To understand the role that the Boulder telecommunications laboratories currently play and can play in the economic vitality of the country, it is important to understand the role of spectrum in the wireless networking and mobile cellular industries and the influence that ITS has in making spectrum available to government and industry. ITS has and with the addition of CTL, will continue to have, a significant impact on analyzing and developing approaches to spectrum management. The influence of spectrum management on economic activity and national security is immense because spectrum resources are fundamental to wireless network capacity.
NEED FOR OBJECTIVE SPECTRUM METROLOGY, MEASUREMENT, AND RESEARCH
The 2014-2015 AWS-3 band auction, a band that was formerly controlled almost exclusively by the federal government, netted the federal government $41.3 billion. Other auctions have raised significant funds as well, including $13.7 billion for the AWS-1 auction in 2006 and $18.9 billion for the 700 MHz auction in 2008.
The rapid rise in the price of spectrum is due to the exponential increase in the number of Internet-connected wireless devices and the rising data demands for the applications that run on these devices, combined with the constrained supply of viable spectrum for these devices. Mobile data used in the United States doubled from 2012 to 2013 and is expected to increase by 650 percent by 2018 with the increased use of smart phones and tablets. For instance, a smart phone uses 49 times more data over a basic handset with more than a 300 percent increase in data anticipated by 2018. Tablets consume 127 times more than a basic handset, with a 370 percent increase expected by 2018.1 The Internet of Things (IoT) is another driving force behind the increased demand for spectrum. IoT revolves around increased machine-to-machine communication; it is built on cloud computing and networks of data-gathering sensors; it is mobile, virtual, and always on. Its real value is at the intersection of gathering data and leveraging it. Cloud-based applications are the key to using leveraged data. Cloud-based applications interpret and analyze the data coming from all of these IoT sensors.
The economic value of spectrum as a natural resource is reflected in the $41.3 billion auctioning of the AWS-3 band. To put the value of spectrum into perspective for the wireless carriers, consider that U.S. carriers invested $33 billion in capital expenditures in 2013.2 Note that when spectrum availability is lacking, cellular networks compensate for this by deploying more infrastructure (frequency reuse) to
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1 Cisco, “Cisco Visual Networking Index: Global Mobile Data Traffic Forecast Update 2014-2019 White Paper,” February 3, 2015, http://www.cisco.com/c/en/us/solutions/collateral/service-provider/visual-networkingindex-vni/white_paper_c11-520862.html.
2 For background on CTIA’s Wireless Industry Survey, see “Investment” at http://www.ctia.org/your-wirelesslife/how-wireless-works/wireless-quick-facts, accessed June 2014.
increase wireless data capacity. They are also now planning on utilizing the unlicensed spectrum, which has caused deep concern among Wireless LAN (WLAN) product and service providers, because that unlicensed spectrum has been relatively fairly shared using 802.11 Listen Before Talk protocols to date. Although the costs are high, wireless products and services produce more than $400 billion per year of economic impact for the United States. This economic impact will no doubt increase as new wireless applications such telehealth, machine-to-machine communications, and augmented reality take off in the coming years, placing even greater demands on spectrum use.
New spectrum (both licensed and unlicensed) to support increased use of mobile and IoT devices has been slow in emerging. The need for expertise to help determine when spectrum is underutilized and when to free it up is essential to insure speedy and reliable transition of exclusive federal spectrum to joint commercial use. This has resulted in higher capital costs for service providers as they compensate for spectrum deficiency with greater infrastructure expenditures. Likewise for license-free devices, such as 802.11 Wi-Fi, which have grown at a remarkable rate. Wi-Fi traffic in the United States is growing at 68 percent per annum, while Wi-Fi households, currently at 63 percent, are forecast to reach 86 percent by 2017.3
In general, the most useful bands in the electromagnetic spectrum are currently already devoted to supporting other services.4 Making room for new wireless services requires transitioning legacy users out of their spectrum to other parts of spectrum by using more efficient technologies before new services can be accommodated in the band.5
In 2013, a Presidential memorandum noted that sharing spectrum that is currently exclusively allocated for federal use will be a partial solution to current spectrum shortage.6 In fact, the 2014-2015 AWS-3 auction sold spectrum that was made available from freeing up federal government spectrum allocations, particularly spectrum allocated to DOD radar. ITS participated in studies that led to the transition of this band, and they continue to lead the transition of other federal bands to support commercial use. The Boulder telecommunications laboratories are among the few government facilities with the necessary skills and specialized equipment capable of performing the measurement and analysis needed for transitioning spectrum from exclusive federal use to shared commercial use. They have extensive experience in propagation and interference measurements and analyses and better access to federal facilities (especially classified or controlled facilities) to explore these issues than commercial industry. However, little fiscal support (under $2 million over the course of 2 years to ITS) has been given to support these activities.
