**Advanced Wireless Communication for the Transportation Sector\
**

**A Roundtable Discussion**

**May 22, 2008**

**SUMMARY REPORT**

U.S. Department of Transportation Headquarters

1200 New Jersey Avenue, S.E.

Washington, DC 20590

![](media/image1.jpeg){width="0.8916666666666667in"
height="0.8819444444444444in"}

Prepared by

Volpe National Transportation Systems Center\
Research and Innovative Technology Administration, U.S. DOT

Cambridge, MA

July 2008

TABLE OF CONTENTS

**Preface.......................................................................................
[3](#preface)**

1.0 Overview of Department of Transportation Viewpoint
[5](#overview-of-department-of-transportation-viewpoint)

2.0 Wireless Communication Technology Trends
[7](#wireless-communication-technology-trends)

> 2.1 Open Systems vs. Closed Systems [7](#_Ref212599516)
>
> 2.2 Technology Architecture and the Business Ecosystem
> [8](#_Ref212599558)
>
> 2.3 A New Technology Development Ecosystem [9](#_Ref212599579)
>
> 2.4 Applications for the Transportation Sector [10](#_Ref212599607)

3.0 Mobile Ad-Hoc Networks (MANETs) [12](#mobile-ad-hoc-networks-manets)

3.1 Overview of Trends [12](#overview-of-trends)

3.2 Role of Standards [12](#role-of-standards)

3.3 Advanced Wireless Applications for the Transportation Sector
[13](#advanced-wireless-applications-for-the-transportation-sector)

3.3.1 The Business Case for Open Platforms and Open Networks
[14](#the-business-case-for-open-platforms-and-open-networks)

3.3.2 Technical Options and Considerations
[16](#technical-options-and-considerations)

3.3.3 Business Models [23](#business-models)

3.3.4 Practical Considerations for Field Applications
[25](#practical-considerations-for-field-applications)

4.0 The Path Forward [27](#the-path-forward)

4.1 Strategic Alignment with DOT Vision and Mission
[27](#strategic-alignment-with-dot-vision-and-mission)

4.2 Implementation and Action Steps
[27](#implementation-and-action-steps)

Appendix A: List of Participants [29](#appendix-a-list-of-participants)

Appendix B: Roundtable Agenda [31](#appendix-b-roundtable-agenda)

Appendix C: Questions and Issues for Further Discussion
[33](#appendix-c-questions-and-issues-for-further-discussion)

Appendix D: List of Acronyms [36](#appendix-d-list-of-acronyms)

# Preface 

On May 22, 2008, the U.S. Department of Transportation's Research and
Innovative Technology Administration (RITA) convened the "Advanced
Wireless Communication for the Transportation Sector Roundtable." It
brought together 40 leading experts in the field of wireless
communications and filled a conference room with a vast amount of
intellectual capacity in the area of communications technology. Experts
represented the private sector, academia, State and local Governments,
and the research and advocacy community. Appendix A provides a full list
of participants.

The roundtable was structured to accommodate presentations, discussion,
and dialogue among participants. Its goal was to share with thought
leaders in the field of wireless communications critical information
about the U.S. Department of Transportation (DOT) vision, interest, and
applications to the transportation sector. The complete agenda is listed
in Appendix B.

The roundtable provided a forum to discuss how to enable internet and
wireless communications technologies to better allow vehicle-to-vehicle,
vehicle-to-infrastructure, and infrastructure-to-system manager
communications in order to avoid crashes and enable improved situational
awareness (including dynamic rerouting and improvements in signal timing
and synchronization based on real time and evolving traffic and weather
conditions).  Other applications of advanced communications technologies
include electronic tolling and fare collection for all modes of
transportation, and developing mobility devices for remote monitoring of
bridges, roads, rails, and other critical infrastructure.

It should be noted that while the DOT currently engages in a number of
activities across all modes that can or do make use of wireless
communications (e.g. aviation, marine, etc.), much of the roundtable
discussion centered on the surface transportation arena.

The session was opened with remarks by Vice Admiral Thomas J. Barrett
(USCG - ret.), Deputy Secretary of Transportation. Having noted the
enormity of the transportation sector -- including its economic impacts
and its relationship to global, not merely domestic issues -- Barrett
offered comments that centered on three key concepts:

-   Importance of the enterprise approach to innovation;

-   Shift in focus on current applications, rather than future ones; and

-   Critical role of openness and open networks.

The enterprise approach adopted by DOT leverages the intellectual
capabilities of experts in the field -- those in the private sector,
researchers in academia, and proponents and advocates throughout the
industry. These experts can enable and energize new ideas and systems.
The approach requires considerable outreach and an ability to "get
people to the table" to share information, transfer knowledge, and
develop strategies for moving forward.

The DOT focus in the area of wireless communications is on safety,
innovation, and identification of 21^st^ Century solutions for
challenges. Vice Admiral Barrett recognized that the field is dynamic
and ever-changing, and powerful tools are being developed. Notably, Vice
Admiral Barrett's purview extends to the next-generation of airspace
management system (i.e., GPS, satellite-based systems). That work
involves shifting the focus on technology from "NextGen" to current
applications. The goal is to identify those technologies and innovations
that can be applied and implemented now, rather than well into the
future.

Significant opportunities exist to make use of expertise in wireless
communications and related technologies. The new language of technology
(including wiki collaboration, mash-ups, and MANETs) is emblematic of
challenges, but more importantly, of potential opportunities for growth.

This growth can be achieved by encouraging openness. As a strong
proponent of open networks, Vice Admiral Barrett is concerned with
spurring innovation and entrepreneurial creativity without "locking it
up." However, standards for open networks are needed, and U.S. DOT looks
forward to continuing the dialogue about open networks with industry
experts.

Finally, Vice Admiral Barrett noted that his participation on a
committee tasked with addressing the civilian side of Precision,
Navigation, and Timing (PNT) issues has allowed him to learn about
astonishing advancements in the area, including the impact on many
different fields i.e., the increase in productivity through use of
precision farming techniques that employ the Global Positioning System
(GPS).

Vice Admiral Barrett's opening remarks inspired and encouraged
participants to offer their knowledge, thoughts, and opinions about
advanced wireless communication in the transportation sector and
provided a foundation for RITA Administrator Paul R. Brubaker to share
the DOT viewpoint on the topic.

# Overview of Department of Transportation Viewpoint

RITA Administrator Paul R. Brubaker was introduced by Volpe National
Transportation Systems Center Acting Director Robert E. Suda. Suda also
provided an overview of the roundtable agenda (Appendix B). Brubaker
offered a framework for the discussion by laying out current challenges
and exploratory/demonstration projects currently underway. His comments
highlighted several key points:

-   Measurable improvements and outcome-based objectives are critical to
    successful deployment of new and advanced wireless communication
    technologies in the transportation sector;

-   The U.S. DOT and State DOT perspectives should be broadened to "open
    the aperture" to make use of technologies that are not currently
    being utilized; and

-   Exploration in partnership with State DOTs and other entities can
    reveal new opportunities, functions, and applications that can
    improve the surface transportation system.

Administrator Brubaker's emphasis on "measurable improvements and
outcome-based objectives" pervades RITA and reflects the *Transportation
Vision for 2030*'s "lofty goals" in the areas of ITS, environmental
stewardship, and reduction of greenhouse gas and NOx emissions.

It was noted that there are six million vehicular crashes each year,
which claim 42,000 lives. Although not an official DOT goal,
Administrator Brubaker is a proponent of a "bold, hairy, audacious goal"
to reduce crashes by 90 percent by the year 2030 as a way to spur
innovation and creative thinking. Meeting this goal can potentially save
34,000 lives, but it can also reduce the economic impact of crashes and
the recurring congestion that causes them. It is estimated that more
than \$200 billion in medical bills, loss of productivity, etc., can be
attributed to those crashes.

The safety and system performance applications of advanced wireless
communication technology are an essential piece of the Department's path
towards 21^st^ Century transportation solutions. While there may be
useful "convenience applications" of advanced wireless technologies, the
safety applications are of paramount importance to the DOT.

In order to meet these goals and objectives, and to successfully
leverage emerging technologies in the transportation sector, it is
crucial that transportation decision-makers be open to innovation and
investigation of these new technologies. Transportation leaders must
take an in-depth look at the technology requirements of the Vehicle
Infrastructure Integration (VII) system to determine which technological
developments can be utilized to more efficiently achieve the program's
stated objectives.

While Dedicated Short Range Communications (DSRC) radio technology has
been the preferred communications solution for VII, it is important to
look beyond DSRC to consider, for example, how to enable mobile ad-hoc
networks to achieve safety and mobility goals. For instance, it is now
possible to layer crash data in GIS maps to provide information to
drivers to warn them about crash-related congestion. New systems could
supply drivers with audible warnings via in-car devices to alert them to
treacherous bends in roadways. These are but a few of the potential
safety applications that leverage advanced wireless communication
technologies.

Finally, Brubaker shared information about exploratory and demonstration
projects in the U.S., noting that Michigan DOT's Director Kirk Steudle
oversaw the successful development of a wireless mesh network for
transportation use. It was suggested that transportation leaders raise
their level of thinking to leverage mobile ad-hoc networks (to enable
tolling, road usage fees, etc.). Doing so can facilitate the creation of
self-healing transportation networks that transmit high value
information to drivers and system managers.

Administrator Brubaker's remarks were followed by a presentation on
current technology trends and perspectives.

