Where Bluetooth Got Its Name

The initial focus of Bluetooth was ad hoc interoperability between mobile phones, headsets, and PDAs, but today it is also seeing application in sensor-based networks. Most Bluetooth devices are recharged regularly. Bluetooth uses FHSS (discussed in Chapter 13) and splits the 2.4GHz ISM band into 79 1MHz channels. Bluetooth devices hop among the 79 channels 1,600 times per second in a pseudorandom pattern. Connected Bluetooth devices are grouped into networks called piconets ; each piconet contains one master and up to seven active slaves. The channel- hopping sequence of each piconet is derived from the master's clock. All the slave devices must remain synchronized with that clock. FEC is used on all packet headers, by transmitting each bit in the header three times. The Hamming Code is also used for FEC of the data payload of some packet types. The Hamming Code introduces a 50% overhead on each data packet but is able to correct all single-bit errors and detect all double-bit errors in each 15-bit codeword (each 15-bit codeword contains 10 bits of information).

Bluetooth wireless technology is set to revolutionize the personal connectivity market by providing freedom from wired connections for portable handheld devices. The Bluetooth SIG is driving development of the technology and bringing it to market. The IEEE Bluetooth standard gives the Bluetooth SIG's specification greater validity and support in the market and is an additional resource for those who implement Bluetooth devices. This collaboration is a good example of how a standards development organization and a special interest group can work together to improve an industry specification and also create a standard.

As of May 2005, 5 million Bluetooth units were shipping per week, demonstrating the wide acceptance of Bluetooth technology in a multitude of applications, such as mobile phones, cars , portable computers, MP3 players, mouse devices, and keyboards. New applications are routinely introduced. For example, one new application involves the digital music kiosks found in thousands of retail locations. These kiosks are beginning to appear with Bluetooth wireless technology, allowing songs to be transferred directly to music-capable mobile phones.

Bluetooth wireless technology is the leading short-range wireless technology on the market today. It is now available in its fourth version of the core specification and continues to develop, building on its inherent strengthssmall-form-factor radio, low power, low cost, built-in security, robustness, ease-of-use, and ad hoc networking abilities . Alas, some North American carriers view Bluetooth as a competitive threat. In an attempt to maximize income, these carriers disable file transfer functionality on the Bluetooth-enabled phones they sell, thus requiring users to incur airtime charges associated with e-mailing files to their computers.

The Bluetooth SIG has identified several key markets for Bluetooth technology, including automotive, consumer, core technology, computing, and telephony. In addition, Bluetooth wireless technology is beginning to play a major role in wireless seismology and telemetry, adding high-data-rate wireless capability to a sensor market that is estimated at some 1 trillion sensors currently deployed. The growing new generation of wireless sensors will take on many roles, including functions such as monitoring ice on roadways , measuring structural fatigue on bridges, and monitoring beachfronts for pollution and littering.

Recently, in keeping with its namesake, Bluetooth came to very positive terms in working with UWB technology (discussed later in this chapter). Demonstrating the next step in the ongoing evolution of WPAN functionality, in January 2006, Alereon (www.alereon.com) hosted the industry's first public demonstration of Bluetooth+WiMedia UWB operating smoothly together under an existing Bluetooth software stack. When it comes to large files and multimedia applications, Bluetooth version 2.0 devices operate at data rates that are frustratingly slow. Bluetooth's maximum data rate of 3Mbps is simply too slow for today's media-centric applications. Combining Bluetooth with WiMedia UWB brings major improvements. The combination of a WiMedia UWB solution from Alereon and Bluetooth software from Open Interface (www.oi-us.com) enables Bluetooth applications that run 500 times the speed of regular Bluetooth and use less than 2% of the battery energy of Bluetooth. Consumers can use this type of solution to share images, phone books, videos , and other Bluetooth content at up to 480Mbps, allowing devices such as megapixel camera phones to download in seconds, rather than minutes.

IEEE 802.15.3 (WPAN-HR and WPAN-AHR)

The IEEE 802.15.3 (WPAN-HR) Task Group for WPANs was chartered to draft and publish a standard for high-rate (20Mbps or greater) WPANs. Besides a high data rate, the new standard provides for low-power, low-cost solutions that address the needs of portable consumer digital imaging and multimedia applications. IEEE 803.15.3 defines the PHY and MAC specifications for high-data-rate wireless connectivity with fixed, portable, and moving devices within or entering a personal operating space. One goal of the WPAN-HR Task Group is to achieve a level of interoperability or coexistence with other 802.15 task groups.

The IEEE 802.15.3 standard has been developed to meet the demanding requirements of portable consumer imaging and multimedia applications, offering QoS to address such environments. It is based on a centralized and connection-oriented ad hoc peer-to-peer networking topology. IEEE 802.15.3 is optimized for low-cost, small-form-factor, and low-power consumer devices, enabling multimedia applications that are not optimized by existing wireless standards.

The current technology operates in the unlicensed 2.4GHz band and supports five selectable data rates11Mbps, 22Mbps, 33Mbps, 44Mbps, and 55Mbpsand three to four nonoverlapping channels. The range is 3 to 150 feet (1 to 50 m), with most usage anticipated in the 15- to 60- foot (5- to 20-m) range. The standard is also secure because it implements privacy, data integrity, mutual-entity authentication, and data-origin authentication for consumer applications.

The IEEE 802.15.3a (WPAN-AHR) Task Group is working to define a project to provide a higher-speed PHY enhancement to 802.15.3, addressing imaging and multimedia applications. This task group is working on an alternative physical layer for piconets with a 30-foot (10-m) range and for a minimum data rate of 110Mbps. The higher data rates being considered by the 802.15.3a Task Group will enable a host of new applications, including the likes of wireless digital TV, high-definition MPEG-2 motion picture transfer, DVD playback, and digital video camcorders. This 802.15.3a PHY work is currently under consideration.

The 802.15.3b Task Group is working on an amendment to 802.15.3 to improve implementation and interoperability of the MAC layer, including minor optimizations, while preserving backward compatibility. The intention is for this amendment to correct errors, clarify ambiguities , and add editorial clarifications.