The legislation to authorize the AWS-3 auction7 gave the federal government only 2 years to develop specifications and transition plans for billions of dollars of government assets to be relocated or altered to facilitate sharing between federal and commercial systems. The committee applauds the rapid transition of federal spectrum to shared commercial use as a very positive economic step. However, the details on how this sharing would be accomplished were not in place by the time the legislation took effect. As a result, federal agencies scrambled to set up mechanisms for sharing this $41 billion asset with the auction winners. The wireless service providers that purchased these spectrum rights took risks with this auction. Better spectrum research and engineering in advance could have helped reduce this risk, thereby increasing auction prices. The basic mechanism of how, when, and where commercial services providers
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3 Telecom Advisory Services, LLC, Final Report—Assessment of the Economic Value of Unlicensed Spectrum in the United States, February 2014, http://www.wififorward.org/wp-content/uploads/2014/01/Value-of-UnlicensedSpectrum-to-the-US-Economy-Full-Report.pdf.
4 For a discussion of current uses of spectrum, see Appendix C, “The Value and Use of Wireless Technology.”
5 This is an expensive proposition for the legacy users, requiring the purchasing of new equipment and services to support deployment.
6 Presidential Memorandum, “Expanding America’s Leadership in Wireless Innovation, Memorandum for the Heads of Executive Departments and Agencies,” The White House, June 14, 2013, https://www.whitehouse.gov/thepress-office/2013/06/14/presidential-memorandum-expanding-americas-leadership-wireless-innovatio.
7 H.R. 3630, Middle Class Tax Relief and Job Creation Act of 2012, Title V6.
will be able to use the AWS-3 spectrum is still being developed—months after the auction and very close to when the service providers legally could be able to begin their deployment.8
The AWS-3 transition issues point to a fundamental problem—the lack of neutral and sound technical knowledge to validate spectrum sharing. (Additional examples of failure in spectrum allocation can be found in Box 4.1.) The R&D for transition mechanisms and means for validating fair sharing in the laboratory and in the field should have been done well before the legislation that authorized the AWS-3 auction, anticipating that these bands might be transitioned. Long-term R&D planning by the Boulder telecommunications laboratories could have mitigated the risks associated with such a transition for both commercial and federal entities. Now the laboratories are in catch-up mode to help find answers to the key issues that would allow sharing of the band. These laboratories are the best option to answer many of the key issues associated with the transition.
A similar need for a neutral, unbiased analysis and validation of sharing mechanisms is happening in the 5 GHz unlicensed band. The WLAN (i.e., IEEE 802.11 or Wi-Fi) system suppliers and service providers are concerned about the efforts of cellular service operators and system suppliers to re-route some of their mobile network traffic into the unlicensed bands. Naturally, both sides are competing for “fair use” of this 5 GHz unlicensed spectrum and are making claims regarding fair sharing or the lack of it, many of which are speculative and without rigorous science, engineering, and practical, realistic testing mechanisms in place. The Boulder telecommunications laboratories could provide this service for the public good.
The problem of providing long-term R&D to support rapid transition of spectrum is, to a great extent, outside of the Boulder telecommunications laboratories’ control. For example, the ITS budget consists of only 30 to 50 percent from federal sources that could be applied to far reaching “what could happen” scenarios. Not only is it a relatively small percentage, the absolute dollars are small relative to the economic value of the spectrum. A limited amount of money was set aside for answering questions related to the 3.5 GHz and AWS-3 transition before the auctions, especially when compared to the value of the spectrum or even the interest lost on the auction revenues due to a delayed deployment. Furthermore, the 2012 legislation prevents significant R&D spending on transition of bands until the R&D is paid for by the auction. Hence, the revenue source that could have been paying for the transition was not available to ITS or other federal entities to speed up the transition of spectrum. While significant technical and economic risks of delays existed, adequate R&D funding was not provided to mitigate these risks.