# Wireless Communication Technology Trends

David Reed, Professor in the Media Lab and Communications Futures
Program at the Massachusetts Institute of Technology (MIT), presented an
overview of trends in the wireless communications arena, and
perspectives from the academic and private sectors. Reed's comments were
organized around two primary topics:

-   Open systems versus closed systems

-   Technology architecture and the business ecosystem

    1.  []{#_Ref212599516 .anchor}**Open Systems vs. Closed Systems**

Reed opened with an anecdote about the business aspects of technology
development. Reed recently talked with leaders at Texas Instruments
(TI), one of the industry's foremost suppliers of CPUs for cellular
phones. The primary business problem cited was the cycle between concept
and delivery, which is approximately five years.

Due to the amount of time to get through requirements development,
product development, marketing, and other required business activities,
it becomes difficult to predict the needs of customers five years hence.
TI is intrigued by open platforms because it has been proven with
empirical evidence that "when you create an open platform with the
intent of creating an industrial sort of ecology around it, all of a
sudden, the business development cycle typically shifts from about five
years down to about three months."

**Thus, an open platform allows for more rapid innovation and deployment
of those innovations as consumer and business needs evolve.** The common
theme is to build an application on a platform or host that can be
reused and invested in by other vendors, and to create incentives for
this model.

Reed noted that cellular telephones have the highest rate of adoption of
any digital device over a period of three years. Other devices continue
to ride on the coattails of cellular phones (like tablet computers and
iPhones).

From a technology perspective, the devices are driven by the processing
power you can put in a chip -- for a cell phone, this could include a
mesh repeater that operates on low-power, can cover long distances, and
has a 2.4 GHz antenna on board. The chip implements Wi-Fi radio
functions and MAC layer functions, and features a fully reprogrammable
microprocessor. In addition, the antennae can be quite small and do not
have to be proportional to wavelength.

The One Laptop per Child initiative leveraged an open platform for its
product precisely in the interest of innovation. Similarly, Linux-based
cell phones work the same way: a developer can write code for any
device, download applications to the phone, and use its 802.11x network
connectivity.

2.  []{#_Ref212599558 .anchor}**Technology Architecture and the Business
    Ecosystem**

One of Reed's key themes was that advanced wireless communication
technologies are progressing extremely rapidly, and this has serious
implications for the business ecosystem: at the 2003 ISART[^1]
conference, only a small handful of participants knew about or were
using Wi-Fi or 802.11 networks. DSRC was the prominent technology, and
Wi-Fi was "under the radar." Today, Hewlett-Packard (HP) manufactures 48
million laptops per year, each with an 802.11 chip in the device. Reed
predicts that soon all cellular phones will have 802.11 chips, and
potentially even cameras. This cycle is driven by consumer technology
and cannot be replicated in other markets. There are four interesting
issues that contributed to these developments:

1.  **Wireless technologies had previously been limited by hardware
    legacy and regulation.** In the past, a new frequency band was
    needed to release a new technology (and it takes quite a long time
    to get a new band). Legacy devices were barriers as it was costly to
    replace physical hardware. This is no longer the case now, as today
    digital systems are used to modulate waveforms. Users do not have to
    replace hardware, but simply download software. Industry and
    Government leaders realized that old analog technologies are very
    inefficient (these use a loud signal to broadcast far away). This
    results in computing capability that allows systems to be updated
    and adapted to one another.

2.  **Digital modulation improved efficiencies.** In the past, radio
    systems were blind to one another; new devices negotiate dynamically
    for the bandwidth -- these talk to and negotiate with one another,
    improving efficiencies in the process.

3.  **Dynamic protocols increase the speed with which devices can be
    added.** As the Internet emerged it invented protocol design to
    manage the higher level space in which negotiation between systems
    happens. In the past there were protocols (e.g., IBM's SNA) but
    these were static and unchanging and were improved by appending
    information to these protocols. This made the addition of new
    devices rather slow. New dynamic protocols increase the speed with
    which you can add devices within existing systems.

4.  **Virtual computing environments can now be constructed.** Virtual
    computing environments are not bound to original technology on which
    these were originally based. Users can run legacy applications on
    new hardware that virtually emulates the original environment.

While discussing the business ecosystem, Reed cited Iridium, the low
earth orbit satellite communications system that was designed to provide
voice communications in developing countries around the world. What went
wrong? Nothing, technically, since it delivered every feature and
function it was supposed to, except that it was designed as a 10-year
project. By the end of the 10-year development cycle, the market had
evolved beyond the capabilities of Iridium's fixed design.

1.  []{#_Ref212599579 .anchor}**A New Technology Development Ecosystem**

Reed's assessment was that the "game needs to be changed." Key
characteristics of the new technology business game are:

-   **A platform that evolves** and co-evolves with standards at a rate
    appropriate for the market. This does not mean that, for example,
    the standard wave form of a chip set is eliminated, but that
    standards evolve along with requirements.

-   **An industry structure that cooperates**. As long as there is a
    market that is wide open, it will be able to do more things in less
    time, and it will be easier to be innovative. Ideally, the
    transportation marketplace includes this element of "coopetition"
    (cooperation plus competition) and expectations for growth
    throughout the industry.

-   **Interoperability is essential** for an industrial ecosystem that
    involves specialist companies to implement systems.

-   **Protocol-based negotiations** of what activities are allowed and
    possible. The negotiations style can change over time as protocols
    evolve, but the essential philosophy must be present.

The core trend is towards platforms that are open enough to be capable
of evolving based on protocols. **Such an environment can drive
investment in innovation that leads to progress.**

Reed's assessment for the transportation sector is that add-on
electronics will be key for automobiles. In-car communication for
entertainment already exists, but devices that allow for communications
between cars can spark innovation in safety and other applications.

***Following Prof. Reed's presentation, the floor was opened for
questions and discussion. Note that the dialogue is organized by topic
areas, not by speakers' names or chronological order of questions.
Discussants' affiliations are noted in parentheses.***

Participants discussed the role of open source mesh wireless networks.
Sascha Meinrath (New America Foundation's Wireless Futures Program)
noted that many of the issues raised during the early part of the
roundtable are the same ones raised before 2000. He made four key points
about trends in advanced wireless communication technologies:

-   There have been advancements in the use of multiple frequencies in
    software defined-radios. Common nomenclature and agile transceivers
    are also on the horizon. Such 802.11 devices can operate on multiple
    different frequencies, pointing to open platforms and devices.

-   Some wireless industry players have challenged the FCC to drive
    innovation back to the network, and remove it from "the central
    authorities" (i.e., allowing cell phones to be network-independent).

-   Smart antennae are being developed, but they are not yet fully
    implemented or utilized.

-   Policy reform is critical for R&D efforts. For example, white space
    devices are making more efficient use of spectrums. These devices
    are critical to advances, but policy reforms can encourage
    implementation and further innovation.

Meinrath asserted that there will never be a full-scale roll-out of
advanced wireless technologies unless there is substantial investment in
innovative projects, not continued investment in "the usual suspects."
DOT should take advantage of new opportunities to work with private
sector players who are driving these innovations.

Rich Howard (Rutgers University and PnP Networks) is a former Vice
President for Wireless technology at Bell Labs. Howard agreed that
roll-out remains an important issue. A large Wi-Fi network may include
400 nodes (just a few blocks in Manhattan); any tests deployed on a
small trial scale would be irrelevant. Rather, huge scale tests are
required. Many participants agreed with this sentiment. Later in the
discussion, Tim Krout (CENGEN) noted that a mesh of 5,000 nodes would be
an adequate test size to prove functionality of a given mesh platform
that would successfully accommodate massive scaling.

Additional issues related to testing and roll-out were raised by
Ferdinand Milanes (CALTRANS). He noted that interoperability in today's
systems remains a significant challenge. Public safety users are on
low-band and high-band systems, with the result that frequently first
responders cannot talk to one another directly. Gateways and other
expensive workarounds may not be feasible. Milanes noted that there are
not a lot of options for public safety radio platforms, but asked the
group to consider if wireless mesh networks could support not only data
but voice communications.

1.  []{#_Ref212599607 .anchor}**Applications for the Transportation
    Sector**

Christopher Wilson (Tele Atlas) noted that all participants agree on the
goal of interoperable radio, but the real question is how to get into
the automotive environment. What is the one application that will drive
people to use an application or in-car device? What is the "killer
app"[^2] that drives this technology into the vehicle?

There was agreement from Douglas Sicker (University of Colorado-Boulder)
who asked participants how the vehicular market differs from existing
markets. He noted that it will be important to identify new risks,
especially in terms of licensing and patenting.

Tim Krout, a former DoD engineer, offered a response and some
suggestions for transportation applications. From Krout's perspective,
there are three primary applications for advanced wireless communication
in the transportation sector:

-   Dissemination of **safety** information;

-   Use of traveler information for **convenience** of system use; and

-   Improvement of **situational awareness** (e.g., monitoring of bridge
    conditions, in-vehicle fuel consumption, congestion pricing
    opportunities)

Krout noted that a wireless communications system cannot be "all things
to all people." Krout suggested that DOT approach the problem
differently and identify the problem transportation network is trying to
solve. Is it necessary to have one radio that serves all functions or
solves all problems? The fundamental policy centers on whether or not an
"80 percent solution" is appropriate.

# Mobile Ad-Hoc Networks (MANETs)

## Overview of Trends

MIT's David Reed presented an overview of trends in the area mobile
ad-hoc networks (MANETs) and their potential to provide alternatives to
existing approaches. Mobile ad-hoc networks have emerged in response to
mobility and networking challenges faced by traditional networks,
including the "command and control" architecture model found in many
Department of Defense systems.

