Abstract: Systems and methods for adaptively allocating resources between a dedicated reference signal and a traffic signal are disclosed. In an exemplary embodiment, a wireless communication system 100 includes a base station 404. The base station 404 includes a receiver 428 that receives a quality metric 432 from a remote station 106. The quality metric 432 indicates the quality of a signal transmitted from the base station 404 and received by the remote station 106. The base station 404 also includes a resource allocation component 434 that uses the quality metric 432 to allocate a resource between the traffic signal 422 and the dedicated reference signal 418. The base station 404 also includes a transmitter 426 that transmits the traffic signal 422 and the dedicated reference signal 418 to the remote station 106.

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 method and apparatus for calculating a representative measurement from multiple data measurements of signals from cellular base stations, thereby facilitating utilization of a cellular network to determine position of a mobile station even in non-line of sight and/or dynamic fading environments. A method for calculating a representative measurement includes determining a window of time, selecting data measurements within the window, and calculating a representative time of arrival responsive thereto, such as averaging all data measurements within the window. A representative RMSE estimate may be calculated. To determine a window of time all data measurements within a predetermined window from an earliest time of arrival may be selected. Alternatively the window may be determined by sliding over the data measurements. The data measurements may be stored in a database in a mobile station, and the database is updated to include each new measurement.

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 for estimating the earliest signal arrival in a wireless communication system is presented. The system includes a base station that transmits a plurality of pilot signals and a mobile station configured to receive a plurality of signals corresponding to the pilot signals. The mobile station includes a receiver containing a searcher correlation mechanism and at least one finger correlation mechanism. The mobile station receiver detects the arrival times and energy levels of the received signals and constructs a searcher histogram and a finger histogram associated with each pilot signal. Each of the searcher and finger histograms represents an arrival time distribution of samples corresponding to the received signals. The mobile station receiver processes samples contained within each of the searcher histograms and the finger histograms to generate a plurality of estimated early signal arrivals. The earliest signal arrival is determined from the plurality of estimated early signal arrivals.

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 system and method for accurately determining time of arrival using a mathematical model that mimics a correlation function. A correlation value is sampled at a predetermined periodic interval and a maximum correlation value, coinciding with a particular point in time, is determined. The mathematical model uses the maximum measured correlation value and correlation values at adjacent sample points to determine coefficients for the selected mathematical model. The coefficients may be calculated and used to determine the actual peak, which may fall in-between the sample points. The actual peak value is used to accurately determine the time of arrival of a signal. Time of arrival signals from a plurality of remote transmitters are used along with conventional triangulation techniques to accurately determine the location of the wireless unit.

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 system and method for estimating the earliest signal arrival in a wireless communication system, is presented herein. In accordance with an embodiment of the invention, the system includes a base station that transmits a plurality of pilot signals and a mobile station configured to receive a plurality of signals corresponding to one of the transmitted pilot signals. The mobile station includes a receiver containing a searcher correlating mechanism and at least one finger correlating mechanism. The mobile station receiver detects the arrival times and energy levels of the received signals and constructs a searcher histogram and a finger histogram representing an arrival time distribution of samples corresponding to the received signals.