Likewise, the 5 GHz band is currently being discussed as a candidate for sharing between federal systems and commercial users.9 However, very little R&D resources are being provided to the Boulder telecommunications laboratories to answer pressing problems related to managing interference between federal and commercial users in this band. Given the economic risks if more spectrum is not made available, a sustained investment will help maintain U.S. competitiveness in the telecommunications arena, especially given that other nations are investing significantly in telecommunications research (see Box 4.2).
Despite significant federal commitments to expand spectrum availability, little funding is available to make significant commitments to expand spectrum availability, and little funding has been made available to the individual laboratories that can provide the research and technical expertise to assist in resolving complicated questions. Moving forward, a substantive change in the mission and funding model of the Boulder telecommunications laboratories may be needed, moving from a reactive technical organization to a pro-active research organization.
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8 NTIA’s transition plans can be viewed at NTIA, “AWS-3 Transition,” http://www.ntia.doc.gov/category/aws-3-transition, accessed September 10, 2015.
9 ITS and CTL have developed initial research plans for the 5 GHz band, but a significant investment and focus on hiring the appropriate talent will be needed for the Boulder telecommunications laboratories to provide needed technical knowledge in a timely manner.
BOX 4.1
Need for Technical Review
There are numerous, often infamous, examples of times when a rigorous technical analysis could have helped in either expediting the transition of spectrum assets or in properly assessing the potential for or reality of harmful interference. In many cases, decisions were tentatively made to proceed with a new use of the spectrum only to find that the use had a more negative effect than anticipated. In other cases, although the incumbent was clearly operating outside its allocated spectrum, the incumbent was deemed “too big to fail,” rendering the new use of the spectrum technically and/or politically infeasible. Finally, in other cases, a suboptimal solution was implemented simply to insure that there would not be any harmful interference to an incumbent service. Understanding the technical details surrounding the current utilization of the spectrum and the potential limitations associated with its use are extremely important. If a detailed technical understanding exists up front, policy decisions can be more appropriately applied to determine how a specific area of spectrum can or cannot be utilized.
Some of these failures were not driven by technical mistakes, per se, but by failure to properly resolve disputed parameters and thresholds among the parties involved. These types of failures often result in overly conservative parameters being selected by the Federal Communications Commission (FCC) and the National Telecommunications and Information Administration to satisfy the incumbent party’s concerns. This inevitably leads to less efficient use of the radio spectrum both today and in the future.
Examples of High-Profile Failures in Spectrum Allocation
The FCC Technological Advisory Council’s white paper on spectrum efficiency metrics1 summarized nine high-profile failures, including the following:
- The prospect of overload interference to legacy Satellite Digital Audio Radio Service (SDARS, aka SiriusXM) receivers from mobile devices in the Wireless Communications Service (WCS) required application of strict technical rules and effectively created 5 MHz guard bands on each side of the SDARS allocation.
- Many C-band satellite earth station receivers operating at 3700-4200 MHz are susceptible to signals from well inside the 3650-3700 MHz band that was transferred from federal to commercial use, risking the possibility that much of the federal transferred spectrum would be useless.
- The use of the 20 MHz advanced wireless services (AWS)-3 band (2155-2175 MHz) for time-division duplex operation was blocked because cellular handsets in the lower adjacent AWS-1 F-block (2145-2155 MHz) were designed to operate across the AWS-3 spectrum, consistent with international (but not U.S.) allocations and, thus, were unable to reject interference from nearby AWS-3 handset transmissions.
- The AWS-1 downlink spectrum at 2110-2155 MHz is upper-adjacent to the broadcast auxiliary service (BAS) at 2025-2110 MHz. AWS-1 licensees were required as the newcomers to correct any harmful interference to the BAS operations. Because BAS equipment had not been designed with sharp filters, AWS-1 operations were found to cause harmful interference to BAS, requiring the AWS-1 licensees to pay to design, purchase, and install new filters for BAS equipment.
