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Most of us are now connected with a wireless device of limited utility be-
cause it is only for voice – our cell phones. We are at the dawn of a major
transition for data connections as it also moves from wired to wireless tech-
nology. The transition of data communications has not happened with a
“grand design”, but is moving inexorably through some interim
technologies to a conclusion in the wireless domains using a va- :LUHOHVV WHFKQRORJ LV H[SHFWHG WR
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riety of technologies. This ARC Strategy Report attempts to
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provide some background on the most significant of these wire-
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manufacturing environment. Wireless technology is expected to DQG * ZLUHOHVV WHOHSKRQ
have a major impact on the manufacturing industries in the next
five years.
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The three wireless technologies most likely to be used in the manufacturing
industries are listed in the following table. There are lots more, some at an
equivalent state of development, and some still in embryonic state not yet
ready for wide commercialism.
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It would be wonderful if there was a single winning technology, but there are
too many applications needing a more direct solution for a volume market.
These three technologies cover the application distances from very short
range (Bluetooth), to medium distances (Wireless LAN), to very long dis-
tances (3G Wireless).
These are all digital communications protocols completely replacing legacy
analog and hybrid radio of previous generations. The only commonality
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among these technologies is that they all use spread spectrum protocols to be
immune from noise and to obtain a base level of privacy.
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The common thread for wireless applications is mobility, where wireless
eliminates the inconvenience and cost of connection to a wired network.
However, applications for wireless go well beyond the cordless aspect to ar-
eas that were never previously considered “connectable.” Wireless, in all its
forms, is another of those enabling technologies that will stimulate new ap-
plications when the cost falls to an appropriate point. This report is all about
the three wireless technologies that ARC expects to achieve low price points
in the next five years.
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Manufacturing plants can be large and widely distributed; therefore, the data
from the plant comes from a wide area. Manufacturing automation requires
access to data at the point where it is generated, and further, requires that
real-time control actions be performed in the plant at the location where it
has dynamic effect on the process itself. Data processing, or in today’s style
“IT,” has usually required that data be transported to a central location for
processing and reporting. IT can often accomplish its goals with periodic or
daily transport of the data it requires, but manufacturing must
+RZHYHU LQ WKH EDFN RI RXU PLQGV process its data in milliseconds or seconds.
ZH DOZDV DVN ´:KDW LI ZH FRXOG
PDNH FRQQHFWLRQV ZLWKRXW ZLUHVµ Process control applications needed to move the operator out of
+HQFH ² ZLUHOHVV the hazardous plant environment that led to use of pneumatic
data transmission in the 1930s. From the 1950s onward, most
data transmission from the plant floor to the control system has been through
copper wires. The maze of copper wiring needed to connect sensors and ac-
tuators to control systems is expensive to design, install, test, commission,
and maintain. For many years the industry has been spending time and re-
sources on serial bus interconnection methods to reduce these costs.
However, in the back of our minds, we always ask “What if we could make
connections without wires?” Hence – wireless.
There has always been a class of device for which the connection cord was
such a large inconvenience that it became impractical to depend on the use of
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the device. Portable barcode readers are an example of this char-
acteristic. Only when portable barcode readers became wireless
did they become convenient enough to require their use in manu-
facturing and warehousing.
Another class of applications are for connection of devices that
are themselves in motion. Temperature sensors in rotary kilns or
drums are commonly connected using wireless technology. Automated
Guided Vehicles (AGV) are a class of equipment in constant motion needing
network connection.
Radio links have been used to connect remote and mobile devices for many
years. In most cases, these links were narrow-band radios (not spread spec-
trum) and required a site license for use. Further, the data transferred was
sent from the remote point in almost raw form for processing on a PC or
other type of computer equipment. The radio link was actually a form of
wireless RS-232 link, and no more. Today, we expect much more of our in-
vestment in sensor and actuator devices. Embedded microprocessors often
have more computing power than the 1980s mainframe computer. No longer
is raw data enough. Fully processed information is required. Embedded
processors need bi-directional communications with other computers and
databases on the network to maximize their ability to control material flows
and perform the work previously assigned to centralized computers. This is
the state of the technology on two-way radio communications for data at the
st
beginning of the 21 century.
