FFT window position in coarse steps with the outer TTL and in fine steps with the inner TTL. | 06-23-2011 |
20110158342 | TIME TRACKING FOR A COMMUNICATION SYSTEM UTILIZING A CYCLIC PREFIX - Techniques for performing time tracking in a communication system utilizing a cyclic prefix are described. In an aspect, a receiver may perform time tracking and determine an FFT window position based on a metric related to inter-symbol interference (ISI) and inter-carrier interference (ICI). The receiver may determine an early energy for signal paths earlier than the current FFT window position, determine a late energy for signal paths later than the current FFT window position, determine the metric based on the early and late energies, compute an update amount for the FFT window position based on the metric, and update the FFT window position based on the update amount with a time tracking loop (TTL). In yet another aspect, the receiver may compute the FFT window position based on a channel impulse response (CIR) estimate directly, without using a TTL. | 06-30-2011 |
20110206151 | MULTI-TERM DEMAPPING FOR MULTI-CHANNEL WIRELESS COMMUNICATION - Providing for reduced complexity or improved accuracy in de-mapping received wireless data streams for multi-channel wireless communication is described herein. By way of example, a low-complexity likelihood algorithm can be employed to de-map data bits from the wireless data streams. In one particular example, the likelihood algorithm can approximate a received bit with a subset of received wireless symbols correlated the bit, reducing algorithm complexity. In other examples, a limited set of received wireless symbols can be employed for the subset, further reducing algorithm complexity. According to at least one other example, logarithmic terms of the algorithm can be approximated with non-logarithmic functions, such as a look-up table, series expansion, polynomial approximation, or the like. These approximations can enhance symbol de-mapping accuracy while maintaining or improving processing overhead for a wireless receiver. | 08-25-2011 |
20110211470 | INTERFERENCE REJECTION BY SOFT-WINDOWING CIR ESTIMATES BASED ON PER-TAP QUALITY ESTIMATES - A channel impulse response (CIR) estimate associated with a communication channel may be processed by determining coefficient values that respectively correspond to taps of the CIR estimate, and multiplying the taps by the respectively corresponding coefficient values. The coefficient values are determined according to a soft decision technique. The resulting modified CIR estimate is used to demodulate a communication signal received via the communication channel. | 09-01-2011 |
20120045024 | METHODS AND APPARATUS FOR ITERATIVE DECODING IN MULTIPLE-INPUT-MULTIPLE-OUTPUT (MIMO) COMMUNICATION SYSTEMS - Methods and apparatus for receiving, processing, and decoding MIMO transmissions in communications systems are described. A non-Gaussian approximation method for simplifying processing complexity where summations are used is described. Use of a priori information to facilitate determination of log likelihood ratios (LLRs) in receivers using iterative decoders is further described. A Gaussian or non-Gaussian approximation method using a priori information may be used to determine a K-best list of values for summation to generate an LLR is also described. | 02-23-2012 |
20120176922 | DOWNLINK FLOW CONTROL BY ADDING NOISE TO A RECEIVER TO REDUCE PHYSICAL LAYER THROUGHPUT - Aspects of the present disclosure relate to wireless communications and techniques and apparatus for downlink flow control at the physical layer of a user equipment (UE). Aspects generally include monitoring one or more parameters related to the UE and intentionally reducing channel quality based on the one or more parameters to trigger downlink flow control. According to aspects, channel quality may be reduced by degrading receiver performance and/or intentionally adding noise to a signal. | 07-12-2012 |
20120219097 | TWO-STEP JOINT DEMAPPING ALGORITHM FOR LLR COMPUTATION OF MIMO SIGNAL BASED ON SPHERE DECODING - Certain aspects of the present disclosure relate to a technique for two-step joint demapping based on sphere decoding for log-likelihood ratio (LLR) computation related to a received multiple-input multiple-output (MIMO) signal. The first step of the proposed algorithm comprises a linear minimum mean square error (LMMSE) based detection to form soft symbol estimates of symbols being transmitted. Then, the LMMSE-based soft symbol estimates can be utilized to form a set of constellation points of a stream interfering to a stream of interest. These candidate constellation points can be then subtracted (canceled) from the received signal to improve the LLR computations of the stream of interest. After the cancellation, the maximum ratio combining (MRC) can be applied to each individual stream to form more refined soft symbol estimates as well as an effective signal-to-noise ratio (SNR) estimate. The refined outputs of the MRC can be utilized to compute LLRs of transmitted bits based on the effective SNR and the refined soft symbol estimates associated with all the candidate constellation points from the set. The LLRs of transmitted bits may be employed by a channel decoder. | 08-30-2012 |
20130235818 | Channel Estimation in Wireless Networks - Aspects of the present disclosure generally relate to wireless communications and, more particularly, to performing channel estimation with modifications for improved system performance. Aspects generally include receiving, at a user equipment (UE), reference signals from a base station in a current subframe, and performing channel estimation, wherein the channel estimation is based at least in part on the reference signals received in the current subframe, a mobility characteristic of the UE, and a configuration of subframes prior to the current subframe. | 09-12-2013 |
20130343267 | METHODS AND APPARATUSES FOR FLASH WCDMA FREQUENCY SCANS - A method and apparatus of wireless communication are configured to capture, at a user equipment, one or more adjacent Universal Mobile Telecommunication System Terrestrial Radio Access Absolute Radio Frequency Channel Numbers (UARFCNs), extract a useful wide band signal from the one or more adjacent UARFCNs, perform a PSCH search on the useful wide band signal to obtain a composite PSCH signal, and reject the one or more UARFCNs where no peaks greater than a noise threshold are detected in the composite PSCH signal. | 12-26-2013 |
20140200685 | THERMAL MITIGATION IN DUAL SIM DUAL ACTIVE DEVICES - A system, a method and an apparatus are described. The apparatus includes a modem that responds to a thermal mitigation request by invoking different levels of thermal mitigation for different concurrently active connections. In some instances, the modem may invoke thermal mitigation with respect to a first active connection and refrain from invoking thermal mitigation with respect to a second active connection maintained by the modem. The apparatus determines the first and second active connections based on subscriptions corresponding to subscriber identification modules, an identification of a power amplifier or group of power amplifiers responsible for a thermal issue in the modem. The selection of mitigation levels for each active connection and decisions to invoke mitigation on one connection while refraining from invoking mitigation on another connection may be based on priorities of the active connections, including quality of service related priorities. | 07-17-2014 |
20140213210 | Method of Robust Receive (Rx) Processing for Radio Frequency Coexistence Management in Dual-SIM-Dual-Active Communication Devices - The various embodiments include a dual-SIM-dual-active (DSDA) device and methods for implementing robust receive (Rx) processing to resolve radio frequency coexistence interference between two subscriptions operating on the DSDA device. The DSDA device may detect when a subscription (the “aggressor”) de-senses the other subscription (the “victim”) as a result of the aggressor's transmissions, and in response, implement robust Rx processing to mitigate the effects of de-sense on the victim while causing minimal impact to the aggressor. | 07-31-2014 |
20140213235 | Method of Robust Transmit (Tx) Processing for Radio Frequency Coexistence Management in Dual-SIM-Dual-Active communication Devices - The various embodiments include a dual-SIM-dual-active (DSDA) device and methods for implementing robust transmit (Tx) processing to resolve radio frequency coexistence interference between two subscriptions operating on the DSDA device. The DSDA device may detect when one subscription (the “aggressor”) de-senses the other subscription (the “victim”) as a result of the aggressor's transmissions, and in response, implement robust Tx processing to mitigate the effects of de-sense on the victim. | 07-31-2014 |