Another interest group (802.15.4IGa) is gathering companies to create a study group to look at support for low-data-rate applications.

UWB

The term ultra-wideband is often used to refer to anything associated with very large bandwidth, and indeed, one of the reasons UWB is called Ultra-Wideband is that it spreads its signal over a very wide band of frequencies. Depending on the application, the actual frequency band used ranges from 960MHz to 10.6GHz. On a more specific basis, in relationship to radio communications, UWB refers to a technique based on transmitting very short-duration pulses , where the occupied bandwidth is very large, allowing for very high data rates.

UWB has a spectrum that occupies a bandwidth greater than 20% of the center frequency, or a bandwidth of at least 500MHz. UWB also uses only a small amount of power and operates in the same bands as existing communications without producing significant interference. Furthermore, UWB is not limited to wireless communications; it can use twisted-pair and coax cables as well, with the potential to transmit data at rates of 1Gbps or faster. Very importantly, UWB complements other longer-range radio technologies, such as Wi-Fi, WiMax, and cellular WANs. It is used to relay data from a host device to other devices in the immediate area (up to 30 feet [10 m]).

UWB is like a twenty-first-century version of Marconi's spark-gap transmitter, which was based on short electromagnetic pulses, transmitting a whopping total of 10bps. However, UWB can send more than 100Mbps, with the potential of up to 1Gbps. The basic concept is to develop, transmit, and receive an extremely short-duration burst of radio frequency energy, typically a few tens of picoseconds (trillionths of a second) to a few nanoseconds (billionths of a second) in duration. UWB can not only carry huge amounts of data over a short distance at very low power but also has the ability to carry signals through doors and other obstacles that tend to reflect signals at more limited bandwidths and higher power.

Familiar forms of radio communications use what is called a carrier wave . Data messages are impressed on the underlying carrier signal through modulation of the amplitude, frequency, or phase of the wave in some way and then are extracted upon reception . UWB does not employ a carrier wave; instead, emissions are composed of a series of intermittent pulses. By varying the pulses' amplitude, polarity, timing, or other characteristics, information is coded into the data stream. This is similar to the technique used in radar applications.

UWB operates at a very low power level, 0.2 milliwatts, thus restricting its range to distances of 300 feet (100 m) or, more typically, as little as 30 feet (10 m). Because the energy levels of the pulses are simply too low to cause problems, interference from UWB transmitters is generally not an issue. A UWB transmitter radiates only 1/3,000 of the average energy emitted by a conventional 600-milliwatt mobile phone, which means it reduces many of the health concerns being expressed and studied in relationship to cellular and PCS networks.

Advantages and Disadvantages of UWB

UWB offers a number of advantages, including the fact that there is growing demand for greater wireless data capacity, and the crowding of regulated radio frequency spectrum favors systems that offer not only high bit rates but also high bit rates concentrated in smaller physical areas. Given the latest trends toward the use of wireless and mobile communications, a new metric called spatial capacity has evolved. Spatial capacity is a measure of the number of bits per second per square meter that can be supported. Table 15.7 compares the spatial capacities of several commonly used short-range networking technologies.

Table 15.7. Comparison of Short-Range Spatial Capacities

There are three key factors of interest in selecting a short-range technology: the range over which the technology can operate, how much power it consumes, and the spatial capacity. As you can see in Table 15.7, while 802.11b can operate over a larger coverage area, up to 300 feet (100 m), it can support only 1Kbps per square meter. In a well-attended cafe or hotel lobby, that is not going to provide hotspot users with the capacity needed to work in a multimedia environment. On the other hand, while UWB has a very short range, only 30 feet (10 m), it can support 1,000Kbps per square meter, and it also consumes very little power as an added bonus. Spatial capacity, which is a gauge of data intensity, will be critical to servicing growing number of users in crowded spaces such as airports, hotels, convention centers, and workplaces.

UWB is expected to achieve a data rate of 100Mbps to 500Mbps across distances of 15 to 30 feet (5 to 10 m), and it is anticipated that these high bit rates will give birth to applications that are not possible today. It is also expected that UWB units will be cheaper, smaller, and less power-hungry than today's devices.

Short-range technology is an ideal way to handle networks of portable (battery- powered ) electronic devices, including PDAs, digital cameras , camcorders, audio/video players, mobile phones, laptop computers, and other mobile devices. The growing presence of wired connections to the Internet is another driver of short-distance wireless technology. Many in the developed world already spend most of the day within 30 feet (10 m) of some kind of wired link to the Internet.

UWB's precision pulses give it the ability to discern buried objects or movement behind walls. It can also be used to determine the position of emitters indoors. UWB provides a location-finding feature, much like a local version of GPS. UWB capabilities are therefore crucial to rescue and law-enforcement missions.

One drawback of UWB is that it is susceptible to interference from other emitters. The ability of a UWB receiver to overcome this problem is sometimes called jamming resistance . This is a key characteristic of good receiver design. Multipath interference is also an issue, and one that also needs to be addressed in the receiver design.

UWB Applications

Key UWB applications include communications, imaging, telematics , location tracking, and various military and government applications. UWB also has the key attributes necessary to add significant value for consumers of wireless home entertainment and mobile multimedia products. Smart phones, media servers, set-top boxes, flat-panel screens, digital camcorders, and other multimedia applications need a high-data-rate and high-QoS wireless connection to help ensure wire-like performance.

