What are the main advantages or disadvantages of using them together?
I am unsure what you mean by using Wi-Fi in conjunction with RFID. Are you referring to transferring data from passive high-frequency (HF) or ultrahigh-frequency (UHF) readers to a back-end server via a Wi-Fi connection, or do you mean using Wi-Fi-based RFID transponders? I'll try to address both.
For the first question, the only real downside is possibly experiencing some latency if you are transmitting a lot of data and possibly overloading your network, which could happen with a wired connection to readers as well. In most cases, readers do not transmit a lot of information. Software on a reader is set up to send only relevant data. For instance, if you have a shelf reader, it might ping each tag every second or two. But if the tag responds, the reader will not need to send the tag ID, its own reader ID and a time and date stamp to a back-end system in order to say the item is still on the shelf. That is assumed. The reader only needs to report when the tag fails to respond after a certain period of time, indicating it has been removed from the shelf. This greatly reduces the amount of data collected and shared over the network.
There are high-volume applications for which latency can become an issue. If you are writing serial numbers to 10,000 shirts coming off a factory line, for instance, and you want to be sure that no other factory your company owns or works with has used the same serial number, you would need to access a central database and check each number. This could result in some latency. There are strategies for assigning blocks of serial numbers to ensure that no duplicates occur, but some firms still prefer to perform near-real-time checks.
As for using Wi-Fi-based active RFID transponders, the main issue I have heard from companies that have deployed such systems is that they need to install additional access points to obtain the location accuracy they require. The tags usually transmit only a serial number and sometimes temperature readings (if they are being used to monitor heat or cold). What's more, the tags can be set to ping every minute or five minutes, depending on how urgent it is to know an item's location, so they will not overwhelm a network with traffic.
I hope that answers your question.
—Mark Roberti, Founder and Editor, RFID Journal
Previous Post What Does “Pitch” Mean? »