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..

Multiplexing and transmission of traffic data and control information in a wireless communication system

Abstract: Techniques for transmitting traffic data and control information in a wireless communication system are described. In an aspect, traffic data and control information may be multiplexed at a coded data level. A user equipment (UE) may encode traffic data to obtain coded traffic data, encode control information to obtain coded control data, multiplex the coded traffic data and the coded control data, modulate the multiplexed data, and generate SC-FDMA symbols. In another aspect, traffic data and control information may be multiplexed at a modulation symbol level. The UE may encode and modulate traffic data to obtain data modulation symbols, encode and modulate control information to obtain control modulation symbols, multiplex the data and control modulation symbols, and generate SC-FDMA symbols. The UE may perform rate matching for traffic data to account for control information. The UE may also perform multiplexing and puncturing for different types of control information.

Efficient operation for co-located WLAN and Bluetooth

Abstract: Techniques to enable efficient operation of co-located WLAN and Bluetooth devices are described. A station (e.g., a cellular phone or a laptop computer) determines the activity of a Bluetooth device and ascertains idle periods of the Bluetooth device. The station communicates with an access point in a WLAN during the idle periods of the Bluetooth device. The station may operate in a power save mode with the access point, send a poll frame to the access point during an idle period, and retrieve the buffered data from the access point during the idle period. The station may also operate in an unscheduled APSD mode with the access point, send a trigger frame to the access point during an idle period to start a service period, and exchange data with the access point during the service period.

Adaptive Loop Filtering for Video Coding

Abstract: Adaptive loop filtering for video coding is to minimize the mean square error between original samples and decoded samples by using Wiener-based adaptive filter. The proposed ALF is located at the last processing stage for each picture and can be regarded as a tool to catch and fix artifacts from previous stages. The suitable filter coefficients are determined by the encoder and explicitly signaled to the decoder. In order to achieve better coding efficiency, especially for high resolution videos, local adaptation is used for luma signals by applying different filters to different regions or blocks in a picture. In addition to filter adaptation, filter on/off control at coding tree unit (CTU) level is also helpful for improving coding efficiency. Syntax-wise, filter coefficients are sent in a picture level header called adaptation parameter set, and filter on/off flags of CTUs are interleaved at CTU level in the slice data. This syntax design not only supports picture level optimization but also achieves a low encoding latency. Simulation results show that the ALF can achieve on average 7% bit rate reduction for 25 HD sequences. The run time increases are 1% and 10% for encoders and decoders, respectively, without special attention to optimization in C++ code.

Type-Based Decentralized Detection in Wireless Sensor Networks

Abstract: Distributed detection strategies for wireless sensor networks are studied under the assumption of spatially and temporally independent and identically distributed (i.i.d.) observations at the sensor nodes. Both intelligent (with knowledge of observation statistics) and dumb (oblivious of observation statistics) sensors are considered. Two types of communication channels are studied: a parallel access channel (PAC) in which each sensor has a dedicated additive white Gaussian noise (AWGN) channel to a decision center, and a multiple-access channel (MAC) in which the decision center receives a coherent superposition of the sensor transmissions. Our results show that the MAC yields significantly superior detection performance for any network power constraint. For intelligent sensors, uncoded (finite duration) communication of local log-likelihood ratios over the MAC achieves the optimal error exponent of the centralized (noise-free channel) benchmark as the number of nodes increases, even with sublinear network power scaling. Motivated by this result, we propose a distributed detection strategy for dumb sensors-histogram fusion-in which each node appropriately quantizes its temporal data and communicates its type or histogram to the decision center. It is shown that uncoded histogram fusion over the MAC is also asymptotically optimal under sublinear network power scaling with an additional advantage: knowledge of observation statistics is needed only at the decision center. Histogram fusion achieves exponential decay in error probability with the number of nodes even under a finite total network power. In principle, a vanishing error probability at a slower subexponential rate can be attained even with vanishing total network power in the limit. These remarkable power/energy savings with the number of nodes are due to the inherent beamforming gain in the MAC

Random access for wireless multiple-access communication systems

Abstract: Techniques for facilitating random access in wireless multiple-access communication systems. A random access channel (RACH) is defined to comprise a "fast" RACH (F-RACH) and a "slow" RACH (S-RACH). The F-RACH and S-RACH can efficiently support user terminals in different operating states and employ different designs. The F-RACH can be used to quickly access the system, and the S-RACH is more robust and can support user terminals in various operating states and conditions. The F-RACH may be used by user terminals that have registered with the system and can compensate for their round trip delays (RTDs) by properly advancing their transmit timing. The S-RACH may be used by user terminals that may or may not have registered with the system, and may or may not be able to compensate for their RTDs. The user terminals may use the F-RACH or S-RACH, or both, to gain access to the system.