UWB applications cover a wide range of scenarios, including the following:

• Monitoring large numbers of sensors dispersed over an area for nuclear , biological, or chemical threats

• Conducting geospatial registration for warfighter visualization

• Supporting survey and construction needs

• Keeping track of mines, armaments, equipment, vehicles, and so on

• Keeping track of personal items, such as one's children, pets, car, purse, luggage, and so on

• Controlling inventory in stores, warehouses, shipyards, railyards, and so on

• Arbitrating rules in a sporting event, providing playback for coaching, or viewing the re-creation of an event

• Automating the home environment, such as keyless locks and rooms that adjust light, temperature, and music sound levels

• Automatically adjusting camera focus and motion-tracking for matching digital effects in motion pictures

• Creating automotive collision detection systems and suspension systems that respond to road conditions

• Performing medical imaging, similar to x-ray and CAT scans

• Performing through-wall imaging for detecting people or objects in law-enforcement or rescue applications

The Future of UWB

Proponents of UWB see a future in which UWB technology will reach ubiquity in LANs and PANs. In addition, UWB has the potential to penetrate WAN markets by using ad hoc or managed mesh networks and to eventually make competing technologies such as W-CDMA and GPRS obsolete. UWB could become the dominant technology in WPANs, WLANs, and WWANs. However, a limiting factor to UWB's dominance in the worldwide WAN is unification of global wireless spectrum allocation standards. The greatest challenges UWB faces are regulatory issues and deadlocked UWB standards disputes in the IEEE.

Some have raised doubts about the future of UWB. Some industry observers suggest that regulations in Europe will be substantially more restrictive than those applied by the FCC. Japan is likely to be even more conservative. Stiff regulations would limit UWB to a smaller slice of spectrum and reduce its speed and range. It would then have more trouble competing against faster versions of Wi-Fi. In addition, IEEE 802.11n is expected to be established by 2007, offering a theoretical limit of 110Mbps to 200Mbps. Accounting for overhead, the resulting throughput will be some 45Mbps. Although UWB can support 480Mbps at short ranges, it would drop off with distanceparticularly if the regulations limit the spectrum it can use. By the time it goes across a room, the data rate of UWB could be more like that of 802.11n.

However, UWB vendors claim that if the lower frequencies are cut out, they can move higher in the spectrum and offer speeds well beyond the currently proposed 480Mbps. Only UWB can promise enough speed to stream HDTV. However, at higher frequencies, there is more absorption , so the effective rangeand the throughput at a given rangeis reduced. Some suggest that that its alliance with Bluetooth may help UWB get regulatory approval.

As mentioned earlier in this chapter, the Bluetooth SIG has been working with the developers of UWB to combine the strengths of Bluetooth and UWB. This alliance allows Bluetooth technology to extend its long-term roadmap to meet the high-speed demands of synchronizing and transferring large amounts of data as well as enabling high-quality video applications for portable devices, while UWB benefits from Bluetooth technology's manifested maturity, qualification program, brand equity, and comprehensive application layer.

WiMedia

In September 2002, nine leading technology companies announced the formation of the WiMedia Alliance (www.wimedia.org). Initial WiMedia Alliance activity was based on the IEEE 802.15.3a (WPAN-AHR) standard, with amendments and enhancements planned for future wireless systems such as UWB. Today, the WiMedia Alliance is a not-for-profit open industry association that promotes and enables the rapid adoption, regulation, standardization, and multivendor interoperability of UWB worldwide. It is dedicated to collaboratively developing and administering specs from the physical layer up, enabling connectivity and interoperability for multiple industry-based protocols. Alliance board members include Alereon (www.alereon.com), Hewlett-Packard (www.hp.com), Intel (www.intel.com), Kodak (www.kodak.com), Microsoft (www.microsoft.com), Nokia (www.nokia.com), Philips (www.philips.com), Samsung Electronics (www. samsung .com), Sony (www.sony.com), STMicroelectronics (www.st.com), Staccato Communications (www.staccatocommunications.com), Texas Instruments (www.ti.com), and Wisair (www.wisair.com).

In June 2003, the Multiband OFDM Alliance SIG (MBOA-SIG) was formed to support the development of the best possible technical solution for the emerging UWB (IEEE 802.15.3a) PHY specification for a diverse set of wireless applications. Today, the WiMedia Alliance represents a combination of the original WiMedia Alliance and the MBOA-SIG, the two leading organizations creating UWB industry specifications and certification programs for PC, consumer electronic, mobile, and automotive applications. The combined WiMedia Alliance is an open industry association that defines the WiMedia/MBOA technology. Alliance members consist of industry leaders based in Asia, Europe, and North America.

WiMedia defines a UWB common radio platform that enables high speeds (480Mbps and beyond), low power consumption, and multimedia data transfers in a WPAN. It is optimized for several key market segments, including PC, consumer electronic, mobile, and automotive applications. The platform incorporates MAC-layer and PHY-layer specifications based on Multiband OFDM (MB-OFDM). ECMA-368 and ECMA-369 are international ISO-based specifications for the WiMedia UWB common radio platform (see www.ecma-international.org).

WiMedia now includes the MBOA UWB technologies that will permit the long battery life that is key for mobile applications. The Wireless USB Promoter Group (www.usb.org/developers/wusb) has endorsed WiMedia as a common platform for its next-generation wireless implementations . The 1394 Trade Association (TA) Wireless Working Group (www.1394ta.org) has approved WiMedia's MAC Convergence Architecture (WiMCA) as a platform for a high-speed wireless IEEE 1394 (FireWire) protocol adaptation layer (PAL) development. The 1394 TA also said it will collaborate with the WiMedia Alliance to develop interoperability test specifications and certification programs for wireless IEEE 1394. WiMedia also plans to develop universal IP addressing protocols in alignment with organizations such as the UPnP Forum (www.upnp.org) and the Digital Living Network Alliance (DLNA; www.dlna.org). In addition, as mentioned earlier, January 2006 saw the successful demonstration of Bluetooth+WiMedia UWB operating smoothly together under an existing Bluetooth software stack.

UWB technology has the inherent capability to optimize wireless connectivity between multimedia devices within a WPAN. The WiMedia UWB common radio platform is unique in that no other existing wireless standard can fulfill the market's stringent requirements, such as low cost, low power consumption, small form factor, high bandwidth, and multimedia QoS support.

