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..

High-Rate Communication for Underwater Acoustic Channels Using Multiple Transmitters and Space–Time Coding: Receiver Structures and Experimental Results

Abstract: In this paper, we consider the use of multiple antennas and space-time coding for high data rate underwater acoustic (UWA) communications. Recent advances in information theory have shown that significant capacity gains can be achieved by using multiple-input-multiple-output (MIMO) systems and space-time coding techniques for rich scattering environments. This is especially significant for the UWA channel where the usable bandwidth is severely limited due to frequency-dependent attenuation. In this paper, we propose to use space-time coding and iterative decoding techniques to obtain high data rates and reliability over shallow-water, medium-range UWA channels. In particular, we propose to use space-time trellis codes (STTCs), layered space-time codes (LSTCs) and their combinations along with three low-complexity adaptive equalizer structures at the receiver. We consider multiband transmissions where the available bandwidth is divided into several subbands with guard bands in between them. We describe the theoretical basis of the proposed receivers along with a comprehensive set of experimental results obtained by processing data collected from real UWA communications experiments carried out in the Pacific Ocean. We demonstrate that by using space-time coding at the transmitter and sophisticated iterative processing at the receiver, we can obtain data rates and spectral efficiencies that are not possible with single transmitter systems at similar ranges and depths. In particular, we have demonstrated reliable transmission at a data rate of 48 kb/s in 23 kHz of bandwidth, and 12 kb/s in 3 kHz of bandwidth (a spectral efficiency of 4 bs-1Hz-1) at a 2-km range.

Combining data from multiple image sensors

Abstract: A method of combining data from multiple sensors is disclosed. The method includes receiving lines of image data at an image processor having an input for a single camera. Each line of the image data includes first line data from a first image captured by a first camera and second line data from a second image captured by a second camera. The method also includes generating an output frame having a first section corresponding to line data of the first image and having a second section corresponding to line data of the second image. The first section and the second section are configured to be used to generate a three-dimensional (3D) image format or a 3D video format.

Method and system for providing beamforming feedback in wireless communication systems

Abstract: Techniques for quickly sending feedback information for beamforming are described A transmitter/initiator sends a first frame comprising training symbols A receiver/responder receives the first frame, determines the amount of time to generate feedback information, and determines the amount of time to send the feedback information The receiver then determines the length of a second frame carrying the feedback information based on the amounts of time to generate and send the feedback information The receiver sends the second frame after waiting a short interframe space (SIFS) period from the end of the first frame, without performing channel access The receiver generates the feedback information based on the training symbols and sends the information in the second frame when ready The transmitter receives the second frame, derives at least one steering matrix based on the feedback information, and sends a third frame with the at least one steering matrix

High speed media access control and direct link protocol

Abstract: Techniques for MAC processing for efficient use of high throughput systems that may be backward compatible with various types of legacy systems are disclosed. In one aspect, a data frame is formed comprising a common portion for transmission in a format receivable by various stations, such as access points and remote stations. The data frame also comprises a dedicated portion, formatted for transmission to a specified remote station. In another aspect, the common portion is unsteered, and the dedicated portion is steered. In another aspect, an access point schedules an allocation in response to a data indication included in a common portion of a data frame transmitted from one remote station to another. In another aspect, a first station transmits a reference to a second station, which measures the reference and generates feedback therefrom.

Wireless position determination using adjusted round trip time measurements

Abstract: One method for wirelessly determining a position of a mobile station includes measuring a round trip time (RTT) to a plurality of wireless access points, estimating a first distance to each wireless access point based upon the round trip time delay and an initial processing time associated with each wireless access point, estimating a second distance to each wireless access point based upon supplemental information, combining the first and second distance estimates to each wireless access point, and calculating the position based upon the combined distance estimates. Another method includes measuring a distance to each wireless access point based upon a wireless signal model, calculating a position of the mobile station based upon the measured distance, determining a computed distance to each wireless access point based upon the calculated position of the mobile station, updating the wireless signal model, and determining whether the wireless signal model has converged.