Wireless communication system, radio frequency communications system, wireless communications method, radio frequency communications method

• US 6,289,209 B1
• Filed: 08/08/1997
• Issued: 09/11/2001
• Est. Priority Date: 12/18/1996
• Status: Expired due to Term

• Current Assignee: Round Rock Research LLC
• Original Assignee: Micron Technology, Inc.
• Inventors: Wood, Clifton W. Jr.
• Primary Examiner(s): Le, Thanh Cong
• Application Number:
  US08/907,689
• Time in Patent Office: 1,495 Days
• Field of Search: 455/41, 455/59, 455/62, 455/67.1, 455/73, 455/575, 455/101, 455/103, 455/106, 455/133, 455/272, 455/277.1, 455/277.2, 340/825.54, 342/42, 342/43, 342/44, 342/50, 342/51, 375/267, 375/299
• US Class Current: 455/277.1
• CPC Class Codes: G06K 19/0723 the record carrier comprising an arrangement for non-contact communication, e.g. wireless communication circuits on transponder cards, non-contact smart cards or RFIDs
• CPC Class Codes: G06K 7/0008 General problems related to the reading of electronic memory record carriers, independent of its reading method, e.g. power transfer
• CPC Class Codes: H04B 7/0608 Antenna selection according to transmission parameters
• CPC Class Codes: H04B 7/0808 comparing all antennas before reception

Abstract

A wireless communications system comprising a first transponder adapted to be coupled to one of a plurality of selectable antennas, having a look-up table including locations holding data representing antennas, and having pointers pointing to selected ones of the locations, the pointers defining an order in which antennas will be used to attempt communication; and a second transponder configured to communicate with the first transponder, wherein the first transponder uses an antenna defined by data in one location of the table for communication with the second transponder, and, if successful communication with the second transponder is not established, the first transponder uses an antenna defined by data in another location of the table selected in accordance with the order defamed by the pointers.

Claims

1. A radio frequency communications system comprising:

a first radio frequency transponder adapted to be coupled to one of a plurality of selectable antennas, including a look-up table having rows holding data representing antennas, and including a pointer array having pointer elements pointing to different rows of the look-up table, the pointer array including a top row and a bottom row, the pointer array defining an order, from the top row of the array to the bottom row of the array, in which antennas will be used to attempt communication; and

a second radio frequency transponder configured to communicate with the first transponder, wherein the first transponder uses an antenna defined by data in the row of the look-up table to which the element in the top row of the pointer array points, for communication with the second transponder, and, if successful communication with the second transponder is not established, the first transponder uses an antenna defined by data in the row of the look-up table to which the element in the second highest row in the array points, and, if successful communication with the second transponder is still not established, the first transponder uses an antenna defined by data in the row of the look-up table to which the element in the third highest row in the array points;

wherein the order defined by the pointer array is selectively rearranged, the first radio frequency transponder being operable in a first mode, wherein the order defined by the pointers is rearranged after a successful communication with the second radio frequency transponder such that the top row of the array points to data representing the first row in the look-up table that resulted in successful communication, and a second mode, wherein the order defined by the pointers is rearranged after a successful communication with the second radio frequency transponder such that the element of the array which pointed to the row in the look-up table that resulted in successful communication points to the next higher row in the look-up table and such that the next higher element of the array points to the row in the look-up table that resulted in successful communication.

2. A radio frequency communications system in accordance with claim 1 wherein the first radio frequency transponder is further operable in a third mode wherein the order defined by the pointers is not rearranged regardless of which row in the look-up table resulted in successful communication with the second transponder.

3. A radio frequency communications system in accordance with claim 1 wherein the first transponder communicates with the second transponder using backscatter communications and, after the first transponder sends data to the second transponder, the first transponder transmits a continuous wave to the second transponder, wherein the communication system includes a dipole antenna coupled to the second transponder, the dipole antenna having two halves, and wherein the second transponder selectively reflects and does not reflect the continuous wave by either shorting or not shorting the two halves of the dipole antenna.

4. A radio frequency communications system in accordance with claim 1 wherein the first transponder communicates with the second transponder using backscatter communications, wherein the first transponder employs separate receive and transmit antennas, and wherein the respective rows of the look-up table store data representing antenna pairs respectively defined by one transmit antenna and one receive antenna.

