Telecommunications – Radiotelephone system – Zoned or cellular telephone system
Reexamination Certificate
1998-03-13
2001-01-30
Hunter, Daniel S. (Department: 2749)
Telecommunications
Radiotelephone system
Zoned or cellular telephone system
C455S422100, C455S432300, C455S456500, C455S457000
Reexamination Certificate
active
06181944
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a mobile station position estimation scheme for estimating a position of a mobile station in a cellular mobile communication system for carrying out communications between a mobile station and base stations, and a base station device and a mobile station device for realizing this mobile station position estimation scheme.
2. Description of the Background Art
In the conventional cellular mobile communication system, it has been impossible to estimate a position of a mobile station in communication state, and for this reason it has been pointed out that there is a problem that a position of a source of an emergency call (such as dial “110” and “119” in Japan, dial “911” in U.S.A.) cannot be identified.
There are well known radio based techniques for estimating a position such as the radio navigation schemes for airplanes and ships (beacon, loran, microwave landing system, etc.). However, these techniques are not suitable for the cellular mobile communications.
Namely, the beacon requires a radar on a mobile station device so that it is not suitable for compact implementation of a mobile station device. The hyperbolic line of position scheme such as loran requires synchronization among base stations. In general, base stations of the cellular mobile communications are not synchronized with each other so that this scheme is not applicable to the cellular mobile communications, except for the IS-95 scheme of the American ELA/TIA standard which has synchronization among base stations. The microwave landing system can measure a position of an airplane within a particular area at high precision by using a special directional antenna, but it is difficult to measure an arbitrary position of a mobile station by using a simple radio equipment.
Recently, the position measurement scheme called GPS (Global Positioning System) that utilizes satellite has become popular, but this is also a system that requires high precision synchronization among satellite stations, and therefore it is applicable only to the IS-95 scheme mentioned above, and not applicable to the general cellular mobile communication systems which are asynchronous systems.
Thus there has been a problem that the conventionally known radio based position estimation techniques are not suitable for the general cellular mobile communications because the compact implementation of a mobile station device or a radio device of a base station becomes difficult and the synchronization among base stations is required.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a mobile station position estimation scheme for a cellular mobile communication system which is capable of estimating a position of a mobile station in a simple manner even in the general cellular mobile communication systems in which base stations are not synchronized.
According to one aspect of the present invention there is provided a mobile station position estimation method in a cellular mobile communication for carrying out communications between mobile stations and base stations, comprising the steps of: (a) exchanging between a base station and a mobile station a first signal sequence and a second signal sequence which are uniquely predetermined for the mobile station; and (b) estimating a position of the mobile station at one station among the base station and the mobile station, by obtaining a phase difference between the first signal sequence and the second signal sequence and calculating an estimated distance between the base station and the mobile station according to the phase difference.
According to another aspect of the present invention there is provided a base station device at a base station in a cellular mobile communication system for carrying out communications between mobile stations and base stations, comprising: a reception unit for receiving a first signal sequence transmitted by a mobile station, which is uniquely predetermined for the mobile station; and a transmission unit for transmitting a second signal sequence which is uniquely predetermined for the mobile station, to the mobile station in synchronization with the first signal sequence received by the reception unit, so as to enable the mobile station to estimate a position of the mobile station by calculating an estimated distance between the base station and the mobile station according to a phase difference between the first signal sequence and the second signal sequence.
According to another aspect of the present invention there is provided a mobile station device at a mobile station in a cellular mobile communication system for carrying out communications between base stations and mobile stations, comprising: a reception unit for receiving a first signal sequence transmitted by a base station, which is uniquely predetermined for the mobile station; and a transmission unit for transmitting a second signal sequence which is uniquely predetermined for the mobile station, to the base station in synchronization with the first signal sequence received by the reception unit, so as to enable the base station to estimate a position of the mobile station by calculating an estimated distance between the base station and the mobile station according to a phase difference between the first signal sequence and the second signal sequence.
According to another aspect of the present invention there is provided a base station device at a base station in a cellular mobile communication system for carrying out communications between mobile stations and base stations, comprising: a transmission unit for transmitting to a mobile station a first signal sequence which is uniquely predetermined for the mobile station; a reception unit for receiving a second signal sequence transmitted by the mobile station, which is uniquely predetermined for the mobile station; and a position estimation unit for estimating a position of the mobile station by obtaining a phase difference by comparing phases of the first signal sequence transmitted by the transmission unit and the second signal sequence received by the reception unit, and calculating an estimated distance between the base station and the mobile station according to the phase difference.
According to another aspect of the present invention there is provided a mobile station device at a mobile station in a cellular mobile communication system for carrying out communications between mobile stations and base stations, comprising: a transmission unit for transmitting to a base station a first signal sequence which is uniquely predetermined for the mobile station; a reception unit for receiving a second signal sequence transmitted by the base station, which is uniquely predetermined for the mobile station; and a position estimation unit for estimating a position of the mobile station by obtaining a phase difference by comparing phases of the first signal sequence transmitted by the transmission unit and the second signal sequence received by the reception unit, and calculating an estimated distance between the base station and the mobile station according to the phase difference.
According to another aspect of the present invention there is provided a base station device at a base station in a cellular mobile communication system for carrying out communications between mobile stations and base stations, comprising: a transmission unit for transmitting to a mobile station a first signal sequence which is uniquely predetermined for the mobile station; a reception unit for receiving a second signal sequence which is uniquely predetermined for the mobile station and information on a first phase difference indicating a phase difference between the first signal sequence and the second signal sequence as obtained by the mobile station, which are transmitted by the mobile station; and a position estimation unit for estimating a position of the mobile station by obtaining a second phase difference by comparing phases of the first signal sequence transmitte
Ohno Kouji
Onoe Seizo
Uebayashi Shinji
Hunter Daniel S.
NTT Mobile Communications Network Inc.
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
Woldetatios Yemane
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