As background, the National Broadband Plan recommends repurposing 120 MHz of from the TV bands to mobile broadband. On June 14 the FCC released an Omnibus Broadband Team Technical Paper that describes some of the analyses supporting this repurposing. Chairman Genachowski asked the Commission staff to hold the Forum to consider ideas in the Paper.

At this Forum there were four areas discussed:

• Advancements in Compression Technology
• Cellularization of Broadcast Architecture
• Improvements in VHF Reception
• Methodologies for Repacking the TV Band

Each area had been the subject of discussion by groups in workshops earlier in the day. At the Forum each of the four groups reported  preliminary findings and recommendations.

After hearing the Forum, which is a preliminary effort, I”d say its gist is that technical changes in the TV industry aren’t going to free up significant TV spectrum for mobile broadband.  There are no advancements in compression technology that can be implemented in a timely manner (i.e., less than 13 years). State-of-the-art in compression technology, and market realities, makes channel sharing by different licensees impractical. Cellularization of broadcast architecture is seen as not practical nor economical. There is room for improvement in VHF reception, perhaps through higher transmit power levels and better, smart receive antennas. An examination of methodologies for repacking the TV band shows no scenarios where stations can avoid sharing channels, unless some stations voluntarily go off-the-air. (And, as we heard in the presentation on compression, sharing is seen as impractical.)

The slides used in each of the four sessions are to be made available on the FCC web site. For those interested in more details now, I share my notes below.

Advancements in Compression Technology

The results of this group were presented by Andrew Setos from the Fox group.

MPEG-2 was published in 1994, and no significant improvements are expected.

Compression equipment has improved such that artifacts are less noticeable, but they are still there. For example, where five years ago there might have been an obvious pixilation, now there is more of a blurring effect.

There are more-modern compression technologies such as MPEG 4. Current TVs do not support MPEG-4, and it could take 13 years to migrate that technology to consumer TVs.

The FCC Technical Paper scenario of multiplexing two HD programs for two different licensees in one 6 MHz channel is not viable due to quality degradation that would result when needing to choose a winner and loser when one HD stream exceeds the bandwidth of the other.

Statistical multiplexing efficiencies are lost with two separate licensees. It can work with the same licensee because the licensee knows what is in the different programs.

As far as pairing an HD station and an SD station in one 6 MHz channel, this is not viable as the trend is toward all HD.

The bit allocation for Mobile DTV is a straight carve-out, and statistical multiplexing does not help.

Cellularization of Broadcast Architecture

Bob Seidel of CBS presented the results of the cellularization group.

A Single Frequency Network (SFN) is much easier with OFDM than with the current 8-VSB modulation method.

“Self-jamming,” or interference between two cells in a SFN, was raised as an undesirable artifact of SFNs that would result in lack of coverage between cells.

SFNs will not help improve reception at the edge of coverage areas because of desired/undesired signal ratios that must be maintained there.

The lack of performance requirements for DTV equalizers is an issue.

Practical issues involved in implementing SFNs include feeding programming to multiple sites, and the cost of building and maintaining multiple sites.

It was suggested that, regarding Mobile DTV, wireless broadband providers should work with broadcasters. The point here is, why broadcast, say, the Super Bowl from hundreds of cell sites when Mobile DTV from one broadcast site will suffice.

Little or no UHF TV spectrum can be repurposed from cellularization.

Improvements in VHF Reception

Kerry Kozad from Dielectric Communications reported on the VHF reception panel.

The group was focused on fixed reception; mobile operation on VHF is not contemplated due to the large mobile antennas that would be required.

The low-VHF band (channels 2-6) is a bigger problem than the high VHF band (channels 7-13). Noise is a bigger problem, for one thing.

There are only 39 stations in the low-VHF band.

Noise varies from location-to-location at low-VHF, making it difficult to have consistent  performance and use common planning factors. There are also undesirable propagation effects at the low VHF band. It would likely require an impractical 15 to 20 dB power increase to alleviate these problems.

High-band VHF suffers from the same noise problems, but not as much. A 10 dB power increase would be required to help significantly.

Receiver antennas can be improved, but not much. The best candidate for improved antenna performance is indoor reception, perhaps through smart antennas working in conjunction with the TV set. The TV and antenna manufacturers have to work together for this to happen.

The FCC should not set consumer antenna performance standards. There are too many variables for a one-size-fits-all performance standard.

It would help to standardize descriptive terminology and performance measurement standards.

The FCC should increase maximum power limits, but be aware that there can be more interference with higher power.

Methodologies for Repacking the TV Band

The spectrum repacking session was led by Bruce Franca from MSTV.