Reed's expertise is in an area that might be referred to as "slightly
mobile ad-hoc social networks." Due to the inexpensive nature of radio
technology and the extensive adoption of wireless devices by general
users, it is reasonable to project that there will be a great deal of
radio communication in the human centered network. The "out of the box"
view of vehicular networks assumes the perspective that users will be
carrying in-car radios. Thus, the "killer app" may not be about cars,
but about the cars talking to the users; however, can the car talk to
the user intelligently?

An important observation about the history of MANETs is that radios can
send signals multiple hops further than they can point-to-point. There
are advantages to eliminating points of failure and inefficiencies in
order to achieve more capacity. If a system is deployed with a lot of
short distance links, you get more capacity in the system. Currently,
with cell towers there is only so much coverage available, such that
cell networks are using handset-to-handset signaling to maximize
available cell tower capacity. According to Reed, in terms of the
transportation sector, when we talk about MANETs (based on radios that
adapt and cooperate) we can provide a map of the environment around us.
Industry leaders and researchers are already starting to build
integrated systems in the indoor communications space; this can also
happen in the vehicular space.

## Role of Standards

Systems with a reasonable amount of standards can take advantage of the
increased capability afforded by MANETs. In places like Intel labs and
Motorola labs, there is a lot of work being done to make systems that
basically exploit all of the radios in the space, and also use other
systems, whether they are broadband, Wi-Fi, or traditional resources. A
system that has a reasonable amount of intelligence can actually take
advantage of these resources. What makes this work are radios that can
understand each other.

The minimum capability of either standardizing on analog wave form or
standardizing some form of capability that can be adapted to each other
is what is called software-defined radio. The advantage of
software-defined radio is, in fact, all of these modern radios are being
pulled that way, whether they expose it or not. Although they may be
defined in terms of analog wave form, they are generating waveforms
digitally. So, you can take advantage of those, for example, to adapt to
rapidly changing populations. For programmers this means that the
digital realm gets programmable access to the (analog) radio spectrum.
In that sense a wealth of new applications can evolve around the
principle of software-defined radios.

The crucial element of packet-systems is that the links can be
short-distance. This is extremely different from the traditional radio
problem of establishing channels. Much of the work on fixed wireless
mesh networks and new adaptable systems shows that they can work well
for many kinds of short distance applications. For many of those
applications, "you'd have to stand on your head to use traditional radio
systems." The result is that the safety element can be extremely dynamic
with short packets.

The field is starting to see users deploy add-on devices in cars that
use Wi-Fi (i.e., Dash Express GPS[^3], although they are not very useful
because they only function with a connection. An issue with Dash and
other Wi-Fi devices (which are like memory chips with Wi-Fi antennae) is
that they are missing critical standards. Reed's assessment is that it
is worth considering options beyond command-and-control networks, but
for vehicle applications, it is important to understand channels and
standards necessary for safety-specific applications.

An important note about packet systems is that the need for a consistent
channel is very short. A microsecond or two has been read into packet
systems to make them work; this actually establishes a channel condition
that stays stable for a reasonable period of time. This is very easy and
quite normal for a Wi-Fi radio that is flying past another Wi-Fi radio.
If the right processor is available, there is enough time to exchange a
fairly large amount of data with multiple packets going through it.

Packet-based radio systems that dynamically build connections on a type
of opportunistic connectivity can be built today. This is one reason
Reed is concerned about the confusion with the term "mesh." There has
been a lot of work on fixed wireless, but vehicular communication "hop
by hop" can actually work quite well for many kinds of naturally
"ad-hoc" applications for short distances (such as measuring traffic,
interacting with a parking meter, etc.).

## Advanced Wireless Applications for the Transportation Sector

Reed's overview provided a foundation for three important speakers to
discuss advances in and uses of mesh networks and MANETs. The
discussants (Robin Chase, L. Aaron Kaplan, and Tim Krout) provided new
perspectives and details on different aspects of advanced wireless
technologies and potential transportation applications. The discussion
summary has been organized around several broad topic areas and includes
an overview of presentations and question-and-answer sessions.

## The Business Case for Open Platforms and Open Networks

Robin Chase (Meadow Networks and ZipCar founder) offered her perspective
on strategies for leveraging wireless communications technologies for
transportation safety financing, congestion mitigation, and innovative
commercial applications. Chase noted that in terms of the transportation
sector, applications will be adopted in a piecemeal fashion in specific
geographies across the country and rely on after-market devices.

Furthermore, she believes there is an opportunity to change the outcome
of DOT transportation investments by ensuring that technical investments
use open platforms that can then be multi-purposed and accessible to
others to build upon. Open platforms also support innovation: new ideas
can be tried, tested, and improved upon at lower cost and with lower
stakes (because no entity would have to build the entire set of
applications or the entire infrastructure on their own). In a rapidly
changing technology environment, Chase believes the desired DOT outcomes
can be financed and achieved at a lower cost and at a faster pace of
both innovation and adoption if open platforms and open networks are
used.

In a positive trend, there are large scale wireless network experiments
underway in Minnesota, Ft. Lauderdale, and other metropolitan areas,
with the expectation that billions of dollars will be spent on these
projects over the next several decades. The vast majority of the larger
markets have deployed (or are considering deploying) closed proprietary
solutions on closed networks. The result will be expensive single
purpose devices and networks that have little likelihood of connectivity
with others being built around the country, and enormous amounts of
embedded excess capacity in the devices and infrastructure. These types
of closed systems will not make use of the latest technologies because
of the lengthy time cycle between development and deployment to the
market. Additionally, one can anticipate no innovation on such systems.
The system provider has little incentive to innovate or improve systems
since they have built to initial specifications; and other companies
cannot get into these systems in order to improve or update their
capabilities.

**The transportation sector now has an opportunity to change the outcome
by making multi-purpose investments and leveraging open platforms to
spark innovation.** This strategy can result in rapidly improved
environments and identification of the "killer app" (according to Chase,
this is congestion and road pricing). Strategies for leveraging advanced
wireless communication systems must include discussion of privacy
issues, an issue at the forefront of the conversation about platforms,
software, and hardware.

Chase identified several historical and current barriers to enabling
advanced wireless communication for transportation safety, financing,
and congestion applications:

-   *Centralized, top-down, massive scale projects* -- London's
    congestion pricing initiative used existing technologies, drew a
    cordon around the central business district (CBD), and used cameras
    to capture license plates. While there was a 90 percent positive
    license capture rate, there was a 10 percent error rate, which had a
    huge negative impact on the cost-effectiveness of the system. The
    city had spent approximately £400 million on the original system,
    but would now like to expand the cordon around the city (at a cost
    of several hundred million more pounds). Had London used a
    vehicle-based open mesh platform, their initial investment would
    have more cost-effective transactions (no camera system generating
    high error rates), accommodated the expanded cordon with little
    incremental cost, and would have provided the foundation for a
    "wireless London" built on the back of the congestion pricing
    infrastructure. Instead, because an open platform did not exist,
    London chose traditional closed proprietary systems for its first
    congestion pricing build, and opted to maintain the status quo in
    its expansion plans.

-   *A hardware environment that prevented improvements* -- New York
    City modeled its congestion pricing initiative after London's. As
    New York City considered congestion pricing, it became clear that it
    would also be politically easier to leverage the installed base of
    EZ pass transponders (a closed proprietary system). This promise
    immediately eliminated opportunities for innovative solutions that
    are newly possible since EZ pass was first created more than a
    decade ago. It also alienated the 25 percent of New Yorkers who have
    not adopted EZ pass because of privacy concerns (EZ freely gives
    location information of specific cars to those who ask) and the
    system's requirement for cameras.

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-   *Political barriers and jurisdictional issue*s. Chase used New York
    City's recent nine-month long political discussion as an example.
    While there are many reasons for the city's inability to ultimately
    gain support for congestion pricing, the rigid technology
    constraints, posed by the closed proprietary systems proposed, were
    major contributors: a system that required flat fixed rates along a
    cordon surrounding downtown Manhattan alienated the other boroughs
    and made the system appear unfair. The camera technology was much
    contested by those seeking to protect the geographic privacy of
    drivers circulating in the city. Adoption of an open mesh-based
    platform in the car would have also reduced jurisdictional friction
    raised by installation of fixed hardware throughout the city; it was
    also considered operationally risky since such a platform had not
    yet been built and used at the scale required for Manhattan. This is
    the opportunity that can be corrected and addressed by the DOT.

Chase also noted that open platforms can be "a magnet of opportunity for
the business realm." For example, if New York City established a mobile
communications system, not only could it enable safety applications, but
also other types of convenience or commercial transactions.

British Telecom offers a good example of this type of openness when it
told broadband buyers that if business users opened their broadband
access points to other BT users within reach of their access points,
they too could be able to roam and use the wireless networks of other BT
business users. This offering improves BT's network efficiencies (see
[www.BTFON.com](http://www.BTFON.com/)). Ultimately, the planned
expectation is that users will be switching networks to use the most
cost-effective network for a given activity. Doing this requires an open
system.

Closed platforms typically associated with huge fixed/mobile systems
(e.g. bus rapid transit (BRT) in Los Angeles, HOT lanes in Florida,
etc.) cannot test new ideas or be platforms for innovation. An open
standard platform is needed for trials that can scale with less risk,
and an open platform with flexible open architecture allows the private
sector to enter into the space. (Another example of a missed opportunity
for a large-scale open platform trial is in New Jersey. Rather than
attempt to use an open platform, New Jersey Transit (NJT) is opting,
conservatively, to explore possibilities based on "tried and true"
devices and networks, which limit NJT's opportunities for future
innovation and interconnectivity.)

Chase closed by reviewing the handout she provided to the group,
pointing out the benefits in terms of costs and time to implementation
that could be gained by pursuing standards-based, open access points and
ad-hoc networks that leverage both existing and new devices and
infrastructure.

