Communications: directive radio wave systems and devices (e.g. – Directive – Including polarized signal communication transmitter or...
Reexamination Certificate
1999-12-10
2001-08-14
Tarcza, Thomas H. (Department: 3662)
Communications: directive radio wave systems and devices (e.g.,
Directive
Including polarized signal communication transmitter or...
C342S357490, C455S456500, C455S404200
Reexamination Certificate
active
06275186
ABSTRACT:
PRIORITY
This application claims priority to an application entitled “Device and Method for Locating Position of Mobile Station in Mobile Communication System” filed in the Korean Industrial Property Office on Dec. 10, 1998 and assigned Ser. No. 98-54143, the contents of which are hereby incorporated by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to the field of wireless communications, and in particular, to a device and method for locating the position of a mobile station (MS) in a mobile communication system.
2. Description of the Related Art
The FCC (Federal Communication Commission) of the U.S. provides that an MS locating service should be implemented for emergency 911 (E911) with a probability of 67% within an error of 125 m or below by October of 2001. Therefore, the CDMA (Code Division Multiple Access) standard (TIA/EIA/IS-95) as well as the IMT-2000 (International Mobile Telecommunication-2000) system makes efforts to provide the MS locating service with use of a reverse link function called “PUF (Power Up Function)”. The PUF is an MS locating scheme in which an MS in an emergency situation transmits probes with gradually increased power to a plurality of adjacent base stations (BSs) on a reverse channel to inform them of its position so that each of the BSs can calculate the distance between the BS and the MS by estimating the time taken for the signal to reach the BS. The PUF is provided in IS-95B.
Implementation of the PUF, however, increases interference and, as a result, decreases system performance. To overcome the problem, the present invention provides an MS locating method for continuous positioning. The MS locating scheme operates on the principle that an MS receives an active pilot and other neighbor pilots on a forward link channel and estimates its relative position from the neighbor BSs in a CDMA communication system. In addition, relative MS positions from at least three BSs are determined by use of at least two time differences of arrival (TDOAs) of signals received from the BSs. In the present invention, the TDOA and SIR (Signal-to-Interference Ratio) of each BS channel are measured to efficiently determine the position of the MS in a CDMA communication system synchronized to the GPS (Global Positioning System).
SUMMARY OF THE INVENTION
It is, therefore, an object of the present invention to provide a device and method for locating an MS by measuring the TDOAs and SIRs of forward pilots received from neighbor BSs in a mobile communication system operated in synchronization.
It is another object of the present invention to provide a device and method for locating an MS using a dedicated searcher in a mobile communication system.
Briefly, these and other objects can be achieved by providing an MS locating device for an MS. The MS receives signals synchronized to a predetermined time from at least one adjacent BS and is located within a serving BS service area of at least one BS. In the MS locating device, an analog to digital converter (ADC) converts signals received from BSs to digital chip sample data, a memory stores the chip sample data, a dedicated searcher detects at least two signals by correlating the chip sample data received from the memory by off-line processing and calculates the signal-to-interference ratios (SIRs) and time difference of arrival (TDOA) of the two signals, and a controller device controls the dedicated searcher to obtain a better estimate of SIRs and TDOAs.
REFERENCES:
patent: 6195559 (2001-02-01), Reudink et al.
Dilworth & Barrese LLP
Mull Fred H
Samsung Electronics Co,. Ltd.
Tarcza Thomas H.
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