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Sometimes pulling wire to connect a computer or a new device to the LAN is
either too costly or physically impossible. The answer to this problem, at
least according to one IEEE standards committee, is to use a wireless LAN for
the physical layer. A very inexpensive solution has been to use infrared light
to “beam” the data through open spaces, but in spite of good specifications
such as IrDA, infrared connections have not become popular. In 2000, over
200 million devices were shipped with IrDA ports, but use of this excellent
standard is almost non-existent. Clearly, something was wrong with IrDA.
The IEEE 802 committee concluded that comprehensive work was necessary
to establish a wireless connection to any of their 802 LANs, and assigned the
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responsibility of defining the wireless physical layer to Subcommittee 11. In
1997, the initial work of IEEE 802.11 was completed and specification 802.11
was issued as an American National Standard (ANS), and later as an ISO
standard. This document defined three (3) different physical layers:
1. Infrared (IR)
2. Direct sequence spread spectrum (DSSS), and
3. Frequency hopping spread spectrum (FHSS)
The standard has defined only the physical layer so that these interfaces will
operate with any of the other LAN/MAN protocols of IEEE 802. Since 802.3
(Ethernet) is the most popular of all these protocols, it is the only one fully
tested and commercialized. You might think of a wireless LAN as a gap be-
tween two ends of an Ethernet cable. This has been referred to as an “air
interface” and is commonly called “wireless Ethernet.”
IEEE 802.11 defined data rates of 1.0 and 2.0 Mbps for both the IR link and
both forms of spread spectrum radio operating in the 2.4 GHz ISM (indus-
trial, scientific., and medical) band. This was initially thought to be fast
enough when networks rarely achieved much faster rates, and internet con-
nections were typically at T1 rates, or 1.544 Mbps. However, with fast
Ethernet operating at 100 Mbps, and broadband internet connections, there
was a demand for higher data rates. In 1999, the Wireless LAN subcommit-
tee released IEEE 802b, which defines only DSSS at a data rate of 1, 2, 5.5, and
11.0 Mbps.
Never satisfied with these slow speeds, the committee went back to work to
define higher data rates at 20 to 54 Mbps, but there is not room in the 2.4
GHz ISM band for higher rates. The higher rates will only be achieved by
operation in the 5.0 GHz frequency band. This standard is called IEEE
802.11a, and is commonly called Hiperlan2, after an early prototype product.
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IrDA was never designed to be more than a simple device connection, not a
local area network. Its most frequent use is to provide a way to synchronize
PDAs (Personal Digital Assistants) with a database on a PC. However, most
PCs are not equipped with an IrDA port. Laptop computers generally are so
equipped, but the port is usually at the rear. Physical inconvenience and lack
of desktop presence probably were at fault in failure of IrDA.
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Designers of 802.11 were quite aware of IrDA’s faults, and specified a higher
power infrared radiation capable of being bounced off walls and reflected by
mirrors to “flood” an office area with infrared (IR) data beams. This leads to
multipath distortion, where the same data arrives along different reflected
paths at slightly different delays. Compensation for multi-
path distortion has been included in the 802.11 specification $OWKRXJK ,5 ZRXOG JHQHUDOO EH VXLWDEOH
to allow its infrared to be used in an office environment IRU PRVW IDFWRU DXWRPDWLRQ
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being implemented, and no more development is planned
for higher data rates. Although IR would generally be suit-
able for many factory automation applications, future use is doubtful because
of the lack of commercial equipment, and the emphasis on spread spectrum
radio communications.
