TransferJet Overview Whitepaper

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Worlds are About to Touch
TransferJetWhitepaper
Revision 1.2

September 2015

TransferJet Consortium© 2009 TransferJet Consortium

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INTRODUCTION
Two worlds exist for today’s consumer: content playback and content creation.
The traditional end user still consumes multimedia content by watching TV,
listening to music, and viewing family photos. At the same time many end users
also spend almost as much time producing content. They produce photos andvideos by using cameras and camcorders. The reason this has become so
popular is simple: it is very easy to create content with modern equipment. But
there is a problem. Content is easier to create than to transfer. This limits thepotential for playback and sharing, and creates a kind of bottleneck between
content creation and content consumption. For example, it is not so easy whenend users want to post high-resolution photos taken by high performance digital
SLR, to Social Network Services in timely manner. Nowadays, content sharing
between devices has more and more opportunities. This white paper presents asolution – TransferJet – which solves the content sharing problem in a way that
also achieves high performance, low cost, high security, highly intuitive, andmost importantly, extreme ease of use.

Figure 1：Positioning of various wireless technology.

TransferJet is a new wireless technology that combines a data transfer rate
faster than Wi-Fi with the ease of NFC (Near Field Communications). This
combination enables TransferJet to deliver a transfer speed of 560 Mbps
available to the end user through a simple “touch” operation.

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TransferJet Overview Whitepaper

TJC_004_whitepaper-rev1.2“TOUCH” MODEL
How does TransferJet achieve all this? The key lies in the “touch” model ofuser operation. This model requires only a simple touch motion from the user tomake things happen. Touch is such a natural motion that people tend to “get it”
very quickly. Consider the case of the train network in Japan. Japanese trainsystems adopted touch for the access gates in all stations. The system was so
successful that within a year or so after deployment it was fully adopted by thegeneral public. It takes only a fraction of a second to pay the train fare bytouching a payment IC card to the card reader while walking through the gate.
Today it is very common for millions of people to stream through these gateseach day, making a touch transaction on every pass. In fact, it is difficult to findpassengers using traditional paper tickets. Similar NFC technologies have been
adopted in other payment applications such as bus fares, taxi fares, shops,restaurants, and so on. Clearly, touch is a very natural and intuitive motion.
That is why TransferJet utilizes this same touch motion and extends theperformance to also support high speed data transfer.

USE CASES
This powerful combination of touch and speed enables high speed transfer oflarge data files (photos, video, etc.)
between two devices including TVs,
smartphones, PCs, tablets, camcorders,
digital still cameras, gaming consoles
and printers. TransferJet enables highspeed data transfer triggered by just asingle touch. Or, more complex usage
scenarios which require additional userinteraction to select the specific data tosend, to select the specific location tostore (or method to process) the received
data can also be implemented. From auser standpoint, TransferJet can bethought of as a universal touch-activatedFigure 2: Displaying digital photos on theTV by simply touching the camera
smart interface which instantly connects
a wide variety of electronic devices. For example, family photos might bedisplayed on a TV just by touching the camera to the TV or a TransferJet padconnected to a STB. Hi-resolution photos captured by a high performance
digital SLR can be posted to social networks and blogs in a timely and efficientmanner by touching the camera to the smartphone or tablet. Anyone can enjoy
TV programs on the go by touching the smartphone to the STB and instantly
transferring HD programs.

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Figure 3: Transferring digital files onthe goFigure 4: Downloading digital contents
to a mobile device by touching a digital
signage spot

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The ease of use enhances these
traditional use cases but also creates
new possibilities. For example, it ispossible to create digital signage anddigital kiosks with new features andcapabilities. A person might get files
such as coupons, movie trailers, andsound clips by touching the smartphoneor tablet to TransferJet pads placed inpublic locations. A theme park visitor
could download electronic maps andevent
schedules
bytouchingTransferJet pads placed at the park
entrance and other locations.
Additional use cases might exploit thecontactless nature of TransferJet andthus eliminate the risks associated withtraditional connector pins that might
corrode, bend, or break. Such properties
make TransferJet ideal in harsh ordemanding environments such as
manufacturing plants, shipyards, cleanrooms, and medical environments.

