Radio-frequency identification (RFID) is one of the fastest-growing wireless technologies. It brings the benefits of both barcode and wireless technology to asset management, product tracking, shipping and transportation ID, inventory control, and location detection.

According to G2 Microsystems' marketing data, based on estimates from five of the major market research firms, the market for asset tracking by RFID is expected to grow from a little over $100 million in 2006 to about $900 million in 2011. The major applications categories are transportation, government/Department of Defense, automotive, enterprise, hospital and pharma, and chemical.

Most RFID uses passive tags that get their power via RF from their readers. This setup makes for a small and cheap tag, but it limits reading range and data storage. Active tags with a battery can provide longer-range reading and reliability, yet they're larger and more expensive.

Designers contemplating an RFID solution often pay less attention to the total cost of ownership (TCO) than they should. In almost every case, a new network system must be built and installed to deal with the blizzard of data created by RFID. Regardless of the RFID technology involved, it still is an extra cost over the already existing networking infrastructure, which 99 times out of 100 is an Ethernet network with Wi-Fi extensions. If only the tags were using Wi-Fi.

Now, designers can turn to a Wi-Fi active RFID tag chip from G2 Microsystems. The G2C501 works directly with existing wireless access points on the network, meaning no new network installation is required. The tags are programmed with a URL, so designers can track them through an existing 802.11 wireless local-area network (WLAN) and the Internet.

Wi-Fi isn't known for its low power consumption. To the contrary, most Wi-Fi chips are power hogs. But who cares when they're used in ac-powered routers, gateways, PCs, and laptops? Still, battery-powered Wi-Fi radios must ba able to operate for years to make it in the RFID space. The G2C501 is up to the task.

The G2C501 dtraws just 10 µA in sleep mode. Current draw is very low during actual usage, which is periodic anywayu. Most transmission duty cycles are very low, making it possible for batteries to last for years. A pair of AA cells and a 40-s report rate yield a five-year battery life. This low power consumption makes all of the chip's features possible.

The chip's standard 2.4-GHz 802.11b transceiver is fully Wi-Fi compatible and acceptable worldwide (see Figure). It talks directly to existing access points, hotspots, or new transceivers. Using existing networks eliminates the need for new infrastructure. Leveraging the existing network can reduce the cost of an RFID system to less than 25% of the cost of a new RFID system with its own readers/interrogators and network wiring.