Magis Networks, Inc.

Other

The Titan Corporation

Quintic Holdings

M2 Networks, Inc.

Photonics Products, Inc.

Photon Products, Inc.

Andre Alain Tabourian

James A Crawford

Ronald F Mathis

Paul N Huntley

Barry L Dorr

Stephen R Mathis

William L Floyd

Dennis Patrick Connors

Javad Razavilar

Neeraj Poojary

Systems and methods for bandwidth reduction in polar modulation systems are described. Detection of problematic signal transition paths may performed, and then, dependent on the signal path, a correction signal may be generated and added to the signal to improve system performance. In typical implementations, detection of problematic signal paths may be performed by determining whether the signal transitions through a particular region in the signal constellation, such as a region about the origin, or whether the signal instantaneous frequency exceeds a predetermined threshold, and then responsively generating the correction signal.

Pulse insertion systems and methods for polar modulation

Methods and apparatus for calibrating the VCO element of a phase-locked loop to correct for non-linearities are disclosed. The modulation port of the VCO may be characterized to generate a tuning model, which may then be used to generate a correction signal to be combined with an input signal and applied to the VCO modulation port. The tuning model may be based on a third or higher order polynomial generated from a plurality of open-loop frequency measurements of the VCO.

Systems and methods for improved VCO gain tracking loop

A waveform acquisition system that captures and digitizes a wideband electrical signal through a bank of front end filters, frequency down converters, and conventional digitizers (A/D converters). A software algorithm reconstructs the composite input signal and applies the necessary corrections to remove the effects of hardware impairments. This approach is possible because it uses a class of filters that exhibit the quality of perfect waveform reconstruction, allowing signals whose spectral components overlap multiple filter bands, to be faithfully reconstructed. A calibration generator switched into the input port serves as a reference for quantifying and removing hardware errors. The channelized analog-to-digital converter (ADC) effectively multiplies the bandwidth and sampling rate of the conventional digitizer performance in a single channel by the number of channels in the system.

Channelized analog-to-digital converter

A pilot phase tracking loop for an OFDM receiver including a phase rotator receiving an incoming signal, a fast Fourier transform coupled to a phase rotator output, and a pilot phase error metric including a discrete Fourier transform portion coupled to the phase rotator output. The pilot phase error metric determines a phase error estimate associated with a received OFDM symbol, e.g., a data symbol, from the phase rotator output. A loop filter is coupled to the pilot phase error metric output and an oscillator is coupled to the loop filter output. The oscillator output is coupled to the phase rotator to adjust the phase of subsequent OFDM symbols of the incoming signal. Phase noise introduced by a radio portion of the OFDM receiver and OFDM transmitter is reduced by the baseband portion of the OFDM receiver improving OFDM signal tracking under poor SNR conditions.

OFDM pilot tone tracking for wireless LAN

A rate and power control algorithm for a communication system, the algorithm including the steps of: assigning a target channel condition metric to be met at a first terminal for signaling received from each of one or more remote terminals of the system, each terminal supporting a plurality of rates and a plurality of transmit power levels, each target channel condition metric based upon the type of service supported by each remote terminal; receiving a signal at the first terminal from each remote terminal; and adjusting a respective target channel condition metric assigned for a respective remote terminal in response to signal information generated from the received signal. In variations, the algorithm is performed in a distributed manner by different cells of a communication system and at least two of the remote terminals support traffic of different types of service.

Method and apparatus for adaptive QoS-based joint rate and power control algorithm in multi-rate wireless systems

A method of transmission level security, and a corresponding transmission security system, the method consists of the steps of: forming a plurality of digital signals representing a symbol to be transmitted over a communication medium, wherein respective ones of the plurality of digital signals are modulated onto respective ones of a plurality of subcarriers according to a multiple carrier modulation scheme; and introducing a predetermined group delay distortion in one or more of the plurality of subcarriers, such that portions of the one or more of the plurality of subcarriers will be received outside of a time window corresponding to the symbol at a receiver. In one implementation, an equipped receiver substantially removes the predetermined group delay distortion such that the portions of the one or more of the plurality of subcarrier fit within the time window.