## Technical Options and Considerations

Both L. Aaron Kaplan (Funk-Feuer Initiative,
[www.olsr.org](http://www.olsr.org/)) and Tim Krout (CenGen) offered
their viewpoints on technical considerations for enabling advanced
wireless communication in the transportation network. Kaplan, whose
connection to this field started when he retrofitted a laptop for Wi-Fi
in Vienna, now oversees a mesh network that uses the Optimized Link
State Routing Protocol[^4] (OLSR) consisting of more than 400 nodes
(still a relatively small network compared to the other existing mesh
networks in Europe).

Larger networks exist in Athens (2,000 nodes, fully meshed), around
Barcelona (\~5500 nodes, Wi-Fi but non-meshed), and in the Czech
Republic, which has a wireless network covering the whole country
([www.czfree.cz](http://www.czfree.cz/) -- Czech language site). Kaplan
asserted that it is a myth that Wi-Fi networks need to be small in size.
There are density issues, but the Czech Republic experience shows that
it is possible to have a national network. However, Kaplan noted that
complete mesh networks will be available only "in the distant future" as
large mesh segments may be a more promising approach. In Vienna, the
network Kaplan created is a Wi-Fi mesh network, based on inexpensive
off-the-shelf 802.11x Wi-Fi equipment, reprogrammed with open source
code (openwrt) and feeding off of one single fiber uplink. The uplink
provides bandwidth for approximately 400 nodes. The average operational
expenditure (OPEX) costs for this network are a few hundred Euros/month
(\~1-2 Euro per user per month). The bandwidth in the Vienna mesh
network goes up to 30 mbit/sec netto. Uplink is 100 Mbit/sec netto.

Kaplan clarified that he also directs the current research and
development of the open source OLSR.org project.[^5] Current trends in
OLSR research include integrating GPS into routing decisions (relative
speed of vehicles will be used to adapt the rate of routing packets),
reducing the number of packets in the air in order to conserve
bandwidth, and reducing the complexity of fast and dynamic route
changes.

The OLSR.org Project has recently demonstrated that the routing daemon
scales well in an 800 node mesh network on an embedded web camera with
only 20 MHz CPU power (roughly equivalent to an Intel 286 processor from
1982). Scalability of OLSR to thousands of nodes is currently a reality.

Kaplan later noted that in Europe many of the community networks use
standard Wi-Fi equipment and the available 2.4 GHz frequencies. One
major obstacle of current Wi-Fi technology is the scarcity of the
spectrum. Based on his own experience building real world Wi-Fi mesh
networks, Kaplan believes that self-interference of nodes and
interference with neighboring nodes is the main stumbling block for
successful deployment of any kind of Wi-Fi network (meshed or
non-meshed). More and better spectrum will be needed.

Overall, Kaplan agreed with Ramming's assessment of the state of the
current technology. Network coding, better layer 1 support, MIMO, more
spectrum and advances in routing metrics and algorithms all combined
show that very large mobile mesh networks can now be feasible.

Tim Krout (CenGen) offered an overview of the Department of Defense
(DoD) innovations, including a MANET based in Iraq that includes
approximately 100,000 nodes. CenGen's vision is to serve the tactical
high mobile user with the "pointiest end of the spear," including
"killer apps" to improve situational awareness and provide vehicle-based
video feeds.

There are several radios available in the DoD environment, including:

-   JTRS -- Joint Tactical Radio System

-   WINT project -- War Fighter Information Network-Tactical

-   EPLAR -- Enhanced Position Location and Reporting in-vehicle radios

-   HNS -- High Beam Networking System

-   SRWF -- Soldier Radio Wave Form (uses and open platform)

-   Blue Force Tracker

DoD and specifically Defense Advanced Research Projects Agency (DARPA)
have "pushed the envelope" in terms of next-generation radio
communications technologies. Advances in EPLAR will make it easier to
configure and program, will be dynamic and meant to be operated and
maintained by the average soldier. Within the next two to three years,
Krout expects to see small JTRS radios available for use in robotic
vehicles, while CenGen is currently developing an open source version of
a JTRS radio.

At the same time, HNS technology is an in-vehicle system delivering
50mbps per sec and has been deployed in "a few hundred vehicles." The
primary research developer for the network is Cisco Systems, which
suggests that there is a larger commercial market available outside of
DoD.

Blue Force Tracker, which uses an l-band, is a satellite communications
based device that leverages the same technology as Iridium phones. There
are currently thousands of vehicles being tracked with the device. Prior
to the Iraq effort, EPLAR was the preferred system, however,
approximately six weeks into the Iraq war production of Blue Force
Trackers was increased in order to outfit more vehicles. While not used
predominantly in Iraq, the device uses a commercial-off-the-shelf (COTS)
cellular card with a Wi-Fi chip. There is no transparency to the user
regarding which network is functioning (cellular or Wi-Fi). DoD has been
encouraging MANETs in order to expand connections to vehicles. Krout
noted the importance of understanding network coding, which is a new way
of passing information between nodes.

J. Christopher Ramming (Consultant) presented a detailed look at some of
the technological considerations related to mesh networks and advanced
wireless communication technology. Ramming recently finished a term of
service at DARPA, which is attempting to make mesh networks a reality.
His work asked key questions such as "is the technology ready," "what
are obstacles, risks, etc."?

DARPA is part of DoD and has a razor sharp focus to take results and
accelerate them into practice; DARPA solves point problems, but it does
not build huge networks.

*"Did DoD finish the job of building the Internet?"*

According to Ramming, "not really" -- there is still a lot of work to do
and support for mobility is currently missing. There is an exciting
opportunity to create the mobile Internet and to use it for driving
applications. In the transportation sector, there are problems to solve
that force us to take the next step.

Ramming then described several known technical challenges and the
evolution of the technology:

Mesh networks and cellular systems are quite similar, but meshes do not
rely on fixed infrastructure. The intended benefits are identical: both
try to achieve ubiquitous computing ("anytime, anywhere" solutions).
This goal forces a shift to a wireless medium.

Importantly, the wireless medium is challenging and very different from
traditional wired infrastructure. First, "the network abstraction may
not be a perfect fit for the wireless systems that are in development."
Nodes and links do not adequately represent interacting electromagnetic
fields. Second, Ramming cited Tim Krout's observation that MANETs
routinely experience more than 10 percent packet loss. And third,
Ramming suggested that participants recall that in designing IP
technologies, latency or efficiencies are not a high priority -- a
single wire will provide 12,800 GHz of bandwidth relative to at most 3
GHz of useable mobile spectrum. The wireless medium forces a look at
efficiencies in design stage, and this is difficult to handle from a
systems architecture perspective.

The Internet is one line of development that allows interconnectivity;
its common packet format has been transformational and has sparked a
great deal of innovation. However, it is important to remember that the
Internet has not fully addressed mobility. Ramming suggested a look at
how the cellular industry has gone beyond interconnectivity to support
mobility. DoD MANETs are another line of development in support of
mobility. "Killer apps" include hard real-time control, but this is
challenging in terms of data security and data assurance.

In terms of moving forward, Ramming asserted that DOT can select its own
timeline, but it will face challenges similar to DoD. Some challenges
may be "postponable." He suggested developing an evolutionary approach
based on prioritizing "a taxonomy of applications that can include many
dimensions: vehicle-to-vehicle, comfort and convenience, hard safety
versus soft safety, scheduled versus event-driven versus on-demand,
location aware versus location independent, unicast and multicast,
elastic traffic streaming, public sector applications versus private
sector applications, latency sensitive versus latency insensitive, and
single hop versus multi-hop versus completely arbitrary, point-to-point,
and point-to-any-point."

[Support for Mobility]{.underline} -- Ramming discussed several ways in
which the original Internet design did not include support for mobility.
The seven-layer OSI model[^6] differs from the four-layer Internet model
in important ways, and in particular the four-layer model does not
include rich support for wireless mobility. For example, there is no
formal session layer that allows for temporary suspension of a session
if there is some kind of mobility event. In addition, many protocols
including Transmission Control Protocol (TCP) were designed for a regime
with low packet error and latency (had wireless mobility been an earlier
requirement for the Internet design certain important protocols might
have evolved differently). And finally, Internet Protocol (IP) addresses
represent both locations and identity, with the impact that topological
mobility is challenging to implement.

However, mobility is increasingly understood and the Internet
Engineering Task Force (IETF) is now exploring solutions to these
challenges. Example solution elements include Mobile IP for global
mobility via a home agent concept, which is similar to approaches used
in cellular networks but that can involve high handoff latency (up to
two seconds have been reported). To address fast handoff, various
approaches to local mobility are being explored, including as
Hierarchical Mobile IPv6 (HMIPv6), Fast-Handovers for Mobile IPv6
(FMIPv6), and work in the IETF Network-based Localized Mobility
Management working group (NETLMPP) to minimize latency and packet loss
in local handoff.

With respect to routing, traditional single-path wide-area Internet
routing protocols are not very appropriate for wireless MANET. However,
there has now been a huge amount of work on MANET routing protocols.
Ramming pointed out that there is a good deal of mesh networking using
OLSR that is appropriate for fairly static regimes. Efforts like Ad hoc
On-Demand Distance Vector (AODV) routing assume much higher rates of
mobility; at the extreme mobility time scales where the solution is not
routing, intelligent flooding becomes the key enabler of mesh networks.

