ITR-ECS-soc: Spectrum Management toward Spectrum PlentyTimothy X Brown, Dennis Akos, Dirk Grunwald, Dale Hatfield, Douglas Sicker, Philip Weiser

University of Colorado, Boulder, 80309-0530, timxb@colorado.edu

Wireless networking technology is the fastest growing segment in the United States telecommunications market and holds out the promise of providing greater broadband competition, increased connectivity in rural areas, and increased communication density in developing nations that are not able to invest in wired infrastructure. But making this vision a reality entails overcoming three formidable barriers that can only be solved through careful interdisciplinary work that pulls together policy, electrical engineering, and computer science expertise. In particular, policymakers need assistance in: (1) identifying opportunities for “underlay technologies,” wherein existing licensed spectrum can be protected while affording access to unlicensed uses, as well as new bands for unlicensed spectrum uses; (2) evaluating the technology – both in hardware and software – that will enable unlicensed uses not to cause undue interference with licensed ones or other unlicensed ones; and (3) determining how to best enforce the requirements – i.e., protocols (or etiquette standards) – that ensure that unlicensed uses can co-exist with one another and with licensed ones without causing undue interference.

Intellectual Merits: This proposal seeks to address these challenges with research that will promote Economic Prosperity and a Vibrant Civil Society (ECS) specifically by looking at the Interaction of Information Systems and Social Systems (soc). The research areas include:

1. A measurement survey of interference and usage in key spectrum bands.

2. An open radio competition designed to demonstrate effective spectrum sharing mechanisms, to explore the consequences of specific mechanisms, and to bring out the challenges and limits of more flexible spectrum policies.

3. Radio architecture and control models that facilitate spectrum sharing.

4. Software defined radio hardware platforms and open source APIs that will be low cost and accessible to the larger research community.

5. Network protocols that enable transmitters to exchange and collect spectrum usage information.

6. Data models that allow for policy rules to be communicated to devices in a meaningful and flexible manner.

7. Strategies, based on careful policy analysis, of when and how the Federal Communications Commission (FCC) should play a role in developing and enforcing the protocols that facilitate effective shared use of unlicensed spectrum.

Broader Impacts: The field of spectrum-policy related research is relatively limited to date, with the FCC’s Spectrum Policy Task Force underscoring the need for more careful interdisciplinary research in this area. At this point, addressing the above three challenges are essential areas for the FCC to develop confidence in before it can implement its ambitious spectrum reform agenda. With a successful completion of this proposal, we believe that the FCC and academics studying this question will gain much needed insight into the realities of implementing the necessary steps to realize the goal of greater access to unlicensed spectrum. This proposal has extensive outreach activities to promote research in this area including conferences, a radio competition, deploying an open source software defined radio platform, and distributing spectrum policy course materials. It also will reach out to rural communities and developing countries to resolve their unique spectrum policy issues.

ITR-ECS-soc: Spectrum Management toward Spectrum PlentyTimothy X Brown, Dennis Akos, Dirk Grunwald, Dale Hatfield, Douglas Sicker, Philip Weiser

University of Colorado, Boulder, 80309-0530, timxb@colorado.edu

1 Research ProblemThe growing use and importance of unlicensed wireless is nothing short of revolutionary. Wireless

networking technology is the fastest growing segment in the United States telecommunications market and holds out the promise of providing the “third wire” to compete with cable and telephone company “last mile” broadband solutions [Cal04]. The opportunity to extend the last 100 feet of “wi-fi” into the last mile (or miles) via “wi-max” is a particularly important challenge for rural areas where cable and telephone broadband facilities have yet to be deployed – as well as for developing nations that are not able to invest in wired infrastructure.

At this point in time, most commentators agree that unlicensed wireless spectrum holds out the promise of providing local broadband solutions. But making this vision a reality entails overcoming three formidable barriers that can only be solved through careful interdisciplinary work that pulls together policy, electrical engineering, and computer science expertise. In particular, policymakers need assistance in: (1) identifying opportunities for “underlay technologies,” wherein existing licensed spectrum can be protected while affording access to unlicensed uses, as well as new bands for unlicensed spectrum uses; (2) evaluating the technology – both in hardware and software – that will enable unlicensed uses not to cause undue interference with licensed ones or other unlicensed ones; and (3) determining how to best enforce the requirements – i.e., protocols (or etiquette standards) – that ensure that unlicensed uses can co-exist with one another and with licensed ones without causing undue interference.

The opportunity to use the existing bands of licensed spectrum more efficiently while not disrupting the uses of licensed users is a tantalizing possibility. As the FCC’s Spectrum Policy Task Force (SPTF) Report explained, “spectrum that is licensed under an exclusive use approach could also be subject to an ‘underlay’ easement that is available to low-power unlicensed devices using a commons [i.e., unlicensed] approach.” [FCC02a, p. 37]. Policymakers need assistance, however, in determining what bands of licensed spectrum could be subject to “underlay easements” along the lines envisioned in the SPTF Report. Just recently, the FCC commenced a proceeding designed to test the SPTF Report recommendation of using an “interference temperature” metric (see [FCC03a]). In that proceeding, the FCC is seeking information – for two specified frequency bands (i.e., fixed satellite uplinks and terrestrial fixed point-to-point links) – on how to define and measure reliably the appropriate interference temperature [FCC03a, p. 3]. Moreover, the FCC has suggested that, if it can determine an appropriate set of technical rules on an interference temperature, it will ascertain (for those bands) what unlicensed devices should be allowed to operate at higher power levels than allowed by current rules. [FCC03a]

The complexity of developing an appropriate interference temperature-based regulatory strategy cannot be underestimated. In general, the FCC has historically relied on its spectrum licensees to press the case as to what level of protection against interference is appropriate. In so doing, it has often erred on the side of developing rules that protect licensees for the very worst case scenarios – thereby leaving large amounts of spectrum unused at any given time. Thus, without careful, independent research, the FCC is at a disadvantage in making judgments about the level of protection against interference that is appropriate for different uses – i.e., where to set the interference temperature. Moreover, in all likelihood, this standard will vary greatly between different bands because “[s]etting a single permissible interference temperature for the entire radio spectrum . . . is not necessary and would be unwise.” [Mar03b] Consequently, in order to implement the recommendations of the SPTF Report, the FCC needs much more independent engineering research about what amount of spectrum is underused, is necessary for particular applications, and can be shared through easements defined by an interference temperature.

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The payoff of developing more nuanced rules against interference is potentially enormous. Under the current regime, a huge amount of unused spectrum is fenced off – even to users in their own homes. But with demands for underlay and unlicensed usages poised to explode, based on the promise of the applications being developed for wi-fi and other innovative technologies, the FCC will face increasing pressure to reform its legacy regulatory regime.[Kes04] The good news is that the technology – in the form of software-defined radios (SDRs) and other interference mitigation techniques – exists to program devices using spectrum to respect interference temperature limitations.1 Evaluating the opportunities for using this technology, however, poses a major challenge for the FCC, as the intersection of spectrum uses and software applications take the FCC into uncharted terrain.

The FCC has only begun to chart its future direction with regard to SDRs and other interference mitigation techniques. In the wake of the FCC’s opening of an investigation into what it calls “cognitive radio technologies,” there is now an acute need for independent, academic research that can explain and demonstrate how new radio hardware and software defined methods can facilitate more efficient and effective uses of spectrum.[FCC03b] The evaluation of the potential of SDRs, however, must do more than simply seek to develop the capability to exploit underused spectrum; it must also be mindful of the opportunities for malicious or unintentional misuses of this technology. As the FCC cautioned in its First Report and Order on SDR, this new technology should not be allowed to become an easy method for users to purposely or inadvertently transmit out of compliance.[FCC01] Preventing such misuse poses a major challenge for the FCC, as it will need to evaluate the wisdom of both proactive measures -- such as distributed system control -- and more reactive measures -- such as its uses of policing and enforcement. (For an examination of these questions, see [Dil02], [Vanu02], and [Chap02]).

To develop SDRs, researchers are examining a broad range of software languages and programming systems. Vanu, Inc., for example, is working on the Radio Description Language (RDL), which serves as an interface to allow waveform code to interact with platform specific software. [Vanu01] Others are working on Waveform Description Language (WDL), which provides both a general programming system to represent waveforms and a means of providing waveform portability across SPS hardware. [WDL02] The Software Communications Architecture (SCA) of the SDR Forum proposes a high-level component-based framework for defining the various interfaces. [SCA01] Researchers at Munich University of Technology have proposed a system profile to provide system context information to the various actors (e.g., terminals, user, services). To date, however, no one has proposed an actual policy model that could be used to define and communicate the rules of operation to or among devices.

