RFID-UWB WLAN Coexistence via Time Division Multiplexing
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Solution Overview
Problem
RFID systems using ultra-wide band (UWB) communications face interference issues when operating in the same space as wireless LANs, which can lead to unreliable tag identification and location determination, especially due to mutual RF interference.
Innovation Solution
The implementation of a system that enables coexistence between RFID/UWB networks and wireless LANs through time division and receiver isolation techniques, such as RTS/CTS handshakes, beacon frames, and RF filters, allowing both systems to operate without interference by synchronizing transmission periods and using frequency division to separate signal bands.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If RFID/UWB and WLAN operate in the same space simultaneously, then both systems can be deployed in the same area, but mutual RF interference occurs causing unreliable tag identification and location determination
Solution Approach 1:
The patent segments the operation time by dividing it into contention periods and contention-free periods. During contention-free periods, RFID/UWB operations are isolated from WLAN interference, ensuring reliable tag identification while allowing both systems to coexist in the same space.
Solution Approach 2:
The patent implements periodic time-division multiplexing where RFID/UWB operations occur during scheduled contention-free periods, and WLAN operations occur during other periods. This periodic separation eliminates mutual interference while maintaining adaptability of both systems.
2Reliability
If transmission range of the reader is limited to prevent unauthorized access, then security is improved, but tags near the limit cannot be identified due to orientation and occlusion issues
Solution Approach 1:
The patent introduces UWB distance determination as an intermediary verification layer between the reader and tag. By measuring the actual distance using UWB time-of-flight measurements, the system can confirm whether a tag is within the authorized range, allowing reliable access control while maintaining accurate location determination for tags at various orientations.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution ensures that RFID/UWB systems can operate effectively in the same space as wireless LANs without interference, reducing noise and distortion, and allowing for accurate tag identification and location determination while minimizing the need for modifications to existing WLAN infrastructure.
Implementation Method 1
The RFID network transfers ultra-wide band signals between a reader and a tag
Implementation Method 2
an access point communicates with a WLAN transceiver using WLAN signals
Implementation Method 3
Co-existence of the two networks is provided either by time division between the ultra-wide band signals and WLAN signals
Implementation Method 4
an RFID system using ultra wide band signaling is susceptible to receive high signal levels from a WLAN operating in the same vicinity
Data Source
AI summary
A system including a radio frequency identification (RFID) network and a wireless local area network (WLAN). The RFID network transfers ultra-wide band signals between a reader and a tag. In the wireless local area network (WLAN) an access point communicates with a WLAN transceiver using WLAN signals. The reader is operatively attached to either the wireless access point or the WLAN transceiver and the WLAN is a back haul network of the RFID network. Co-existence of the two networks is provided either by time division between the ultra-wide band signals and WLAN signals; and/or receiver isolation of said RFID network from said WLAN signals.