Finally, NACK-oriented reliable multicast (NORM), backpressure-based
transport algorithms, Disruption Tolerant Networking, and the
recommendations for TCP tuning in RFC3481 are all a step toward
transport protocols that are wireless-friendly. With respect to wireless
mobility, Ramming's recommendation is that DOT chooses a set of initial
protocols and put an architectural "stake in the ground." While this may
be controversial, it seems important for progress in this area to have a
specific "straw man" architecture for community consideration. Ramming
believes that "no other Federal agency appears to have the specific
challenge or the responsibility that DOT has."

L. Aaron Kaplan (Funk-Feuer Initiative) noted in a later clarification
that link state algorithms were integrated into the Vienna OLSR network.
Additional practical experimentation will integrate GPS-based devices so
that intelligent flooding based on relative speeds of vehicles can
occur. In a later clarification, Kaplan also explained that there are
two aspects of the term \"mobility\": (1) mobility for small mobile
devices such as cell phones or PDAs. These require AODV since AODV saves
battery life, however, AODV does not permanently send packets, and, (2)
mobility in terms of vehicular networks where fast handovers are a
strict requirement. In these settings, AODV is not suitable since it
needs to (reactively) determine the complete route before sending the
first packet. Subsequent requests will also be quick, but if the
topology changes rapidly (as in car meshes), it starts a new cycle of
asking for the best route.

Kaplan believes that this is why CenGen is using OLSR for vehicular
networks rather than AODV: they are more mobile (in the second meaning).
For saving battery life, AODV is the optimal solution. And thus it is
the algorithm of choice for some scenarios, like the \$100 laptop that
tries to save power. Additional information can be found at
[folk.uio.no/kenneho/studies/essay/.]{.underline}

Sascha Meinrath pointed out that link state work was undertaken 2001 and
2002, and that DoD is now rediscovering these routing protocols that are
"half a decade old." He noted that by 2004 or 2005, developers working
with OLSR+Fisheye (Fisheye is HSLS ported into Linux) began to merge it
with the best of AODV and HSLS. This presents a classic example of where
open source is far ahead of real world implementation.

Babak Daneshrad (University of California -- Los Angeles) noted that it
is important to remember layer 1-- the physical layer, which is
"subservient to everything else above it." In terms of Bluetooth, Wi-Fi,
and cellular, the physical layer is different in each scenario for a
reason because usage scenarios are different.

Daneshrad noted that participants need to address these issues of
different types of usage scenarios (from in-car video to the passing of
tiny messages back and forth between vehicles and infrastructure). For
example, if a system operated on 2.4 GHz band, interference mitigation
could happen at the physical layer but also at higher communications
layers. He asked, "Can we look at interference mitigation and layer 1?"
If Wi-Fi is ubiquitous, how does the field deal with delivering very
sensitive and critical information in an "interference-rich
environment?"

Daneshrad asked participants to think about notion of "elastic links" --
stretching out a link until the network catches up and then performs the
crossover. For example, a link can be stretched from 100 megabits per
second in a room, to 100 kilobits per second on long distance links
stretching several kilometers.

Richard Howard (Rutgers University) echoed Daneshrad's comments and
noted that users can move from texting on typewriter to YouTube because
there was so much additional capacity available on the network. However,
with radio (GSM), users cannot move from data or audio to video without
using the entire spectrum from one channel. Howard considers this more
than an "engineering problem" and a fundamental issue.

Ramming believes that mobility as a whole is an "addressable problem"
with the technology available today, though difficult choices will have
to be made. However, he offered that the "fully connected mobile ad-hoc
network" is a myth and that wireless-friendly reliable transport
protocols (for example Disruption Tolerant Networking) will need to
replace or augment TCP in certain future mobile environments and
applications.

[Transport Protocols for Sparse and Dense MANET Deployments]{.underline}
-- Ramming went on to discuss two important regimes:

1.  Sparse and partial MANET deployments (early stages)

2.  Dense deployments (later evolutionary stages)

Ramming noted that in the early days of deployment and currently, there
is always downtime in DoD's MANETs. Even on I-80 in LA *\[sic\]* at
night, the potential for disconnection in a fully equipped vehicular
network could be as much as 35 percent. Disruption-tolerant networking
can be an enabler of applications in these sparse regimes. Disruption
tolerance allows a shift away from the idea that there needs to be a
link from the source to the destination at all times in order to make
communications work. Systems do not merely copy-and-forward at
intermediate nodes; rather, the model is copy-carry-store-forward. This
approach can vastly improve situational awareness application discussed
earlier and is even used in developing countries to enable
communications. DOT could consider using similar protocols for certain
delay-insensitive applications.

The dense regime is also important to consider and is equally
interesting. In an extremely heavily loaded network, it is important to
look at network coding (the primitives for networking: first there were
circuits in a telephone network, then packets in the Internet; network
coding is the next step operating on bits and information). The network
coding concept is not link oriented but broadcast oriented and allows
information to be transmitted even with unreliable connections. This is
a form of intelligent flooding that may allow for improved reliability
in the future for certain safety applications but should be viewed as a
"bleeding edge."

[Information Security]{.underline} -- An additional issue is information
assurance and security. Wireless networks are changing the cyber-defense
paradigm because there is no perimeter to defend. This transforms the
problem of defense from perimeter to insider threat. DARPA has several
programs underway to address this, but the problem is challenging. The
key approach may be to focus on the security solutions that are
available now, rather than attempting to address every possible threat.
For example, protocol leashes, watchdogs, and reputation systems allow
parts of the network to police each other and identify harmful behavior.
These solutions force all parts of the network to "stay within the
rules." Some ideas for dealing with network integrity and cyberattack
are not completely ready to deploy, but this may be tolerable in the
short run because some of the "soft safety" applications that are being
considered by DOT may not require extreme assurances.

Krout (CenGen) agreed, noting that security issues are not only present
in vehicular networking, but that the problem is being addressed in the
commercial world. The available techniques approach the solution by
making problems visible and transparent, such as policing cars. Once
harmful actions are visible, the problem can be reduced.

Ramming offered that authentication, authorization, and accountability
are other issues to consider. There have been advances in ideas like
proof-carrying authorization, physical layer authentication and
fingerprinting that allow system administrators to determine if
information is coming from the node that is broadcasting (making it much
more difficult to spoof an automobile or some other center of
information). However, there is no complete solution, and many
vulnerabilities lie with human error and misconfiguration. System
administrators must take some risks, and complete security may not be
achievable.

Michail Bletsas (One Laptop per Child) framed security issues in terms
of encryption and privacy, not information integrity. He cited the
effectiveness of end-to-end approaches, and noted that users do not rely
on the layer 2 encryption for credit card transactions; rather users
rely on Secure Sockets Layer (SSL)---the end-to-end encryption approach.

He continued with a word about MANETs: if they are married to network
coding at the application level, one "killer app" is social situational
awareness. This allows users to make intelligent decisions about
traffic, but does not require the user to know his or her own position,
only those of others around them. He posited that there is no efficient
way to use cellular technology to propagate that information down the
network, so MANETs have advantages. He suggested that participants
refrain from attempting to use MANETs to replace solutions that already
exist and work well. MANETs can extend or augment what is available.

[Scalability]{.underline} -- Ramming noted that the field has only have
seen small deployments of MANETs, and that there is a pernicious
assumption that MANETs will be used like a telephone network (where
users can call anywhere, anytime and use all of the multiple hops). This
results in dismal scaling results in research papers. On the other hand,
many of the DOT applications only need to have communications within a
few hops. So long as DOT does not try to create a MANET-based
general-purpose cellular network, there is hope that current scaling
laws will not be problematic.

[Latency and Other Recent Developments]{.underline} -- Ramming noted
that DARPA's Tactical Targeting Network Technology (TTNT) tries to
achieve 2 millisecond packet transfer at 100 nautical miles (very low
latency). He further noted that MIMO and directional networking may also
provide benefits for DOT applications, and that emerging hop-by-hop
protocols may resolve problematic interactions between MAC scheduling
and congestion management techniques in protocols like TCP.

Ramming underscored the need for standardized protocols for mobility
applications and consideration of dynamic network coding (like DTN) to
improve robustness in the short term.

***Following the technical presentations, the floor was opened for
questions and discussion. Note that the dialogue is organized by topic
areas, not by speakers' names or chronological order of questions.
Discussants' affiliations are noted in parentheses.***

Kevin Lu (Telecordia) observed that his company realized it would have
been too costly to install optical fiber in every house, and shifted the
focus to cable and DSL modems. Lu noted that The Telecommunications
Industry Association is ready to work with DOT to develop standards for
vehicular telematics. Some examples of relevant technologies and
industry players include OnStar, ATX, Connexis, CrossCountry, and
Qualcomm. Lu suggested that there may be opportunities to team up with
automakers for commercial applications, such as the way Ford partnered
with OnStar (the deployment took 10 years, but there were 4.5 million
calls from active subscribers last year alone.

Robin Chase noted that given the long time to turn over the fleet in
America (25 years), innovation will necessarily be in after-market
devices being installed in the existing 240 million vehicles already on
the road.

In terms of ITS solutions available today, Francois Simon (ARINC) asked,
"Is MANET safe for safety messages?" and how can the number of nodes
required be minimized? These questions remained unresolved (see Section
4.2). Simon posited that perhaps layers can be identified and separated
to use different systems, so that you separate the DSRC layer from the
MAC layer and put everything above DSRC on a MANET. The concept is that
applications are placed in separate "buckets" that can leverage
different types of systems.

Cisco Systems' Howard Lock agreed and suggested that DOT should be
looking for scalable physical systems and radios that can be isolated
from the upper architecture. He further suggested separating the routing
layer from the stack, and isolating the service layer.

Lock then pointed out that security remains a key concern, and that open
systems like MANETs are potentially vulnerable to malicious code and
mischievous behavior. As an anecdote, he noted that he would not want to
rely on a mesh network to transmit safety information or personal
critical data.