- TV receiver performance was a significant issue for the access of unlicensed devices in unused portions of the TV bands (i.e., the TV white spaces). The roll-off of the TV filters is the dominant factor limiting the amount of energy that a TV white space device may emit on allowed TV channels and, therefore, the limiting factor to potential applications for the devices.
- Receiver performance relative to adjacent channel and intermodulation characteristics was a major element in the issue of re-banding the 800 MHz spectrum to avoid interference between Nextel and public safety operations on interleaved channels.
- LightSquared’s proposed deployment of ancillary terrestrial component base stations as part of a hybrid terrestrial–satellite service has raised significant concerns about potential harmful interference to the GPS service operating in the upper-adjacent spectrum due to the potential for receiver overload—that is, power transmitted in LightSquared’s licensed frequencies causing degradation of GPS devices that did not filter out this energy sufficiently well.
- The original 800 MHz band-plan for Nextel and public safety land mobile radios had the Nextel and public safety channels interleaved under the assumption that there would be no harmful interference between the two. The use case for Nextel radically changed, as it became more of a professional’s cell phone service. Ultimately a new band plan was required to separate the services and add a guard band in order to eliminate the harmful interference.
Each of these failures could have been minimized or eliminated if the proper technical analysis had been conducted. This is the type of work where the Institute for Telecommunication Sciences excels—where it could have been engaged to provide technical analysis and establish appropriate and balanced technical parameters.
It is recognized (and communicated to the committee during interviews) that ITS has already provided very valuable assistance in the AWS-3 auction by providing technical analysis of the interference potentials that could arise in a shared-use environment, and ITS is serving as an independent and trusted third party in negotiating the operating parameters. Although ITS provided technical efforts prior to the AWS-3, the committee does not yet know how sufficient this was, especially given its short timespan to prepare a technical analysis.
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1 Federal Communications Commission, Technological Advisory Council, “Spectrum Efficiency Metrics,” White Paper, 2011, Appendix C.
BOX 4.2
Comparison of the Boulder Telecommunications Laboratories with International Research Laboratories
The committee was asked to assess how well the performance of ITS compares to similar research organizations with similar functionalities. Given that there are few, if any, similar domestic research laboratories, the work of the National Institute of Standards and Technology’s (NIST’s) Communications Technology Laboratory (CTL), the National Telecommunications and Information Administration’s (NTIA’s) Institute for Telecommunication Sciences (ITS), and the Center for Advanced Communications (CAC) was compared with five international organizations that perform similar types of technical work. The chief motivation behind the technical work in other countries is quite different from that in the United States when you examine mission statements and institutional behaviors. The five organizations reviewed were the following:
- Communications Research Centre (CRC), Canada;
- Electronics and Telecommunications Research Institute (ETRI), Republic of Korea;
- Information and Communications Research Laboratories (ITRL), Taiwan;
- Institute for Information Sciences and Technologies (INS2I), France; and
- National Institute of Information and Communications Technology (NICT), Japan.
A common theme for the five other countries is that the organizations exist to increase economic benefit to their countries and specifically to enhance the expertise and competitiveness of their indigenous telecommunications industries. Several of the organizations keep metrics on how many companies are spawned in their countries by their work. In general, there appears to be a much tighter collaboration and interaction between the private sector enterprise companies or entities and the government organizations. This is generally not the case for the U.S. organizations—“economic” themes do not appear in ITS, CTL, or CAC’s mission statements.
Another theme that is apparent, especially in the French and Canadian organizations, is the contribution by those organizations to a national industrial policy in those countries. In general, the U.S. government has shied away from establishing a national industrial policy in the field of telecommunications. Rather, the United States has focused on international standards and policies to ensure a level and fair playing field for the U.S. communications and information technology sectors. Indeed, while ETRI and NICT have dozens of active participants in IEEE 802 standards activities, NIST and NTIA participate in a very limited fashion—only one or two individuals and on a part-time basis.
In terms of research areas, U.S. and foreign organizations examine similar topics. However, there is more emphasis in the international organizations on commercialization and transfer of research and technology into their domestic industries. In some cases, especially in France, the international organizations perform more fundamental or basic research than the U.S. organizations. A sample of technical papers would indicate that the quality of research at the U.S. and foreign organizational laboratories is comparable.
