# US 8,542,098 B2 · Location determination and guidance using radio frequency identification > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 8,542,098 B2 - Document ID: US8542098B2 - Status: Granted - Kind: B2 - Application number: 13/448,153 - Filed: 2012-04-16 - Published: 2012-08-09 - Granted: 2013-09-24 - Earliest claimed: 2007-03-14 - Assignees: AT&T Intellectual Property II, L.P. - Applicants: Thomas Killian; Christopher Rice - Inventors: Thomas Killian; Christopher Rice - Web page: https://patentgrep.com/patent/US8542098B2 ## CPC - G01S 13/825: {with exchange of information between interrogator and responder} - G01C 21/20: Instruments for performing navigational calculations (G01C21/24, G01C21/26 take precedence) - G01C 21/206: {specially adapted for indoor navigation} - G01C 21/343: {Calculating itineraries (travelling salesman problem G06Q10/04; optimisation of routes G06Q10/047)} - G01S: RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES - G01C: MEASURING DISTANCES, LEVELS OR BEARINGS; SURVEYING; NAVIGATION; GYROSCOPIC INSTRUMENTS; PHOTOGRAMMETRY OR VIDEOGRAMMETRY (measuring liquid level G01F; radio navigation, determining distance or velocity by use of propagation effects, e.g. Doppler effects, propagation time, of radio waves, analogous arrangements using other waves G01S) ## Abstract A method and system for location determination and guidance using radio frequency identification (RFID) are disclosed. A location of a mobile RFID reader can be determined by detecting stationary RFID tags located at fixed locations. Each RFID tag stores location information associated with its position as well as location information of at least one other RFID tag. The location information stored by each RFID tag can be used to direct a user from one RFID tag to another. Thus, RFID technology is also used to guide mobile RFID reader between the fixed locations of the stationary RFID tags. ## Claims ### Claim 1 A method of operation of a portable device, comprising: transmitting, by a processor, a radio frequency signal; detecting, by the processor, a plurality of radio frequency identification tags based on a plurality of signals received in response to the radio frequency signal; receiving, by the processor, from the plurality of radio frequency identification tags, first location information of a first radio frequency identification tag and second location information of a second radio frequency identification tag; and determining, by the processor, a route from a location of the portable device to a location of the second radio frequency identification tag based on the second location information and the first location information, wherein the second location information further comprises map information showing a route between a location of the first radio frequency identification tag and the location of the second radio frequency identification tag. ### Claim 2 (depends on 1) The method of claim 1, wherein the first location information comprises the location of the first radio frequency identification tag and the second location information comprises the location of the second radio frequency identification tag. ### Claim 3 (depends on 1) The method of claim 1, wherein the detecting the plurality of radio frequency identification tags comprises: detecting all radio frequency identification tags within a range of the radio frequency signal transmitted from the portable device. ### Claim 4 (depends on 3) The method of claim 3, wherein the receiving from the plurality of radio frequency identification tags, the first location information and the second location information comprises: selecting a first radio frequency identification tag from the radio frequency identification tags within the range of the radio frequency signal; and receiving the first location information and the second location information from the first radio frequency identification tag that is selected. ### Claim 5 (depends on 1) The method of claim 1, further comprising: transmitting additional first location information to one of the plurality of radio frequency identification tags. ### Claim 6 (depends on 1) The method of claim 1, further comprising: transmitting additional second location information to one of the plurality of radio frequency identification tags. ### Claim 7 A mobile radio frequency identification reader device, comprising: a processor; and a computer-readable medium storing a plurality of instructions which, when executed by the processor, cause the processor to perform operations, the operations comprising: transmitting a radio frequency signal; detecting a plurality of radio frequency identification tags based on a plurality of signals received in response to the radio frequency signal; receiving from the plurality of radio frequency identification tags, first location information of a first radio frequency identification tag and second location information of a second radio frequency identification tag; and determining a route from a location of the portable device to a location of the second radio frequency identification tag based on the second location information and the first location information, wherein the second location information further comprises map information showing a route between a location of the first radio frequency identification tag and the location of the second radio frequency identification tag. ### Claim 8 (depends on 7) The mobile radio frequency identification reader device of claim 7, wherein the first location information comprises the location of the first radio frequency identification tag and the second location information comprises the location of the second radio frequency identification tag. ### Claim 9 (depends on 7) The mobile radio frequency identification reader device of claim 7, wherein the detecting the plurality of radio frequency identification tags comprises: detecting all radio frequency identification tags within a range of the radio frequency signal transmitted from the portable device. ### Claim 10 (depends on 9) The mobile radio frequency identification reader device of claim 9, wherein the receiving from the plurality of radio frequency identification tags, the first location information and the second location information comprises: selecting a first radio frequency identification tag from the radio frequency identification tags within the range of the radio frequency signal; and receiving the first location information and the second location information from the first radio frequency identification tag that is selected. ### Claim 11 (depends on 7) The mobile radio frequency identification reader device of claim 7, further comprising: transmitting additional first location information to one of the plurality of radio frequency identification tags. ### Claim 12 (depends on 7) The mobile radio frequency identification reader device of claim 7, further comprising: transmitting additional second location information to one of the plurality of radio frequency identification tags. ### Claim 13 A non-transitory computer-readable medium storing a plurality of instructions which, when executed by a processor, cause the processor to perform operations for providing security on a mobile endpoint device, the operations comprising: transmitting a radio frequency signal; detecting a plurality of radio frequency identification tags based on a plurality of signals received in response to the radio frequency signal; receiving from the plurality of radio frequency identification tags, first location information of a first radio frequency identification tag and second location information of a second radio frequency identification tag; and determining a route from a location of the portable device to a location of the second radio frequency identification tag based on the second location information and the first location information, wherein the second location information further comprises map information showing a route between a location of the first radio frequency identification tag and the location of the second radio frequency identification tag. ### Claim 14 (depends on 13) The non-transitory computer-readable medium of claim 13, wherein the first location information comprises the location of the first radio frequency identification tag and the second location information comprises the location of the second radio frequency identification tag. ### Claim 15 (depends on 13) The non-transitory computer-readable medium of claim 13, wherein the detecting the plurality of radio frequency identification tags comprises: detecting all radio frequency identification tags within a range of the radio frequency signal transmitted from the portable device. ### Claim 16 (depends on 15) The non-transitory computer-readable medium of claim 15, wherein the receiving from the plurality of radio frequency identification tags, the first location information and the second location information comprises: selecting a first radio frequency identification tag from the radio frequency identification tags within the range of the radio frequency signal; and receiving the first location information and the second location information from the first radio frequency identification tag that is selected. ### Claim 17 (depends on 13) The non-transitory computer-readable medium of claim 13, further comprising: transmitting additional first location information to one of the plurality of radio frequency identification tags. ### Claim 18 (depends on 13) The non-transitory computer-readable medium of claim 13, further comprising: transmitting additional second location information to one of the plurality of radio frequency identification tags.