He summarized the status of new modeling efforts and reviewed Technical Paper study assumptions.

Population loss (loss of people served) is one of the costs in reclaiming spectrum.

The focus is on reclamation in the UHF band, as mobile broadband operators are not interested in VHF spectrum.

The study assumptions included locating all stations in channels 2-30, and adding no new stations to channels 2-6.

The minimum number of stations that must share in this scenario are 248. From 20 to 40 percent of Designated Market Areas (DMAs) are impacted and must share, depending on border protection.

A more careful approach to DTV interference is suggested. In analog television, interference can be increased 8 dB before someone notices, and can increase 20-30 dB  before someone stops watching. In DTV, however, most TV sets go from perfect picture to no picture in 1 dB.

Interference performance is governed mostly by DTV receive performance.

Different propagation models are available, but there is no indication any are generally better than the Longley-Rice model.

One question was whether protected service areas should be adjusted to more accurately reflect viewing practices, and if so, how. Nielsen reports 10.9 million over-the-air homes, but it is not clear what that means. For example, a home with both FIOS and over-the-air reception is not considered over-the-air by Nielsen.

Hispanic households have a high percentage of over-the-air reception: 20% in Los Angeles, 35% in Houston, and 28% in Phoenix.

50 million DTV converter boxes were sold.

In discussion, it was noted that this panel’s results refer to sharing being “required.” That assumes no stations voluntarily choose to go off the air. If sufficient stations choose to go off, sharing is not required.

• Polytechnic Institute of NYU filed an application (with supporting exhibit) for experimental license to conduct a network research project using WiMAX on 2535-2540 MHz. This is part of the nationwide Global Environment for Network Innovations (GENI) project, a suite of infrastructure that will support experimental research in network science and engineering. GENI is supported by the National Science Foundation and managed by the GENI Project Office at BBN Technologies.

• Mnemonics, Inc. filed an application (with supporting exhibits) for experimental license to operate in support of a research project that is to develop and demonstrate the viability of wirelessly extracting measured data from a network of passive surface acoustic wave (SAW) sensor devices. This sensing technique is said to have several advantages over existing sensors, including no wired connections needed to extract data, no power requirements, operation up to 1000 degrees C., and sensor cost in-quantity in the tens of cents each. Operation will be on 915 MHz.

• Worcester Polytechnic Institute filed an application (with supporting exhibits) for special temporary authority to operate on 512-608 and 614-698 MHz. This is in support of research and evaluation of equipment that uses radio-location technology to precisely identify the location of firefighters and firefighter deployed sensors within a building.

• Zimmerman Associates filed an application (with supporting exhibits) for special temporary authority to test prototype equipment that uses ultra wideband (UWB) technology developed by Time Domain Corporation. The equipment generates a signal that is pulse position modulated. The position of the modulated pulse varies randomly in time producing an emission that approximates Gaussian noise. The nominal center frequency of the signal is 4.4 to 4.5 GHz with the half power point bandwidth at 3.1 to 5.6 GHz. The radiated power of the device is below the general limits set forth in Part 15. This testing is in support of a U.S. Army contract.

• The Moment Lab, University of California, Santa Barbara filed an application (with supporting exhibit) for experimental license to conduct experimentation regarding use of the TV white spaces. The Lab seeks to evaluate its solutions for modulation and coding scheme and channel width adaptation on long-distance (rural) white-space links. Operation will be on 512-608 and 614-698 MHz.

• Panasonic Avionics Corporation filed an application (with supporting exhibit) for experimental license  to conduct ground testing in support of Panasonic’s Global Communications Suite (GCS) featuring the “eXconnect” Ku-band aeronautical mobile-satellite service (AMSS) system supporting wireless connectivity for devices such as GSM phones and Wi-Fi enabled laptops. Using low-power wireless transceivers onboard aircraft, GCS processes passenger communications for transmission to ground networks via satellite communications networks. Operation will be on various frequencies between 421 and 5825 MHz.

• Ingegneria Dei Sistemi S.p.a. filed an application for special temporary authority to operate equipment for landslide monitoring as part of a demonstration for the US Geological Survey. The equipment is classified in Europe as a portable Short range Device (SRD) as it said to be compatible with primary services. Compliance testing of this equipment with the applicable requirements in the US, however, has not been yet been accomplished. Operation will be on 17.1-17.3 GHz.

• DRS EW & Network Systems filed an application for special temporary authority to test identification, friend or foe (IFF) equipment that is being developed under a contract with Italian Air Force. Operation is between 1030 and 1090 MHz.