The laboratory size was drastically different as well. The combined headcount for CTL, ITS, and CAC is less than 200, while the French INS2I alone has a staff of more than 4,000, and the Korean ETRI has almost 2,000.
EMERGING RESEARCH AREAS RELEVANT TO THE MISSIONS OF ITS AND CTL
Today, there are more wireless connections to the Internet than wired, and the proportion will continue to increase as the volume of wireless Internet connections continues to grow very rapidly.10 Future demand for wireless communication will come from both conventional wireless networks’ endpoints (cellphones, tablets, laptops, and radio and TV receivers) and an expansion in the number and type of new connected devices, including vehicles, sensors of many types, appliances, thermostats, and other familiar objects, even light bulbs (the IoT). Meeting these demands will depend on better understanding of technical challenges in three principal areas: (1) spectrum use, management, and enforcement; (2) system-level optimization and related issues; and (3) public safety and, more generally, mission-critical communications research.
Frequency Use, Management, and Enforcement
There are three ways to increase the capacity of a communications network: (1) increase amount of spectrum available by adding more spectrum or through reducing the coverage area of each transmitter (sectorizing or cell splitting); (2) improve sharing among existing users while limiting the impact of interference; or (3) improve the underlying transmission technology. Additionally, as spectrum becomes increasingly crowded, understanding how to enforce regulatory restrictions will be essential, especially at spectrum boundaries.
Availability of Frequency Bands
Examples of areas where ITS and CTL should consider developing or extending their expertise and physical resources include the following:
- Propagation modeling, approaches to sharing, and the use of MIMO techniques in mm-wave bands—hot research topics and of great current interest at the FCC.11 Nearly all of the best “beachfront property” (microwaves, frequencies below 3 GHz) has been allocated and assigned, but large amounts of spectrum are available in bands corresponding to millimeter wavelengths (or tens of gigahertz). Accurate, comprehensive, and low-cost techniques to measure and monitor spectrum utilization need to be developed and certified. The Boulder telecommunications laboratories should also explore cutting-edge research areas in new spectrum, such as the use of terahertz wireless data transmission.
- Understanding the characteristics of the noise floor over time in various interesting areas of the spectrum—including sensitive areas supporting satellite communications, cellular communications, various military use bands, etc. This would need to be done in a variety of geographic environments and under various environmental circumstances. The implications of these noise observations would be of enormous value in understanding the degree to which
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10 Cisco, “Cisco Visual Networking Index: Global Mobile Data Traffic Forecast Update 2014-2019 White Paper,” February 3, 2015, http://www.cisco.com/c/en/us/solutions/collateral/service-provider/visual-networkingindex-vni/white_paper_c11-520862.html.
11 Federal Communications Commission, Notice of Inquiry, FCC 14-154, In the Matter of: Use of Spectrum Bands Above 24 GHz For Mobile Radio Services; Amendment of the Commission’s Rules Regarding the 37.0-38.6 GHz and 38.6-40.0 GHz Bands; Implementation of Section 309(j) of the Communications Act—Competitive Bidding, 37.0-38.6 GHz and 38.6-40.0 GHz Bands; Petition for Rulemaking of the Fixed Wireless Communications Coalition to Create Service Rules for the 42-43.5 GHz Band, October 17, 2014, https://apps.fcc.gov/edocs_public/attachmatch/FCC-14-154A1.pdf.
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targeted wireless services are being impacted today and how they are likely to be impacted in the future.
- Understanding the out-of-band characteristics of receivers for a wide variety of device classes. If we are to move to ever-denser spectrum use, an understanding the receiver-based inhibitors to “more efficient” spectral use in various spectral areas will be of enormous import.
- Related to the previous bullet, a focus on enhancing the understanding of the technology underpinnings for the proposed Interference Limits Policy12 with its focus on establishing a Harms Claims Threshold13 would be of significant value. This technique promises to be a great boon in sorting out the long-standing receiver-related interference issue because there are still significant challenges in translating the current theory into a practical approach to interference management.
- Understanding the commercial spectral environments around major military bases and, conversely, government (especially DOD) usage of spectrum around major cities, would be enormously helpful. This would particularly valuable in supporting the sharing (or not) of spectrum in environments where there is a current shortage (either temporal, e.g., during a military exercise, or recurring, as occurs during “rush hour” in major transportation hubs).