IEEE 802.15.4 (ZigBee)

At the end of the 1990s, many engineers began to see that Bluetooth and Wi-Fi, while excellent short-range solutions, were not the best solutions for some applications, particularly self-organizing ad hoc networks of various industrial controls, building and home automation devices, security and smoke alarms, and medical devices. With inspiration from the simple one-chip design of Bluetooth radios, a community of like-minded engineers began the development of ZigBee, a wireless communication protocol designed for small building devices. The IEEE 802.15.4 standard, completed in May 2003, defines the technical specifications of the PHY and MAC layers for ZigBee. The IEEE 802.15.4 specification is mainly designed for command and control, for which a 200Kbps data rate is more than adequate.

The IEEE 802.15 Task Group 4 (TG4; www.ieee802.org/15/pub/TG4.html) was chartered to investigate a solution with several key characteristics: a low data rate with a very long battery life (months to even years) and very low complexity. ZigBee operates, internationally, in the unlicensed frequency bands. Potential applications for ZigBee include sensors, interactive toys, smart badges, remote controls, and home and building automation tools. The ZigBee 1.0 specifications were ratified in December 2004, and version 1.1 is now in the works.

As with many of the other WPAN technologies, there are relationships between the formal IEEE task group and the representative industry alliancein this case between 802.15 TG4 and the ZigBee Alliance (www.zigbee.org). The ZigBee Alliance, formed in October 2002, is a nonprofit industry consortium of companies working together to enable reliable, cost-effective , low-power, wirelessly networked monitoring and control products based on an open global standard. The member companies are working together to develop standardized application software on top of the IEEE 802.15.4 standard. The goal of the ZigBee Alliance is to give consumers the most flexible building systems available by introducing the ZigBee wireless technology into a number of building devices. As of mid-December 2005, the ZigBee Alliance membership had surpassed 200 member companies from 24 countries spanning six continents, with OEMs and end product manufacturers representing over 30% of the global membership. The ZigBee Alliance focuses on four main areas: defining the network, security, and application software layers of the protocol; providing interoperability and conformance testing for ZigBee devices; promoting the ZigBee brand globally; and managing the evolution of the technology.

ZigBee Devices and Networks

ZigBee was created to support wireless communications between devices without the expense of having to run wires between them. ZigBee's benefits include flexibility and scalability, reduction in design and installation time, interoperability, longer battery life, and low cost. It is made for two-way communication among devices and can be used to build a general-purpose, inexpensive, self-organizing network of devices. This protocol opens the door to the flexibility and benefits of interoperability. Because ZigBee uses open standards, it reduces the costs and risks associated with building the technology into devices. ZigBee is a short-range, low-power protocol specifically designed for small building devices such as thermostats, lighting controls, ballasts, environmental sensors, and medical devices. It is meant to offer short-distance, low-speed transmissions that require little power. As a result, the battery life of ZigBee devices can range from six months to two years or longer, using only a single alkaline battery.

There are three types of ZigBee devices:

• Reduced-function device (RFD) The simplest ZigBee device is the RFD , also referred to as the end device . It is smart enough to talk to the network but has no routing abilities; in other words, it cannot relay data from other devices. End devices are often battery powered. Typical end devices function as thermostats, humidistats, light switches, smoke detectors, and various other sensors. These devices are often built as peel-and-stick products, where installation is intended to be simple and product placement is either aesthetic , functional, or according to some governmental requirement. These end devices do not form a mesh by themselves ; instead, they are usually asleep in order to conserve their batteries.

• Full-function device (FFD) The next level up the network from the RFD is called the FFD , or router . It is fully mesh capable and mains powered (i.e., powered from some other permanent source). FFDs can establish multiple peer-to-peer links with other routing nodes, and they accept connections from RFD devices, performing the role of intermediate routers, passing data from other devices. An FFD may also serve as a gateway to the Internet or other networks. Packets generated by RFD devices may pass through multiple FFDs to travel from the source to a destination, which is generally a load-controlling function (e.g., HVAC motor, lighting load control, damper actuator, siren). However, the destination may also be a data-collecting device (e.g., a computer or security console) or even a gateway to the Internet or other non-ZigBee network.

• ZigBee coordinator The mains-powered coordinator assumes the most important role in a ZigBee network, acting as the root of the network tree and bridging to other networks. It has the authority to establish networks and perform any network management that might be required. The coordinator also has routing capability and may serve as a gateway to the Internet or to other networks, and it can store information about the network. Because it contains the most memory, it is the most expensive of the three devices in a ZigBee network.

A ZigBee network is capable of supporting up to 254 FFDs, 1 coordinator, and potentially thousands of RFDs. Most importantly, because the ZigBee protocol expects most messages to receive acknowledgments in order to verify successful reception, all devices are transceivers (i.e., they transmit and receive). Figure 15.7 shows an example of a ZigBee home network.

ZigBee devices operate in unlicensed spectrum worldwide and are based on DSSS technology. They operate at the maximum data rates shown in Table 15.8, and their transmission range is 30 to 250 feet (10 to 75 m).

Table 15.8. ZigBee Maximum Data Rates

The ZigBee standard is designed to provide reliable data transmission of modest amounts of data up to 250 feet (75 m) while consuming very little power. It also offers support for critical-latency devices, such as joysticks. ZigBee offers lower power consumption, lower cost, higher density of nodes per network, and simplicity of protocols compared with other wireless connectivity schemes. Because ZigBee's topology allows as many as 254 nodes per network, it is ideal for industrial applications. ZigBee is the only standards-based technology designed to address the unique needs of low-cost, low-power, wireless sensor networks for remote monitoring, home control, and building automation network applications in the industrial and consumer markets.

ZigBee supports three network topologies:

• Star This topology can provide for very long-life operation and is the most common topology.

• Mesh This topology enables high levels of reliability and scalability while providing more than one communications path through the network wireless link.

• Cluster tree This topology uses a hybrid star/mesh topology that combines the benefits of both for high levels of reliability and support for battery-powered nodes.

The Future of ZigBee

Future applications of the ZigBee protocol include its use in tracking and asset management systems, generators, elevators, and so on, gathering data that can be transformed into viable information and enabling users to run their businesses more efficiently .

