Telecommunications – Radiotelephone system – Zoned or cellular telephone system
Reexamination Certificate
1999-06-08
2001-08-28
Nguyen, Lee (Department: 2683)
Telecommunications
Radiotelephone system
Zoned or cellular telephone system
C342S450000, C342S451000, C342S453000
Reexamination Certificate
active
06282426
ABSTRACT:
The present invention relates generally to a manner by which to determine the geographic positioning of a wireless communication station, such as a cellular mobile station. More particularly, the present invention relates to apparatus, and associated methodology, by which to determine the geographic positioning of the wireless communication station when the wireless communication station is operated using TOA- (time-of-arrival) signaling in a non-ideal propagation environment. Accurate determination of the location at which a wireless communication station is positioned is determinable, for instance, when the wireless station is operated in an NLOS (non-line-of-sight) condition, or in situations in which fewer than three TOA-signals are detected at the wireless station.
BACKGROUND OF THE INVENTION
Advancements in communication technologies have permitted the implementation of mobile communication systems, such as a cellular communication system. Telephonic communication, of both voice and data, is generally possible through the use of a mobile communication system.
Communication by way of a mobile communication system is advantageous as communications can be effectuated by way of a mobile station carryable by a user. Improved mobility of communications is possible as a wireline connection is not required to form a communication link.
Telephonic communications effectuated by use of a cellular communication system, as well as various other types of mobile communication systems, appear to a user generally to be similar to those effectuated by way of a conventional, wireline telephonic network.
However, the mobile nature of a mobile communication system prevents simple tracking of the location at which a call is placed, such as a call for emergency assistance by a user of a mobile station operable in such a system.
When a call is originated at a conventional wireline device, the geographical position from which the call is originated is easily determinable. A simple mapping between the telephonic identity of the originating, wireline device and the location at which the device is installed, indicates the geographical positioning of the originating party. In contrast, because of the inherent mobility permitted of a mobile station, a subscriber of a mobile station is able to originate a call with the mobile station at almost any location within a geographical area encompassed by the cellular communication system. The geographical position at which the call is originated is, therefore, not easily determinable. Determination of the location at which a call is originated is vitally important, for instance, in a request for emergency assistance. If a request for emergency assistance is made by way of a mobile station and the originating party is unable to indicate to emergency personnel the location from which the request for emergency assistance is made, delivery of the emergency assistance might be, at the least, delayed.
Proposals have been set forth to overcome this shortcoming of use of a radio communication system. One such proposal makes use of GPS (global positioning system) technologies. GPS receivers are available to receive and detect TOA- (time-of-arrival) signals generated by satellite based transmitters (the “satellites”). Three signals received from three separate satellites at a GPS receiver are used by the GPS receiver to determine an accurate 3D (three dimensional) geographic positioning of the GPS receiver if the GPS receiver is synchronized to the satellites. Incorporation of GPS receiver circuitry in a mobile station permits the geographical positioning of the mobile station to be determinable. And, such incorporation, is proposed to overcome the inability to automatically determine the physical positioning of a mobile station.
Accurate position determination utilizing GPS techniques, however, requires the detection of three separate TOA-signals delivered directly, i.e., by line-of-sight from the three satellite-based, or other, transmitters. The GPS receiver, or mobile station incorporating circuitry capable of detecting TOA-signals, such as those generated by satellite-based transmitters, might be positioned at a location, or otherwise be operated in a non-ideal propagation environment, in which three line-of-sight TOA-signals cannot be detected. For instance, in an urban area, topographical features, such as building structures, might prevent line-of-sight detection of a TOA-signal. Instead, only non-line-of-sight (NLOS) detection might be possible. Also, only two TOA-signals, or perhaps only a single TOA-signal, might be detectable. Conventional GPS techniques do not compensate for NLOS conditions, or for the determination of a location fix if only two TOA-signals are detectable.
A manner by which to determine the geographical position of a wireless communication station when operated in a non-ideal propagation environment would be advantageous.
It is in light of this background information related to determination of geographic positioning of a wireless communication station that the significant improvements of the present invention have evolved.
SUMMARY OF THE INVENTION
The present invention, accordingly, advantageously provides apparatus, and an associated methodology, by which to determine the geographical positioning of a wireless communication station, such as a cellular mobile station, even when the communication station is operated in a non-ideal propagation environment.
Operation of an embodiment of the present invention permits accurate determination of the location at which a wireless communication station is positioned, even when the communication station is positioned in a non-ideal propagation environment, such as that which sometimes exists in an urban area.
In one implementation, the wireless communication station forms a mobile station, such as a mobile station operable in a cellular communication system. TOA (time-of-arrival) signals, such as those generated in a GPS (global positioning system), or a radio base station operable in a cellular communication system, are detectable by the mobile station. Such TOA-signals are utilized to determine the geographical positioning of the mobile station.
When three separate TOA-signals are delivered to the mobile station by line-of-sight (LOS) transmission by a TOA-signal sending station determination of the mobile station is accurately determinable utilizing conventional trilateration techniques. However, use of conventional trilateration techniques does not provide an entirely accurate determination of the geographical positioning of the mobile station in the event that the mobile station is cause to be operated in a non-ideal propagation environment.
Operation of an embodiment of the present invention permits more accurate determinations to be made of the geographical positioning of the mobile station when the mobile station is operated in a non-ideal propagation environment.
In one aspect of the present invention, an accurate determination of the geographical positioning of a wireless communication station is made even if one or more of three TOA-signals are delivered to the mobile station by a non-line-of-sight (NLOS) delivery. NLOS delivery of the TOA-signals might occur, for instance, when the communication station is positioned in an urban area, and a building is positioned between the TOA-signal sending station and the wireless communication station to block a direct, LOS transmission of the TOA-signals. Compensation is made for range residue, i.e., error caused by NLOS delivery of the TOA-signals, thereby to provide an accurate indication of the geographical positioning of the wireless communication station.
In one implementation, a location fix is calculated in conventional manner at the wireless communication station. Indications of the calculated location fix are provided to a location computing station. When implemented in a cellular communication system, indications of the location fix are calculated at the mobile station and transmitted to network infrastructure. A location computing stat
Fraccarol Federico
Nguyen Lee
Nokia Mobile Phones Limited
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