Sharing and Interference Studies
In an environment with many types of devices operating in ever closer proximity, the risk of inadvertent harmful interference significantly increases. What people often forget is that, at some level, every transmitting device interferes with every receiving device. ITS has traditionally performed studies of applications in which interference has to be avoided. In the future, it will be important for the Boulder telecommunications laboratories to have expertise and resources to understand dense, interference-limited networks that operate in both licensed and unlicensed frequency bands. The distinction between base stations or access points and terminals will be blurred in the future with the proliferation of personal “MyFi” and “Sat-Fi” access points as well as Wi-Fi tethering using smartphones. Device-to-device communications and ad hoc networks are emerging application areas that will significantly add to the interference challenges.
Today, given the ubiquity and high economic value of network services, there are a wealth of theoretical models and a large body of practical measurements relating to interference of signals in the various licensed cellular bands. For similar reasons, the physical layer and medium access layer of Wi-Fi (IEEE 802.11) and Bluetooth standards anticipate interference among devices operating with these protocols. In the future, spectrum sharing, new cellular standards, and the anticipated proliferation of new devices will substantially complicate interference environments. Examples of research challenges include the following:
- Improving the understanding of some of the limits associated with unlicensed use of the spectrum. This is particularly important in specific areas—that is, the “tragedy of the commons”14 problem that has been long discussed and is increasingly being seen in various “high-density” traffic areas. The Boulder telecommunications laboratories are uniquely positioned to provide further support
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12Interference limits policies are methods to describe the environment in which a receiver must operate without necessarily specifying receiver performance.
13Harms claim thresholds are a type of interference limits policy where in-band and out-of-band interfering signals levels must be exceeded before a radio system can claim that it is experiencing harmful interference.
14 The “tragedy of the commons” comes from the practice of having a central commons or shared property at the center of many towns. Having an area that is shared by all is a great concept until the commons becomes over shared to the degree that it is no longer productively usable by anyone because everyone is using it at the same time.
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of U-NII work because they have the expertise, access to classified information (relevant to DOD work), and structures to partner with industry.
- Expanding contributions into the area of cross-usage-sharing models—for example, radar and terrestrial communications, or various government and commercial satellites services and terrestrial communications. There are many uses of the spectrum today that need to be carefully considered in sharing models.
- Applying resources to better understand various non-communications sources of harmful interference, including electrical power lines, new lighting systems, and high-performance wired data systems.
- Understanding the aggregate impact of multiple sources of low-level transmissions that appear as “white noise” in specific bands. This issue is of particular concern as the era of the IoT begins to emerge. With millions, or even billions, of often uncoordinated devices all communicating, or even just sending “pings” to identify that they are present and available, the aggregate effect could be profound.
- Contributing in the area of propagation models. Today, there are an ever-increasing number of models and, with them, an ever-increasing level of debate on when to apply which model and why one model provides very different answers than other models. Ultimately, there is a need for a consolidated propagation modeling tool that will select the model or models that are appropriate to represent the environment in question and produce the needed model for a given set of circumstances.
The trends of increased device deployment and shared access to spectrum suggest that harmful interference will arise with greater frequency. Traditionally, interference was avoided through the use of conservative frequency planning and liberal use of guard bands; however, spectrum sharing may result in more liberal access to frequencies, which would in turn raise concerns over the identification and remediation of an interfering system. Due to this, there will be an increased desire on behalf of spectrum users (particularly the incumbents) to have a means of assessing and responding to such events when they arise. Furthermore, many of the frequency bands where spectrum sharing is likely to happen are bands assigned to federal users; therefore, it is logical that NTIA and NIST would be interested in understanding and potentially responding to these interference events. The committee sees a logical role for the Boulder telecommunications laboratories to engage in the area of spectrum monitoring and enforcement, such as defining methods of measurement, assessment, and thresholds.