At the software level, a model that could enable SDR-enabled devices to communicate with one another would need to capture the requirements of the existing spectrum rules and yet be appropriately flexible to embrace the more dynamic spectrum usage opportunities that are likely to emerge. By developing a data model that accurately and flexibly allows policies to be communicated among devices, we should be able to move from the present static approach to spectrum management to a more efficient and reliable dynamic approach. Significantly, enabling these devices to represent data in this manner

1 As the Spectrum Policy Task Force observed [FCC02a, p. 30],

Interference temperature sensory and control mechanisms could be used to maintain both in-band and out-of-band emissions within permissible limits. For example, a low power unlicensed RF device could be designed to scan its particular frequency band before transmitting. Its built-in “thermometer” would record interference temperature data and compute the appropriate statistical aggregate value. The device would then project the increase in interference temperature due to its operation over its nominal range. This value would be compared with the permissible limit. If its operation would exceed the limit, the device’s controller could execute an appropriate response such as reducing power, switching to a different transmit frequency (if available) or, perhaps, continuing the scanning/sensing process to locate an opportune time to transmit. The technology now exists to build such sensory control systems. Automated transmitter power control, for instance, is used in certain types of wireless and satellite communications systems. Cordless telephones also adapt to the environment by selecting an unused frequency.

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could be quite useful in providing a data model for making authorization or licensing decisions, particularly when combined with other authentication, authorization, and accounting mechanisms.

The challenge of identifying additional usable spectrum and developing the technology necessary to enable unlicensed uses is matched only by the challenges of enforcing the rules that will enable multiple parties to share access to the same unlicensed spectrum. As noted above, some (and perhaps many) of the relevant rules will be implemented through software code (in SDRs), thereby requiring the FCC to develop a means of ensuring that the relevant software is being used as envisioned. Unfortunately, most advocates of spectrum policy reform seeking increased unlicensed uses leave the critical and complex question of enforcement as an afterthought to be worried about at some later date (e.g. [Ben02]). That later date, however, is rapidly approaching and the FCC is looking for guidance on how to address this issue.

The entire premise of a regime that frees up more unlicensed spectrum in the form of underlay easements depends on the presence of enforceable rules. The SPTF Report explicitly linked these two points in its recommendations, explaining that a “clearer interference definition [must be accompanied] with effective enforcement.” [FCC02a, p. 34] Other respected commentators have emphasized this link as well (e.g. “an option of a non-interfering easement requires a careful definition [--and, a fortiori, enforcement] of what constitutes interference” [FaF03, p. 21] and in supervising unlicensed uses, the “FCC’s rules should be as clear as practicable [and] strictly enforced” [Car03]).

The fear that looms large over the burgeoning success of the unlicensed spectrum model is that the use of “common spectrum” will lead to the “tragedy of the commons.” This fear, detailed effectively by some commentators, is that a good not limited by any price will be subject to overuse.[Ben03] Advocates of increased unlicensed spectrum respond, as the Task Force noted, that “established technical ‘etiquettes’ or standards that set power limits and other criteria for operation of unlicensed devices to mitigate potential interference” between the users can overcome the tragedy of the commons problem.[FCC02a, p. 35] In particular, such standards can take the form of “regulatory guidance, requirements such as power and emission limits, and sharing etiquettes” – such as the “listen before talk” protocol.[FCC02a, p. 40] But stating that such protocols can be effective only partially responds to the tragedy of the commons concern. A full response requires, as unlicensed spectrum advocates have yet to acknowledge, a thorough evaluation of why and where private ordering will be sufficient to prevent overuse – i.e., a refusal to comply with limiting power limits or protocols. In general, game theory tells us that without some form of effective coordination between actors speaking in a room (like private actors using unlicensed spectrum), they will reach a Nash equilibrium where each continues to raise their voice in order to be heard, even if the result is worse off for all of them when no one can hear one another [Kla03]. To be sure, there are likely to be some (and, perhaps, a number of) cases where private ordering solutions will be sufficient to prevent a tragedy of the commons-type result, but it is incumbent upon the FCC to identify when that will happen and when governmental oversight will be necessary to prevent a tragedy of the commons-type result. The existing literature in this area has yet to come close to grappling with this issue and the FCC is thus navigating its approach in this area without the benefit of careful, independent research.

In short, this proposal envisions undertaking three necessary tasks related to the FCC’s goal of facilitating increasing unlicensed spectrum uses:

1. Identify spectrum where either “underlay easements” can be used on an unlicensed basis without disturbing licensed uses and, to the extent practicable, identifying underused blocks of spectrum that might be designated for unlicensed uses adhering to certain sharing mechanisms;

2. Develop and demonstrate means of using software-defined radios and other interference mitigation techniques that will enable “underlay easements” to be used in a manner that ensures no interference to licensed uses as well as developing and demonstrating means of using

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technology to facilitate shared access to blocks of unlicensed spectrum without compromising other unlicensed solutions; and

3. Develop a means of enforcing compliance with design protocols and other interference mitigation measures (both technical and policy/regulatory) to avoid cheating and using unlicensed spectrum in a manner other than that contemplated by interference rules.

We discuss each of these in more detail below.

1.1 Measurement Campaign to Characterize Spectrum Available For Sharing

It has been well documented that current spectral allocations are underutilized [FCC02a]. However, it is a daunting task to identify and characterize which specific frequency allocations should be candidates for revision with uniform consensus. As an attempt to address the issue, yet make the problem tractable, a measurement campaign will be conducted on two diverse frequency bands. The two bands represent spectral allocations at opposite extremes of the range of those bands that are viewed as least hospital to unlicensed uses and those viewed as most hospital. The goal of this inquiry will be to utilize diverse and numerous spectral measurements in a variety of geographic location of these specific frequency bands to better understand their operating environment, provide insight as to their spectral utilization, and potential for future sharing. Since these two bands represent diverse categories of spectrum allocation, results of this investigation will allow conclusions to be drawn which bound possible future spectral adaptations.

The specific bands are: (1) the 2.4 GHz Industrial, Scientific, and Medical (ISM) band [2441.75 ± 41.75 MHz]; and (2) the Global Positioning System (GPS) L1 band [1575.42 ± 10 MHz]. These two bands have been selected as a result of their diverse characteristics and recent visibility within the proposed spectral modernization.

The 2.4 GHz ISM band has become increasingly popular due the possibility for unlicensed multifaceted applications to operate within this frequency band. Of particular interest for this investigation, in addition to the spectral measurements, is to attempt to assess the effectiveness of this band and regulation in various environments. The research will examine the potential this band holds for additional applications and devices, given the current span of devices and protocols currently operating within the frequency space. In short, the goal will be to assess the effectiveness of such a frequency allocation and regulation.

The GPS L1 frequency band was one of the principle spectral allocations which impacted the resulting regulatory power levels allowed for Ultra Wideband (UWB) emissions across the frequency span 960–1610 MHz [LAP00]. The GPS band is one identified where changes to incumbent rules are unlikely and would be subject to heavy criticism. The potential interaction with GPS, and resulting theoretical and experimental studies, resulted in minimal spectral overlay potential for UWB below 3.1 GHz. The GPS L1 signal is transmitted within a designated aeronautical radio navigation service (ARNS) band, regulated under Aviation Part 87, which is quite restrictive to facilitate safety/life critical services. The GPS signal is unique in that it is a code division multiple access spread spectrum signal whose received power is below the thermal noise floor for traditional receivers. Thus, reception and processing is sensitive to any additional interference. The goal of spectral measurements within this band will be to extend past studies and investigate how effective this particular spectral allocation is being utilized as well as its sensitivities to existing interference within the band.

In short, the goal of this component of the investigation is to provide a comprehensive study, via analysis and measurements, of two diverse frequency allocations – and assess the effectiveness of their corresponding regulation as well as how such allocations fit into the future of spectrum management. We will build on past spectral measurement studies and references on conducting such measurements: [IEE86, IEE96, IEE01, NTI95, NTI96, NTI97, NTI02, NAS03].

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1.2 Demonstrate New Technical Solutions for Software Defined Radio and Other Interference Mitigation Approaches to Facilitate Underlay Easements and Blocks of Unlicensed Spectrum on a Shared Basis

There are a series of technical approaches that, if employed successfully, can facilitate new underlay easements that will increase available unlicensed spectrum. The simplest underlay approach would be to define a measure such as an interference temperature that underlay transmitters can measure to decide whether they can transmit or not. The interference temperature is only a metric and setting an appropriate value for a given service is necessary.[Mar03b] The interference temperature is a simple in-band power measure. More sophisticated measures are possible. To use television as an example, the measure may depend directly on the properties of the TV signal. When close to the television transmitter and the measured TV signal is strong, the underlay user could be permitted to transmit at greater power than when they are further from the TV transmitter. The transmit power could further depend on the timing of the TV signal with allowed transmit powers different during say blanking intervals in an analog TV stream.

A fundamental problem with measuring transmitter signals is that interference occurs at the receiver and not the transmitter. An underlay user can affect a sufficiently close receiver even when the licensed transmitter signal is strong. Also, directional antennas can destroy the ability to correctly measure the interference environment. In the below diagram, because the underlay transmitter antenna is facing away from the licensed transmitter it may not detect the licensed transmitter. But, it is transmitting directly toward the licensed receiver. Even without directional antennas, a hill or other obstacles may have the same effect. Scenarios, such as these, show that measuring transmitter signals may not be effective.