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9. The original spread spectrum idea was conceived by movie actress Hedy
Lamarr (real name: Hedwig Maria Eva Kiesler), and her piano composer
friend, George Antheil, who patented the method and donated it to the US
Government in 1943. The idea for frequency hopping was conceived as a
method to allow secure radio communications, without the fear of intercep-
tion, and one that would be able to function in the presence of high power
jamming signals used to disrupt battlefield communications.
IEEE 802.11 defines a specific instance of FHSS for the unlicensed ISM radio
band 2.4 to 2.4835 GHz. Specifically, it defines 79 different frequencies in
that band, and therefore, 78 different frequency transitions are defined for
each of the 79 base frequencies of the carrier signal. Signals are transmitted
for 400 ms before the carrier is switched to the next frequency. This is com-
monly called “slow” frequency hopping.
Two different FHSS systems each operating in the same area (co-location)
could occasionally collide by operating at the same carrier frequency. Addi-
tionally, any other noise on one of the frequency bands will cause
interference. Bluetooth is one of those technologies operating in the 2.4 GHz
band that will cause some interference with wireless LANs. There is no spe-
cific error detection specified for the physical layer, so any data errors caused
by interference will be detected through an error in the CRC (Cyclic Redun-
dancy Check) performed by the Data Link Layer. No specific management
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for the physical layer is defined by the standard, although suppliers may im-
plement their own. One such common function of FHSS management would
be to detect frequency bands consistently generating framing errors, and to
eliminate them from the list of available frequencies.
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11. Another method of spreading the signal across the 85 MHz of the 2.4 to 2.485
GHz frequency band is called direct sequence spread spectrum. DSSS is
harder to understand than FHSS, but accomplishes the same goals of noise
rejection, and resistance to jamming. Imagine that DSSS is like FHSS, but the
switching time between frequencies is very short – less than one bit time at
the transmitted data rate. Each bit of data is sent at multiple frequencies (11
in IEEE 802.11b) providing some redundancy. Since the frequencies are se-
lected at random within the allowable frequency band, covert detection is
practically impossible.
For many technical reasons, most of the advanced development has been de-
voted to DSSS. IEEE 802.11b defines a data rate of 11 Mbps, and uses only
DSSS technology. At present, it seems that DSSS is the only wireless LAN
technology being developed for broad interoperability. The most under-
standable reason is the speed of 11 Mbps is within the range of wired
networks, while the 1-2 Mbps of FHSS is probably suitable only for connec-
tion of slower peripheral devices such as barcode readers and handheld
terminals. In fact, although too technical for this report, behavior of DSSS in
most ways is superior, or at worst equivalent, to FHSS.
One of the differences between FHSS and DSSS is the statutory limit, which
prevents co-located FHSS from synchronization, which would prevent colli-
sions resulting from networks in the same area from picking the same
frequency at the same time. DSSS is allowed to probe for potential interfer-
ence by statute so that it may detect it before transmission. Some of the
statutes are written this way because IEEE 802.11 (and Bluetooth) operate in
the unlicensed ISM radio band, and are very limited in radiated energy. US
Government regulations are established for this band to allow sharing by
many technologies. Most other governments share the same findings and
echo the same regulations for this band as the US Federal Communications
Commission.
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The most significant recent development has been the availability of low cost
CMOS chips for the 5 GHz frequency band (5.15-35 and 5.725-5.825), previ-
ously requiring expensive Gallium Arsinide (GAs) semiconductors. This has
resulted in a surge of interest in IEEE 802.11a, the high data rate DSSS tech-
nology supporting up to 54 Mbps. At present, this band is not shared with
any other radio service actually in use, and it does not contain a
harmonic of the water absorption band. IEEE 802.11a has been $5 EHOLHYHV WKDW ,((( D
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distortion (signal bounces off walls and objects) over 802.11b.
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Chips for 802.11a are already available in development quanti-
ties and commercial products are likely to become available in
2002. Convergence with the European-developed HiperLAN2 is highly
likely, removing international objections to this standard. ARC believes that
IEEE 802.11a defines a wireless protocol suitable for use in the industrial en-
vironment, and will dominate the industrial wireless LAN market by 2005.