## Business Models 

Krout discussed various business models and opportunity areas for
leveraging advanced wireless communication technologies:

-   *Hard and soft safety applications* -- What makes the transportation
    applications unique in terms of vehicular applications is the small
    amount of time relevant to situations, for example, only 50
    milliseconds between a few vehicles can avoid a crash.

-   *Singe radio systems* -- These may be viable where the "80 percent
    solution" is acceptable.

-   *Wi-Fi approach for safety applications* -- Safety applications in a
    few thousand vehicles could be deployed fairly quickly using a Wi-Fi
    based approach using two, three, or four-hop communications. A MANET
    could be technologically feasible in an application that requires
    quick reaction and low latency, but it is probably not workable for
    safety applications.

***There were several comments from participants related to business
models and the business ecosystem.***

While discussing the services approach to vehicle-based technologies,
Dennis Govoni (Sun Microsystems) offered

that the automobile is not an open system, and that it\
will be challenging (if not impossible) for open source communications
to get into the automobile market. Govoni suggested leveraging private
sector resources to help solve technology problems. He noted that the
Internet can serve as a model for solving problems for two key reasons:
first, the Internet has a very simple protocol (packet protocol), and
second, the Internet "doesn't remember anything" -- it is a fluid
system, and it does not matter if the network is Wi-Fi, copper wire,
fiber, etc. Thus, vehicles must have an open interface to map to this.

Govoni pointed out that recently purchased vehicles include a
"maintenance minder" that connects to a network. "Automakers are already
thinking about solutions, and a potential next step for \[the group\] is
to select several good use cases and see what infrastructure is really
required as a platform for selected applications."

Howard Lock also pointed out that as DOT moves towards demonstration and
deployment, small scale test are not relevant for large scale roll-out.
His suggestions for moving forward include:

-   Broaden the conversation to include other industries (such as
    hospitality, building trades);

-   Involve other Federal departments who can participate through
    governance or funding; and

-   Pursue innovation through a business model; do not approach the
    issue as a technology problem.

Lock also suggested an interesting approach to use: "the consumer
carries their devices and the auto builder simply produces a platform
\[the user\] plugs into." This leverages the "increased sophistication
of consumer devices" and shifts the risk and responsibility for
communications tools from automakers to consumers.

From a local government perspective, some municipalities have benefitted
from extensive fiber optic and Wi-Fi infrastructure. Dana McDaniel (City
of Dublin, Ohio) noted that the surge towards Wi-Fi being successfully
deployed uses an anchor-tenant model based on departments like DOT,
State DOTs, or cities to determine whether or not to use Wi-Fi to
deliver efficient service. He offers central Ohio as a test site, as
Dublin owns 25 percent of its network.

Howard Lock (Cisco Systems) offered some final advice on business
models:

1.  *Avoid technology religion:* There are many different perspectives
    on the issue, and players should be open to many solutions. For
    example, when asked about security, Lock said it needs to be
    pervasive in the network on a end-to-end basis. It's less important
    to be "stuck" on a particular technology, but to focus instead on
    the business model.

2.  *Do not be too far ahead of the curve:* Cisco recognized that a
    company or application may fail if too far ahead of the curve. If
    DOT is making investments in VII and the timing is right, he
    suggests a small-scale investment and a focus on "ruthless
    execution."

3.  *Connect the dots:* Steve Jobs (Apple, Inc.) talks about connecting
    the dots, meaning, "killer apps" are almost never clear looking
    forward, only looking back. They will appear after a system is
    built, so it is important to rethink the need to identify the
    "killer app" before launching the system.

## Practical Considerations for Field Applications

The group as a whole raised many practical considerations for field
applications of advanced wireless technologies. Tim Krout (CenGen) noted
that actionable steps are important. He identified five to six cities
that received large amounts of research dollars to investigate these
technologies.

Krout agreed that DOT could put a "stake in the ground" in terms of
mobility protocols. From a deployment perspective, he suggested a model
where 5,000 transceivers are installed in vehicles to create a test bed
in a small-sized city. This could allow for advancement and innovation.
A generic Linux processor could be used in a shoe-box-sized system to
create a test bed with "amazing results" and substantial improvement in
all areas.

Stan Pietrowicz (Telecordia) asked participants to consider Paul
Brubaker's opening remark about how to accelerate deployment of mobility
and safety applications in this space. He noted that mobility and safety
may not be served by the same platform, system, or same radio. Safety
applications for vehicle-to-vehicle operations are different from
mobility applications. Safety requires communications between strangers,
low latencies, and features privacy issues. The first mandate for safety
applications is that at least two cars have to have the system in place.
At the normal rate of vehicle attrition, that equates to a 20- to
25-year fleet turnover cycle.

He continued that in-vehicle message signage indicating a crash two cars
ahead is shortsighted, and privacy considerations create unique
requirements and authentication challenges. It is not desirable to
transmit inaccurate data, especially if vehicles (not only their
drivers) are reacting to that information. Thus, intrusion detection
systems will be important -- not necessarily for encryption but for
authentication (with the complex follow-on issue of determining how to
remove intruders from the system). With regard to mobility, vehicle
routing and traffic information, these could be subscriber-based
"opt-in" information services. This would complement mandatory safety
applications.

Christopher Wilson (TeleAtlas) offered an idea regarding authentication:
ranging signals built into the communications signals either on OFDM,
802.11, or on top of DSRC systems. David Reed (MIT) noted that OFDM
ranging is not a current challenge, but questions remain about how to
extract data from the MAC layer off of a Wi-Fi card. He asserted that if
you can measure the time, you can measure the phase. Professor Reed
agreed that this approach might be possible, and noted that ranging, not
at speed, is something some vendors are looking at.

[Practical Procurement and Maintenance Issues]{.underline} -- Ferdinand
Milanes (CALTRANS) offered a sobering perspective on procurement and
maintenance, stating that it is difficult for public entities (such as
CALTRANS) to purchase a product through sole-source procurement when
only one vendor exists. This scenario can present barriers to
implementation.

Next, Milanes suggests considering the maintenance back-end. Field staff
with minimal knowledge or expertise in communications technology would
be responsible for maintaining state-of-the-art equipment. This needs to
be factored into system design. Furthermore, it would be important to
minimize field staff exposure to safety hazards of working near busy
roadways and reduce the need for roadside equipment. Alternative energy
also might be necessary as often there is no AC power on the roadside.

Milanes suggested partnering with the private sector where possible.
California has a wireless right-of-way (ROW) agreement with several
cellular companies, which offer CALTRANS space on their towers. The
State DOT installs repeaters on the ROW instead of geographically
challenging areas (like mountaintops). Finally, he asked if major
telecoms like Nextel and Cingular might ask for the DSRC bands that the
FCC has allocated (the 5.9 GHz ITS and 4.9 GHz public safety bands) if
public entities opt not to use these.

Kirk Steudle (Michigan DOT) offered some background about Michigan's two
mesh networks which are fully functional. Steudle indicated he took part
in a seminar with Shelly Rome and Richard Paul, and realized the
importance of installing a mesh-based Wi-Fi network on a bridge. Thus,
the DOT was challenged to install a system on the Mackinac Bridge in
three weeks to monitor the structure during the annual bridge walk that
has attracted up to 85,000 participants. The system is Wi-Fi based and
functional. Steudle is willing to give others a demonstration of the
system in Michigan, if interested. It is being replicated for other
bridges and exemplifies how wireless communications can be used for
purposes of interest to State DOTs beyond traffic safety and congestion
management.

Lastly, in terms of practical considerations, Barry Einsig (Tyco)
suggested that separating security-dependent safety applications from
commercial applications can avoid legal issues. He suggests deploying
experimental projects in confined areas (e.g., the island of Hawaii) in
order to reduce intrusion or contamination by other users. The
demonstration project could have two parts: one that features all safety
applications and one that features all of the commercial applications.

# The Path Forward

## 4.1 Strategic Alignment with DOT Vision and Mission

The DOT Transportation Vision for 2030, published by RITA in 2008, lays
out many broad goals for the transportation sector. RITA Administrator
Paul Brubaker recommended that participants review the document, and
noted the importance of not waiting until 2025 to talk about how to
achieve the vision. **The key question is, "How do you reverse engineer
the program to get on path to success?"**

Brubaker noted that Moore's law[^7] is alive and well, and there
continue to be advances like nano-sensor road coatings. DOT spends
approximately \$100 million each year on ITS activities, and as the
transportation authorization bill comes up for consideration, it will be
important to leverage the expertise of the roundtable group to open the
aperture and identify ways to reverse engineer a plan based on the
goals.

Brubaker cautioned that the group should not "let the perfect be the
enemy of the good." Rather, as U.S. DOT has defined three phases of VII
(near-term, mid-term, and long-term), priorities will need to be
established and requirements developed. The hope is to funnel the
group's energy and turn it into actionable results in order to save
lives, improve mobility, improve the environment, and expand modal
choice.

## Implementation and Action Steps

According to Robin Chase (Meadow Networks), DOT has a unique opportunity
because of the power of ubiquity (the agency's influence is greater than
any one company). The DOT perspective comes from a network of roads,
bridges, and highways, and has a history of providing a basic generic
platform for individuals and companies to "get their jobs done." There
is now an opportunity to provide that same generic open platform in the
mobile space. Chase's expectation is that this will be a mixed network,
relying on a number of different but interoperable networks, devices,
and applications.

