Qualcomm Incorporated

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Douglas Neal Rowitch

Abhay Arvind Joshi

Way-Shing Lee

Peter J Black

Shimman Arvind Patel

Parvathanathan Subrahmanya

Brian K Butler

Gilbert Christopher Sih

Roland Reinhard Rick

James A Hutchison, Iv

Arthur James Neufeld

Simon Turner

Brian Clarke Banister

Ramin Rezaiifar

Inyup Kang

Farrokh Abrishamkar

Remi Jonathan Gurski

Don Nielsen Andrus

Steven Yoon

Ravi Govindarajula

Maruthy Vedam

A novel and improved method and apparatus provide for controlling an operation of an access terminal while processing a signal from an access point in a communication system. Various aspects of the invention provide for an access terminal to disable a handoff process when its demodulator or decoder is operating to demodulate or decode a control message received from an access point. The operation of the access terminal is controlled in a manner that prevents terminating prematurely the demodulation and decoding process of a control signal by a handoff process. As a result, the access terminal may continue operating in a normal wake up/ sleep cycle period while conserving its battery power.

Method and apparatus for controlling operation of an access terminal in a communication system

Techniques to efficiently attempt acquisition of a packet data system (e.g., an IS-856 system). If a terminal has acquired one or more channels in a voice/data system (e.g., an IS-2000 system), then it can attempt acquisition on channels in the packet data system that are co-located with the acquired channels in the voice/data system. Multiple acquisition modes may be used, and on-going acquisition attempts on the co-located channels may be performed using one acquisition mode at a time in order to reduce power consumption. Acquisition attempts may be performed in a 'ping-pong' manner to improve the likelihood of acquisition. For a ping-pong search, an acquisition attempt is made on the most recently acquired channel prior to an acquisition attempt on each of the remaining channels. Received signal strength estimates may also be obtained for selected channels and may be used to determine whether or not to attempt acquisition on these channels.

Method and apparatus for performing acquisition in power save mode for wireless communication systems

In an antenna diversity environment, the timing offset of the receiver's fingers are based on the timing offset of the received peaks of the base station transmit signals. In a system with non-negligible multipath spacing, the timing offset of the received peaks of the base station transmit signals are not necessarily at the same location. In one embodiment, the demodulating elements for the signal from each base station antenna use the same offset for demodulating and determining an error signal based on pilot signal sampling prior to the timing offset and subsequent to the timing offset. The error signals are averaged and used by a time tracking loop to track the incoming signal. In another embodiment, the demodulating elements for the signal from each base station antenna independently time track the signals with different timing offsets for each finger. The preferred embodiment depends on the method used by the base station to multiplex the data onto multiple transmit antennas.

Time tracking in a non-negligible multipath spacing environment

For coverage determination and system switching, a terminal obtains pilot strength estimates for base stations in first and second wireless communication systems (e.g., packet data system and voice/data system) and received signal quality estimates for at least one serving base station in the first system. The terminal derives various metrics based on the received signal quality estimates and pilot strength estimates. The terminal may perform handoff to the second system if weak coverage is detected for the first system, a received signal quality metric (Q) for the first system is below a Qthreshold, and a pilot strength metric (V) for the second system exceeds a Vthreshold. The terminal may perform handoff to the first system if good coverage is detected for this system, metric Q exceeds a Qthreshold, or a maximum pilot strength metric (M) for the first system exceeds a Mthreshold.

Coverage determination and switching between overlay communication systems

Demodulator architectures for processing a received signal in a wireless communications system. The demodulator includes a number of correlators coupled to a combiner. Each correlator typically receives and despreads input samples (which are generated from the received signal) with a respective despreading sequence to provide despread samples. Each correlator then decovers the despread samples to provide decovered 'half-symbols' and further demodulates the decovered half-symbols with pilot estimates to generate correlated symbols. The decovering is performed with a Walsh symbol having a length (T) that is half the length (2T) of a Walsh symbol used to cover the data symbols in the transmitted signal. The combiner selectively combines correlated symbols from the assigned correlators to provide demodulated symbols. One or more correlators can be assigned to process one or more instances of each transmitted signal. The pilot estimates used within each assigned correlator to demodulate the decovered half-symbols are generated based on the signal instance being processed by that correlator.