We advise against use of FHSS and 802.11b for wireless LANs, except to
solve immediate short-term problems.
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The original application for Bluetooth was for “cordless” applications: elimi-
nate the connecting cord between headphones and the cell phone;
synchronize PDA data bases without a connection cord; and, allow PDAs to
print without making a physical connection to a printer. Since then, the Blue-
tooth SIG (Special Interest Group) has developed extensive protocols not
normally found in data communications. One of the applications, which
many Bluetooth advocates believe will be the largest use of the technology,
will be for the transmission of digitized voice – telephony.
One of the defined functions of Bluetooth is the automatic formation of “pi-
conets” – spontaneous networks with up to eight (8) nodes at a time
connected. File sharing and transfer, printer sharing, and all the usual peer-
level network functions are provided similar to a Windows Network
Neighborhood. If there are more than eight nodes in one location, they will
all appear on as many other nodes as possible forming multiple network
paths.
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Bluetooth is a full network protocol definition, not just a physical layer such
as Wireless LAN. While it operates in the same network band as IEEE
802.11, the ISM band at 2.4 to 2.485 GHz, it only uses FHSS with much faster
hopping than 802.11. The hopping rate is 1600 hops per second, which when
coupled with the very low power of 1600 picowatts, should result in minimal
interference with 802.11 FHSS. However, there has been some reported in-
terference with 802.11b DSSS when used in the same area.
One of the Bluetooth protocols is its ability to discover other Bluetooth nodes
in its vicinity and spontaneously form a piconet attachment. Therefore,
when applications are ready to connect as a microphone/headphone, ex-
change business cards, or synchronize a contact database, they need not
concern themselves with the attachment step. Each of these applications will
be enabled or disabled in advance and usually will require specific identifica-
tion before the attachment can take place. This is especially important for
database synchronization or the formation of piconets since these steps may
expose data to unwanted transfers. Lack of security in this function is more
than compensated by the convenience that goes way beyond plug-and-play.
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Bluetooth is expected to be part of every cell phone and PDA sold by 2003.
This huge market volume is expected to reduce the cost of the chip to less
than US$5.00 in this time frame. With the trend to commercial-off-the-shelf
(COTS) technology, Bluetooth clearly fits. Because Bluetooth will most often
be applied to a battery driven device, it must draw little power, and must run
cool as well. These characteristics make Bluetooth useful for portable devices
or devices mounted on moving machinery.
Bluetooth is a viable data communications protocol and will support the up-
per layers of the protocol stack including Internet protocols and applications
such as TCP/IP, FTP, SNMP, SMTP, and UDP. While transmitted energy is
expected to be low, raising the signal level closer to the allowed ISM band
maximum of 250 milliwatts from the traditional 1600 picowatts, increases
distance between nodes. If signals are only directed to a single node, as for a
switch or centralized controller, then directional antennas may be used to
further increase reception distance. Bluetooth transmitting with an omnidi-
rectional antenna at 250 milliwatts should be able to reach at least 100 meters.
Except for the lower level protocols, there is no essential difference between
Bluetooth and any other LAN technology operating in the 2.4 GHz band.
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Embedded Bluetooth is expected to appear in many industrial automation
products.
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The world’s wireless telephones are converging toward a common technol-
ogy called CDMA (Code Division Multiple Access) originally created and
patented by Qualcomm, and freely licensed for use in 3G Wire-
less. The ITU (International Telecommunications Union), 7KH ZRUOG·V ZLUHOHVV WHOHSKRQHV DUH
which sets the world’s standards for telecommunications has FRQYHUJLQJ WRZDUG D FRPPRQ
set a goal called IT-2000 – a standard that defines the converged WHFKQRORJ FDOOHG '0$ RGH
technology for all wireless telephones. If this standard would 'LYLVLRQ 0XOWLSOH $FFHVV
15. be achieved, it would be possible to use a single wireless tele-
phone anywhere in the world. But, alas, this dream has been subverted by
commercial forces wanting to preserve the life of today’s wireless central of-
fice switching equipment. As a result, we will see CDMA used all over the
world, but not with identical protocols or at the same radio frequency.