Many of these problems can be solved by focusing on the licensed receiver. At present, however, there are no rules on licensed receiver performance. Specific receiver performance requirements on sensitivity, band filtering, etc. will open up additional underlay opportunities and provide a consistent model to judge underlay interference potential. To that end, the FCC has not only opened up an investigation of the interference temperature concept, but also of the possibility of regulating receiver standards [FCC 03c]. Under a regime of receiver standard regulation, active receivers could greatly improve the ability of underlay users to detect potential interference situations. If a licensed receiver, for example, sent out a periodic low power beacon, then the underlay transmitter could accurately measure the path loss between the underlay transmitter and the licensed receiver and infer what communication could coexist with the licensed receiver. For the FCC to adopt any regime regulating receivers, it must first identify which technologies are the most promising for facilitating more efficient and effective uses of wireless spectrum.

The underlay rules may also vary geographically. In rural areas, where many bands are unused, underlay users can operate at higher powers. Urban areas also have unused bands and reserved guard bands. A licensed user will need a mechanism to discover these opportunities. Use of some licensed bands varies over time. Public safety bands which are critical in crisis situations are less used during typical periods. Mechanisms are needed for licensed users to give up portions of the band when not in use, but, to have assurances that they it will be available when needed. Measurements by the underlay user may not be sufficient to exploit these opportunities. An explicit mechanism may be one avenue of approach. For instance the underlay user may listen to broadcast beacons describing the current local underlay rules, or, the underlay user may use location information (e.g. GPS) combined with stored usage maps.

Licensed TX Licensed RX

Underlay TX Underlay RX

Hill

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In general, there are four alternative technical approaches that, if employed successfully, could facilitate new underlay easements that will increase available unlicensed spectrum. The first encompasses the large body of work in modulation and coding that tries to reduce the bandwidth required to transmit a given user signal. The second includes methods where applications share bandwidth based on physical properties of the signal. Examples include listen-before-talk (in which the transmitter first checks that received power is below a threshold before transmitting) and ultra wideband (UWB) where the transmitter radiates below a designated power spectrum profile. The third includes methods where the applications share bandwidth by exchanging information. This includes protocols like IEEE 802.11b where transmitters negotiate with each other in order to determine who can transmit; ad hoc (mesh) networks where nodes relay traffic for each other; and mobile telephone networks, which have infrastructure transmitters that organize the end-user communication. Finally, the fourth model covers methods where the radio is adaptive to the communication environment and can be as simple as reducing transmit power to reduce interference or as sophisticated as choosing the modulation, center frequency, and antenna beam pattern based on the other communication.

We will address each of the above technical approaches in five broad areas that will define the effectiveness and nature of such approaches. First, we will initiate a radio competition to provide a realistic test bed for cooperative, competitive, and dynamic spectrum management regimes. Second, we consider software defined radios (SDR) that can implement more complex adaptive architectures. Third, we will develop and disseminate a specific SDR platform to other research groups so as to facilitate open source shared research and experimentation and make the competition more accessible. Fourth, we will design lightweight network protocols for the sharing of local spectrum management information. Finally, we will define middleware and data representations for dynamic distributed spectrum management schemes.

1.2.1 Radio Competition

Spectrum regulation has relied on simple maximum transmit power, bandwidth, and out-of-band limits with minor embellishments. Over time, radio complexity is growing and costs are decreasing. Radios are capable of operating under more sophisticated rules at reasonable costs to consumers. For instance, receivers may be required to announce their presence using a known protocol. Or, communicators in a band may be required to understand a simple etiquette that allows them to cooperatively negotiate communication in a local area. But, widespread experimentation is lacking and we seek to provide the hardware, software, and test bed tools to broaden the scope of researchers working on this problem.

Before such protocols can be adopted, it is necessary to characterize their effectiveness, the consequences (intended or not) of their use, and understand how the protocols are enforced. When such evaluation is complete, the regulators need to be persuaded that the protocols will work in practice. Much of the characterization is possible through simulation or the building of a small number of radios. The challenge will be to characterize the performance when many disparate users are simultaneously active. Game theory can provide some insights, but, is unlikely to be predictive in the larger problem.

In short, a mechanism is needed to simulate the dynamic larger world situation of many potentially competitive users using different technologies sharing a localized space. We propose to use an open radio competition. In other fields such as artificial intelligence (RoboCup [Rob04a]), and unmanned aerial vehicles (Design, Build, and Fly [DBF04]), such open competitions have served multiple useful purposes. First, they focus research on realizing practical gains. Second, they attract more researchers including undergraduate and graduate students and industrial groups. Third, they accelerate the exchange of ideas among researchers. Fourth, the merits and deficiencies of different approaches are more readily identified. Finally, it raises the visibility of the research beyond the research community.

Each competition would have a specific radio challenge. Typical examples might include:

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Competitors construct a radio pair that implements a licensed transmitter measurement approach to underlay in specified bands. They would be judged on their ability to communicate as an underlay user without affecting the licensed receivers.

Competitors construct a radio pair that will operate as an underlay in the presence of licensed receivers that implement a known beacon protocol. Competitors would be judged on their ability to communicate as an underlay user without affecting the licensed receivers.

Competitors construct radios that can implement a specific spectrum sharing etiquette. Different competitors would be placed in the same location and judged by the total amount of communication that all competitors are capable of.

Competitors in these competitions would be invited to compete in any way they wish including to construct radios that seek to “hog” unlicensed spectrum and undermine the effectiveness of other devices by deviating from the spectrum sharing requirements without being easily identified as a “cheater.”

The radio challenges will be at different levels: software, common platform, and open platform. Software competition will compete in a simulated environment similar to [Rob04b]. Candidate platforms would include Opnet [Opn04], ns-2 [NS204], and OMNeT [Omn04]. The common platform competition will compete using a readily available software defined radio hardware platform defined at CU. The open platform competition will compete using any hardware and software combination that satisfies the competition rules. The purpose of the different levels is to encourage participation even from groups with limited RF engineering or hardware experience.

The University of Colorado will take the lead in organizing and promoting the competitions. It will draw on its close ties with the National Institute of Standards and Technology--who have extensive facilities for radio testing and measurement--and the Institute of Telecommunication Sciences--which is a scientific advisor to NTIA on telecommunications and spectrum policy. ITS also runs a potential competition facility, the Table Mountain National Radio Quiet Zone [TM04], a large outdoor radio testing area near Boulder with a history of providing technical underpinnings to spectrum regulation debates (e.g. [AlM03]). Table Mountain is in the process of doing an extensive measurement survey across all bands up to 2.8GHz. This survey will provide a background signal baseline if a contest were to be held there. The competition will start in the second year and continue annually after that. Once started, in future years, the goal will be to have a rotating competition that moves to different institutions.

1.2.2 Software Defined Radio Architecture

Decisions relating to the architectural model for future SDR have profound implications for how these devices and networks are designed, controlled and operated.

First, these architectural decisions guide the hardware and software requirements. Consider, for example, the computational needs of a SDR that actively decides its operational mode after communicating with peers versus the computational needs of a SDR that simply receives its instructions from a central authority. Second, these architectural decisions guide the control of the environment. Some design models may assume a strong command and control mode, wherein the devices respond to modifications decisions promulgated from an assigned authority. This differs substantially from a mode wherein devices cooperate in modifying their operation. Third, these architectural decisions guide the potential data models and operation associated with these devices. We could consider various modes whereby the device might acquire information about its environment. For example, we could optimize operation based on the amount of information available to the devices (e.g., noise floor characteristics, neighbor proximity or available spectrum). In other words, in an information rich environment the devices could assume a number of different operational modes and hierarchies, with the intent of optimizing shared spectrum usage.

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In considering the degree to which spectrum management can be distributed to the end devices, we could examine a number of cooperative designs. Specifically, we could consider how the network devices might cooperate across a variety of conditions, such as in spectrum allocations and geography where a device may not be permitted to operate. For example, in one architecture, devices might neither cooperate nor be controlled by a centralized authority. A question to consider is how optimally might these devices operate without the overhead of cooperation. In a different architecture, spectrum decision could occur in a highly distributed and cooperative manner; however for certain bands or geographies the devices fall back into a centralized control operation. This fall back could be elicited due to public safety requirements or because the modes of operation desired within a specific band or geography. The goal is to better understand the potential tradeoffs associated with each design so that we might propose a variety of optimized solutions for various constraints and allowances.

1.2.3 Hardware

(a) Gnu Radio Prototype Hardware(b) Xilinx XtremeDSP Development Kit

Motherboard

Figure 1: Sample Hardware Platforms Available In First Year of Proposal

For research in software defined radio to be effective, there must be a credible experimental component, including a hardware and software platform for such experimentation. Although SDR is only recently gaining currency in academic research, numerous prototype systems are available for military and commercial research purposes; these systems have the benefit of solid RF designs and highlevel software tools, but they are also expensive and are often only available for military contractors.

Two “hobby” SDR systems have been developed. The first, the Flex Radio (www.flex-radio.com), uses a general purpose computer for signal processing and a high quality audio card for data capture. Experience at Colorado with this hardware platform is encouraging, because it provides a simple programming interface that is quickly grasped by students. However, because of the inexpensive data capture hardware, that platform can only sample a 40Khz band in the 0-60Mhz range. The Gnu Software Radio prototype, shown in Figure1(a), provides four high precision A/D and D/A converters integrated into a signal card using an FPGA for basic signal processing and a USB2 controller for interfacing to a host system; the RF front-end is not part of this package. This system is not currently available, and may be redesigned because of performance problems. The Gnu Radio hardware also does not use the common hardware interface frequency (IF) of 70Mhz used by most research platforms. Readily available commercial SDR platforms include the Xilinx XtremeDSP development kit, shown in Figure1(b). That system includes a pair of high-resolution A/D and D/A converts, host interconnects using PCI interfaces or USB2. More importantly, it includes an established toolchain that includes signal processing components from Xilinx.

