Abstract: In general, this disclosure describes techniques for changing a sampling frequency of a digital signal. In particular, the techniques provide a more accurate way to determining a relative timing between a desired output sample and a corresponding input sample using a non-approximated integer representation of the relative timing. The relative timing between the desired output sample and corresponding input sample may be represented using a first component that identifies a latest input sample of the digital signal used to generate intermediate samples, a second component that identifies an intermediate sample, and a third component that identifies a timing difference between the desired output sample and the intermediate sample. Each of the components may be recursively updated using non-approximated integer values.

Abstract: A cache stores data for use in rasterizing graphics data. The size of the cache is equal to a selected tile size. A processor performs the rasterization of the graphics image by subdividing the graphics image into a plurality of sub-blocks. The sub-blocks are processed, based on a block processing order, by further subdivision of the sub-blocks into tiles for those sub-blocks that have graphics image data. The tiles have a size equal to the selected tile size. Data, associated with a tile, is loaded into the cache, and the cache data is utilized to generate pixels for the associated tile of the graphics image.

Abstract: Techniques for maintaining packet data connectivity in a wireless communications network are presented. A mobile station detects a change from a first packet control function (PCF) to a second PCF. The first PCF is connected to a first packet data service node (PDSN). The second PCF is connected to a second PDSN. The mobile station consults a database configured to map at least one previously visited PCF to a servicing PDSN. Based at least in part on the consulting, the mobile station observes one from among a plurality of predetermined origination patterns, wherein an origination pattern defines origination functions to be performed by the mobile station. As such, zombie PPP and mobile IP instances may be detected and handled.

Abstract: This disclosure is directed to a frequency synthesizer for use in a wireless communication device. The frequency synthesizer includes an oscillator, such as a voltage controlled oscillator (VCO) and a &Sgr;&Dgr;-controlled phase-locked loop (PLL) that determines and controls the of the output frequency of the frequency synthesizer. The &Sgr;&Dgr;-controlled PLL may implement a dithering signal generation technique that can reduce or eliminate the introduction of an average frequency offset.

Abstract: A system for digital filtering includes a set of logic gates, a state storage, and a multiplexer. The state storage includes two or more storage banks and may also include combinatorial logic and/or at least one lookup table. In one application, a filtering operation according to a finite-impulse-response filter coefficient vector is performed without runtime multiplications. Applications to symmetric and antisymmetric filter coefficient vectors are described, as well as applications to filter coefficient vectors of arbitrary odd or even length.

Abstract: Techniques to search for a gated pilot reference in a wireless communication system. In one method, an overall code space in which the pilot may be found is partitioned into a number of groups of code sets, with each code set representative of all possible chip offsets of a specific PN sequence. The groups are ordered based on the likelihood of detecting the pilot in each of the groups. The groups of code sets are then used to search for the pilot, one group at a time, starting with the group most likely to result in successful pilot acquisition and ending with the group least likely to result in successful pilot acquisition. The search is terminated upon successful acquisition. The pilot search may be performed using detect, dwell, and pull-in substages. The detect substage for one group may be performed in parallel with the pull-in substage for another group.

Abstract: Techniques to combine soft-decision power control symbols received for multiple active base stations. In one method, a received signal is initially processed to derive soft-decision (multi-bit valued) symbols for power control commands transmitted from a number of base stations. Each soft-decision symbol for each base station is then scaled based on a scaling factor associated with the base station and which is related to the received signal quality for the power control symbols for the base station. The scaling allows power control symbols for more reliably received base stations to be given greater weights. The scaled soft-decision symbols for each power control period are then combined to provide a decision metric for the period. Each decision metric is then compared against a particular threshold, and a power control decision is derived for each decision metric based on the result of the comparison.

Abstract: An integrated circuit including a Multi-Threshold CMOS (MTCMOS) latch combining low voltage threshold CMOS circuits with high voltage threshold CMOS circuits. The low voltage threshold circuits including a majority of the circuits in the signal path of the latch to ensure high performance of the latch. The latch further including high voltage threshold circuits to eliminate leakage paths from the low voltage threshold circuits when the latch is in a sleep mode. A single-phase latch and a two-phase latch are provided. Each of the latches is implemented with master and slave registers. Data is held in either the master register or the slave register depending on the phase or phases of the clock signals. A multiplexer may alternatively be implemented prior to the master latch for controlling an input signal path during sleep and active modes of the latch and for providing a second input signal path for test.