New Spectrum-Efficient Technologies
Emerging technologies that have particular relevance to the mission of ITS and CTL include the following:
- Massive MIMO, which combine use of millimeter wavelength devices and MIMO to create extremely large numbers of antennas forming small beam-forming antenna arrays, can be used to enable very-high-performance broadband communications systems currently being explored for use in fifth-generation (5G) cellular systems and other applications;
- Adaptive modulation and coding, in which the condition of radio channels is sensed and transmission techniques are adjusted to most efficiently utilize the available spectrum resources;
- Improved base modulation schemes with higher-order QAM (quadrature amplitude modulation) extending the spectrum efficiency (i.e., the number of bits per Hertz being transmitted and received);
- Channel bonding and, especially, non-contiguous channel bonding to enable very wide spectrum channels to be assigned for very-high-speed broadband deployments;
- Dynamic spectrum sharing, which is being explored in commercial, government and mixed commercial/government environments, increasing the need for protocols that reduce or eliminate adjacent channel interference and imposing significantly greater sophistication in spectrum management techniques; and
- Full duplex bi-directional operation on a single frequency channel—a technology that is just emerging from the university research environment for which the potential applications and performance improvements are still poorly understood.
Much of the current work completed by the Boulder telecommunications laboratories focuses on narrow aspects of the wireless communication systems. While important, work should also consider system-level properties, including information assurance, power consumption, and hardware implications of spectrum congestion.
Information Assurance
One of the key systems-level issues of communication integrity is information assurance—the ability to have secure and reliable communications. As critical infrastructure systems become more dependent on wireless technology, these systems become vulnerable to new “attack vectors” through exploitation of the openness of the wireless communication channel. Potential topics include the following:
- Evaluation of quantum communications and physical layer security techniques that rely on propagation paths rather than cryptography. Both laboratories have relevant expertise and insight into propagation measurement and could provide a valuable independent evaluation function as these kinds of security systems emerge in the market.
- Intentional interference. FirstNet is a nationwide public safety network that is based on LTE cellular. It is well known that it can be neutralized though interference, intentional or unintentional, on the control channels. LTE jammers can be easily ordered over the Internet from China. Similar issues will affect Dedicated Short Range Communication (DSRC), the expected communication mode for smart cars and highways. ITS’s ability to perform interference analysis is well known, but future work to determine vulnerabilities must take this interference analysis a step further to understand the ramifications on overall system performance and cost.
- Wireless protocol and device vulnerabilities. As radios become increasingly programmable, they can easily be hacked to exploit the vulnerabilities of wireless communication protocols, a problem that will be exacerbated by the rapid movement to the IoT. This proliferation of wireless devices brings with it an extraordinarily broad attack surface, if not properly organized and controlled.
Low-Power (Green) Wireless Communications
One of the biggest technical challenges with cellular and Wi-Fi-equipped devices (such as smartphones, tablets, and laptops) is battery life, which is even more of a challenge with IoT devices that have much smaller batteries and are expected to operate for years. One possible solution to energy consumption is to improve the energy efficiency the hardware, signal processing, and software in radios.
An alternative is energy harvesting from the environment in which the devices are located. This is a fertile field for innovation.
Hardware Considerations
In order to support a growing density of devices and users, spectrum is reused by reducing the size of cells and deploying more (and lower power) wireless access points and cellular base stations that must be connected to the backbone network (so-called backhaul). Two challenges include how to drive the overall cost of system deployment down sufficiently to make this approach affordable, including the often civil engineering-centric backhaul, and how to make it easier to upgrade this infrastructure as new wireless technologies are developed and introduced.
Location-Aware Services to Support Public Safety
As new technologies emerge, public safety communications tools will need to be integrated into the new environment. PSCR has provided significant work in testing for these new environments and will continue to contribute significantly as FirstNET is further developed and deployed. However, while the work is important, little is done in terms of cutting-edge R&D. PSCR is currently developing several research roadmaps to determine allocation of the funds provided to PSCR from the AWS-3 auction. The committee is encouraged by the first of these, which identifies location services as a key area of research.
Better contextual awareness and more accurate proximity-based services for smart phones offer great potential benefits for public safety applications. Technologies under development can provide a very accurate estimate (e.g., to within 10 cm) of the location and position of a device, both indoors and outside, using a precise fix on the location of Wi-Fi access points and precision timing of its radio transmissions. For example, if such technologies were deployed, everyone in a burning building could be located precisely through their smart phones.