None of these parts are ideal. The Gnu Radio hardware provides great flexibility and low cost, but uses a nonstandard interface frequency, reducing the availability of high-frequency conversion hardware

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(e.g. Frequency shifters to reach the 900Mhz or 2.4Ghz ISM bands). The Xilinx part uses a complex (but high performance) PCI interface to access the device. As part of the proposed work, we plan on developing a modern, flexible hardware platform for SDR using hybrid reconfigurable platforms and then providing software support using the Gnu Radio project software libraries. A hybrid reconfigurable system is one that combines on-board processing and reconfigurable logic; for example, the Xilinx Virtex-IIPro family of FPGA's combine one or more 200Mhz CPU's with reconfigurable logic that includes numerous “DSP blocks” for signal processing applications. Our experience with a Virtex-IIPro prototype system highlights the benefit of such a system – the on-board CPU is used to run the Linux operating system and communicate with external systems using a 100Mb/s Ethernet interface. Extensive signal processing can be done by the FPGA fabric and the on-board processor can perform considerable MAC-layer processing; this greatly reduces the interface complexity, making it easier for students to use the system.

We propose to work with the Xilinx Digital Signal Processing group in Longmont, Colorado to develop a prototype SDR system based on the Virtex-II Pro. The board will be designed by students at the University of Colorado who have experience in developing low-cost sensor network systems and RF interfaces. The system will use four each A/D and D/A channels to be as flexible as the Gnu Radio hardware, but will use a 70Mhz IF to enable the use of existing RF front ends. We will develop a set of open-source DSP components in VHDL that can be instantiated on the Virtex-II Pro FPGA and extend the embedded Linux system on that system to simplify stream processing of signals from the DSP components. The system will use the same Xilinx development tools currently used at many universities for computer design classes. Each SDR system will provide an integrated 800-1000Mhz RF front-end (e.g. based on the Maxim MAX2442) for “out of the box” experimentation with the single board system. The system will also be able to interface to the numerous RF front ends that use the 70Mhz interface frequency, enabling experimentation in the 2.4Ghz and 5.8Ghz bands.

Prior to the development of this system, researchers at Xilinx have agreed to provide several of the current Xilinx XtremeDSP prototype systems so that researchers can gain familiarity with that platform. We will also purchase the current Gnu Radio prototypes to understand the strengths and weakness of those systems.

The end result of this development will be a flexible, fully-integrated radio suitable for experimentation and the “SDR competition”. The entire design will be “open sourced”, and we will work with a contract manufacturer to provide assembled systems for purchase by other Universities.

1.2.4 Network Protocols

Relative to the 7-layer OSI reference communication model [LGW04], spectrum rules focus on physical and link layers, while the network layer is conspicuously absent. With a dense population of communication devices, the many devices are capable of much better performance collectively than if they communicate independently. Results with ad hoc wireless networks have shown marked performance improvements in power and communication capacity when the radio devices cooperate in their communication [DBB02,GuK00,She96]]. One approach is to allow cooperative technologies to develop independently under the existing physical and link layers. But, it may be that competing, incompatible technologies will result, e.g. the interference problems between 802.11b and Bluetooth [How02]. With the potential for spectrum performance improvement, we will investigate potential network protocols that will enable this improved performance. For example two collocated radios may exchange measurements about licensed receivers in the area or they could negotiate non-interfering power, frequencies, or antenna patterns.

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1.2.5 Data Models

In terms of bridging the gap that exists between the rules that govern the use of spectrum and SDRs that make use of this spectrum, we propose to develop a policy data and middleware model. In many ways, this could be thought of as the development of a Spectrum Policy Markup Language (SPML) and the subsequent implementation of such a language. This effort will first involve capturing the elements that are necessary for expressing the context of spectrum rules in a manner that can be communicated as some meaningful syntax. This task will focus on defining what the present rules encompass (e.g., fixed spectrum, power, location) and then consider what additional elements might exist in a more dynamic spectrum policy environment (e.g., spectrum assignment, utilization information, user density). After defining these elements, we will turn our focus toward methods for expressing this information. This will take the form of further developing meaningful data and information models, likely built on the simple eXtensible Markup Language (XML) data model. [W3C-04] Initially, we will not focus on the formalities of this effort (such as standardizing the explicit information model), but rather work on developing a working prototype. We will then consider what bindings and profiles might be necessary to convey this information to the proper interface of the device. In general terms, we will pursue a web-based approach, as advocated by W3C. [W3C]. This approach will work from an XML model, which will be adapted for the exchange of spectrum context information. XML provides a standard for describing structured information and contents. The benefits of using XML as a data container are its simplicity and richness of the data structure. The general characteristics make it particularly well suited to the task of representing spectrum policy decisions. Clearly, this approach does present some issues, such as the size of the XML data set. Therefore, part of this research will be to examine the tradeoffs and subsequently consider possible solutions, such as compression schemes to address the size issue.

The ultimate goal is to provide a policy data model and accompanying middleware that will by used to create a dynamic, distributed spectrum management scheme.

1.3 Developing the Regulatory Strategy for Enforcing Protocols That Facilitate Underlay Easements and Blocks of Unlicensed Spectrum on a Shared Basis

For the FCC, the increased importance of unlicensed spectrum challenges its historic treatment of that resource. For most of its history, unlicensed spectrum often consisted of “junk spectrum” used for niche market opportunities where rival uses could easily co-exist and, to the extent that they caused interference with one another, there was not a huge cause for concern. In recent years, however, the possibilities unleashed through new technologies such as wi-fi have given rise to a new appreciation for the potential of unlicensed wireless spectrum. And from all indications, we are only seeing the tip of the iceberg.

Spectrum, like other resources, is subject to overuse. Multiple transmissions at the same time, using the same frequency, and in the same location can lead all of them to be garbled or delayed. In short, there are two solutions to avoid this result: a property-like system, where one licensee can control who uses a particular frequency in a particular area, or a commons-based system where there are particular protocols that everyone follows to ensure that rival transmissions do not interfere unduly with one another. There are great advantages to the second model, where an innovator can introduce a new technology without control of the underlying spectrum, but it is also subject to “cheaters” who decide to transmit at greater than allowed power limits or not to follow prescribed protocols (i.e., listen before you talk). These cheaters, if not checked through social pressures or regulation, can threaten to undermine the basis of the commons-based system because otherwise legitimate users will feel pressure to similarly break the rules (lest they be at a disadvantage vis a vis the cheaters).

The tragedy of the commons scenario – under which “the cheaters” undermine the entire system – is not a hypothetical concern. Even putting aside the rich literature in economics that addresses this concern, the experience of bands of spectrum left open for all to use underscore the real danger that this threat poses.[Har68] Even those suggesting that the tragedy of the commons concern is overstated

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recognize that, with respect to uses like “citizen’s band” (CB) radio, the large amounts of interference caused by amplifiers and other non-envisioned uses undermined the once significant popularity of this medium.[Tin03] One can easily envision a similar problem occurring with a boom in wireless networking if the devices fail to work as advertised because rival uses create undue interference – such as occurs with uses such as the “Wi-fi Hog” invented at MIT – and undermines the level of promised performance.

Much of the literature touting the promise of unlicensed spectrum answers the tragedy of the commons concern with the “comedy of the commons” scenario.[Ben02] This scenario envisions a positive feedback loop wherein users all cooperate by using common protocols that actually improve the experience of their neighbors. This scenario draws support from careful empirical work that has identified scenarios under which neighbors do work together in this fashion.[Ost90] The problem in this argument, however, is that this empirical work specifies that the comedy of the commons scenario is most likely where neighbors know one another, are limited in number, and share understood common objectives. In the CB radio context, for example, the medium could work well when a defined universe of hobbyists and truckers all used it followed certain social norms. But the entry of those who neither understood nor cared to follow the social norms undermined the medium’s reliability and previous character.

The more sophisticated version of the comedy of the commons argument for unlicensed uses envisions that technical standard setting committees composed of the interested equipment manufacturers can work together to develop the relevant protocols. This argument envisions both that this increasingly diverse set of interests will be able to agree upon protocols that will enable unlicensed spectrum to work together and with licensed uses without causing undue interference and that compliance with those protocols will be self-enforcing. Along these lines, commons advocates point with anticipation to the efforts by the IEEE Task Group 802.15.2 to develop recommended practices for the collaborative use of Wi-Fi and Bluetooth devices in the 2.4 GHz band, suggesting that this effort may well be all that is needed to ensure the success of increased unlicensed uses. This argument may well be wishful thinking, however, because there are persuasive “economic arguments that question whether marketplace forces alone would result in competing protocols reaching a stable equilibrium in the marketplace that would maximize the throughput of a band.” [FCC02b].

