Qualcomm Incorporated

Brian K Harms

Anthony C K Soong

Brian K Butler

Sherman A Gregory

Avneesh Agrawal

Lindsay A Weaver, Jr

Thomas J Funk

Larry D Flowers

Todd A Pressley

Bruce S Schwartz

Gordon Skinner, Deceased

Robin Night

Gordon Skinner

Robin D Knight

Lindsay A Weaver

Anthony C Soong

Larry D c/o Qualcomm Incorporated Flowers

Techniques for generating reference signals for multiple communication systems are described. An apparatus comprises a reference oscillator, a frequency control unit, and a plurality of frequency synthesizers. The reference oscillator generates a main reference signal and may be a crystal oscillator or some other type of oscillator. The frequency control unit estimates the frequency error of the main reference signal and provides a frequency error estimate. The plurality of frequency synthesizers receive the main reference signal and generate a plurality of system reference signals for a plurality of systems. At least one (e.g., each) frequency synthesizer corrects the frequency error of the main reference signal based on the frequency error estimate from the frequency control unit. Each frequency synthesizer may include a sigma-delta modulator used to generate a divider control for a phase locked loop (PLL). The divider control corrects for the frequency error of the main reference signal.

Reference signal generation for multiple communication systems

A system and method for narrowing the range of frequency uncertainty of a Doppler shifted pilot signal in a satellite or other communications system with relative signal source and receiver motion. The satellite communications system includes a user terminal (for example, a mobile wireless telephone), a gateway (terrestrial base station), and at least one satellite with unknown position and unknown relative velocity. The method includes the steps of shifting the pilot signal over a plurality of frequency hypotheses, coherently accumulating samples of the pilot signal over a plurality of chips, measuring the energy of the accumulated pilot signal samples, accumulating the energy measurements over a plurality of chips to produce an energy accumulation value, and determining which of the plurality of frequency hypotheses results in the highest energy accumulation value.

System and method for narrowing the range of frequency uncertainty of a doppler shifted signal

The present invention is a method and apparatus for detecting the presence of or acquiring a signal in a data stream, where the signal has been spread using a pseudonoise sequence. The method comprises the steps of delaying a pseudonoise sequence by a plurality of predetermined delays to produce a plurality of delayed pseudonoise sequences, combining each of the delayed pseudonoise sequences with the data stream to produce a plurality of despread data streams, and accumulating each of the despread data streams for a preselected duration to produce a plurality of coherent sums. Each of the coherent sums are accumulated for a further duration to produce a plurality of non-coherent sums. The non-coherent sums are examined to determine the most likely PN offset hypothesis.

User terminal parallel searcher

The invention is a CDMA transmission control technology that includes various combinations of the following functionality: decresting, in-band to out-of-band ratio (RIO), power control, and spectral shaping. Decresting reduces peaks in the CDMA signal. RIO generates a ratio based on the signal strength of in-band versus out-of-band portions of the CDMA signal. Power control adjusts the gain of the CDMA signal based on quadrature signal calculations. Spectral shaping attenuates in-band portions of the CDMA signal adjacent to the corner frequencies. The CDMA transmission control technology can be implemented in a CDMA base station to extend range and capacity.

CDMA signal transmission control

The invention is a CDMA decresting technology that reduces or eliminates peaks in the CDMA signal. The CDMA technology generates a correction signal in response to peaks in the CDMA signal that exceed a value. The value typically corresponds to the maximum power level of a power amplifier. The CDMA technology combines the correction signal with the CDMA signal to generate a decrested CDMA signal with reduced peaks. In some examples of the invention, the CDMA technology processes polar coordinate representations of the quadrature components of the CDMA signal to generate the correction signal. Using the invention, the power amplifier in a CDMA base station can operate at increased power levels without exceeding out-of-band signal power limitations. As a result, the base station operates more efficiently and with a greater range or capacity.

Decresting peaks in a CDMA signal

A technique for spreading information signals in a spread spectrum communication system to provide increased signal acquisition speed. A first PN spreading code or code set is used to spread information signals along with a second PN spreading code sequence or function. The second PN code is synchronized with the first PN spreading code, but has a larger code period so that each code chip of the second PN code extends over the entire period of the first PN code. The longer period spreading code forms an outer code which helps provide unambiguous beam identification and easily acquired frame timing in the presence of dynamically changing signal path delay, improving signal acquisition.

Multi-layered PN code spreading in a multi-user communications system

The invention is a CDMA spectral shaping technology that attenuates the out-of-band signal power in the CDMA signal. The in-band CDMA signal is attenuated near the corner frequencies to reduce components that provide a disproportionate contribution to the out-of-band signal power. The power amplifier in the CDMA base station can then operate at higher power levels without exceeding out-of-band signal power limitations. As a result, the power amplifier operates more efficiently and extends the range or capacity of the base station. In some examples of the invention, spectral shaping digital filters are placed between the cell site modem and the digital-to-analog converter in the base station. In other examples of the invention, spectral shaping analog filters are placed between the digital-to-analog converter and the low-pass filter in the base station.

Spectral shaping a CDMA signal

The invention is CDMA quadrature signal technology that controls the transmit power of a CDMA signal. The CDMA quadrature signal technology receives a CDMA signal, and in response, process quadrature components of the CDMA signal to generate a power control signal. The CDMA quadrature signal technology adjusts the gain of the CDMA signal in response to the power control signal. A CDMA transmitter transmits the CDMA signal after the gain is adjusted. One example of the CDMA transmitter is a CDMA base station. Using the invention, a multi-sector CDMA base station can control power without transferring gain information to base station components for all sectors. The invention eliminates unnecessary data transfer and storage.

CDMA signal power control using quadrature signal calculations

A technique for using energy received by subscriber units over multiple orthogonal channels within a spread spectrum communication system to acquire signal timing by controlling signal amplitude integration intervals used in detecting such timing. Received signals are despread and respective amplitudes integrated over periods that are divisible by factors of 2 into the length of Walsh functions used to generate orthogonal signal channels. Non-coherent combinations of the results of this integration are subsequently formed over periods that commence and terminate on Walsh function boundaries, and used to determine when a correct time offset has been selected for despreading signals. Additional advantages are realized by assigning signals that consistently provide a higher energy content such as paging, synchronization, and most frequently assigned traffic channels to specific orthogonal channels within the communication system. In exemplary embodiments, Walsh functions of length 128 are used as channelizing codes and a pilot signal is assigned to channel 0. This results in traffic channels or paging and synchronization functions being assigned to channel 64 when the integration periods are 64 chips long, and to channels 32, 64, and 96 when the periods are 32 chips long. In this manner, additional energy is available during the integration process for use in determining when correct signal acquisition timing offsets have been selected, without the use of additional hardware.

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Boulder, CO, United States of America

Brian K Harms