Radio communication apparatus, radio communication system and radio communication method

Patent metadata

Field	Value
Publication number	US-11108449-B2
Application number	US-201916728177-A
Country	US
Kind code	B2
Filing date	Dec 27, 2019
Priority date	Mar 26, 2019
Publication date	Aug 31, 2021
Grant date	Aug 31, 2021

Abstract

A radio communication apparatus is described that includes a reception antenna, a converter, a calculator, and a separator. The reception antenna receives a mixed signal including two or more backscatter signals respectively transmitted from two or more tag devices and the converter converts the mixed signal into complex data on a complex plane. The calculator calculates phase angles of carrier waves of the two or more backscatter signals to approximate the phase angles into a complex data sequence of a predetermined length, and generates a projector matrix formed of a combination of the phase angles of carrier waves of the two or more backscatter signals. The separator separates the two or more backscatter signals from the mixed signal based on an inverse matrix of the projector matrix and the complex data sequence.

First claim

What is claimed is:

1. A radio communication apparatus comprising:
one or more reception antennas that receive a mixed signal including two or more backscatter signals respectively transmitted from two or more tag devices,
a converter that converts the mixed signal into complex data on a complex plane,
a calculator that calculates at least phase angles of carrier waves of the two or more backscatter signals in order to approximate the phase angles to a complex data sequence of a predetermined length, the complex data sequence formed of the complex data, wherein the calculator generates a projector matrix formed of a combination of the phase angles of carrier waves of the two or more backscatter signals, and
a separator that separates the two or more backscatter signals from the mixed signal based on an inverse matrix of the projector matrix and the complex data sequence
wherein a number of reception antennas, out of the one or more reception antennas, used in calculating the phase angles of the carrier waves of the two or more backscatter signals, is less than a number of the two or more tag devices.

2. The radio communication apparatus according to claim 1 , comprising:
a transmission antenna that transmits a carrier signal used for transmitting the two or more backscatter signals from two or more tag devices respectively.

3. The radio communication apparatus according to claim 1 , wherein
a number of the one or more reception antennas is less than the number of the two or more tag devices.

4. The radio communication apparatus according to claim 1 , wherein
a number of the one or more reception antennas is an integer equal to or more than ½ of the number of the two or more tag devices.

5. The radio communication apparatus according to claim 4 , wherein
two or more reception antennas are assigned to a predetermined tag device which is one of the two or more tag devices, and
the separator separates two or more predetermined backscatter signals respectively from two or more mixed signal received by the two or more reception antennas, and acquires the backscatter signal for the predetermined tag device by combining the two or more predetermined backscatter signals.

6. The radio communication apparatus according to claim 1 , wherein
the two or more backscatter signals are adjusted to cross an origin on the complex plane.

7. A radio communication system comprising a radio communication apparatus and two or more tag devices, wherein:
the two or more tag devices each comprise:
a transmitter that transmits a backscatter signal, and

the radio communication apparatus comprises:
one or more reception antennas that receive a mixed signal including two or more backscatter signals respectively transmitted from the two or more tag devices,
a converter that converts the mixed signal into complex data on a complex plane,
a calculator that calculates at least phase angles of carrier waves of the two or more backscatter signals in order to approximate the phase angles to a complex data sequence of a predetermined length, the complex data sequence formed of the complex data, wherein the calculator generates a projector matrix formed of a combination of the phase angles of carrier waves of the two or more backscatter signals, and
a separator that separates the two or more backscatter signals from the mixed signal based on an inverse matrix of the projector matrix and the complex data sequence,

wherein a number of reception antennas, out of the one or more reception antennas, used in calculating the phase angles of the carrier waves of the two or more backscatter signals, is less than a number of the two or more tag devices.

8. A radio communication method comprising steps of:
receiving a mixed signal including two or more backscatter signals respectively transmitted from two or more tag devices by one or more reception antennas,
converting the mixed signal into complex data on a complex plane,
calculating at least phase angles of carrier waves of the two or more backscatter signals in order to approximate the phase angles to a complex data sequence of a predetermined length, the complex data sequence formed of the complex data, and generating a projector matrix formed of a combination of the phase angles of carrier waves of the two or more backscatter signals, and
separating the two or more backscatter signals from the mixed signal based on an inverse matrix of the projector matrix and the complex data sequence,
wherein a number of reception antennas, out of the one or more reception antennas, used in calculating the phase angles of the carrier waves of the two or more backscatter signals, is less than a number of the two or more tag devices.

Assignees

• Univ Keio
• School Judicial Person Ikutokugakuen
• Kyowa Electronic Instruments

Inventors

• Mitsugi Jin
• Ichikawa Haruhisa
• KAWAKITA Yuusuke
• Egawa Kiyoshi

Classifications

• G06K7/0008 Primary

  General problems related to the reading of electronic memory record carriers, independent of its reading method, e.g. power transfer · CPC title

• G06K19/0723

  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 title

• H04B7/0615 Primary

  of weighted versions of same signal · CPC title

• H04B7/0854

  using error minimizing algorithms, e.g. minimum mean squared error [MMSE], "cross-correlation" or matrix inversion · CPC title

• G06K7/10356

  using a plurality of antennas, e.g. configurations including means to resolve interference between the plurality of antennas · CPC title