The IEEE 802.15.4 group says that one day it might be common to find 50 ZigBee radio chips in a house. Those chips could serve duty in a home's 10 to 15 light switches, several fire and smoke detectors, thermostats, 5 or 6 toys and interactive game machines, and other human input devices. Radio-frequency-based ZigBee will eventually replace all the infrared (IR) links at home. ZigBee is not designed for video or CD-quality audio, but it could be used to send text or voice messages. No QoS provision is built into ZigBee.

In January 2006, the ZigBee Alliance announced its ZigBee Certification program, which ensures that products are fully interoperable out of the box and can easily participate in a ZigBee network. Member companies can now test the growing number of ZigBee-ready products already on the consumer market so they can be fully branded as ZigBee Certified for home, industrial, or commercial use. Independent test service providers will oversee and conduct the ZigBee Alliance's certification testing to ensure that products are interoperable in a variety of environments and end- user applications.

RFID

RFID is a method of remotely storing and retrieving data by using devices called RFID tags . An RFID tag is a small object that can be attached to or incorporated into a product, an animal, or a person and then read by an RFID reader. The origins of RFID technology take us back to the early 1920s, when MIT developed a similar technology as a way for robots to talk to one another. The first known device that has been recognized as a predecessor to RFID technology was a passive covert listening device invented in 1945 by Leon Theremin to be used as an espionage tool for the Soviet government. A similar technology, called Indentification Friend or Foe (IFF), was invented by the British in 1939 and used extensively by the Allies during World War II to identify and authenticate allied planes and other vehicles. RFID is being used today for the same purposes. However, it is now also recognized that an investment in RFID technology can improve the efficiency of many enterprise operations, reduce errors, and improve on operating costs.

With RFID, any movable item or asset can be identified and tracked better and more efficiently. The first RFID systems deployed for tracking and access applications entered the marketplace during the 1980s. As the technology matures, it is clear that we can expect more pervasive and most likely more invasive applications for RFID. Industry analysts predict explosive growth for RFID over the next several years, forecasting that by 2010, there will be some 33 billion tags produced, compared to just 1.3 billion in 2005. Retail, automotive, and pharmaceutical companies are expected to lead in the adoption of RFID.

Several organizations are involved in drafting standards for RFID technology. Both the ISO (www.iso.org) and EPCglobal (www.epcglobalinc.org) have had many initiatives related to RFID standards. EPCglobal is an important organization to the RFID movement: It is leading the development of industry-driven standards for the electronic product code (EPC) to support the use of RFID in today's fast-moving, information-rich trading networks. It is a subscriber-driven organization comprising industry leaders and organizations, focused on creating global standards for the EPCglobal network.

Currently, the purpose of an RFID system is to allow a tag to transmit data to an RFID reader, which then processes the data according to the application requirements. The information transmitted can provide identification or location data and can also include more specific information, such as date of purchase, price, color , size , and so on.

RFID tags are envisioned as a replacement for universal product code (UPC) barcodes because they have a number of important advantages over the older barcode technology. RFID codes are long enough that every RFID tag may have a unique code, whereas UPC codes are limited to a single code for all instances of a particular product. The uniqueness of RFID tags means that a product may be individually tracked as it moves from location to location, finally ending up in the consumer's hands. This may help to combat theft and other forms of product loss. It has also been proposed to use RFID for point-of-sale store checkout to replace the cashier with an automatic system, with the option of erasing all RFID tags at checkout and paying by credit card or inserting money into a payment machine. Other innovative uses have also been proposed, such as allowing a refrigerator to track the expiration dates of the food it contains.

How an RFID System Works

RFID systems are composed of several components : tags, readers, edge servers, middleware, and application software. The key element of RFID technology is an RFID transponder , usually called a tag . An RFID tag is a small object, such as an adhesive sticker, that can be attached to or incorporated into an object (anything from a pallet of laundry detergent to a racecar tire to a pet's neck). An RFID tag is a tiny microchip composed of a processor, memory, and a radio transmitter that is mounted onto a substrate or an enclosure. The amount of memory varies from just a few characters to kilobytes. An RFID tag's antenna enables it to receive and respond to radio frequency queries from an RFID reader, also known as a transceiver or an interrogator , which has its own antenna.

Here's how an RFID system works (see Figure 15.8):

1. An RFID reader, which can interface through wired or wireless media to a main computer, transfers energy to RFID tags by emitting electromagnetic waves through the air.

2. RFID tag antennas collect the RF energy from the reader antenna and use it to power up the microchip.

3. Tags listen for a radio signal sent by an RFID reader.

4. When an RFID tag receives a query, it responds by transmitting its unique ID code and other data back to the reader. The data transmitted from the tags can provide identification or location information about the object or specifics such as date of purchase or price.

5. The reader receives the tag responses and processes them accordingly , sending the information to a host computer or external devices through its control lines.

No contact or even line of sight is needed to read data from a product that contains an RFID tag. RFID technology works in rain, snow, and other environments where barcode or optical scanning technology is useless.

RFID Tags

Different types of RFID tags address different applications requirements:

• Read-only A read-only tag is preprogrammed with a unique identification.

• Read/write A read/write tag is used for applications that require data to be stored in the tag so the information can be dynamically updated.

• Write once, read many times (WORM) WORM tags allow for an ID number to be written to the tag once, and it can't be changed, but the information can be read many times.

In addition, RFID tags can be either active or passive. Active RFID tags must have a power source but have longer ranges of operation and larger memories than passive tags, providing the ability to store additional information sent by the reader. Active tags, about the size of a dime and designed for communications up to 100 feet (30 m) from the RFID reader, are powered by a battery and are always on. They are larger and more expensive than passive RFID tags but can hold more data about the tagged object and are commonly used for high-value asset tracking. Active RFID tags can be read/write. Many active tags have practical ranges of tens of meters and a battery life of up to 10 years. One of the most common applications for active tags is in the transportation sector (e.g., for highway tolls).

