wilamowski-b-m-irwin-j-d-industrial-communication-systems-2011

Radio Frequency Identification 8-13
congestions are often seen in the microwave ISM frequency because 2450.MHz is currently used in
microwave ovens, active RFIDs, wireless local area networks, and various wireless interconnect gadgets.
The selection of 5800.MHz is not advisable because the relevant technologies for mass production of
low-cost tags are far from mature.
In summary, regulators of the major trading blocks of nations have reached a consensus in assigning
some of the ISM slots in the ultrahigh frequency band for the license-free passive RFID.
8.17 UHF RFID
Using the method of backscattering, a long-range passive RFID system with a low-cost compact tag
could be designed. Since it is operating at one of the empty UHF frequency slots in the ISM band, it is
called the UHF RFID or simply the RFID.
Recall that one of the major objectives in developing the RFID is to replace the existing bar code
with a long-range, hands-free, rewritable, tamper resistant, immune of electromagnetic interference,
efficient, and versatile one, yet the advantages of the bar code, such as low-cost, low-profile, long-life,
smallness, and robustness are kept intact. To be honest, no electronic device could be cheaper than the
bar code. Similarly, no wireless device could be immunized from electromagnetic interference but its
vulnerability (EMI/EMC) could be assessed for comparison. Hence, it is a choice between the vicinity
card and the UHF RFID, as both have met most requirements, apparently.
Since the microelectronic technologies used in making HF components are more mature than
that of the UHF ones, chips for vicinity cards are less expensive. As the HF band is less utilized, the
vicinity card is subject to less intersystem interference. Moreover, due to its principle of operation, the
range of coverage of the vicinity card is very small, and therefore it is not vulnerable to intrasystem
interference. In other words, on the EMI/EMC, the vicinity card wins. However, due to its limited
range of coverage, the vicinity card is rejected because it does not satisfy the requirement on a longrange
operation.
For various technical, economical, medical, and political reasons, most of the active and passive RFID
systems mentioned under the preceding headings will not be replaced by the UHF RFID in the foreseeable
future. However, the importance of these RFID technologies will fade with the gradual eminence
of the UHF RFID. Hence, attention will be focused on the UHF RFID hereafter, unless stated otherwise.
8.18 Supply Chain Management
As a bar code replacement, an RFID tag is embedded in every pallet or product for shipment. Due to
globalization, the shipment may have to travel thousands of kilometers on land, on sea, and in air. At a
national border, it has to endure the long waiting line for custom control, quarantine check, and other
inspections. Then, the cargos are stored in one of the warehouses of the distributor before they are sent
to the point-of-sale. It is a journey of months that involves tens of handlers speaking different languages
and dialects.
Equipped with an active RFID tag, significant saving in waiting time inside and outside a container
port or an airport could be achieved by dispatching the container trucks via a WiFi wireless local area
network to move in an orderly fashion. Assisted by the same active RFID system, the loading and the
unloading of the containers could be carried out more efficiently. On the other hand, clearance of custom
control and other paper work could be speeded up for merchandise equipped with a passive RFID
tag. The passive RFID system is also applicable in accelerating inventory control at various warehouses
and the eventual retail outlet.
Unfortunately, a container port or an airport is only one of the bottlenecks along a 1000-km
journey. Instead of waiting helplessly at the receiving end, a retailer would like to know the location
of the merchandise selected for the upcoming sales promotion. In fact, the said cargo could be sitting
© 2011 by Taylor and Francis Group, LLC