Method and apparatus for demodulating signals processed in a transmit diversity mode

A wireless mobile telephone () is operated so as manage the performance of 'off-frequency searches,' that is, searches for base station pilot signals that differ in frequency from the pilot signals in the mobile station's active set. Whenever frequency searching is performed (such as responsive to emerging from a reduced-power sleep mode), the mobile station performs on-frequency pilot signal searching () upon a prescribed active set frequency. Only if a prescribed off-frequency searching condition (-) is satisfied, the mobile station additionally performs off-frequency pilot signal searching () upon one or more neighboring base stations' frequencies.

Method and apparatus to optimize off-frequency pilot searching by wireless mobile station

The velocity of a wireless communications device (WCD) () is estimated. In response to this estimate a power control command rate is determined. The WCDtransmits power control signals to a base station () according to the power control command rate. The power control command rate may be determined by mapping the estimated velocity to a velocity range, and selecting a rate that corresponds to the velocity range as the power control command rate. Velocity is estimated by measuring a level crossing rate of a multipath signal.

Velocity responsive power control

Techniques to determine whether or not a terminal is under the coverage of a current wireless communication system (e.g., a packet data system) and to switch from the current system to another wireless communication system (e.g., a voice/data system). In one method, at least one measurement of at least one parameter for at least one base station in the current system is initially obtained. The measurement(s) may be SNR measurements. A metric is derived based on the measurement(s) and used (typically along with a metric threshold and a timer) to determine whether or not the terminal is within the coverage of the current system. A switch to another system is initiated if the terminal is deemed to be outside the coverage of the current system. The two systems provide at least one common service (e.g., packet data service).

Method and apparatus for determining coverage and switching between overlay communication systems

This disclosure is directed to techniques for estimating signal-to-noise ratio (SNR) of signals received by a wireless communication device. The techniques take advantage of spatial receive diversity in a wireless communication device to achieve accurate estimates of SNR. In general, a spatial projection wiener filter function can be applied to incoming symbol estimates to support efficient computation of SNR. The estimated SNR can be used to produce power control commands for use in forward power control.

Signal-to-noise estimation in wireless communication devices with receive diversity

A multi-carrier filter for a wireless communications system employing a multi-carrier signal. The multi-carrier filter includes a first mechanism for receiving the multi-carrier signal and extracting carrier signal components of the multi-carrier signal in response thereto. A second mechanism filters the carrier signal components and outputs a demodulated and filtered multi-bandwidth signal in response thereto. In the specific embodiment, the first mechanism includes a rotator. The multi-carrier signal is a 3&times; bandwidth multi-carrier signal having three carrier components. The three carrier components include a center carrier, a left carrier, and a right carrier. The center carrier, the left carrier, and the right carrier are separated by approximately 1.25 MHz. The rotator is a lookup table rotator that includes a mechanism for selectively rotating the multi-carrier-signal clockwise or counter clockwise and outputting the left carrier or the right carrier, respectively, in response thereto.

Efficient multicarrier filter

Demodulator architectures for processing a received signal in a wireless communications system. The demodulator includes a number of correlators coupled to a combiner. Each correlator typically receives and despreads input samples (which are generated from the received signal) with a respective despreading sequence to provide despread samples. Each correlator then decovers the despread samples to provide decovered &ldquo;half-symbols&rdquo; and further demodulates the decovered half-symbols with pilot estimates to generate correlated symbols. The decovering is performed with a Walsh symbol having a length (T) that is half the length (2T) of a Walsh symbol used to cover the data symbols in the transmitted signal. The combiner selectively combines correlated symbols from the assigned correlators to provide demodulated symbols. One or more correlators can be assigned to process one or more instances of each transmitted signal. The pilot estimates used within each assigned correlator to demodulate the decovered half-symbols are generated based on the signal instance being processed by that correlator.

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San Diego, CA, United States of America

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