Passive RFID tags do not have their own power supplies or batteries. Instead, the minute electrical current induced in the antenna by the incoming RF scan from the reader provides enough power for the tag to send a response. The received signal charges an internal capacitor on the tag, which in turn supplies the power required to communicate with the reader. Because passive tags do not contain power supplies, they can be much smaller than active tags and have an unlimited life span. As of 2006, the smallest commercially available passive tags measured just 0.3 mm across and were thinner than a sheet of paper, making them just about invisible. Due to its power and cost, the response of a passive RFID tag is generally brief, typically just an ID number. Passive RFID tags can be read from a distance of about 20 feet (6 m). A semipassive RFID tag contains a small battery that boosts the range. Passive tags are generally read-only, so the data they contain cannot be altered or written over. Some of the most common uses of passive RFID include animal identification, waste management, security and access control, work-in-process, asset tracking, and electronic commerce. The Chek Lap Kok airport in Hong Kong uses passive RFID tags to track the movement of every piece of luggage that passes through the baggage-handling system.

Because passive tags are cheaper to manufacture than active tags, the majority of RFID tags in existence today are the passive type. As of 2006, passive tags, when bought in high volumes, cost an average of US$0.24 each. With volumes of 10 million units or more, the cost can drop to around US$0.07 per tag. The goal is to produce tags for less than US$0.05 to make widespread RFID tagging commercially viable.

The main benefits of RFID include the fact that tags can be read from a distance and from any orientation, so they do not require line-of-sight conditions in order to be read. Read/write tags offer the additional benefit of allowing data to be changed dynamically at any time. Another benefit of RFID is that multiple tags can be read at the same time and in bulk very quickly. Finally, the tags can be easily embedded into any nonmetallic object, enabling the tags to work in harsh environments and providing permanent identification for the life of the object. However, the environment into which RFID will be implemented must be carefully considered because factors such as the presence of metal, electrical noise, extreme temperatures , liquids, and physical stress may affect performance.

RFID Readers

RFID readers are used to query RFID tags in order to obtain identification, location, and other information about the object the tag is embedded in. In addition, the reader antenna sends RF energy to the RFID tag antennas, which use that energy to power up the microchip.

There are two types of RFID readers:

• Read-only These readers can only query or read information from a nearby RFID tag; they cannot write information to tags. They are found in fixed, stationary applications as well as portable, handheld varieties.

• Read/write These readers, also known as encoders , read and also write information in RFID tags. RFID encoders can be used to program information into a blank RFID tag. A common application is to combine this type of RFID reader with a barcode printer to print smart labels. A smart label contains a UPC barcode on the front and an RFID tag embedded on the back.

RFID Frequencies

Even though no global body currently governs RFID frequencies (each country can set its own rules), there are four main frequency bands for RFID tags, as shown in Table 15.9.

Table 15.9. RFID Frequency Bands

LF and HF can be used globally without a license. UHF cannot be used globally because there is no single global standard. Despite the availability of various bands in which RFID can operate, there is not just one that can address all applications. Each band has specific attributes that make it suitable for different applications.

LF RFID

The reading range of LF RFID can vary from a few centimeters to a couple meters, depending on the size of the tags and the reader being used. One of the key features of LF RFID is that it is not as affected by surrounding metals as other types of RFID, making it ideal for identifying metal items such as vehicles, equipment, tools, and metal containers. The largest user for LF RFID is the automotive industry. A car key has an LF tag embedded in it that works with a reader mounted in the ignition. Other automotive applications include vehicle identification for highway and parking lot access. LF RFID penetrates most other materials, such as water and body tissue , which makes it ideal for animal identification (for endangered species and for pets and livestock) and beer keg tracking.

The limitations of LF RFID are that if used in industrial environments, electric motors may interfere with the LF system. Due to the size of the antenna required, LF tags are typically more expensive than HF tags, which limits LF to applications where the tags can be reused. However, LF is used worldwide, and there are no restrictions on its use.

HF RFID

Passive HF, at 13.56MHz, is a globally accepted frequency, which means any system operating at HF can be used globally. However, there are some differences between the regulations in the different regions of the world, related primarily to power and bandwidth. In North America, the FCC limits the reader antenna power to 3 watts, while European regulations allow for 4 watts. HF is also the basis of numerous standards, such as ISO 14443, 15693, and 18000-3.

With HF, the signal travels well through most materials, including liquid and body tissue. However, it is more affected by surrounding metals than LF. In comparison to LF, the benefits of HF are lower tag costs, better communication speed, and the ability to read multiple tags at once. The higher the frequency, the higher the data throughput and the faster the communications between the tags and the reader, and at HF, a reader can read up to 50 tags per second. The increase in speed also allows for the reader to communicate with multiple tags at the same time.

HF RFID tags are used in book tracking for libraries and bookstores, pallet tracking, building access control, airline baggage tracking, apparel item tracking, and identification badges.

UHF RFID

Whereas HF and LF work fairly well in the presence of liquids, today's UHF systems do not work in such environments. Metal poses a serious challenge for any RFID implementation, but especially in the UHF range. Moreover, the longer read distance of UHF is a disadvantage in applications such as banking and access control. However, its high data throughput facilitates higher read rates, with 800 reads per second possible in theory, although 200 reads per second is closer to reality. UHF RFID tags are commonly used commercially to track pallets and containers as well as trucks and trailers in shipping yards, and UHF vendors are targeting the supply-chain market, where longer read distances are required.

UHF tags can be used globally when they are specially tailored according to regional regulations because there are no globally unified regulations for radio frequencies in this ISM band range. However, one of the biggest challenges that has impeded the widespread implementation of UHF RFID is lack of globally accepted standards and regulations. Different frequency designations and power and safety regulations are in place in different regions of the world. In North America, UHF operates at 902MHz to 928MHz; in Europe, it works in the 860MHz to 868MHz range; and in Japan, it operates at 950MHz to 956MHz.