Wireless telephony will certainly be useful in the factory or process plant to
contact people who are not deskbound. 3G is a far superior technology to the
old CB radios. However, it is not for voice alone that we are suggesting a
strong interest in 3G wireless – it is the high digital data rate of this technol-
ogy:
• 384 Kbps while the mobile terminal is in motion.
• 2.0 Mbps (or higher) when the terminal is not in motion (fixed).
These data rates are suitable for most data transfers in industrial automation
applications, particularly for remote units. Other characteristics of 3G wire-
less are also appealing:
• CDMA is a highly noise-resistant protocol using DSSS technology.
• The appeal of a very large COTS market for low cost support silicon.
• Use of one product anywhere in the world.
• Availability of low cost telephones and PDAs for handheld terminals.
While the world’s wireless telephone providers are all moving in the CDMA
direction, the protocols will differ somewhat depending upon the spectrum
available and the previous cell phone technology used in that country.
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GSM (Global System Mobile) is the most widely used digital cell phone tech-
nology in the world. It is a form of TDMA (Time Division Multiple Access)
with time segments of about 50 ms. This allows up to 200 users to share the
frequency in the vicinity of the cell transceiver. It is used at different fre-
quencies in different parts of the world: 800, 900, and 1900 MHz. The most
significant feature of GSM is the SIM (System Identification Module), a tiny
card usually referred-to as a “chip” inserted into a cell phone to give it all of
your account information including your telephone number. The US-based
TDMA networks do not use a SIM.
The limitation of GSM and TDMA are clear – the limit of 200 users per cell
means that conversations are frequently dropped when you move into the
range of a different cell, which is already at full capacity, and often there is
no dial tone in crowded metropolitan areas. In any time division multiplex-
ing protocol, the time assignment is fixed as long as you are off-hook, even
when you are not speaking or listening. Less clear, is the quality of service
since all speech is digitized and compressed. The GSM voice encoder (CO-
DEC) has sufficient fidelity for most speech, but little else, and limits speeds
when used as a modem.
CDMA (code division multiple access) uses DSSS and is a packet-based
transmission method. When speaking, voice is encoded into digital data,
compressed and assembled into packets that are transmitted when the chan-
nel is available. No packets are sent during quiet periods. Since human
speech contains many pauses, CDMA is usually more than 50 percent more
efficient than TDMA or GSM. For reasons of bandwidth efficiency, the ITU
selected CDMA as the technology for IT-2000.
Wireless telephony carriers currently using CDMA face minimal equipment
upgrades to convert directly to IT-2000, but are being cautious in their con-
versions to avoid making promises they cannot keep. They are rolling out
the increased digital bandwidth in steps starting with today’s 19.2 kbps to 64
k, then 128 k, 256 k, 384 k and finally 2.0 Mbps, all for stationary perform-
ance. Rates for stations in motion are less. No technical changes are required
for each of these steps, but the providers have an opportunity to learn about
service delivery and system bottlenecks. Operation of 3G networks would
not be on the same frequencies as today’s service, which can be continued
until fully replaced by 3G.
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GSM and TDMA digital cell phone providers have to make some very ex-
pensive equipment upgrades to move to IT-2000, and will not do it in one
step. Their strategy is called EDGE and has been labeled a “2.5G” strategy,
nd
since the current technology is 2 generation, and they are not yet at 3G.
Edge allows concurrent use of the same frequencies as GSM and TDMA
without interfering with it. This allows the providers to continue to service
current customers and use the same radio transceivers as present, but with
the new switching equipment. A second step would install new transceivers
and obsolete older service.
