Abstract: Techniques for cell reacquisition and reselection that increases time spent in low-power mode while effectively monitoring neighbor cells are disclosed. In one aspect, one or more windows around the expected location of the serving cell are searched in the period of time prior to the page indicator. In another aspect, intra-frequency neighbor cells are searched first to determine reselection candidates. Various other aspects are also presented. These aspects have the benefit of increasing time spent in low-power mode, thereby reducing power consumption and increasing standby time.

Abstract: Techniques for reducing the time required for frequency scan in acquisition are disclosed. In one aspect, received power measurements are made at one or more of the possible carrier frequencies and system search is performed on one or more of those frequencies when the power measurement exceeds a threshold. In another aspect, the power is measured at one or more frequencies in a band of frequencies surrounding a frequency at which the measured power exceeded a threshold. If the measured power at one or more of the frequencies in the band exceeds a second threshold, a system search is performed at one or more of those frequencies. In yet another aspect, frequencies meeting certain criteria are sorted in order of measured power prior to system search or further power measurement, and subsequent processing is performed in order of descending measured power. Various other aspects are also presented.

Abstract: A system and method are disclosed by which the effects of time of arrival (TOA) errors may be reduced. In a mobile unit, a correlation pulse is generated when a signal transmitted from a base station is detected. The transmitted signal may be reflected or defracted such that multipath signals arrive at the mobile unit. This leads to a distortion in the generated correlation pulse and errors in accurate TOA measurements. The present invention models the response function and calculates the width of the pulse using the modeling function with a dynamically adjustable factor to indicate at what point down from the peak the pulse width will be calculated. Based on the calculation of pulse width, a type of multipath signal may be determined and an appropriate correction factor applied to the measured TOA to provide a more accurate TOA determination.

Abstract: A quick paging channel (QPCH) is used to receive paging indicators that indicate that a wireless communication device (WCD) has a message on a paging channel relating to, for example, an incoming call to the WCD. When the condition of the quick paging channel is too low to receive paging indicators reliably, the quick paging channel is disabled to avoid false alarms, and the slotted paging channel is used to receive paging messages without monitoring the QPCH. When the QPCH signal is strong, the probability of false alarms is lower, and the quick paging channel is enabled. By using the quick paging channel to receive paging indicators only when the QPCH signal is strong, the wireless communication device can remain in a sleep state for greater periods of time as compared with the use of a slotted paging channel. As a result, standby time may be significantly improved.

Abstract: Techniques for tracking closely spaced multipath and preventing finger merge without monitoring relative positions between each of a plurality of fingers are disclosed. In one aspect, motion limits are determined for each finger. Time-tracking commands that would move the position of a finger outside its respective motion limits are suppressed. In another aspect, motion limits are updated dynamically, the motion limits of each finger determined in accordance with the motion limits of fingers adjacent to it. Various other aspects are also presented. These aspects have the benefit of preventing finger merge, which allows the allocation of multiple fingers to closely spaced multipath, thus increasing performance and system capacity, and mitigating misallocation of system resources.

Abstract: A position determination system and apparatus for utilizing a network of cellular base stations to determine position of a mobile station includes taking a plurality of statistically independent data measurements of the pilot signals from the base stations. Each of the data measurements includes an earliest time of arrival, providing multiple independent measurements for each of the pilot signals. For each cellular base station, a representative measurement is calculated responsive to the independent measurements, which is used to determine position of the mobile station using an AFLT algorithm and/or in conjunction with a GPS algorithm. In some embodiments, the data measurements for each pilot signal further include an RMSE estimate and time of measurement for each time of arrival, and an energy measurement for all resolvable paths. If the mobile station comprises a cell phone, a cell search list and a GPS search list may be provided by a cell base station.

Abstract: A method and communication system for assigning the plurality of fingers to demodulation paths in a path list which insures that at least one finger will be assigned to a demodulation path supporting a supplemental channel, if one exists. The method involves determining whether any of the fingers is demodulating a supplemental channel (112). When no fingers are demodulating supplemental channels, the it is determined whether the sector containing the path under consideration supports supplemental channels (114). If the sector containing the path under consideration supports supplemental channels, then the method determines the strength of the signal path relative to the weakest finger (116).

Abstract: A method and communication system for assigning the plurality of fingers to demodulation paths in a path list which insures that at least one finger will be assigned to a demodulation path supporting a supplemental channel, if one exists. The method involves determining whether any of the fingers is demodulating a supplemental channel (112). When no fingers are demodulating supplemental channels, the it is determined whether the sector containing the path under consideration supports supplemental channels (114). If the sector containing the path under consideration supports supplemental channels, then the method determines the strength of the signal path relative to the weakest finger (116).