EPCglobal (www.epcglobalinc.org) worked through 2004 to pave the way for ratification of the UHF Generation 2 Air Interface Protocol (commonly referred to as the Gen2 standard) by driving regulatory agenciesfrom the ETSI to Japan's Ministry Post and Telecomto open bandwidth in the UHF spectrum so RFID could operate seamlessly through supply chains across continents. Gen2, which was ratified as an EPCglobal standard in December 2004, has been accepted by the ISO. Some of the requirements for this standard include convergence to one global, interoperable standard; increased speed and ease of global adoption; increased functionality and performance; and increased production and competition.

Gen2 is heralded as the first UHF RFID open architecture designed by a committee. Many supply-chain benefits depend on Gen2: global interoperability, international vendor support, multiple read and write capabilities that could potentially change the economic climate by delivering a quicker return on investment, and increased data communication speeds more than double those of the tags available today. The read rate for Gen2 tags in the United States under a simulated environment is 1,500 per second, versus roughly 100 tags per second for tags available today. (The read rate for Gen2 tags in Europe, however, is only 500 to 600 tags per second because U.S. regulations allow for wider frequency bandwidth.) As the industry switches to Gen2, many companies will face huge conversion costs. On the other hand, because Gen2 establishes interoperability and bandwidth technologies, it is anticipated that Gen2 will boost adoption of RFID.

Microwave RFID

Microwave RFID tags are used in long-range access control for vehicles, such as GM's OnStar system. Additional microwave RFID applications include electronic highway toll collection; reading of seismic activity, greatly simplifying remote data collection; and vehicle tire tracking.

RFID Privacy

There are some major privacy concerns regarding RFID use, including the following:

• The purchaser of an item will not necessarily be aware of the presence of the tag or be able to remove it.

• The tag can be read at a distance without the knowledge of the individual.

• If a tagged item is paid for by credit card or in conjunction with use of a loyalty card, it would be possible to tie the unique ID of that item to the identity of the purchaser.

• Tags create, or are proposed to create, globally unique serial numbers for all products, even though that would create privacy problems and is unnecessary for most applications.

• The ability to continue to enjoy a lifestyle that offers relative anonymity today is undermined by the presence of tags and readers.

• Governments could obtain information gathered by RFID readers for the surveillance or monitoring of citizens ' activities. Equally frightening, such information could be misused by hackers and criminals.

• Even our most intimate activities could be monitored if tags were implemented in everyday objects such as floor tiles, shelf paper, cabinets , appliances, exercise equipment, medications, medical implants, and all sorts of packaged products and consumer goods.

Most concerns revolve around the fact that RFID tags affixed to products remain functional even after the products have been purchased and taken home and thus can be used for surveillance and other nefarious purposes unrelated to their supply-chain inventory functions. Although RFID tags are only officially intended for short-distance use, they can be interrogated from greater distances by anyone who has a high-gain antenna, potentially allowing the contents of a house to be scanned at a distance. Even short-range scanning is a concern if all the items detected are logged in a database every time a person passes a reader, or if it is done for nefarious reasons, such as a mugger using a handheld scanner to obtain an instant assessment of the wealth of potential victims. With permanent RFID serial numbers, an item leaks unexpected information about a person even after disposalfor example, items being resold or given away enable mapping of a person's social network.

Another privacy issue has to do with RFID's support for a singulation (i.e., anticollision) protocol. This is the means by which a reader enumerates all the tags responding to it without them mutually interfering. The structure of the most common version of this protocol is such that all but the last bit of each tag's serial number can be deduced by passively eavesdropping on just the reader's part of the protocol. Because of this, whenever RFID tags are near readers, the distance at which a tag's signal can be eavesdropped is irrelevant; what counts is the distance at which the much more powerful reader can be received. Just how far this is depends on the type of the reader, but in the extreme case, some readers have a maximum power output of 4 watts, which could be received from tens of kilometers away.

Rarely is information encrypted between a tag and the reader. This creates opportunities for malicious people to eavesdrop on communications and reuse them in nefarious waysfor instance, quickly and easily duplicating a passport. Similarly, there is no standard authentication protocol between a tag and the reader. Again, considering the passport as an example, it is currently possible to conduct a man-in-the-middle attack between a tag-equipped passport and the reader on the desk of the passport control officer. An attacker could substitute information on-the-fly , possibly circumventing detention in one case while making life very difficult for some other innocent citizen standing in line. Fortunately, governments are starting to realize the risks associated with electronic passports and are examining security controls to mitigate such risks.

EPCglobal's Gen2 standard includes privacy-related guidelines for the use of RFID-based EPCs. The Guidelines on EPC Usage for Consumer Products were adopted as a basic framework for responsible use and deployment of EPC (see www.epcglobalinc.org/public_policy/public_policy_guidelines.html). These guidelines include the requirement to give consumers clear notice of the presence of EPCs and to inform them of the choice they have to discard, disable, or remove EPC tags.

It is crucial that we ensure that RFID technology is used to improve our lives and our business practices without intruding on privacy. To this end, governments, the private sector, and other agencies must safeguard principles of informed consent , data confidentiality, and security; courts and governments around the world are now in the process of determining related legal issues. The Electronic Privacy Information Center (EPIC) has a great deal of additional information about RFID privacy as well as interesting projects on its Web site (www.epic.org/privacy/rfid).

The Future of RFID

It appears that RFID is well on its way to becoming a large part of our lives. More than 1.3 billion RFID tags were produced in 2005, and that figure is expected to soar to 33 billion by 2010 (In-Stat, "RFID Tags and Chips: Opportunities in the Second Generation," www.instat.com, January 18, 2006). Production will vary widely by industry segment for several years. For example, RFID has been used in automotive keys since 1991, with 150 million units now in use. This quantity greatly exceeded other segments until recently. By far the biggest RFID segment in coming years will be supply-chain management. Wal-Mart, the world's largest retailer, has spurred this projected growth by mandating that its top 100 (and then its top 300) suppliers use RFID at the pallet/case level.