The FCC, like the Working Group in the SPTF Report addressing unlicensed uses, appreciates that the vision of a self-correcting policing of the commons may well be more fantasy than reality. This is not to suggest that the enlightened self-interest of at least some equipment manufacturers will not be an important force in developing solutions or that the FCC needs to occupy the entire realm of developing and enforcing protocols. It does suggest, however, that the FCC must look both for ways to develop a regulatory framework that relies on and works in concert with the efforts of private bodies as well as recognizes the important role for government oversight and involvement [FCC02b]. This effort might require, for example, the FCC to ask the private body to report back on its progress and the FCC to ultimately enforce the use of the protocols recommended by the body. This proposal would investigate under what commons protocols defining uses of common spectrum are most likely to be developed and enforced as well as how the FCC can best oversee, facilitate, and play a role in this process. It will also consider to what extent the FCC’s old tools (i.e., equipment certification and a process for fining those using the spectrum illegally) can be made to work effectively in this environment and to what extent that new interference mitigation techniques will require the development of new approaches.

2 Research ObjectivesThe research in this proposal would target the following objectives.

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1. Initiate an open radio competition designed to demonstrate effective spectrum sharing mechanisms, to explore the consequences of specific mechanisms, and to bring out the challenges and limits of more flexible spectrum policies.

2. Conduct multiple geographic diverse measurements within two specific frequency bands which represent extremes in spectral allocations. Define and characterize the spectral efficiency of each band. In addition, estimate the potential of each band for spectral sharing and new approaches toward spectral allocations which will help bound the future allocation/regulation possibilities.

3. Examine architectural and design options with respect to hardware and software requirements, information requirement, potential for cooperative operation and implications of command and control. The objective is to determine a set of optimal architectural and operational models.

4. Develop a software designed radio hardware platform and open source API’s that will be low cost and accessible to the larger research community.

5. Design network protocols that enable transmitters to exchange and collect spectrum usage information. This includes implementations and open source release for experimentation and development.

6. Define a data model and middleware architecture that allows for policy rules to be communicated to devices in a meaningful and flexible manner. This includes the specification of data elements, data models, schemas, profiles and bindings.

The results of the above research objectives will interact with and inform our final and most important objective.

7. To develop a strategy, based on careful policy analysis, of when and how the FCC should play a role in developing and enforcing the protocols that facilitate effective shared use of unlicensed spectrum.

3 Work PlanThe proposal will be a three year effort.

3.1 Year 1 efforts

(a) The hardware and protocol development will start with a requirements definition process that will interact with our initial spectrum measurements and regulatory framework development. We will complete the architecture and design assessment; assess the measurement procedure and equipment; develop the requirements for expressing policy rules, the formats for such expressions, and network protocols for their exchange; determine which middleware approach to pursue; explore potential SDR platforms; and define a radio competition framework.

(b) The heart of the first year’s effort at developing a regulatory framework will be to identify the conditions where a self-regulating strategy can work in enforcing protocols that facilitate shared uses of unlicensed spectrum. At a minimum, this will envision a paper that highlights the need for an appreciation for how FCC involvement – taking an active role in enforcement, for example – is necessary to ensure an effective use of unlicensed spectrum. A policy conference with this theme will be held.

3.2 Year 2 efforts

(a) The second year hardware and protocol development will be an implementation process that will feed the developing regulatory framework. We will focus the details of the data model and how the elements contained in this model will be communicated; we will incorporate this model into our hardware platform

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and develop APIs to ease software development; and the first radio competition will be designed and held. The spectral measurement campaign will be a concentrated within this year.

(b) The heart of the second year’s effort with regard to developing a regulatory framework will be developing a “best practices” model for how the FCC can work, possibly in partnership with existing standard setting bodies, to enforce protocols that facilitate effective uses of unlicensed spectrum. A policy conference on this theme will be held.

3.3 Year 3 efforts

(a) This final year will focus on the performance and capabilities of the hardware and protocols. Limitations on throughput, rate of adaptation, and ability to avoid harmful interference with licensed users will be assessed. The experiences from the first radio competition will be evaluated and the second radio competition will be held.

(b) The heart of the regulatory strategy efforts in the final year will be to link up the regulatory reform proposals with the learning about interference mitigation strategies and available spectrum, thereby weaving the three components together into a coherent case for regulatory reform. In so doing, we would envision drawing on international case studies, experiments in local (likely rural) communities, and analogous areas to make the case both domestically and internationally for how to best facilitate effective use of unlicensed spectrum. A policy conference on this theme will be held.

4 Relation to Longer-term Goals and Results from Prior NSF SupportDirk Grunwald and Tim Brown are jointly working on ANI-0082998 “ITR: Energy and Quality of

Service Aware Ad-Hoc Networking,” We have developed mechanisms to reduce system power in ad hoc networks, with hardware implementations and extensive testing on hardware and software test beds. The proposal is currently supporting two masters and three Ph.D. students. Publications from this grant include [BDS03, BrG01, BGZ01, DBB02, GrG03a, GrG03b, JGD02, NJG02, SBB03].

The work in this proposal supports Tim Brown’s longer term goals in developing adaptive wireless network elements that cooperate for their communication. In ongoing projects, he is developing hardware platforms for 802.11b networks for an outdoor, long range, mobile ad hoc network.

Dirk Grunwald received a NSF Research Initiation Award CCR 9010624 ``Empirical Studies of Process Distribution and Redistribution in Multicomputers,'' was an investigator on NSF Grand Challenge ASC-9217394 ``Coupled-Field and GAFD Turbulence,'' and was a PI on MIP-9706286 ``Memory Prefetching.'' He has also been supported by ARPA, NASA, Hewlett-Packard, Digital Equipment Corporation, Compaq, Microsoft and the state of Colorado.

Students supported by NSF 0072870 ``Speculation Control for Energy Efficiency'' have published papers related to aspects of speculation control and microarchitectural denial of service. Additional funding and equipment for work on thread level speculation control was provided by Intel.

NSF Award 9988548 ``Energy Efficient Operating Systems for Pocket Computers'' has produced papers on the evaluation of different clock scaling, power efficient disk systems, and energy efficiency in pervasive computing systems. The project has developed a multi-architecture system for supporting ``clock and voltage scaling'' on different computer platforms. Work is progressing beyond the original focus on clock and voltage scaling to reducing power due to I/O and on other aspects of mobile computing platforms including privacy and anonymity in mobile systems.

NSF Award 0082998 ``Energy and Quality of Service Aware Ad-Hoc Networking'' has produced and deployed a ad hoc mobile computing environment that combines elements of the Click Modular Router, locally developed ad hoc networking components and embedded Linux systems. This system also uses a co-simulation environment based on extensions to the ``ns2'' network simulator that lets the same code

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base be used in simulation and deployment. This system facilitates investigation into MAC, network and transport layer improvements for wireless networks.

Dr. Grunwald is also a co-PI on an NSF RI award, 0080146 ``CISE Research Infrastructure: Digital Common Space.'' This award provides infrastructure support for mobile and wireless computing with the Department of Computer Science, including this project.

Dr. Grunwald is a co-PI on an NSF Network Resources Testbed award, ``Heterogeneous Wireless Access Network Test Bed'', a joint award with Stevens Institute. To date, that proposal has funded work on a common software router platform coupled with a software defined radio system provided by Vanu, Inc.

The focal point of Dennis Akos' research and teaching has been on satellite navigation receivers and optimizing their performance.  This has included the impact of radio frequency interference and spectral overlays.  Global Navigation Satellite Systems (GNSS), such as the Global Positioning System (GPS), are being proposed for a number of safety critical systems and operate in protected frequencies bands.   Any possible changes to how these frequencies bands are utilized and regulated must be considered prudently as it is of critical importance to achieve the highest, most robust performance.   At the same time, the functionality of GPS is greatly enhanced through the use of a local communications link to provide differential corrections.  The current, or apparent, spectral congestion, complicates the availability of such data links.  Improved use of the existing frequency spectrum will also enable enhanced GPS performance as well.  Lastly, Dennis' efforts in software radio architectures for GNSS have included radio architectures well suited to better spectrum management.  Thus this research will help to determine spectral allocations that can be used more effective, yet preserving the integrity of the safety of life systems which operate within the current allocations.

Douglas C. Sicker is currently working on developing adaptive middleware solutions for various networking problems.  Much of this work involves the development of formats, bindings, profiles and protocols to assist the user (or an accurately the application) in performing some real-time communication, such as voice or videoconferencing.  Part of this work was funded through an NSF Middleware grant to Internet2 and has been contributed to the IETF SIPPING working group. His other research interest is in the area of policy models for future telecommunications regulation.  Specifically, he is interested in examining what policy and regulatory models might best apply to future communications technology and architectures. Recently he has become interested in combining his technical and policy interests and applying them to the area of adaptive wireless devices.  More specifically, he is interested in developing formats and profiles that could be used to invoke spectrum policies.  By developing a structure that accurately and flexibly allows policies to be communicated among devices, we should be able to move from the present static approach to spectrum management to a more efficient and reliable dynamic approach.

For both Professors Hatfield and Weiser, the intersection of technical standard setting and public policy is a continuing area of interest. Dale Hatfield, who as the FCC’s Chief Technologist and Chief Engineer, played a critical role in the discussions that led up to the FCC’s Spectrum Policy Task Force report. Moreover, he has written widely on spectrum policy in the past, including a leading role in the Aspen Institute’s analysis of spectrum policy [Hat03] and seminal work that helped to define spectrum policy research and analysis [Hat84]. In taking on this project, both Professors Hatfield and Weiser believe they can facilitate a much greater awareness of the intricacies related to this issue than currently appreciated by most academics and policymakers.