Abstract: A parameter estimator for estimating one or more parameter(s) from a correlation function derived from a signal using a dynamically variable search window is described. The parameter estimator may be employed in a subscriber station to estimate the time of arrival of one or more base station pilot signals in a wireless communication system. This information may be utilized in an overall advanced forward link trilateration (AFLT) process for estimating the location of the subscriber station.

Abstract: A method of producing a reliability metric for a parameter estimate derived from a signal using correlation analysis is described. The method begins by obtaining an indication of whether a non line of sight signal condition is present or likely and/or obtaining an indication of whether a multi-path signal condition is present or likely. Responsive to one or both of these indications, the method derives a reliability metric for the parameter estimate. In one embodiment, the parameter estimate is an estimate of time of arrival (TOA) of the signal, and the reliability metric is root mean square error (RMSE) of the time of arrival estimate. This embodiment obtains an indication of whether a non line of sight signal condition is present or likely based on a measure of the strength of the correlation function at the peak thereof.

Abstract: A parameter estimator for estimating one or more parameter(s) from a signal is described. A correlation function is derived from the signal, and the correlation function analyzed to determine if one or more first peak(s) are present, and, if so, distinguishable from the sidelobe(s) of a second peak. If the one or more first peak(s) are present and distinguishable from the sidelobe(s) of the second peak, the one or more parameter(s) are estimated from the one or more first peak(s). If the one or more first peak(s) are not present, or, if present, are not distinguishable from the sidelobe(s) of the second peak, the one or more parameter(s) are estimated from the second peak. The parameter estimator may be employed in a subscriber station to estimate a parameter such as the time of arrival of one or more base station or sector pilot signals in a wireless communication system.

Abstract: A parameter estimator for estimating one or more parameter(s) from a correlation function derived from a signal using a dynamically variable integration time is described. The parameter estimator may be employed in a subscriber station to estimate the time of arrival of one or more base station or sector pilot signals in a wireless communication system. This information may be utilized in an overall advanced forward link trilateration (AFLT) process for estimating the location of the subscriber station.

Abstract: A method for assigning tracking elements includes sorting a list of potential assignments according to a diversity criterion. In one example, a list of received signal instances is sorted first according to a measure of energy and then sorted again according to the diversity criterion. In a further embodiment, a demodulation element may be labeled available for assignment yet continue to output demodulated symbols in a locked state. Applications to a mobile station of a CDMA system for cellular telephony are discussed.

Abstract: A system and method are disclosed by which the effects of time of arrival errors may be reduced. In a mobile unit, such as a CDMA device, a correlation pulse is generated when a transmitted code matches a stored reference code. In the absence of multipath effects, correlation pulses are generated in response to the detection of multiple transmissions of the reference code from multiple transmitters. However, multipath effects distort the generated correlation pulses leading to errors in the time of arrival measurements. The present invention calculates the width of the correlation pulses and determines a delay correction factor based on the pulse width. The delay correction factor is added to the measured delay time to provide a more accurate delay time, thus permitting more accurate location measurements based on time of arrival. In alternative embodiments, other signal factors may also be used to apply delay correction factors.

Abstract: A quick paging channel (QPCH) is used to receive paging indicators that indicate that a wireless communication device (WCD) has a message on a paging channel relating to, for example, an incoming call to the WCD. When the condition of the quick paging channel is too low to receive paging indicators reliably, the quick paging channel is disabled to avoid false alarms, and the slotted paging channel is used to receive paging messages without monitoring the QPCH. When the QPCH signal is strong, the probability of false alarms is lower, and the quick paging channel is enabled. By using the quick paging channel to receive paging indicators only when the QPCH signal is strong, the wireless communication device can remain in a sleep state for greater periods of time as compared with the use of a slotted paging channel. As a result, standby time may be significantly improved.

Abstract: An apparatus, such as a subscriber unit or a base station within a spread spectrum communication system, may add one or more additional “virtual” paths to a list of candidate paths when assigning demodulation elements. These “virtual” paths are added as candidate paths even though a corresponding peak was not necessarily detected within a received spread spectrum system. The list of paths may include a first path having a time offset approximately equal to a time offset for one of the demodulation elements, and the virtual path having a short time separation from the first path. The time separation between the paths may be, for example, less than 2 chips.

Abstract: Techniques to detect whether or not a remote terminal is under the coverage of a repeater within a wireless communication network, which may be based on (1) a list of base stations expected to be received while under the repeater's coverage, (2) the characterized environment of the repeater, and/or (3) the propagation delays for a transmission received at the remote terminal. Additional ambiguity resulting from being under a repeater's coverage may also be accounted for and/or compensated by (1) discarding time measurements from repeated base stations, (2) adjusting the processing for position estimation to account for the additional ambiguity due to the repeater, (3) computing a series of position estimates based on multiple transmissions received from the same originating base station and selecting the best estimate, and/or (4) computing a series of position estimates based on multiple transmissions from multiple originating base stations and selecting the best estimate.