Method of calculating the position of a mobile radio station based on shortest propagation time
First Claim
1. A method of calculating a position of a first radio station intended to be connected to a second radio station, said calculating method using measurements of a radio signal, called location signal, sent by one of said radio stations, called emitting radio station, to the other of said radio station, called receiving radio station, and propagated to said receiving radio station along a plurality of radio paths including a shortest radio path, characterized in that said locating signal includes a plurality of identical messages, combined by said receiving radio station in order to obtain a signal of higher energy of which the shortest path is detected, said measurements of the location signal being based on said shortest path.
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Abstract
The invention relates to a location method based on distance measurements. In such methods the distance between a mobile station and a base station is measured by finding the one-way propagation time between the two radio stations. This one-way propagation time is obtained by sending a location signal and measuring the time of arrival of said location signal.
The problem is that the signals which are detected at the receiving station and which are used for such measurements often correspond to reflected radio paths which are longer than direct radio paths. This results in an inaccurate position.
The invention proposes a method to ensure that the distance calculation will be done by using the first time of arrival of the location signal, said first time of arrival corresponding to a propagation through the shortest radio path which is likely to be the direct path.
This is achieved by using a location signal which includes a plurality of identical messages, and by combining said messages on reception in order to obtain a signal of higher energy of which the shortest path is detected.
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Citations
10 Claims
- 1. A method of calculating a position of a first radio station intended to be connected to a second radio station, said calculating method using measurements of a radio signal, called location signal, sent by one of said radio stations, called emitting radio station, to the other of said radio station, called receiving radio station, and propagated to said receiving radio station along a plurality of radio paths including a shortest radio path, characterized in that said locating signal includes a plurality of identical messages, combined by said receiving radio station in order to obtain a signal of higher energy of which the shortest path is detected, said measurements of the location signal being based on said shortest path.
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6. A communication network comprising a first radio station intended to communicate with a second radio station which may move with respect to said first radio station, at least one of said radio stations comprising sending means to send a radio signal called location signal propagated to the other one of said radio stations via a plurality of radio paths including a shortest path, and the other one of said radio stations comprising measuring means for making measurements of said location signal and calculating means for calculating a position of said second radio station from said measurements, characterized in that said location signal includes a plurality of identical messages, combined by the other one of said radio stations in order to obtain a signal of higher energy of which the shortest path is detected, said measurements of the location signal being based on said shortest path.
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9. A radio station comprising sending means for sending a radio signal called location signal which may be propagated via a plurality of radio paths including a shortest path, measurements of said location message being used for calculating a position of said radio station, characterized in that said locating signal includes a plurality of identical messages, intended to be combined for obtaining a signal of higher energy from which the shortest path is detectable.
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10. A radio station intended to receive location signals including a plurality of identical messages via a plurality of radio paths including a shortest path, characterized in that it comprises:
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sampling means for sampling received signals, first detection means for detecting a first message of a received location signal, said first message being received in a time slot called reception time slot, first storage means for storing samples received in a time slot surrounding said reception time slot, second storage means for storing samples received in time slots surrounding the reception time slots of at least part of the repeated messages of said received location signal, processing means for calculating a correlation function of said stored samples with a pattern related to said message, second detection means for detecting a first maximum of said cross-correlation function, and first maximum being used for distance calculation.
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Specification
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- Resources
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Current AssigneeJuha Heikki Antero Rapeli
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Original AssigneeJuha Heikki Antero Rapeli
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InventorsRapeli, Juha Heikki Antero
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Application NumberUS10/732,876Publication NumberTime in Patent OfficeDaysField of SearchUS Class Current342/450CPC Class CodesG01S 13/74 Systems using reradiation o...G01S 7/02 of systems according to gro...G01S 7/292 Extracting wanted echo-signalsH04W 64/00 Locating users or terminals...