Chase recommends that DOT require open standards and open networks for
its major infrastructure investments, increasing the likelihood of
long-term interoperability and inclusion of rapidly evolving new
wireless standards, as well as providing opportunity for innovation. She
further recommends that U.S. DOT support the creation of an open
platform and an open network, and conduct some experiments using these
tools. Outside of DOT, she sees ancillary benefits of leveraging the
mobile Internet for homeland security, energy efficiency and
sustainability, congestion pricing, economic development, and private
sector involvement.

Since DOT is committed to its "enterprise approach" to innovation, the
Department will continue to learn from experts in the private and public
sectors. In order to maintain dialogue and information exchange, Volpe
Center Acting Director Robert Suda will establish a ***community of
practice*** on this topic. The Web-based community of practice will
allow roundtable attendants to consider key issues and questions, share
new ideas, and foster connections among leaders in the technology,
communications, and transportation sectors. Presentations on this topic
from roundtable participants will be posted for review and download on
the community of practice Web site.

# Appendix A: List of Participants

John Augustine

Deputy Director

Intelligent Transportation Systems (ITS) Joint Program Office (JPO)

DOT

Vice Admiral Thomas Barrett\
Deputy Secretary of Transportation\
DOT

Cyrus Behroozi\
Chief Scientist

TROPOS\
\
Michail Bletsas\
Founder/Connectivity Officer\
One Laptop Per Child (OLPC)\
\
Paul R. Brubaker

Administrator\
Research and Innovative Technology Administration\
DOT

Robin Chase\
CEO

Meadow Networks, Inc.

Max Coffman

Senate Appropriations Subcommittee on Transportation, Housing and Urban
Development and Related Agencies

Babak Daneshrad

Professor

University of California -- Los Angeles

Sunil Daluvoy\
New Business Development\
Google\
\
Barry Einsig\
Director of Marketing/Research\
Tyco Electronics

Paul Feenstra

Director, Government, International & Public Affairs

Research and Innovative Technology Administration

DOT

Dennis Govoni\
Chief Scientist\
Sun Microsystems Federal\
\
Richard E. Howard\
Professor

Winlab, Rutgers University

Richard R. John\
Director Emeritus

Volpe National Transportation Systems Center\
DOT

Leon (L.) Aaron Kaplan\
Founder

Funk-Feuer Initiative (Vienna/Graz wireless network)\
\
Tim Krout\
Vice President for Engineering\
CenGen, Inc.\
\
Gregory Kreuger, PE

Project Manager for ITS

State of Michigan DOT

Howard Lock\
Transportation Sector Director\
CISCO Systems\
\
Kevin W. Lu\
Chief Scientist of Vehicular Telmatics\
at Advanced Technology Solutions\
Telecordia Technologies, Inc.

Dana McDaniel\
Deputy City Manager &\
Director of Economic Development\
City of Dublin, Ohio

Cheryl McQueary\
Deputy Administrator

Research and Innovative Technology Administration\
DOT

Sascha Meinrath\
Research Director

New America Foundation\
\
Ferdinand Milanes\
Chief, Office of Radio Communications\
Division of Maintenance\
California Department of Transportation

David Napoliello

Majority on the House Appropriations

Subcommittee on Transportation, Housing and Urban Development and
Related Agencies

Suzanne Newhouse Transportation Counsel for the Senate Committee on
Commerce, Science and Transportation (Minority Side)

Stan Pietrowicz

Principal Consultant to Government & Public Sector Business Unit

Telecordia Technologies, Inc.

Scott Propp

Director of MOTODRIVE

Motorola, Inc.

J. Christopher Ramming\
Consultant

David P. Reed\
Adjunct Professor

Massachusetts Institute of Technology

Gary Ritter

SafeTrip-21 Technical Director

Research and Innovative Technology Administration\
DOT

Michael Schagrin

Vehicle Infrastructure Integration (VII) Applications Program Manager,
Acting VII Lead

Intelligent Transportation Systems (ITS) Joint Program Office (JPO)

DOT

Paul Schmid\
Legislative Assistant\
U.S. Representative Ellen Tauscher (CA-10; Co-Chair of the Congressional
ITS Caucus)

Douglas Sicker\
Professor

University of Colorado-Boulder\
\
Francois Simon\
Senior Researcher/Engineer\
ARINC\
\
Kirk Steudle\
Secretary of Transportation\
Michigan Department of Transportation\
\
Robert Suda\
Acting Director\
Volpe National Transportation Systems Center\
DOT

Jack Wells

Chief Economist

Office of the Secretary of Transportation

DOT

Christopher Wilson\
Director of Strategic Research\
Tele Atlas

# Appendix B: Roundtable Agenda

May 22, 2008

Oklahoma City Room

1200 New Jersey Avenue, S.E., E33-461

Washington, DC 20590

+------+-------------------------------------+-------------------------+
| 1:   | **Welcome**                         | Paul R. Brubaker,       |
| 00pm |                                     | Administrator, Research |
|      |                                     | and Innovative          |
|      |                                     | Technology              |
|      |                                     | Administration          |
+------+-------------------------------------+-------------------------+
| 1:   | **Introductory Remarks**            | Vice Admiral Thomas J.  |
| 05pm |                                     | Barrett, USCG (ret.)    |
|      |                                     |                         |
|      |                                     | Deputy Secretary of     |
|      |                                     | Transportation          |
+------+-------------------------------------+-------------------------+
| 1:   | **Overview of Today's Agenda**      | Robert E. Suda, Acting  |
| 15pm |                                     | Director\               |
|      |                                     | John A. Volpe National  |
|      |                                     | Transportation\         |
|      |                                     | Systems Center\         |
|      |                                     | U.S. DOT/Research and   |
|      |                                     | Innovative Technology   |
|      |                                     | Administration          |
+------+-------------------------------------+-------------------------+
| 1:   | **U.S. DOT Viewpoint**              | Paul R. Brubaker        |
| 20pm |                                     |                         |
|      | -   Historical Approach: DSCR       |                         |
|      |                                     |                         |
|      | -   Current Challenges: Timeline,   |                         |
|      |     technical, political, budgetary |                         |
|      |                                     |                         |
|      | -   U.S. DOT/State and Local        |                         |
|      |     Strategic Exploration:          |                         |
|      |                                     |                         |
|      | > Open standards, after market,     |                         |
|      | > engage with consumer market       |                         |
+------+-------------------------------------+-------------------------+
| 1:   | **Technology Trends and             | David Reed, Professor   |
| 30pm | Perspectives**                      |                         |
|      |                                     | Massachusetts Institute |
|      | -   Open systems vs. closed systems | of Technology           |
|      |                                     |                         |
|      | -   Architecture and the business   |                         |
|      |     ecosystem                       |                         |
|      |                                     |                         |
|      | -   Discussion: What are the        |                         |
|      |     implications for DOT?           |                         |
+------+-------------------------------------+-------------------------+
| 1:   | **Mobile ad hoc networks (MANETS)   | David Reed              |
| 50pm | as a potential alternative to       |                         |
|      | existing approaches**               | Robin Chase, Chief      |
|      |                                     | Executive Officer,      |
|      | -   Technical aspects               | Meadow Networks         |
|      |                                     |                         |
|      | -   Financial, economic, business   | Leon Aaron Kaplan,      |
|      |     model advantages                | Co-Founder, Funk-Feuer  |
|      |                                     | Initiative              |
|      | -   Current Implications:           |                         |
|      |                                     | Tim Krout, Vice         |
|      |     -   Large Fixed, open source,   | President for           |
|      |         muni wifi                   |                         |
|      |                                     | Engineering, CenGen     |
|      |     -   Military, mobile            |                         |
+------+-------------------------------------+-------------------------+
| 3:   | **BREAK**                           |                         |
| 00pm |                                     |                         |
+------+-------------------------------------+-------------------------+

+------+-------------------------------------+-------------------------+
| 3:   | **Technical Issues (Discussion and  | J. Christopher Ramming, |
| 10pm | Synthesis)\                         | Consultant              |
|      | **                                  |                         |
|      |                                     |                         |
|      | -   Known technical challenges      |                         |
|      |                                     |                         |
|      | -   *Discussion:* What are the      |                         |
|      |     degrees of difficulty,          |                         |
|      |     priorities, and time            |                         |
|      |     requirements?                   |                         |
|      |                                     |                         |
|      | -   Synthesis                       |                         |
+------+-------------------------------------+-------------------------+
| 4:   | **The Path Forward (Next Steps)**   | Paul R. Brubaker        |
| 00pm |                                     |                         |
|      | Discussion:                         | Robert E. Suda          |
|      |                                     |                         |
|      | What are the barriers to increasing |                         |
|      | scale of implementation; what are   |                         |
|      | benchmarks? How do we engage the    |                         |
|      | public and private sectors and      |                         |
|      | enable experimentation?             |                         |
+------+-------------------------------------+-------------------------+
| 4:   | Summary Remarks                     | Robin Chase             |
| 45pm |                                     |                         |
+------+-------------------------------------+-------------------------+
| 5:   | Closing Remarks and Adjournment     | Paul R. Brubaker        |
| 00pm |                                     |                         |
+------+-------------------------------------+-------------------------+

# Appendix C: Questions and Issues for Further Discussion

A roundtable such as this one, which brought together participants with
widely varying background and perspectives, is sure to spark an
assortment of questions and discussion items. This appendix offers some
questions and issues for ongoing dialogue. Some of these questions were
raised by participants and discussants during the event, while others
were identified after informal discourse and ongoing dialogue about the
topic with key attendees after the event. These questions are important
to DOT's understanding of this issue.