Professor Weiser’s research agenda has focused, almost entirely, on institutional strategies for implementing telecommunications and Internet policy. (In another line of his scholarship, he has received NSF funding as a co-PI to conduct a longitudinal panel survey examining how jury deliberation changes jurors’ subsequent political attitudes and behaviors (Directorate for Social, Behavioral & Economic Sciences: Law and Social Science Program, NSF Award #0318513).) His penultimate work in the telecommunications policy area will be a book (written with Jon Nuechterlein), tentatively entitled

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“Understanding Telecommunications Policy: The Law and Economics of Competition in The Digital Age” to be published by MIT Press in early 2005. His past work on this topic has included particular attention to situations where public good-type standards – such as the protocols necessary to facilitate unlicensed uses – are likely to be developed and enforced through private efforts and where governmental intervention is necessary to ensure that they are developed and enforced effectively. In particular, Professor Weiser developed and employed such an analysis in past articles [Wei01,Wei03].

Dale Hatfield, as Chief Technologist and then Chief of the Office of Engineering and Technology at the FCC, played a critical role in both internal and external discussions that led to a number of initiatives including the agency's actions in spectrum leasing and in launching the Spectrum Policy Task Force. His work in spectrum management spans three decades and includes a widely cited early (1977) paper on measures of spectral efficiency in land mobile radio systems. [Hat77] In addition to writing and teaching in the area, on numerous occasions, Mr. Hatfield has also testified on spectrum management topics before Congress. In doing so, he brings a unique background having served in senior level positions in spectrum management in both the FCC and in the Executive Branch (as Acting Assistant Secretary of Commerce for Communications and Information).

5 Impact of the ProposalThe field of spectrum policy-related research is relatively limited to date, with the FCC’s Spectrum

Policy Task Force underscoring the need for more careful interdisciplinary research in this area. At this point, the three areas identified in the proposal – characterizing existing spectrum and feasible sharing methodologies, developing and demonstrating the effectiveness of software-defined protocols, and enforcing adherence to those protocols are – are all essential areas for the FCC to develop confidence in before it can implement its ambitious spectrum reform agenda. As noted above, there are only a limited number of academic studies in this area and, to date at least, the FCC has yet to receive much constructive feedback on these issues. With a successful completion of this proposal, we believe that the FCC and academics studying this question will gain much needed insight into the realities of implementing some of the solutions and necessary steps both to realize the SPTF Report’s recommendations and the goal of facilitating greater access to unlicensed spectrum.

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6 Coordination PlanThe University of Colorado enjoys a privileged position in the world of spectrum policy and thus is

uniquely suited to sponsor a research initiative on spectrum policy reform. Notably, the Interdisciplinary Telecommunications Program (ITP) has brought together a series of accomplished teachers and researchers – including Dale Hatfield, Tim Brown, Doug Sicker, and Phil Weiser – all of whom possess critical and related expertise in this area. They are joined by Dirk Grunwald and Dennis Akos who bring specific technical research capabilities to the proposal. Of the group, Tim Brown, Dirk Grunwald, and Dennis Akos are accomplished researchers in the area of wireless spectrum technology and Dale Hatfield, Doug Sicker, and Phil Weiser all (in addition to their academic credentials) served recently in senior telecommunications policy positions. Moreover, the reputation of the Program and its faculty ensures that numerous talented students from across the United States and the world will be available to work on this project. Since its founding in the early 1970s, ITP has educated CEOs of companies such as StorageTek and WildBlue, top flight academics, and leading government policymakers.

6.1 Specific Roles on the Proposal:

The proposal is comprised of faculty from Interdisciplinary Telecommunications, Law, Electrical Engineering, Computer Science, and Aerospace Engineering.

Tim Brown, with a joint appointment between ITP and Electrical and Computer Engineering, will be responsible for the overall success of the proposal. His research will contribute to the network protocols and measurement work under the proposal. He will also take the lead on developing the radio competition and running the ISART conference described below.

Dennis Akos, Aerospace Engineering, will be responsible for the spectrum allocation assessments and measurements. His research will contribute to the measurement methodology, the hardware platform development, and the competition framework.

Dirk Grunwald, with a joint appointment between Computer Science and Electrical and Computer Engineering, will be responsible for the SDR platform development. His research will contribute to producing an easy to program and use SDR hardware and to the network protocols. He will take the lead on making the platform available through open source mechanisms.

Dale Hatfield, ITP, will be responsible for overseeing the connections between technology and policy as well as for developing the regulatory framework envisioned by the proposal. His research will contribute to best practices in spectrum management and the specific rules for spectrum sharing. He will also take the lead in interfacing with the proposal’s advisory board described below.

Doug Sicker, with a joint appointment between ITP and Computer Science, will be responsible for developing the data model and middleware for the proposal. His research will contribute to defining information models and architectures that support shared spectrum.

Phil Weiser, with a joint appointment between ITP and Law, will be responsible for developing (along with Dale Hatfield) and promoting the regulatory framework envisioned by the proposal to the larger policy community. His research will contribute to enforcement of shared spectrum policy rules. He will also run an annual Silicon Flatirons spectrum policy conference described below.

6.2 Cross Discipline Coordination:

The personnel on the proposal have worked closely on a number of past projects and have regular interactions that cross the technology-policy boundary. The faculty will meet on a regular basis and jointly advise students to augment these interactions. Specific cross-disciplinary activities are described in the next section.

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6.3 Coordination Mechanisms:

The University of Colorado enjoys an unparalleled reputation for spurring thinking on spectrum policy topics. Over the last four years, the Silicon Flatirons Telecommunications Program [SFT04] has established itself – under Professor Weiser’s leadership - as a unique center for evaluating spectrum policy reform issues. During that time, Silicon Flatirons has hosted major policy addresses on spectrum policy by FCC Chairman Powell [Pow01], FCC Commissioner Jonathan Adelstein [Ade03], FCC Spectrum Policy Co-Chairs Peter Tenhula and Paul Kolodzy as well as a debate between Gerald Faulhaber and David Reed on the merits of the unlicensed versus the licensed approaches. Moreover, Silicon Flatirons has established the Journal on Telecommunications and High Technology Law, which has helped to elevate telecommunications policy debates. [Whi03]. Consequently, Boulder is increasing known as “a hotbed for telecom policy” and a place for “creative discussions” among leaders in government, academia, and industry. [Mar03a] An annual Silicon Flatirons conference specifically on the issue of spectrum policy involving all project personnel will be organized under this proposal.

Developing a spectrum policy research program in Boulder is also a natural because the National Institute of Standards and Technology (NIST) and the Institute for Telecommunication Science (ITS) government laboratories are located here. Among other things, ITS helps to support the International Symposium on Advanced Radio Technologies (ISART), which Professors Brown and Sicker have organized [ISA04]. This year’s conference is attracting the leaders in the spectrum policy field, including former FCC Chief Technologist David Farber, DARPA Program Manager Preston Marshall, FCC Chief of Staff Bryan Tramont, and Assistant Secretary of Commerce for NTIA, Michael Gallaghar. The personnel on this project will continue to support the organization of this conference.

As part of this initiative, the research team would leverage the existing reputations and traditions of Silicon Flatirons and ISART to develop a more sustained evaluation of the spectrum policy issues at the heart of this proposal. To help raise the level of attention given to and support our thinking about these issues, we envision relying on a top flight Advisory Board. Thus far, former former FCC Chief Economist and Wharton Professor Gerald Faulhaber and Rutgers Law Professor Ellen Goodman have agreed to support our efforts and we envision attracting two or three other leaders in the field as well (such as FCC Spectrum Policy Task Force Chair Paul Kolodzy and former FCC Wireless Bureau Chief Tom Sugrue (and current Vice President at T-Mobile)). Among other things, we would envision bringing out these individuals at least annually for a planning meeting that would coincide with ISART and/or a Silicon Flatirons conference.

Boulder’s ideal location and our ongoing strengths will facilitate a number of other benefits for our project. First off, we envision holding the radio competition in conjunction with ISART to connect the technology developments with spectrum policy and raise awareness among spectrum policy regulators. Second, we believe that the Interdisciplinary Telecommunications Program distance learning infrastructure will enable Dale Hatfield, in concert with other members of the research team, to develop a course that can be used around the world to provide a valuable primer on the state of spectrum policy. Third, we would envision developing a policy lunch series that would enable governmental, industry, and academics interested in these issues to meet at regular intervals to share ideas. Finally, we would envision developing partnerships with state government leaders in Colorado and elsewhere to investigate and experiment with using unlicensed wireless solutions to provide broadband in rural areas.

Finally, we envision a significant outreach program both to rural areas and internationally. The learning about how to facilitate the best uses of unlicensed spectrum is only beginning and countries around the world – as well as rural constituencies across the United States – are eager for insights about to harness innovative technologies involving unlicensed spectrum. In many cases, governments will be able (and, perhaps, will need) to play an oversight role that identifies “cheaters” and ensures effective use of spectrum. By publishing and publicizing our findings, as well as looking for and documenting best practices, we believe we can ensure that our research is both well grounded and put into practice.

