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 multiple data streams in a wireless multi-carrier communication system

Abstract: Techniques for multiplexing and transmitting multiple data streams are described. Transmission of the multiple data streams occurs in “super-frames”. Each super-frame has a predetermined time duration and is further divided into multiple (e.g., four) frames. Each data block for each data stream is outer encoded to generate a corresponding code block. Each code block is partitioned into multiple subblocks, and each data packet in each code block is inner encoded and modulated to generate modulation symbols for the packet. The multiple subblocks for each code block are transmitted in the multiple frames of the same super-frame, one subblock per frame. Each data stream is allocated a number of transmission units in each super-frame and is assigned specific transmission units to achieve efficient packing. A wireless device can select and receive individual data streams.

Investigation of Prediction Accuracy, Sensitivity, and Parameter Stability of Large-Scale Propagation Path Loss Models for 5G Wireless Communications

Abstract: This paper compares three candidate large-scale propagation path loss models for use over the entire microwave and millimeter-wave (mmWave) radio spectrum: the alpha–beta–gamma (ABG) model, the close-in (CI) free-space reference distance model, and the CI model with a frequency-weighted path loss exponent (CIF). Each of these models has been recently studied for use in standards bodies such as 3rd Generation Partnership Project (3GPP) and for use in the design of fifth-generation wireless systems in urban macrocell, urban microcell, and indoor office and shopping mall scenarios. Here, we compare the accuracy and sensitivity of these models using measured data from 30 propagation measurement data sets from 2 to 73 GHz over distances ranging from 4 to 1238 m. A series of sensitivity analyses of the three models shows that the four-parameter ABG model underpredicts path loss when relatively close to the transmitter, and overpredicts path loss far from the transmitter, and that the physically based two-parameter CI model and three-parameter CIF model offer computational simplicity, have very similar goodness of fit (i.e., the shadow fading standard deviation), exhibit more stable model parameter behavior across frequencies and distances, and yield smaller prediction error in sensitivity tests across distances and frequencies, when compared to the four-parameter ABG model. Results show the CI model with a 1-m reference distance is suitable for outdoor environments, while the CIF model is more appropriate for indoor modeling. The CI and CIF models are easily implemented in existing 3GPP models by making a very subtle modification—by replacing a floating non-physically based constant with a frequency-dependent constant that represents free-space path loss in the first meter of propagation. This paper shows this subtle change does not change the mathematical form of existing ITU/3GPP models and offers much easier analysis, intuitive appeal, better model parameter stability, and better accuracy in sensitivity tests over a vast range of microwave and mmWave frequencies, scenarios, and distances, while using a simpler model with fewer parameters.

Mobile users: to update or not to update?

Abstract: Tracking strategies for mobile users in wireless networks are studied. In order to save the cost of using the wireless links mobile users should not update their location whenever they cross boundaries of adjacent cells. The paper focuses on three natural strategies in which the mobile users make the decisions when and where to update: the time-based strategy, the number of movements-based strategy, and the distance-based strategy. The authors consider both memoryless movement patterns and movements with Markovian memory along a topology of cells arranged as a ring. They analyze the performance of each one of the three strategies under such movements, and show the performance differences between the strategies. >

Video coding with large macroblocks

Abstract: Techniques are described for encoding and decoding digital video data using macroblocks that are larger than the macroblocks prescribed by conventional video encoding and decoding standards. For example, the techniques include encoding and decoding a video stream using macroblocks comprising greater than 16×16 pixels. In one example, an apparatus includes a video encoder configured to encode a coded unit comprising a plurality of video blocks, wherein at least one of the plurality of video blocks comprises a size of more than 16×16 pixels and to generate syntax information for the coded unit that includes a maximum size value, wherein the maximum size value indicates a size of a largest one of the plurality of video blocks in the coded unit. The syntax information may also include a minimum size value. In this manner, the encoder may indicate to a decoder the proper syntax decoder to apply to the coded unit.

Signal classification using statistical moments

Abstract: An automatic modulation classification algorithm utilizing the statistical moments of the signal phase is developed and used to classify the modulation type of general M-ary PSK signals. It is shown that the nth moment (n even) of the phase of the signal is a monotonic increasing function of M. On the basis of this property, the authors formulate a general hypothesis test, develop a decision rule, and derive an analytic expression for the probability of misclassification. Two examples are given to demonstrate the performance of the algorithm. The algorithm is compared with the quasi-log-likelihood radio (qLLRC), square-law (SLC), and phase-based (PBC) classifiers. The algorithm is outperformed by qLLRC at low CNR but is comparable to SLC and is better than PBC. The qLLRC algorithm is only valid at CNR >