Advanced atomic clock and gyro-based solutions of the future could also make it possible to locate a device, and hence a person, continuously from the time the device is manufactured. These timing and location-based technologies can be critically important, not only in locating and saving lives in burning buildings, but also in providing precise timelines using location logs for events—for example, leading up to a crime and including apprehension of the criminal by the arresting officer. These important technologies need to be carefully understood and tested, and the resources at NIST, and to some degree ITS, could be enormously valuable in this area.
NEED FOR STANDARDS DEVELOPMENT PARTICIPATION
Interoperability standards are of critical importance to both the data network and telecommunications industries. They enable a large number of vendors to supply the components necessary to assemble the vast and complex wired and wireless network infrastructure critical to connecting citizens and businesses in the United States and throughout the world. Interoperability standards are an essential ingredient to today’s dynamic and growing online economy. These standards are developed in voluntary standards development organizations, such as the Institute of Electrical and Electronics Engineers, IETF, the International Organization for Standardization, and the International Telecommunication Union, by the stakeholders interested in designing, building, and deploying networks of all types—from long-range, high-capacity optical networks (e.g., IEEE 802.3 400 gigabit per second Ethernet) to pervasive low-cost, yet high-performance local area wireless networks (e.g., IEEE 802.11 WLANs, Wi-Fi). New standards are being contemplated for emerging spectrum-sharing applications, including sharing in the 3.5 GHz
band (radar and communications), the 5.9 GHz DSRC band (auto and WLAN), and sharing of the unlicensed 5 GHz band (WLAN and mobile cellular radio access network).
The Boulder telecommunications laboratories have had limited participation in the well-known world-class networking and cellular industry standards settings bodies such as the IEEE 802 LAN/MAN Standards Committee (developing technologies commonly known as Ethernet, Wi-Fi, etc.), 3GPP, or IETF. Yet each of these organizations is responsible for producing the technical specifications that have enabled the current Internet and mobile cellular infrastructures that connect billions of end users, and they are aggressively working to develop the next generation of specifications that will result in new products and services over the next 10 years.
As noted above, the demand for shared-spectrum applications will only increase with time. The Boulder telecommunications laboratories are in an excellent position to act as an independent organization to evaluate the efficacy of proposed sharing standards and to test equipment and systems for compliance to these emerging classes of fair-sharing standards-based protocols. This will benefit our regulatory agencies, the FCC and NTIA, in their quest to preserve existing services while nurturing a more efficient utilization of our increasingly scarce spectrum resources. Furthermore, the vendors involved in deploying all aspects of wireless networks (services, infrastructure, network elements, hardware devices, and test equipment), in particular, can take advantage of the compliance testing and evaluation services the Boulder telecommunications laboratories could provide to them. One of the unique advantages of the laboratories is vendor independence. They are not beholden to any party that stands to benefit from the test results; hence, they can afford to be truly unbiased in their testing, providing valuable feedback to the community regarding how well the interoperability standards meet their multi-vendor interoperability objectives.
FINDING: Advances in communications and networking technologies will have a significant positive social and economic impact, provided that the associated increasing demand for wireless communications can be met. New spectrum (both licensed and unlicensed) to support increased use of mobile and IOT devices has been slow in emerging. Neutral technical expertise is needed for determining when spectrum is underutilized, reviewing technology for shared use, and evaluating interference and enforcement.
RECOMMENDATION: The Department of Commerce (DOC) should develop short- and long-term application and basic research plans that would provide the country with the necessary knowledge base in spectrum areas and enhance the capability for spectrum sharing and repurposing analysis. DOC plans should include opportunities for various users of spectrum to identify their needs and long-term objectives. A research agenda should consider the most efficient use of the laboratories’ resources and develop an effective organizational structure and funding strategy to ensure research goals are met and resources are effectively used.
RECOMMENDATION: The Boulder telecommunications laboratories should expand their visible leadership role by providing technical expertise for agencies and policy makers and by providing objective scientific expertise.
RECOMMENDATION: The Boulder telecommunications laboratories should fully engage in the current and emerging work in the IEEE 802 LAN/MAN Standards Committee, the 3rd Generation Partnership Project, and the Internet Engineering Task Force. This must be a long-term commitment, because the time constant for standards evolution is on the order of 3 to 10 years.
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