Title:
MEASURING DISTANCE USING WIRELESS COMMUNICATION
Document Type and Number:
WIPO Patent Application WO2005020600
Kind Code:
A3
Abstract:
A method of estimating the distance between a first wireless communication terminal and a second wireless communication terminal includes: (i) receiving at the first terminal a received signal comprising a composite multipath derivative of a RF transmission signal transmitted by a second terminal which transmission signal comprises an OFDM signal; and (ii) processing the received signal including performing a demodulation operation to produce a demodulated signal; and characterised by: (iii) resolving the demodulated signal into a plurality of components corresponding to different path length components included in the received signal; (iv) identifying which of the resolved components corresponds to a shortest path length; and (v) for the identified component, computing a time of travel from the second terminal to the first terminal. the first terminal may be operable to determine a strength value for each of the resolved components. The strength value may be compared with a threshold value to determine if the strength value is to be considered as non-zero, whereby the component having that strength value is to be included to find the component having the shortest path length. Also described is a terminal which operates to carry out these steps and a method of transmitting and receiving an OFDM signal which includes these steps. The transmitted signal which is transmitted by the second terminal and received in a multipath derivative form by the first terminal may conveniently be the PLCP (Physical Layer Convergence Procedure) Training Signal defined in the 802.11 standard. This is the 'Long Training Sequence' normally provided at the beginning of a transmission by a terminal in a LAN (e.g. a RU). The purpose of this signal is to allow another terminal (e.g. an AP) to synchronize with the terminal.
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Inventors:
LUZZATTO ARIEL (IL)
SERFATY SALOMON (IL)
SERFATY SALOMON (IL)
Application Number:
PCT/EP2004/051289
Publication Date:
April 28, 2005
Filing Date:
June 29, 2004
Export Citation:
Assignee:
MOTOROLA INC (US)
LUZZATTO ARIEL (IL)
SERFATY SALOMON (IL)
MOTOROLA LTD (GB)
LUZZATTO ARIEL (IL)
SERFATY SALOMON (IL)
MOTOROLA LTD (GB)
International Classes:
A63F13/12; G01S11/06; H04L27/26; H04L29/06; G01S1/02; G01S5/14; G01S11/02; (IPC1-7): G01S5/14; H04L27/26
Foreign References:
| EP0613021A1 | 1994-08-31 | |||
| CA2396639A1 | 2003-02-07 | |||
| US5056106A | 1991-10-08 |
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