-   ***What are the advantages and disadvantages of using a single
    system (e.g. DSRC, MANETs, mesh, etc.), and, is a mesh wireless
    network appropriate for safety applications?***

> It was clear that there are many different opinions about the
> capabilities and characteristics of mesh networks or MANETs vis-à-vis
> DSRC and other existing technologies. There is no simple answer to
> this question, but additional dialogue among experts and leaders in
> the field can help DOT managers move towards an appropriate solution.
> There is a series of related questions surrounding goals, objectives,
> and technical requirements that will inform the dialogue about the
> usefulness and appropriateness of mesh networks for safety-critical
> applications.

-   ***What are the advantages of open platforms and systems versus
    closed or fixed systems?*** Many discussants noted the effect open
    platforms and systems can have on the technology development and
    deployment cycle. The transportation sector is unique and is not
    simply another business or industry sector. Because technology
    applications may be used to protect and enhance public safety on
    roadways, there may be arguments for closed, fixed, or static
    systems. A full investigation of the advantages and disadvantages of
    open platforms and systems should be valuable to DOT leaders.

-   ***Is the 80 percent solution acceptable?***

> Tim Krout (CenGen) discussed the "80 percent solution" early in the
> day. The reference speaks to the idea that no single system can
> perform all required functions for all parties in all scenarios, and
> instead, there may be a technology solution that meets 80 percent of
> desired objectives. In terms of the transportation network in general,
> and specifically safety critical applications, it will be important
> for DOT to determine if an "80 percent solution" is acceptable in this
> environment.

-   ***How vulnerable are mesh networks to human interference, natural
    disasters, and security breaches?***

> As DOT evolves its requirements for safety applications that leverage
> advanced networking capabilities, it will be instructive to assess the
> level of vulnerability for mesh networks compared to other networks,
> and contingencies in place to handle system interference, assure
> reliability, and maintain appropriate levels of latency.

-   ***Who has control or jurisdiction over the transportation
    network?***

> There was brief discussion towards the end of the roundtable about the
> opportunity for DOT to carry out large-scale deployment tests.
> However, if partnerships with private sector hardware and software
> providers are cultivated, it will be critical for those private sector
> entities to fully understand the range of jurisdictional and
> institutional issues associated with the roll-out of an advanced
> wireless communication system for safety applications in the
> transportation network. Some applications may be more complex than
> others -- from a technology standpoint, from an institutional
> standpoint, or from a public relations standpoint. It will be
> important to address these issues early on, and to ensure that all
> parties understand roles and capabilities.

-   ***What are the unintended consequences of leveraging advanced
    wireless communication technologies in the transportation sector?***

> Any policy decision, business process, or technology application will
> undoubtedly have unintended consequences -- sometimes positive,
> sometimes negative. In this case, there are unresolved questions about
> unintended consequences -- especially as they relate to hard safety
> applications and liability for public safety and security.

-   ***In terms of workforce transition, how would a new system be
    installed and maintained?***

> There is a transition period for the adoption of any new technology
> application, including advanced wireless communication technologies.
> There are multiple questions related to implementation and deployment,
> including how to manage demands on the transportation workforce, and
> how to predict the length of time for users to transition to using
> vehicle-to-infrastructure and vehicle-to-vehicle communication
> systems.

-   ***How can current mobile technologies be leveraged to accelerate
    deployment of a variety of safety applications, many of which were
    originally designed to use 5.9GHz DSRC technology?***

> There are a range of safety and mobility applications that can use
> different communications technologies with different infrastructure
> requirements. It will be important for key stakeholders, including
> Federal transportation leaders, to have ongoing dialogue about how to
> leverage currently-available advanced wireless technologies to support
> applications originally conceived to use 5.9 GHz DSRC radio
> technology.

-   ***What is the role of public education in improving communication
    between vehicles and infrastructure?***

> As DOT considers deploying applications that may use advanced wireless
> technologies to create a fully connected transportation network, the
> agency should also consider the role of education and communication
> with the public. There are related questions and issues surrounding
> user needs and expectations, and public use and acceptance of new
> technologies.

-   ***What are the implications of a multi-application vehicle
    communications solution that extends beyond safety functions?***

> Because technology requirements for transportation applications will
> differ, it will be important to explore how to use existing advanced
> wireless technologies and other communications technologies to develop
> a solution that includes multiple applications and that can be
> deployed in a timely manner.

-   ***How can advanced wireless technologies contribute to national
    interoperability and deployment of a fully connected transportation
    system?***

> National interoperability is essential to widespread deployment
> regardless of the technology employed (DSRC, MANET, etc.).  Mobile ITS
> and electronic communications technologies are advancing rapidly, but
> an important issue for ongoing discussion is the extent to which
> multiple and different technologies can be leveraged now or deployed
> over time in order for drivers and transportation system managers to
> realize safety and other benefits.  

-   ***Continue to discuss the full spectrum of technologies and
    applications that are being considered.***

> Consumer electronics devices such as cellular telephones, personal
> navigation devices, and mobile Internet devices are some of the
> enabling technologies that can provide vehicle and infrastructure
> communications applications. DSRC wireless communications capabilities
> are another important means of delivering a range of mobility and
> "safety beneficial" applications. It will be important to continue to
> discuss available technologies and applications that can be deployed
> to meet DOT's objectives.

-   ***How might the political and financial context impact the use of
    advanced wireless technologies to enable safety and other benefits
    through vehicle-to-vehicle, vehicle-to-infrastructure, and
    vehicle-to-system manager communications over a 10 to 20 year
    period*?**

> DOT hopes to make use of traditional and advanced wireless
> technologies to connect the transportation network over a fairly
> long-term period, with several phases of deployment. It will be
> helpful to reflect on the political and financial implications of
> deploying such a network over time, especially as commercial partners
> begin to play a role in deploying complementary technologies, devices,
> and applications.

# Appendix D: List of Acronyms

  --------------------- -------------------------------------------------
  **AODV**              Ad-hoc On-Demand Distance Vector Routing Protocol

  **BHAG**              Bold, hairy, audacious goal

  **BRT**               Bus rapid transit

  **CALTRANS**          California Department of Transportation

  **COTS**              Commercial-off-the-shelf \[application\]

  **CPU**               Central processing unit (or \"processor\")

  **DARPA**             Defense Advanced Research Projects Agency (part
                        of DoD)

  **DoD**               United Stated Department of Defense

  **DOT**               United States Department of Transportation

  **DSL**               Digital subscriber line

  **DSRC**              Dedicated short range communications

  **DTN**               Delay Tolerant Networking

  **EPLAR**             Enhanced Position Location and Reporting

  **FCC**               Federal Communications Commission

  **GHz**               Gigahertz unit of frequency

  **GIS**               Geographic information systems

  **GPS**               Global Positioning System

  **GSM**               Global System for Mobile communications

  **HNS**               High Beam Networking System

  **HOT**               High-occupancy toll

  **HSLS**              Hazy Sighted Link State Routing Protocol

  **IP**                Internet Protocol

  **ISART**             International Symposium on Advanced Radio
                        Technologies

  **ITS**               Intelligent Transportation Systems

  **JTRS**              Joint Tactical Radio System

  **LMTP**              Local Mail Transfer Protocol

  **MAC**               Media Access Control

  **MANETs**            Mobile ad-hoc networks

  **MIMO**              Multiple-input multiple-output

  **NOx**               Generic term for nitrogen oxides produced during
                        combustion

  **OFDM**              Orthogonal frequency-division multiplexing

  **OLSR**              Optimized Link State Routing Protocol

  **OSI**               Open Systems Interconnection Basic Reference
                        Model

  **PNT**               Precision, Navigation, and Timing

  **RITA**              DOT\'s Research and Innovative Technology
                        Administration

  **ROW**               Right-of-way

  **SNA**               Systems network architecture developed by IBM

  **SRWF**              Soldier Radio Wave Form

  **SSL**               Secure Sockets Layer

  **TCP**               Transmission Control Protocol

  **TTNT**              DARPA's Tactical Targeting Network Technology

  **VII**               Vehicle Infrastructure Integration

  **WINT**              War Fighter Information Network-Tactical
  --------------------- -------------------------------------------------

[^1]: ISART stands for International Symposium on Advanced Radio
    Technologies. It hosts an annual conference that serves the
    government radio and technology market.

[^2]: A killer application (commonly shortened to killer app), in the
    jargon of computer programmers, has been used to refer to any
    computer program that is so necessary or desirable that it provides
    the core value of some larger technology, such as a gaming console,
    software, operating system, or piece of computer hardware. Simply
    put, a killer app is an application so compelling that someone will
    buy the hardware or software components necessary to run it.

[^3]: Dash Express touts itself as the first two-way, Internet-connected
    GPS navigation system. Its GPS unit leverages the SIRFstarIII
    satellite signal processor, the Wi-Fi receiver and antenna connects
    to networks from a car using a high gain antenna, and the cellular
    radio and antenna uses cellular (GPRS) network to keep the device
    connected at all times. See [www.dash.net](http://www.dash.net/).

[^4]: OSLR is a proactive link-state routing protocol that floods a
    topology table of its neighbors to all nodes in the network, which
    then compute optimal forwarding paths locally.

[^5]: Kaplan offered comments in the next several paragraphs after the
    roundtable took place, in order to provide additional detailed
    information about the OLSR project and his experiences with mesh
    networks.

[^6]: The Open Systems Interconnection Basic Reference Model (OSI
    Reference Model or OSI Model for short) is a layered, abstract
    description for communications and computer network protocol design.
    It was developed as part of the Open Systems Interconnection (OSI)
    initiative and is sometimes known as the OSI seven-layer model.

[^7]: Moore\'s Law: the number of transistors that can be inexpensively
    placed on an integrated circuit is increasing exponentially,
    doubling approximately every two years. The observation was first
    made by Intel co-founder Gordon E. Moore in a 1965 paper.