Transmission security for wireless communications

A pilot phase tracking loop for an OFDM receiver including a phase rotator for receiving an incoming signal, which is coupled to a Fourier transform, which is coupled to a pilot phase error metric for determining a phase error estimate associated with a received OFDM symbol, e.g., a data symbol. The pilot phase error metric is coupled to a loop filter, which is coupled to an oscillator, which is coupled back to the phase rotator. The phase rotator rotates the incoming signal by the filtered phase error estimate for subsequent OFDM symbols to reduce the phase noise of the signaling output from the phase rotator. Thus, the phase noise introduced by a radio portion of the OFDM receiver and an OFDM transmitter is compensated for by the pilot phase error estimation in the baseband portion of the OFDM receiver and improved OFDM signal tracking is accomplished under poor SNR conditions.

A method and apparatus of pilot phase error estimation in an orthogonal frequency division multiplexed (OFDM) receiver including the steps of: determining pilot reference points corresponding to a plurality of pilots of an OFDM preamble waveform; and estimating an aggregate phase error of a subsequent OFDM data symbol relative to the pilot reference points using complex signal measurements corresponding to each of the plurality of pilots of the subsequent OFOM data symbol and the pilot reference points. For example, a maximum likelihood based estimation is performed using the complex signal measurements and the pilot reference points. Thus, the poor phase performance in a radio portion of the OFDM receiver is compensated for by the pilot phase error estimation in the baseband portion of the OFDM receiver and improved OFDM signal tracking accomplished under poor SNR conditions.

Optimum phase error metric for OFDM pilot tone tracking in wireless LAN

A card-based diversity antenna structure includes a card and at least two antenna elements. The card has active circuitry attached thereto and connectors located at a first end thereof configured for engagement with an interface slot. The at least two antenna elements are attached to the card at a second end thereof and are coupled to the active circuitry. At least two antenna elements are sufficiently spaced apart so as to achieve spatial diversity. The polarizations of two of the at least two antenna elements may be orthogonal to each other so as to achieve polarization diversity. The antenna structure delivers good receive and transmit diversity performance and is well suited to the form factor limits imposed by the dimensions of small cards, such as PCMCIA cards. The configuration is very convenient for application in the 5 to 6 GHz frequency band.

Card-based diversity antenna structure for wireless communications

An antenna assembly that can conform to two or more noncoplanar walls of a housing associated with numerous different devices that communicate in a WLAN. At least two antenna elements are included with a first antenna element attached to a portion of a first wall and a second antenna element attached to a portion of a second wall. Active circuitry is attached to the backside of the antenna assembly and coupled to the antenna elements. The antenna assembly can be included on a base that can be easily added-on to a product. Spatial and/or polarization diversity can be achieved in a small form-factor at high frequencies, including the 5 to 6 GHz frequency band.

Conformal box antenna

A method of transmission level security, and a corresponding transmission security system, the method consists of the steps of: forming a plurality of digital signals representing a symbol to be transmitted over a communication medium, wherein respective ones of the plurality of digital signals are modulated onto respective ones of a plurality of subcarriers according to a multiple carrier modulation scheme; and introducing a group delay distortion in one or more of the plurality of subcarriers, wherein a peak-to-peak variation of the group delay distortion is greater than a guard time interval corresponding to the symbol, such that portions of the one or more of the plurality of subcarriers will be received outside of a time window corresponding to the symbol at a receiver.

An antenna structure for small wireless communication devices includes multiple antenna elements to achieve diversity and uniform hemispherical coverage gain. Individual patch antennas are located on separate surfaces of a polyhedron or hemispherical dome structure. The antenna structure is well-suited for operation at high frequencies, including the 5 to 6 GHz band. The antenna elements and RF circuitry can be combined in a small integrated enclosure, and the structure is suited for use in a base station of a WLAN.

Diversity antenna structure for wireless communications

A waveform generating system generates one or more quadrature amplitude modulated (QAM) spectrum pairs which are combined with a frequency modulated (FM) spectrum in the center. The QAM spectrums are offset in frequency to result in a gap in the center to allow combining of the FM spectrum without interference.

Growing community of inventors

San Diego, CA, United States of America

James A Crawford