The combination of RFID and WiFi technology is a great combination for a Real-Time Location Systems or RTLS. Find out here about the RFID technology and how it works.
The RFID Application
What is RFID?
Before going into RFID application, first I want to show you some simple facts about the RFID technology.
Radio-Frequency Identification (RFID) is the method of automatic identification based on RFID tags or transponders. RFID tags are devices which can carry the data. They could be attached to product, person or animal. RFID tags are made of chips and antennas.
The RFID History
RFID is not a new technology. The Russian inventor Leon Theremin has invented an espionage tool in 1945 which was the forerunner of the RFID tag. A vibrated diaphragm has slightly changed the shape of the resonator and reflected radio frequency. It was passive, but activated from an outside source.
Types of RFID Tags
There are two types of RFID tags:
Passive RFID Tags
Passive tags don’t have the internal power supply. The most of RFID produced today are passive. They can be used within close proximity of a passive RFID tag reader or interrogator. They use only the reader as the power source. Their range is up to 20 feet or six meters and they are quite cheap.
Active RFID Tags
Active RFID tags need an internal power supply. This internal power supply enables the active RFID tags to transmit information at great range. They are larger compared to the passive tags.
Semi-passive RFID Tags
Semi-passive RFID tags also need internal batteries. The difference between active and semi-passive tags is that active tag broadcast radio waves to a reader, while semi-passive use the reader for broadcasting.
Active and semi-passive RFID tags are more expensive, but some of them have the range up to 330 feet or 100 meters.
RFID rags can be also grouped by the type of storage they use:
- WORM (write once, read many)
Read-write tags can be read and written many times. Read-only RFID tags can contain only data which is stored when they were made. On the WORM tags you can add the additional data, but only once.
There are many RFID applications. RFID tags can be used in many ways:
- Tracking of goods
- Tracking of persons and animals
- In sports for checking authenticity and tracking performance
- Access management – public transport
- Toll collection
- Travel documents – passports
- Baggage tracking in airports
- Mobile payments
- Touch-free payment systems
- For identifying and managing the assets
- Accurate knowledge of the current inventory
RFID Application and WiFi
RFID application, with the WiFi, is the ideal combination for RTLS (Real-Time Location System). WiFi ID is the active RFID tag which uses 802.11 standard and 2.4 GHz frequency for communication. The WiFi IDs connect to the access point and enables the location and tracking of devices.
Read more about the WiFi technology on WiFi Technology is Changing the World we are Living.
With the RFID application with WiFi, there are two ways to determine the locations:
- RSSI – Radio Signal Strength Information
- TDOA – Time Difference Of Arrival
RSSI – Radio Signal Strength Information
RSSI is the best choice for
- Indoor environments
- Outdoor environment with the proper network planning
RSSI can work with any access point or wireless router. They can work based on measuring the signal strength from the tag perspective or from the access point perspective.
TDOA – Time Difference of Arrival
TDOA measures the time of the WiFi IDs signals from multiple readers at the same time and it is better for outdoor or large indoor environments.
TDOA requires vendor specific receivers and WiFi IDs.