Figure 5: Sampling/downloading music
files to a mobile device by touching amusic kiosk panel

SPECIFICATIONS
Clearly, the unique qualities of TransferJet make it useful for many applications.
Let’s delve a little deeper into the technical details. TransferJet can transfer
data at a peak speed of 560 Mbps, with an effective throughput up to 375 Mbps.
The maximum range of operation is on the order of a few centimeters and thenetwork topology is always point-to-point. These last two features greatly
enhance the simplicity of the system. The short range makes it possible tooperate in the near field of the radio signal using very little transmission power –less than -70 dBm/MHz. The point-to-point topology greatly simplifies the setup
and management procedures. And since the near field electric induction field isnon-polarized, the two devices do not have to be precisely oriented to achieve agood connection. The spectrum is centered at 4.48 GHz, and occupies abandwidth of 560 MHz. This choice of spectrum, coupled with extremely lowtransmission power, enables unlicensed operation in Japan, Europe, the USand many other regulatory domains. In addition, TransferJet contains a robust© 2009 TransferJet Consortium

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protocol which includes error detection and correction, packet
acknowledgement, and packet resend. All of these details work together tominimize complexity and RF interference. The low transmission power andpoint-to-point topology help to minimize power consumption. Finally, eachTransferJet device can detect the presence of another device as it comeswithin range. Therefore, it is possible to save power by transmitting only whenanother device is detected. This is another advantage of the touch model.
CenterFrequency

Transmission
PowerTransmission
Rate

4.48 GHz
Below -70 dBm/MHz (average)
It satisfies regulatory requirement in many
countries and regions, such as ETSI EN 302 065.
Also, in case of this system, it is confirmed to meetthe requirement of low-intensity radio wave
regulation in Japan.
560 Mbps (max)/375 Mbps (effective throughput)
System can adjust the transmission ratedepending on the wireless environment.

Connection
Distance

A few centimeters

Topology

1-to1

Antenna
Element

Electric induction field coupler
Figure 6: TransferJet Specifications

RANGE
At first glance, the short range of a few centimeters might be considered adisadvantage. But when combined with the touch usage model, it actually offers
tremendous advantages. We’ve already mentioned the low power consumption.
In addition, the short range virtually eliminates problems with multipath fading or
shadowing which plague longer range solutions such as Wi-Fi or Bluetooth.
Thus the connection is very reliable without any need for complex equalizers oradvanced modulation schemes such as OFDM. This also helps to minimize
cost and power consumption. But the biggest advantage is the ability for eachTransferJet device to discover another TransferJet device that comes within
range. Since the range is so short, the protocol can reach a key conclusion
upon making this discovery: the user has just authorized a connection with thediscovered device. Therefore, the protocol can connect the two devices with nofurther action required from the user. Once this connection is made, theapplication can take further steps such as transfer a file, query the user, display
a file menu, etc. In this sense, the touch motion in the TransferJet world is© 2009 TransferJet Consortium

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similar to the cable plug-in action in the USB world. One might say that
TransferJet provides the ease of a USB cable – without the cable. As withevery other wireless protocol, devices must proceed through the necessary
stages – search, discovery, selection, authentication, connection, and transfer –in order to complete a desired activity. But TransferJet is unique because allthese steps are collapsed into a single motion: the “touch”.

COUPLERIt may come as a surprise that limiting connectivity to a predetermined shortrange is inherently difficult. Remember, if two TransferJet devices are not incontact (or near-contact) with each other, they should do nothing - not evendetect each other's presence.
That is a very tricky task for a conventional antenna. A typical antenna isdesigned to radiate a signal as far as possible. To better understand thisbehavior, consider the field equations shown below for an ideal dipole excitedby a sinusoidal current.

Figure 7: TransferJet Coupler design and field equations for an ideal dipole.

The variables in the above equations are as follows:
R = range or distance from the dipole in metersk = ω µε or angular wave number of a plane wave
p = QL (where Q is the peak charge and L is the length of the dipole)ω = angular frequency of the sinusoid in radians/sec
ε = permittivity of the propagating medium (air)µ = permeability of the propagating medium (air)© 2009 TransferJet Consortium

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Notice the field strength of the far-field parts of the signal vary inversely withrange. The near field parts, on the other hand, vary inversely with the square ofrange. Therefore, the near field intensity drops off much faster with range than
the far field. The far field also radiates real power. The far field transverse E andH components form the conventional transverse electromagnetic (TEM) wave
common in wireless communications. By contrast, the near field is inductive
because it does not radiate real power but instead stores power in the near field.
The inductive power is only dissipated if another TransferJet coupler appears
in the near field. Finally, the near field contains a longitudinal component. This
component is important because it is not polarized, making it much easier for
the user to align two devices as previously mentioned.
All these factors are combined to produce the unique TransferJet coupler. The
design of one such coupler is shown in Figure 7 along with the coordinate
system from the ideal dipole analysis.
This coupler is not a conventional antenna but instead is designed to suppressthe far field component and emphasize the near field signal. The approachcreates a virtual bubble of signal energy that drops off very quickly at any range
beyond a few centimeters. The result is a usable sensitivity within this distance
range. Two typical TransferJet devices establish a connection when brought
together. But once established, the link will not break unless the devices areseparated beyond the bubble distance. This “soft engagement” feature further
enhances the convenience and ease to the end user.