Abstract: Novel techniques are disclosed for detecting discontinuous transmission (DTX) over a communication channel. A received data frame is characterized as one of a Good frame, Erasure, or DTX. If a Good frame is not initially detected, a multi-dimensional quality metric is used to characterize the received frame as either an Erasure or DTX. A two dimensional quality metric may be generated using energy per bit to noise power ratio as a first dimension and re-encoded symbol error count as a second dimension. Alternatively, re-encoded symbol energy may be used as the second dimension of the quality metric. The communication channel may be a CDMA wireless communication channel capable of DTX and the device may be a base station, base station controller, or mobile station.

Abstract: Techniques for searching in asynchronous systems are disclosed. In one aspect, a plurality of codes, such as SSCs, are correlated with a received signal at a plurality of offsets to produce a code/slot energy corresponding to each code/slot boundary pair. Unique subsets of the code/slot energies are summed to produce code sequence energies, the maximum of which indicates a located code sequence and slot boundary. In another aspect, the correlation is performed by sub-correlating the received signal with a common sequence, and performing a Fast Hadamard Transform (FHT) on the results. In yet another aspect, one sub-correlator can be used to search a plurality of peaks simultaneously. Various other aspects of the invention are also presented.

Abstract: Techniques for processing transmissions in a communications (e.g., CDMA) system. Samples are received and assembled into one or more traffics, with each traffic including one or more portions (e.g., radio frames, coded blocks) suitable for processing independently. The priority of each portion is determined based on its processing delays requirement, which can be estimated based on, for example, the time interval over which the samples in the traffic are interleaved, the processing deadline, and so on. A portion in a traffic having the highest priority is selected and scheduled for processing. The processing can include reordering the samples in the selected portion in accordance with a particular reordering scheme, accumulating redundant samples and inserting place holders (e.g., don't cares) for deleted samples in the selected portion, and decoding the reordered samples in the selected portion.

Abstract: A method and apparatus to dynamically adjust parameters of a filter for a pilot signal. An incoming signal containing a pilot signal is filtered using non-identical filters, and the magnitudes of the filtered signals are compared to estimate a bandwidth of the pilot signal. Noise in the incoming signal may also be estimated, preferably from a portion of the incoming signal not expected to contain the pilot signal. Based on the comparison of the filtered signal magnitudes, which may be compensated to remove the noise contribution, the parameters of a filter applied to the incoming signal to isolate the pilot signal are varied. The parameters may vary the bandwidth of a pilot signal filter. The non-identical filters used in the pilot signal bandwidth estimation may be IIR or FIR filters having different passbands, or may be a correlation of the incoming signal with sinusoids of different frequencies.

Abstract: When all of the fingers of a wireless rake receiver are “out-of-lock,” the transmit power is initially maintained at a constant level. When the “out-of-lock” condition persists for an extended period of time, transmit power is increased in an effort to reacquire a lock with a subscriber unit or base station, as the case may be. An increase in transmit power may be effective in reacquiring lock when the cause of the out-of-lock condition is slow fading, rather than fast fading. Slow fading may be evidenced by persistence of the out-of-lock condition for an extended period of time. The length of the out-of-lock condition is used to selectively control transmit power and thereby promote quality of service. Transmit power is only increased when the fingers remain out-of-lock for an extended period of time, thereby avoiding undue increases in transmit power that could produce interference among different subscriber units.

Abstract: A received symbol stream is oversampled and correlated with a known sync word to determine the correlation properties of the oversampled signal with a known sync word. A linear filter, such as a moving average window filter, is convolved with the correlation signal to generate a convolution signal. Once the convolution signal has reached a predetermined threshold, it is scanned over a predetermined window of oversamples. If the convolution signal exceeds the threshold for the window of oversamples, the sync word has been found and the symbol stream is down-sampled at intervals that depend on the data rate of the symbol stream. This down-sampling process may be done by picking the center oversample corresponding to each information symbol given the timing alignment, or by doing a majority vote over a multiple number of samples centered around the center oversample.

Abstract: Novel techniques are disclosed for adjusting a power control setpoint to compensate for imperfect signal detection in a communication channel capable of discontinuous transmission (DTX). The power control setpoint is compensated for false detections by adjusting the power control setpoint by a dynamically determined setpoint back off amount upon detection of a Good frame. The amount of the setpoint back off is a function of the measured signal quality of the detected Good frame and the number of Erasure indications received immediately preceding the Good frame indication.

Abstract: An apparatus for extinguishing fires in enclosures having an air ramp with an automatic trap door. When the trap door is tripped, the air flow is reduced. Fires can be extinguished through the reduced air flow. The air ramp includes a center section having an upwardly ramped center area, a trap door which is moveably attached to the center area and a front section which is connected to the center section. The front section allows the air ramp to be mounted in an enclosure.