# US 8,570,157 B1 · Local processing of received RFID tag responses

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- Number: US 8,570,157 B1
- Document ID: US8570157B1
- Status: Granted
- Kind: B1
- Application number: 13/410,532
- Filed: 2012-03-02
- Granted: 2013-10-29
- Earliest claimed: 2005-08-31
- Assignees: Impinj, Inc.
- Applicants: Christopher J. Diorio; Kurt E. Sundstrom; Dan Bowman
- Inventors: Christopher J. Diorio; Kurt E. Sundstrom; Dan Bowman
- Web page: https://patentgrep.com/patent/US8570157B1

## CPC

- G06K 17/0022: {arrangements or provisions for transferring data to distant stations, e.g. from a sensing device ("transfer between computer elements G06F13/00 "; data-transmission H04L)}
- G06K 7/10108: {interrogating only those RFIDs that fulfill a predetermined requirement, e.g. selecting all RFIDs having the same speed and moving in a cloud like fashion, e.g. on the same train; interrogating only RFIDs having a certain predetermined temperature, e.g. in the same fridge, another possibility being the active ignoring of a group of tags that fulfill a predetermined requirement, equivalent to the Boolean NOT operation}
- G06K: GRAPHICAL DATA READING (image or video recognition or understanding G06V); PRESENTATION OF DATA; RECORD CARRIERS; HANDLING RECORD CARRIERS

## Abstract

Radio frequency identification (RFID) tags are selected for inventorying using a combination of preselect and/or post select criteria. The selection commands can be for selecting according to a tag memory content, by invoking the mask address or by comparing other tag characteristics. Selection criteria can be determined locally at a modem block of a reader or provided to the modem block by higher layers of the reader. Tags meeting the selection criteria are reported to the higher layers for further actions. Some tags may be held while waiting for instructions from the higher layer block(s). The instructions may involve one or more access operations, which may be performed using a higher transmit power than other operations.

## Claims

### Claim 1

An RFID reader system for receiving and processing RFID tag responses, comprising:
a first layer; and
a second layer, in which the first layer is configured to:
receive a postselect mask from the second layer;
inventory a tag population at a transmit power;
receive a tag response;
if the response does not meet a preselect criterion, then discard the response; else
report the response; and
apply a postselect criterion by comparing the response to the postselect mask;
if the response meets the postselect criterion then
pause the inventory and handing off control from the first layer to the second layer;
receive instructions from the second layer; and
if the instructions include performing an access operation on the tag, then:
determine an amount by which to increase the transmit power for the access operation;
increase the transmit power by the determined amount;
perform the access operation based on the instructions;
then decrease the transmit power;
then continue to inventory the tag population.

### Claim 2 (depends on 1)

The system of claim 1, wherein the first layer is configured to increase the transmit power from a first level to a second level, then decrease it to the first level.

### Claim 3 (depends on 1)

The system of claim 1, wherein the first layer is configured to increase the transmit power from a first level to a second level, then decrease it to a third level different from the first level.

### Claim 4 (depends on 1)

The system of claim 1, wherein determining the amount includes receiving the amount in the instructions.

### Claim 5 (depends on 4)

The system of claim 4, wherein the amount is determined based on one or more of: a tag response power level, a tag response frequency, a tag response phase, a tag type, an access operation type, and a noise level.

### Claim 6 (depends on 1)

The system of claim 1, wherein the access operation is one of a read command, a write command, a lock command, a kill command, a security command, a file management command, and a custom command.

### Claim 7 (depends on 1)

The system of claim 1, wherein the first layer is configured to pause the inventory until expiration of a predetermined waiting period.

### Claim 8 (depends on 1)

The system of claim 1, wherein the first layer is further configured to:
generate associated data for the tag response; and
report to the second layer the associated data.

### Claim 9 (depends on 8)

The system of claim 8, in which the associated data includes at least one of: a time stamp, an indication about a received signal strength of the tag response, an RF channel used by the tag, and a reader antenna.

### Claim 10

A method for a first layer of a multilayer RFID reader system to process a plurality of received RFID tag responses, the method comprising:
receiving a postselect mask from a second layer;
inventorying a tag population at a transmit power;
receiving a response from a tag;
if the response does not meet a preselect criterion, then discarding the response; else
reporting the response and applying a postselect criterion by comparing the response to the postselect mask;
if the response meets the postselect criterion then
pausing the inventory and handing off control from the first layer to the second layer;
receiving control and instructions back from the second layer; and
if the instructions include performing an access operation on the tag, then:
determining an amount by which to increase the transmit power for the access operation;
increasing the transmit power by the determined amount;
performing the access operation on the tag based on the instructions;
then decreasing the transmit power;
then continuing to inventory the tag population.

### Claim 11 (depends on 10)

The method of claim 10, wherein determining the amount includes receiving the amount in the instructions.

### Claim 12 (depends on 10)

The method of claim 10, wherein the transmit power is increased from a first level to a second level, then decreased to the first level.

### Claim 13 (depends on 10)

The method of claim 10, wherein the transmit power is increased from a first level to a second level, then decreased to a third level different from the first level.

### Claim 14 (depends on 10)

The method of claim 10, wherein the amount is determined based on one or more of: a tag response power level, a tag response frequency, a tag response phase, a tag type, an access operation type, and a noise level.

### Claim 15 (depends on 10)

The method of claim 10, wherein performing the access operation includes transmitting one of a read command, a write command, a lock command, a kill command, a security command, a file management command, and a custom command.

### Claim 16 (depends on 10)

The method of claim 10, in which the inventory is paused until expiration of a predetermined waiting period.

### Claim 17 (depends on 10)

The method of claim 10, further comprising:
generating associated data for the tag response; and
reporting to the second layer the associated data.

### Claim 18 (depends on 17)

The method of claim 17, in which the associated data includes at least one of: a time stamp, an indication about a received signal strength of the tag response, an RF channel used by the tag, and a reader antenna.