SECURITY
Although TransferJet is a near field, point-to-point technology, it is still awireless network. So is it secure? This is a very key question. Wirelessnetworks such as Wi-Fi and Bluetooth have extensive and complex encryption
technologies built in to the link layer to make sure that an unauthorized receivercannot access private information. Such link layer encryption is necessary forlong range networks because it is impossible to physically restrict access to thenetwork as would be possible with a cabled solution such as Ethernet or USB.
For security purposes, TransferJet is more like a physical cable. Therefore, it
intentionally has no encryption built into the link layer. It would be very difficult
for an attacker to gain access to a TransferJet connection from some distantlocation. The attacker would have to be physically a few centimeters away inorder to access the connection. If the attacker has to be that close, they mightjust as well plug in a USB cable. By eliminating link layer security, TransferJetsaves power and cost, and further reduces complexity for the user. But it ispossible to add encryption at the application layer. Some applications must
protect a file’s integrity during file transfer regardless of the connection type.
TransferJet is perfectly compatible with these application-level security© 2009 TransferJet Consortium

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measures. Since each device has a unique ID, it is possible to uniquely identify
any device that attempts to establish a connection. So TransferJet achieves
the best of both worlds, the simplicity and freedom of touch, with the security ofa cable.

PROTOCOL STACKThe TransferJet protocol operates under three basic principles:1) Point-to-point: Connections are always point-to-point. Multi-point
topologies are not supported.
2) Symmetry: All devices are capable of initiating or receiving a connection
request.
3) Backwards compatibility: The protocol should be as backwards
compatible as possible with existing legacy architectures.
To implement these principles, the TransferJet protocol defines three layers:
The Protocol Conversion Layer (PCL), the Connection Layer (CNL), and the
Physical layer (PHY) as shown in the figure.
The Physical layer, or PHY, implements the actual radio. This layer converts thedigital information into an RF signal suitable for transmission across theTransferJet couplers. The Connection Layer, or CNL, manages connections
and data delivery. For connection management the CNL is responsible forestablishing and releasing the connection to a peer TransferJet device. For
data delivery, the CNL provides packets to carry the data payload and confirm
successful delivery of those packets to the peer device. The Protocol
Conversion Layer, or PCL, is responsible for converting from an Application’s
existing interface standards (such as SCSI or OBEX), and the TransferJetnative protocol. In this way, for example, a stationary device can access data ona mobile device without modification to the application layer software. As ofJune, 2015, OBEX, SCSI (incl. SD over SCSI), PTP/MTP, Serial Port, and TCPIP are supported in the form of PCL specifications.

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Figure 8: TransferJet Stack Architecture

REGULATORY
Since TransferJet communicates using a radio signal, it must comply withgovernment regulations in any geographic region in which it operates. In theregions that have clearly established regulations, including Japan, Korea, China,the EU, and the US, TransferJet is compliant for operation indoors or outdoors.
The regulatory situation of major region is shown below.

Figure 9: UWB Regulatory Landscape© 2009 TransferJet Consortium

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TransferJet CONSORTIUM
Clearly, the technology offers significant benefits to the end user. But any datatransfer requires two TransferJet devices in order to define a use case andcomplete a transaction. Therefore, multiple products must adopt TransferJet inorder for it to be successful in the market. That is the purpose of theTransferJet Consortium (www.transferjet.org/en).
TransferJet Consortium has two classes of membership: Adopters andPromoters. Adopters will be able to access, as licensees, documents including
all technical specifications and guidelines related to TransferJet, in order todevelop, manufacture, and sell products compliant with those specifications andguidelines. Promoters participate in the development of the technical andcompliance specifications as well as the overall management and operation ofthe consortium.
The TransferJet specifications include protocols, architecture, use cases, test
specification, certification program, trademark guideline and son on.
Core part of the TransferJet technical specifications have also been officiallyapproved as an ISO/IEC17568 standard.

Figure 10: Brand Logo

Figure 11: Symbol Logo

Figure 12: Target Point Logo

Figure 13: Example of Target Point
Logo Placement© 2009 TransferJet Consortium

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TransferJet regular typeface and TransferJet logos are trademarks licensed byTransferJet Consortium Incorporated Association.
Wi-Fi is a registered trademark or a trademark of Wi-Fi Alliance.
The Bluetooth® word mark and logos are registered trademarks owned byBluetooth SIG, Inc.,
All other trademarks, company names and logos appearing in this document
are the property of their respective owners.

© 2009 TransferJet Consortium

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