RuBee

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RuBee (IEEE 1902.1) is a protocol that uses Long Wave (LW) magnetic signals to transfer information. The technology is in its final stages of development by the IEEE.[1]. The protocol is similar to WiFi (IEEE 802.11), Zigbee (IEEE 802.15.4) and Bluetooth (IEEE 802.15) which are all radiating transceivers. The new specification, which builds upon the technological breakthroughs realized in HF and UHF RFID technology, will improve on the visibility network protocol known as RuBee.kHz. Visibility networks are employed to provide the status and location of people or other high-value assets in a user-configured region.

RuBee is a bidirectional, on-demand, peer-to-peer radiating transceiver protocol operating at frequencies below 450 kHz and optimally at 132 kHz. This protocol functions successfully in harsh environments with networks of many thousands of tags and has a range of 3 to 30 m. By 'harsh environments' is meant the ability to read and write data near steel or water — and around corners. Thus RuBee tags function in environments where other tags, especially EPC (Electronic Product Code) tags fail.

RuBee networks are already deployed in commercial applications including smart shelves for high-value medical devices in hospitals and operating rooms; smart, in-store and warehouse shelves for inventory tracking and a variety of agricultural visibility networks for livestock, elk and other exotic animals. The new IEEE P1902.1 standard will address physical and data-link layers based on existing RuBee protocol now in use. This standard, which will be essential for the widespread international use of RuBee, will support interoperation of RuBee tags, RuBee chips, RuBee network routers and other RuBee equipment now slated to be rolled out by several different manufacturers.

[edit] How RuBee works

IEEE P1902.1 RuBee employs inductive communication which means it relies upon magnetic energy — rather than electric energy. This stems from the fact that it operates below 450 kHz, which is below the AM radio band. Thus virtually all of the energy radiated by a RuBee base station or a RuBee tag is magnetic (H), rather than electric (E). RFID uses both forms depending on the frequency. Low frequency (LF - usually around 125 KHz) and high frequency (HF - usually around 13.56MHz) radio tags use magnetic coupling, whereas UHF and microwave tags use radio in which the electric field is more important. In retail applications in the USA, 900 MHz UHF tags predominate, in which almost all the energy is electric — or as it is commonly termed 'RF'.

If strong enough, magnetic waves can pass through almost anything, even rock. That same rock blocks RF after only a few feet. Another important distinction between magnetic E waves and RF is that the strength of an RF signal falls off from a linear wire or a sphere as 1/r, whereas the strength of a magnetic wave falls off far faster at the rate of 1/r3. This means that assuming the same input power is applied to a magnetic source and a RF source, the magnetic signal will not travel nearly as far as the RF signal.

At first glance this difference in fall-off rate may appear as a negative for a magnetic signal, but as we explain below it turns out to be quite a plus for a RuBee local visibility network. Secondly, magnetic signals are generated far more efficiently at low frequencies than electric fields.

[edit] Advantages

It is the relatively short range of magnetic signals and RuBee's use of LW energy that brings about a number of unexpected advantages:

• Long Battery Life – Because lower frequencies are always used for magnetic waves, the chips and detectors can run at low speed, consuming almost no power and using lowest-cost chip technology (4-micron CMOS). LW magnetic wave tag systems can and have run on low-cost lithium batteries for 15 years – at the expected battery shelf life.
• Tag Data Travels with the Asset – Because data is stored in the tag, IT (Information Technology) costs are reduced. This means that with a low-cost handheld reader one can simply read a RuBee tag and learn about the asset — manufacturing data, expiry date, lot number, etc. — wthout having to go to an IT system to look it up. In addition, the distance between the reader and the asset is not critical. RuBee can also write to a tag at the same range as it can read it. Whereas RFID uses EEPROM memory and writing to the tag is awkward. (In the case of RFID, range is limited, more power is required and write times are long.)
• Safe – A RuBee base station produces only microwatts of radio energy. RuBee's LW magnetic waves are not absorbed by biological tissues and are not even regulated by OSHA. In fact, RuBee produces less power and lower field strengths than the metal detectors in airports and the anti-theft detectors in retail stores operating at similar frequencies — by a factor of about 10 to 100.
• Superior Range – RuBee has a maximum volumetric range of approximately 10,000 square feet (100 ft. x 100 ft.), using volumetric loop antennas — compared to 8 inches to 20 feet for "beacon" or dipole antennas employed with passive HF and UHF RFID tag systems. From even a small volumetric antenna (1 ft. x 1ft.), RuBee can read a tag within an egg-shaped sphere of about 10 ft. x 15 ft.
• Cost Effective - With RuBee, relatively simple base stations and routers can be employed, which means receivers and card readers can be reasonably priced. In addition, the tags often include a single chip, a battery, a crystal and an antenna and can be priced competitively with respect to RFID tags with memory and/or battery.
• Less Noise – Because ambient noise in a region falls off as 1/r3, RuBee exhibits reduced susceptibility to any extraneous noise.

The higher frequency RFID radio communications systems have one major advantage: higher communication bandwidth. Whereas low frequency systems can handle approximately 9600 baud, at most and typical at 1,200 baud. However experience has shown that the lower baud rate is rarely an issue in closed-loop visibility networks. That is why RuBee, which is the only visibility protocol known to use inductive communicaton, works so well, where real-time visibility of assets is the crucial requirement.

[edit] References

• "IEEE Begins Wireless, Long-Wave Standard for Healthcare, Retail and Livestock Visibility Networks; IEEE P1902.1 Standard to Offer Local Network Protocol for Thousands of Low-Cost Radio Tags Having a Long Battery Life," Business Wire, June 8, 2006
• "Visible Assets Promotes RuBee Tags for Tough-to-Track Goods," by Mary Catherine O'Connor, RF Journal, June 19, 2006, http://www.rfidjournal.com/article/articleprint/2436/-1/1/