RFID Cross Reads

RFID Cross Reads

Read1 - Link

• Identify and control stray reads
• Lay around tags inside an extended interrogation zone
• Stray reads from handling units which do not go through the RFID gate
• Stray reads from handling unit going through neighboring RFID gate

Passive RFID tags do not have any internal power available
Passive tags have typically very long shelf lives

Advances in eliminating cross Reads

• Impinj provides lay around tag suppression as an proprietary extension to LLRP protocol
• Thingmagic has patented methodology to determine tag distance based on phase angle change over frequency change
• Received Signal Strength Indicator (RSSI)
• Doppler shift based tag movement detection methods have been explored by Sensormatic. The company has patented Doppler shift based methodology to be used in fork lift truck application
• A camera can also be used as a motion trigger for RFID reader
• Triggered reading reduces the amount of stray reads, especially when RFID gates are adjacent

Data Sources - Monitored variables are:

• RSSI
• Mean RSSI
• Standard deviation of RSSI
• Phase angle rotation
• Standard deviation of phase angle rotation
• Doppler shift
• Mean of Doppler shift absolute values

Variables measured for each RFID read event are

• RSSI
• Doppler shift
• Phase angle rotation
• Receiving antenna
• Channel

Thoughts - Identifying Cross Reads, Eliminating Cross Reads

• Data Sources from Multiple Reads
• Identify those reads that are cross Reads
• Label the cross reads
• Analyze and identify if they follow any pattern
• Feature Variables - Received Signal Strength Indicator (RSSI), Last Read Zones

Anti-Collision Algorithms: A Cross-Layer Approach

Read 2 - Link1
Read 3 - KDE, Link2, Link3

Happy Learning!!!