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Why do we care about 3G in the industrial setting? Consider the volume of
the 3G marketplace and the silicon that will support it. This is the effect of
COTS (Commercial-Off-The-Shelf) technology and the low prices that go
along with a dominating technology. Industrial equipment will be devel-
oped around 3G silicon and will use this digital voice channel
for many mobile applications not needing the high band- $5 H[SHFWV WKDW * WHFKQRORJ ZLOO
width of wireless LAN that will always be more expensive. QRW EH WRWDOO XQGHU FRQWURO RI WKH
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control of the wireless telephone service providers. 3G will
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become the basis for the office, campus, and commercial
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18. building telephone network now known as the PBX (Private
Branch eXchange). After all, the telephone network is opti-
mized for the efficient and demanding service of voice transmission, whereas
a LAN is optimized for high speed data transmission. They do not mix very
well! When the LAN is based on wire, then there is an incentive to fold te-
lephony into that same wire to save on the cost of a parallel set of wires for
the telephone. Remove the LAN wire and substitute wireless LAN, and the
incentive is removed to share LAN and telephony applications. Thus is born
the market for the Wireless PBX based not on wireless LAN, but on a local
installation of 3G transceivers. When you find a comfortable 3G telephone
handset, with its Bluetooth headset, you will carry it with you wherever you
wonder, and you will never be out of touch – find the OFF switch!
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There have been industrial applications of radio technology for many years
for both mobile and remote access. As radio technology, available frequen-
cies, and bandwidth demand have changed over the years, the choice of the
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radio has changed. These new wireless standards are certain to affect the
choice of radio technology as well. For example, as 3G wireless moves out
from the major metropolitan areas to include more rural zones, many oil and
gas wells and pumping/gathering stations will be covered. Instead of using
narrowband radio or expensive telephone lines, SCADA remote stations will
convert to 3G wireless transmission. The immediate beneficiaries of 3G wire-
less for SCADA, will be in water and waste treatment applications, which
are, by definition, in major metropolitan areas already well covered by cellu-
lar radio systems.
Only a few years ago, handheld barcode readers were wired to local PCs for
data acquisition in internal supply chain applications. When narrowband
radio became affordable, the bothersome wire was replaced with the tech-
nology known as RFDC. In the past year, RFDC has been replaced by
wireless LAN technology based on IEEE 802.11. We feel that the low data
rates and the low cost of 3G will again convert this market to the use of 3G
wireless connection.
Automated guided vehicles (AGV) have not been as widely used in North
American factories as they have in Asia. One of the problems in use of AGVs
is that once they are assigned a destination, they will follow a predetermined
path to that destination and are essentially out of communications with the
materials flow control system. Use of wireless LAN is not a good solution to
communications with AGVs, since they are by definition, roaming stations,
and the roaming problem is very difficult to correct on wireless LANs. 3G
wireless protocol is designed for handoff between cells and maintains con-
nections while roaming. This makes it a superior technology for use in data
acquisition and control of AGVs. With a sustained 3G connection, AGVs can
now be fully tracked and even redirected in mid-course if necessary.
It is highly likely that 3G wireless will become the backup for
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the wireless LAN for high bandwidth applications inside the
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corporate walls or factory. It will also become the logical ex-
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LQVLGH WKH FRUSRUDWH ZDOOV RU IDFWRU tension to the corporate LAN operating outside the factory
,W ZLOO DOVR EHFRPH WKH ORJLFDO walls, much as today the telephone modem links the business
H[WHQVLRQ WR WKH FRUSRUDWH /$1 LAN to the roving worker. We expect that the handoff from
RSHUDWLQJ RXWVLGH WKH IDFWRU ZDOOV the wireless LAN to the 3G network and returning will become
seamless and transparent to the user as they move around the
factory, occasionally moving out and into the range of wireless LAN access
points, but never out of touch with one or more PBX cells.
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