5. A radio frequency communications system in accordance with claim 1 wherein the second transponder comprises a radio frequency identification device including memory storing data identifying the second transponder.

6. A radio frequency communications system wireless communications system in accordance with claim 1 and further comprising a plurality of transmit antennas, wherein the first transponder includes a switch for selecting which of the transmit antennas will be employed for wireless transmission by the first transponder, and wherein one of the transmit antennas is spaced apart from another of the transmit antennas by at least one wavelength.

7. A radio frequency communications method comprising:

defining a table having rows holding data representing antennas, and defining an array of pointer elements respectively storing location values pointing to different rows of the table, the array including a top and a bottom, the array defining an order, from the top of the array to the bottom of the array, in which antennas will be used to attempt communication;

causing a first transponder to use an antenna defined by data in the table in a row pointed to by the pointer element at the top of the array for communication with a second transponder, and, if successful communication with the second transponder is not established, causing the first transponder to use an antenna defined by data in a row pointed to by the next highest pointer element of the array; and

rearranging the order in accordance with a selected one of a first mode, wherein the location value pointing to data representing the first antenna that resulted in successful communication is moved to the top element of the array, and a second mode, wherein the location value pointing to data representing the first antenna that resulted in successful communication is swapped with the location value in the next higher element in the array.

8. A radio frequency communications method in accordance with claim 7 wherein the rearranging step further includes a selectable third mode, wherein the location values are not rearranged regardless of which antenna selection results in successful communication with the second transponder.

9. A radio frequency communications method in accordance with claim 7 and further comprising the step of causing the first transponder to communicate with the second transponder using backscatter communications and, after the first transponder sends data to the second transponder, causing the first transponder to transmit a continuous wave to the second transponder, and causing the second transponder to communicate with the first transponder by selectively reflecting and not reflecting the continuous wave by either shorting or not shorting two halves of a dipole antenna.

10. A radio frequency communications method in accordance with claim 7 and further comprising causing the first transponder to communicate with the second transponder using backscatter communications, and coupling the first transponder to separate receive and transmit antennas, and storing data in the respective rows of table representing antenna pairs respectively including one transmit antenna and one receive antenna.

11. A radio frequency communications method in accordance with claim 7 and further comprising the step of storing identifying data in the second transponder, and causing the second transponder to communicate the identifying data to the first transponder in response to a command from the first transponder.

12. A backscatter radio frequency communications system comprising:

a plurality of transmit antennas and receive antennas;

a first radio frequency transponder selectively coupled to an antenna pair defined by one of the transmit antennas and one of the receive antennas, including a table having rows holding data representing antenna pairs, and including an array of pointers defined by array elements respectively storing location values pointing to different rows of the table, the array having a top element, a bottom element, and intermediate elements, the array defining an order, from the top of the array to the bottom of the array, in which antennas will be used by the first transponder to attempt communication;

a second radio frequency transponder configured to communicate with the first transponder, wherein the first transponder uses an antenna pair defined by data in a row of the table pointed to by the location value stored in the top element of the array for communication with the second transponder, and, if successful communication with the second transponder is not established, the transponder uses an antenna pair defined by data pointed to by the location value stored in the next highest element of the array, the first transponder being configured to communicate with the second transponder using backscatter communications wherein, after the first transponder sends data to the second transponder, the first transponder transmits a continuous wave to the second transponder;

a dipole antenna coupled to the second transponder, the dipole antenna having two halves, the second transponder being configured to reflect and not reflect the continuous wave by either shorting or not shorting the two halves of the dipole antenna to communicate with the first transponder; and

wherein the order of the location values in the array is selectively reordered, and the first transponder is operable in a first mode, wherein the location value pointing to data representing the first antenna pair that resulted in successful communication is moved to the top of the array, a second mode, wherein the location value pointing to data representing the first antenna pair that resulted in successful communication is swapped with the location value in the next higher element in the array, and a third mode wherein the location values stored in the array are not rearranged regardless of which antenna selection results in successful communication with the second transponder.