The spread and use of RFID in most sectors will be largely determined by cost, and the costs of RFID tags and labels are dropping quickly. Pharmaceutical companies are investigating using RFID tags to reduce counterfeiting and black-market sales. Other market segments expected to incorporate the use of RFID include livestock, domestic pets, humans , cartons/supply-chain uses, large freight containers, package tracking, consumer products, and security/banking/purchasing/access control. But will RFID replace UPC barcode technology? Most likely not, and certainly not in the near term. RFID tags still cost more than UPC labels, and different data capture and tracking technologies offer different capabilities. Many businesses will likely combine RFID with existing technologies such as barcode readers or digital cameras to achieve expanded data capture and tracking capabilities that meet their specific business needs.

NFC

In the midst of the various WPAN technologies discussed so far in this chapter, a new technology is quietly taking shape that could alter the use of consumer electronics and change the way users shop, travel, and send data. Near Field Communication (NFC) evolved from a combination of RFID, interconnection (i.e., information exchange via network technology), and contactless identification technologies. (With contactless identification , a smart card has an antenna embedded inside it, enabling communication with a card reader without physical contact. The chip on the smart card stores data and programs that are protected by advanced security features. Contactless smart cards are passed near an antenna, or reader, to carry out a transaction.) With NFC-enabled mobile phones, transactions can be conducted by simply touching a point-of-sales device or ticket gate. Contactless cards are the ideal solution for transactions that must be processed very quickly, as in physical access control, mass transit, or vending services. NFC provides high-bandwidth content acquisition and transfer, contactless payment capability, and smart object interaction. One of the key attributes of NFC is that it introduces convenience to increasingly connected digital consumers, allowing new genres of interactions with interactive advertising posters and kiosks, instant ticketing, and the transmission of audio, pictures, and video.

NFC technology is showing tremendous promise for transforming consumer commerce, connectivity, and content consumption, enhancing end-user experiences while redefining communications, content, and payment business models. NFC is expected to be deployed beginning in 2007, first in wireless handsets and then in other kinds of consumer electronics, from PCs to cameras, printers, set-top boxes, and the growing range of smart devices.

The success of NFC depends on open, interoperable, standards-based NFC environments. To help in this quest, the NFC Forum (www.nfc-forum.org) is adding fuel to the technology's expansion. The NFC Forum was founded by Nokia (www.nokia.com), Philips (www.philips.com), and Sony (www.sony.com) in 2004, and since then, dozens of companies have signed up for the industry group. The NFC Forum now boasts more than 60 collaborating members, including wireless carriers, handset OEMs, application developers, payment processors, infrastructure providers, content owners , card issuers , and banks and merchants . NFC is standardized in a number of ISO, Ecma International, and ETSI standards, providing for maximum flexibility as the technology seeks compatibility with existing devices, especially smart cards.

NFC, a short-range, contactless communications protocol, enables easy-to-use, secure connectivity between devices. It can also be used to configure and initiate other wireless network connections, including Bluetooth and Wi-Fi. It is a wireless technology that operates in the globally available and unregulated 13.56MHz frequency band, over a typical distance of a few centimeters, but with a maximum working distance of 5 to 6.5 feet (1.5 to 2 m). It supports three data transfer rates: 106Kbps, 212Kbps, and 424Kbps. By using magnetic field induction, NFC allows two devices embedded with chips to exchange information by being in close proximity. There are no intermediate devices, which means NFC acts as a peer-to-peer transmission. NFC enables a handset or mobile device to act as a contactless transfer medium.

NFC chips will be embedded in a variety of devices, allowing the exchange of information within a very short distance. This makes for a very intuitive pairing of devices with a minimal authentication process. There are three modes of operation:

• Passive communication mode In this one-way mode, the initiator device provides a carrier field, the target device responds by modulating that field, and the target device draws power from the initiator's electromagnetic field.

• Active communication mode In this bidirectional mode, both devices need power supplies, and the initiator and target devices generate their own fields to communicate.

• Transponder This bidirectional mode allows tags without access to electric grids or batteries to communicate with an NFC device within range by drawing power from that NFC device.

Nokia and Motorola have both introduced devices supporting the technology, and they are designed in part to serve as payment devices. Nokia has an NFC-enabled phone available, the 3220. With the Nokia NFC shell, this handset allows consumers access to browsing and text message services simply by touching tags that contain service shortcuts. The NFC-enabled phone can be used as a loyalty card, credit card, or train or bus ticket. Purchases normally made with a credit card can be made with the phone because the phone is, in fact, a credit card. NFC will find uses in areas such as e-ticketing, where the customer holds his or her mobile phone close to the ticket kiosk to start the transaction. The customer interacts with the service and then completes the purchase by confirming the transaction on the NFC-enabled mobile phone. Arriving at the concert hall, the customer then holds his or her mobile phone close to a reader fitted to the entrance turnstile, which allows access after the reader checks the validity of the ticket.

Each NFC device has the potential to replace a wallet full of credit cards, which is a liability if it falls into the wrong hands. NFC proponents are quick to note that a lost or stolen mobile phone can be disabled with a single call to the service provider, but canceling a wallet full of credit and bank cards requires at least an hour . One of the most important things to be aware of is that NFC security is a matter of accepting or not accepting a message from another device. Users must therefore constantly be aware of the status of their devices, and know, for example, whether they are configured to automatically connect with nearby NFC devices. There are also some threats unique to NFC, as well as opportunities for clever thieves . For example, as RFID chips and readers become more pervasive, we can imagine a new technique emerging, something being referred to as billboard phishing , where the impersonator could possibly paste posters, with embedded phony RFID chips, over kiosks, posters, or turnstiles . In this case, how is the user to know whether what they are touching is fake or legitimate ? As with RFID technology, security professionals need to help shape the security policies and protocols that might affect device authentication and other issues. To this end, the NFC Forum has formed a security workgroup to develop industry standards.

NFC technology is currently being used extensively in Asia and the Pacific, and it is being used less in Europe and even less in the United States. However, we can expect to see NFC expand rapidly , especially in payment transaction scenarios and public transportation.