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6.4 Coordination Budget:

As seen in the previous section, the coordination plan is comprised of significant joint activities among project personnel. The budget supports this coordination plan in a number of ways. The conference activities are supported by the participant support costs, speaker travel and per diem, and 20% of the undergraduate hourly. The advisory board is supported by the advisory board travel and per diem and consulting fees. The radio competition is supported by the participant support costs, and 20% of the undergraduate hourly in years 2 and 3. The joint course development is supported by the publication costs and one international trip per year. The rural outreach by project personnel is supported by the 3 domestic trips per year. Together these costs total: $186,000. This is approximately 10% of the budget.

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References[Ade03] Jonathan S. Adelstein, Silicon Flatirons Seminar, Boulder, CO, April 9, 2003. http://hraunfoss.fcc.gov/edocs_public/attachmatch/DOC-234658A1.pdf

[Alm03] J. Wayde Allen, Ted Mullen, Digital Television (DTV) Field Strength and Video Quality Study, NTIA Technical Memorandum TM-03-405, August, 2003.

[Ben02] Yochai Benkler, “Some Economics of Wireless Communications,” 16 Harv. J.L. & Tech. 25, (2002).

[Ben03] Stuart Minor Benjamin, “Spectrum Abundance and The Choice Between Private and Public Control,” 78 N.Y.U. L. Rev. 2007 (2003)

[BDS03] S. Bhandare, S. Doshi, S. Sanghani, and T. X Brown. “Comparison of two wireless ad hoc routing protocols on a hardware test-bed.” In Proc. Wireless Communication Networking Conference. IEEE, 2003.

[BrG01] T. X Brown and H. N. Gabow. A comparison of energy aware routing objectives in a wireless ad hoc network. In Proc. 39th Annual Allerton Conference on Communication, Control, and Computing, pages 791–792, October 3–5 2001.

[BGZ01] T. X Brown, H. N. Gabow, and Q. Zhang. Maximum flow-life curve for a wireless ad hoc network. In Proc. Symposium on Mobile Ad Hoc Networking and Computing, pages 128–136. ACM, 2001.

[Cal04] Michael Calabrese, “Spectrum Reform an Urgent Priority,” The Hill, February 4, 2004, http://www.thehill.com/news/020404/ss_calabrese.aspx

[Car03] Kenneth R. Carter et al., “Unlicensed and Unshackled: A Joint OSP-OET White Paper on Unlicensed Devices and Their Regulatory Issues” 50 (May 2003) http://hraunfoss.fcc.gov/edocs_public/attachmatch/DOC-234741A1.pdf

[Chap02] Chapin, J., “Software Radio Technology and Challenges”, 2002, white paper available at www.vanu.com/ publications/vanuinc-telemetry-10-23-02.pdf.

[DBB02] S. Doshi, S. Bhandare, T. X Brown, “An On-demand minimum energy routing protocol for a wireless ad hoc network,” Mobile Computing and Communications Review, vol. 6, no. 2, July 2002.

[DBF04] AIAA Design/Build/Fly competition homepage, http://www.ae.uiuc.edu/aiaadbf/

[Dil02] Dillinger, et.al., “Decentralized Software Distribution for SDR Terminals,” IEEE Wireless Communications, April, 2002.

[FaF03] Gerald Faulhaber and David Farber, “Spectrum Management: Property Rights, Markets, and the Commons,” Telecommunications Policy Research Conference Proc. (2003) http://rider.wharton.upenn.edu/~faulhabe/SPECTRUM_MANAGEMENTv51.pdf.

[FCC01] Federal Communications Commission, First Report and Order on Software Defined Radio, Docket No. 01-264, Sept., 2001.

[FCC02a] Federal Communications Commission, Spectrum Policy Task Force Report, ET Docket No. 02-135, November 2002.

[FCC02b] Federal Communication Commission, “Spectrum Policy Task Force, Report of the Unlicensed Devices and Experimental Licenses Working Group” 12-13 (Nov. 15, 2002) http://www.fcc.gov/sptf/files/E&UWGFinalReport.doc.

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[FCC03a] Federal Communications Commission. In re Matter of Establishment of an Interference Temperature Metric to Quantify and Manage Interference and to Expand Available Unlicensed Operation in Certain Fixed, Mobile and Satellite Frequency Bands, ET Docket No. 03-237, Notice of Inquiry and Notice of Proposed Rulemaking (Nov. 28, 2003)

[FCC03b] Federal Communications Commission, Facilitating Opportunities for Flexible, Efficient, and Reliable Spectrum Use Employing Cognitive Radio Technologies, ET Docket No. 03-108, Notice of Proposed Rulemaking (Dec. 30, 2003).

[FCC03c] Federal Communications Commission, See Interference Immunity Performance Specifications for Radio Receivers, ET Docket No. 03-65, 18 FCC Rcd 6039 (2003).

[GrG03a] Marco Gruteser and Dirk Grunwald. Anonymous usage of location-based services through spatial and temporal cloaking. In Proceedings of the First International Conference on Mobile Systems, Applications, and Services, 2003.

[GrG03b] Marco Gruteser and Dirk Grunwald. A methodological assessment of location privacy risks in wireless hotspot networks. In Proceedings of the First International Conference on Security in Pervasive Computing, 2003.

[GuK00] Gupta, P.; Kumar, P.R.; The capacity of wireless networks, Information Theory, IEEE Transactions on, Volume: 46 Issue: 2, March 2000 Page(s): 388-404

[Har68] Garrett Hardin, The Tragedy of the Commons, 162 Science 1243, 1244- 45 (1968)

[Hat77] Hatfield, D. N., “Measures of spectral efficiency in land mobile radio,” IEEE Trans. Electromagn. Compat., vol. EMC-19, pp. 266-268, Aug. 1977.

[Hat84] Hatfield, D. N., “FCC Regulation of Land Mobile Radio – A Case History,” chapter 3 in Telecommunications: An Interdisciplinary Text, Leonard Lewin Ed., Artech House, 1984

[Hat03] Hatfield, D. N., “The Current Status of Spectrum Management,” in Balancing Policy Options in a Turbulent Telecommunications Market, A Report to the Seventeenth Annual Aspen Institute Conference on Telecommunications Policy, Robert Entman, Rapporteur, 2003.

[How02] Howitt, I.; Bluetooth performance in the presence of 802.11b WLAN, Vehicular Technology, IEEE Transactions on, Volume: 51 Issue: 6, Nov. 2002 Page(s): 1640-1651

[IEE86] IEEE Report 430-1986 IEEE Standard Procedures for the Measurement of Radio Noise from Overhead Power Lines and Substations (1986)

[IEE96] IEEE Report C63.2-1996 American National standard for Electromagnetic Noise and Field Strength Instrumentation, 10 Hz to 40 GHz – Specifications (1996)

[IEE01] IEEE Report C63.4-2001 American National Standard for Methods of Measurement of Radio Noise Emissions from Low Voltage Electrical and Electronic Equipment in the Range 9 KHz to 40 GHz (2001)

[ISA04] The International Symposium on Advanced Radio Technologies, 2004. http://its.bldrdoc.gov/meetings/art/index.php

[JGD02] Ashish Jain, Marco Gruteser, Jing Deng, Feng Zhao, and Dirk Grunwald. Exploiting physical layer power control mechanisms in ieee 802.11b network interfaces. Technical Report CU-CS-924-01, University of Colorado, Boulder, CO, 2002.

[Kes04] Michelle Kessler, Wi-Fi Changes Virtually Everything, USA Today (February 18, 2004) http://www.usatoday.com/tech/webguide/internetlife/2004-02-18-wifi_x.htm.

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[Kla03] Erica Klarreich, “The Bidding Game,” Beyond Discovery, (March 2003) http://www.beyonddiscovery.org/content/view.txt.asp?a=3681

[LGW04] Alberto Leon-Garcia, Indra Widjaja, Communication Networks, Fundamental Concepts and Key Architectures, 2nd Ed. McGraw Hill, 900p. 2004.

[LAP00] Ming Luo, Dennis Akos, Sam Pullen, Per Enge, "Potential Interference to GPS from UWB Transmitters, Test Results. Phase 1A: Accuracy and Loss-of-Lock testing for Aviation Receivers," Stanford University, 26 October 2000.

[Mar03a] Sue Marek, “Professor Draws Regulators To Boulder,” Wireless Week ( July 15, 2003) http://www.wirelessweek.com/article/CA310934?ticker=Q&type=stockwatch.

[Mar03b] Paul Margie, “Can You Hear Me Now?: Getting Better Reception from the FCC's Spectrum Policy,” 2003 Stan. Tech. L. Rev. 5, 22 (2003) http://stlr.stanford.edu/STLR/Articles/03_STLR_5/index.htm.

[Moh02] Mohyeldin, et.al., “Structure and Management of SDR System Profiles”, 2002, 2002 Software Defined Radio Technical Conference, 11, 2002. http://www.sdrforum.org/sdr02/papers.html.

[NAS03] NASA Noise Floor and Ultra Wideband (UWB) Effects Study RF Test Program Overview, Doc. 33263/1 (2003)[NTI95] NTIA Report 95-321 Broadband spectrum Survey at Denver, Colorado (1995)

[NTI96] NTIA Report 96-330 The Natural and Man-Made Noise Environment in the PCS Bands (1996)

[NTI97] NTIA Report 97-336 Broadband spectrum Survey at Los Angeles, California (1997)

[NTI02] NTIA report 02-390 Man-Made Noise Floor Measurements at VHF and UHF Frequen-cies (2002)

[NS204] The network simulator, ns-2, http://www.isi.edu/nsnam/ns/

[NJG02] Michael Neufeld, Ashish Jain, and Dirk Grunwald. Nsclick: bridging network simulation and deployment. In Proceedings of the 5th ACM international workshop on Modeling analysis and simulation of wireless and mobile systems, pages 74–81. ACM Press, 2002.

[Omn04] OMNeT++ Discrete Event Simulator http://www.omnetpp.org/

[Opn04] Opnet Modeler http://www.opnet.com

[Ost90] Elinor Ostrom, Governing the Commons: The Evolution of Institutions for Collective Action (1990).

[Pow01] Michael K. Powell, “Digital Broadband Migration Part II,” Press Conference, Boulder, CO, October 23, 2001. http://www.fcc.gov/Speeches/Powell/2001/spmkp109.html

[Rob04a] The RoboCup Official Site, http://www.robocup.org/

[Rob04b] The RoboCup Soccer Simulator, http://sserver.sourceforge.net/

[SBB03] S. Sanghani, T. X Brown, S. Bhandare, and S. Doshi. Tabletop emulation of mobile ad hoc wireless networks. In Proc. Wireless Communication Networking Conference. IEEE, 2003.

[SCA01] The SCA W orking Group Document Summary, See www.sdrforum.org/MTGS/mtg_24_jun01/01_i_0028_v0_1_00_scastatus_mcclimens_05_28_01.pdf

[She96] Timothy J. Shepard, “A Channel Access Scheme for Large Dense Packet Radio Networks,” ACM SIGCOMM 1996.

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[SFT04] Silicon Flatirons Telecommunication Program, http://www.silicon-flatirons.org/

[Tin03] Carol Ting et al, The U.S. Experience With Non-Traditional Approaches to Spectrum Management, Presented at Telecommunications Policy Research Conference, September 19, 2003, http://quello.msu.edu/wp/wp-05-03.pdf.

[TM04] Table Mountain National Radio Quiet Zone, http://www.its.bldrdoc.gov/table_mountain/

[Vanu01] Chapin, et.al., “Experiences Implementing GSM in RDL,“ MILCOM 2001, Oct. 2001.

W3C01] W3C Consortium “Composite Capability/Preference Profiles (CC/PP): Structure and Vocabularies”. W3C Working Draft , 2001; URL: http://www.w3.org/TR/CCPP-vocab/

[W3C04] Data Object Models described at http://www.w3.org/DOM/DOMTR

[WDL02] WDL Overview, at http://www.computing.surrey.ac.uk/personal/pg/E.Willink/wdl/WdlOverview.html

[Wei01] Phil Weiser, “Standard Setting, Internet Governance, and Self-Regulation,” 28 N. Kent. L. J. 822 (2001).

[Wei03] Phil Weiser, “The Internet, Innovation, and Intellectual Property Policy,” 103 Colum. L. Rev. 534 (2003)

[Whi03] Richard S. Whitt, “A Horizontal Leap Forward” MCI White Paper, (December 2003) http://global.mci.com/about/publicpolicy/presentations/horizontallayerswhitepaper.pdf

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7 Budget JustificationThis proposal has a number of elements that span technical research requiring specialized equipment

to research dissemination through conferences, an advisory board, and a radio competition. The bulk of the budget funds personnel including 7-10 students over the proposal. Participant support costs are included to pay for participant travel and expenses associated with running the competition and the conferences.

The travel budget can be broken down to personnel travel for the purpose of presenting the work (seven domestic and one international trip); travel associated with bringing speakers and advisory board members for annual conferences and board meetings ($15k/yr); and personnel travel for coordinated outreach (three domestic and one international trip).

The other direct costs category includes funds for university software support, and monies for buying computer and software for personnel necessary for the completion of the project. The publication costs include $5k/yr to cover the cost of packaging courses that result from the coordinated course development. The books and manuals line covers the cost of specialized literature for th FPGA programming and firmware development. The consultants fees is $1000/yr for each of the advisory board members to cover their time and effort. Tuition covers a mix of in state and out of state students present in our research groups.

A significant hardware effort will be required to conduct the comprehensive measurement campaign, the investigation of various SDR architectures, as well as hosting/judging a radio competition. The facilities and existing equipment at the University of Colorado will be utilized to their best extent but it is inevitable to order specific hardware for the investigation. The two primary hardware components will be: (1) a high accuracy spectrum analyzer for use within the spectral measurement campaign; and (2) a vector signal analyzer which can be used for calibration and as a reference within the radio competition. It is important to recognize that the hardware will be used between different research elements to maximize effectiveness. For example, the spectrum analyzer will be the key component in the spectral measurement effort, but it will also be used extensively within the radio competition.

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Hardware Equipment for Measurement Campaign (estimated)

Agilent 8561EC Spectrum Analyzer 30 Hz – 6.5 GHz capabilities with signal identification and

phase noise measurement capabilities

$42.5k

Preamplification & Frequency Selective Components low noise amplifiers, cavity filters, switches

$7K

RF Cabling and Adapters $5KAntenna Elements

directive high gain, broadband, multi/element array, and omnidirectional varieties; motion control for directive antennas

$16k

Commercial Receiver Elements GPS receiver(s) with automatic gain monitoring capabilities,

various 2.4 GHz devices (WiFi, Bluetooth, Cordless telephones/cameras)

$16.5k

Analog-to-Digital & Digital-to-Analog Converters (ADC & DAC) Standalone ADC & DAC evaluation boards, PC-based data

acquisition boards

$6k

Accessories Power conditioning, thermal monitors, remote power supplies,

$7k

Total $100k (est)

Hardware Equipment for SDR Development/Spectral Contest (estimated)

Agilent 89641 Vector Signal Analyzer Single RF channel, 20 MHz – 6 GHz tuner module, software

demodulation, host PC control

$50k

Antenna/Front-End Toolbox Includes various elements not used in the measurements

campaign: antennas, discrete components for the construction of a superheterodyne front end designs, GNU Radio Microtune evaluation board(s)

$20k

Digital Interface Components Data bridges between the digitizing and computational

elements> USBv2, Firewire/1394, FPGA-based PC data buses

$15k

Signal Processing Elements Reconfigurable hardware for the implementation of SDR

algorithms: FPGA, DSP, and Microprocessor development environments

$12.5k

Total $100k (est)

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8 Facilities and EquipmentThis proposal will use the facilities available to the University of Colorado Department of Electrical

and Computer Engineering, Department of Computer Science Aerospace Engineering, and the Interdisciplinary Telecommunications Program.

The engineering school has built one new building in 1997 (the Integrated Teaching and Learning Lab) and in September 2002 completed a new building committed to research (the Discovery Learning Center). This DLC houses the PI's Pervasive Communication Lab. This lab studies densely interconnected networks, low power wireless devices, and limits of networked communication. This lab consists of RF test and measurement equipment, industry standard radio system design tools, a dozen 802.11b equipped laptops and PDAs, and a hardware test bed that allows us to emulate wireless network scenarios in a controlled environment. A current focus is the development of energy aware ad hoc wireless protocols based on LINUX and 802.11b

The Department of Electrical and Computer Engineering and Interdisciplinary Telecommunications Program will provide the office space and basic infrastructure for the program. The ITP has a 1600 square feet multimillion-dollar telecommunications lab with state-of-the-art routers, switches, network performance testers, RF and cellular system measurement equipment, and network, cellular, and satellite system modeling software. The laboratory provides instruction opportunities in the latest telecommunication technologies, offers a facility for student and faculty research, serves as a focus for partnership with industry, and supports department activities in both on-campus and distance learning. The laboratory has the capacity to simulate large wireless, telephony and data networks. The current capabilities include VoIP, PBXs, ATM, Frame Relay, DSL, ISDN, as well as very extensive advanced routing and switching technologies including MPLS and VLANs. In terms of specific wireless equipment, the laboratory contains a wide range of wireless networking and test gear. This includes wireless LAN gear for traffic analysis, packet sniffing, signal strength evaluation, channel contention, utilization-throughput, collisions generation/evaluation, channel scanning, security assessment, installation site survey, connection troubleshooting. We also have extensive cellular equipment, including PCS interfaces, a cell site test set, PCS a frequency converter and a CDMA mobile station test set (see http://itdlab.colorado.edu/equipment.html)

The Aerospace Engineering Sciences department has multiple labs devoted to navigation systems and receiver design. These include an array of various Global Positioning System receivers as well as various antenna and radio frequency front end components all used within navigation receiver design.

Computer science has an NSF RI funded Tera-flop computing farm available for simulation work. It also has a $2M NSF RI titled “Digital Common Spaces” which funds a variety of wireless networking equipment including experimental indoor and “last mile” wireless prototypes. They have research groups working on sensor networks and ad hoc wireless network technologies, which add equipment, facilities, and expertise for this proposal.

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