• Boundary County Community Television filed an application (with supporting exhibits) for experimental license to operate using vacant spectrum in the television broadcast bands (white spaces) for the testing of fixed white-space devices. Boundary County Community Television is working jointly with Spectrum Bridge in investigating the usefulness of available white space (UHF/VHF) spectrum by providing “rural broadband access and support of video, sensor, low power AM broadcast radio using IP streaming, Wi-Fi access and medical records exchange.” The two companies will also be working with the U.S. Customs and Forest Service in application development and evaluation. Operation will be on 174-216, 470-608, and 614-698 MHz near Bonners Ferry, Idaho.

• Magna Electronics filed an application (with supporting exhibits), apparently for experimental license (the application form is not available at this time). Magna Electronics says it is developing an automotive 77 GHz radar for use in the reduction of vehicular accidents through situational awareness. Research is underway to detect forward objects of interest that may cause an accident, to either warn the driver or autonomously brake the vehicle to reduce the impact energy. Magna also notes that over 1.8 million rear end collisions are reported in the United States annually; this is more than 1/3 of all reported accidents and is the leading accident type.

• Dell Marketing filed an application (with supporting exhibits) for special temporary authority to conduct market studies that focus on consumer acceptability of mobile digital television transmitted using the ATSC A/153 standard. This authority applies only to reception devices.  Transmission will be made from regularly licensed TV stations. The reception devices to be used in the test (up to 1000 specially configured Dell Netbook computers) will include tuners for the reception of ATSC A/53 conventional DTV signals and ATSC A/153 mobile DTV signals but not analog tuners. Frequencies to be used include 54-72, 76-88, 174-216, and 470-698 MHz.

According to Dell, “The receivers at issue are not to be sold directly to the public. Instead,, the receivers are to be sold to Dell commercial customers who, as a result of the tests they are to conduct, will be able to provide feedback as to such issues as the field performance of the receivers, acceptability of the user interface, consumer expectations and acceptability of possible prices (e.g. “Would you be willing to pay _____ for this device, provided that it includes DTV/MDTV reception capability?”), consumer use data (hours per day of viewing, principle reasons for viewing, reasons for stopping viewing), and perceived value of the service.”

Dell also says “Half of the proposed units will be sold to a major multi-channel video programming provider for use in a test in which the provider will make the receivers available to selected consumers who agree to participate in the test. The others are to be made available for sale to broadcast television transmission equipment makers who will provide them to broadcast stations for demonstration and consumer feedback purposes in connection with the launch of mobile television service this summer. In both cases, a condition of Dell’s sale will be to provide Dell feedback that will assist Dell in both product design and marketing, including being able to set initial prices should the Commission agree ultimately to permit the widespread marketing of portable receivers without analog tuners that are designed for on-the-go reception and are powered primarily from batteries.”

• Alcatel-Lucent filed an application (with associated exhibits) for experimental license to operate on various frequencies between 698 and 2155 MHz to evaluate LTE technology over-the-air. Specific tests are to include validation of call processing, handoffs, power control, and data scheduler algorithms.

• Inmarsat Hawaii filed an application (with supporting exhibits) for experimental license to conduct technical demonstrations using new, pre-production Global Satellite Phone Service (“GSPS”) prototype handsets, test these handsets in connection with their production and the deployment of other parts of the GSPS network, and otherwise develop radio techniques, equipment, operational data and engineering data related to GSPS. Inmarsat Hawaii says that “GSPS will be a highly competitive offering in terms of hardware costs, airtime rates and service quality, with a strong combination of form and functionality that Inmarsat believes will change the landscape in the provision of the mobile satellite services. The requested experimental authority would facilitate the introduction of GSPS to the U.S. by enabling Inmarsat to develop the technical expertise to extend and enhance existing uses of L-band spectrum through the introduction of GSPS.”

• Associated Air Center filed an application for special temporary authority to perform electromagnetic interference susceptibility tests to demonstrate that the use of on-board cell phones do not cause interference on any electrical equipment installed on the aircraft while on the ground. “A direct influence on the aircrafts navigation and communication systems is not expected, but a susceptibility investigation is considered neccessary [sic] as the electromagnetic field levels are in close vicinity of the signal source might raise to levels that cause interference. The testing will concentrate on demonstrating the electromagnetic compatibility of RF bands used for CDMA, GSM, PDC and UMTS cell phones within a aircraft environment [sic].” Operation will be on various frequencies between 410 and 2700 MHz.

• Booz Allen Hamilton filed an application for special temporary authority to evaluate the RF performance of commercial IEEE 802.16e (Mobile WiMAX) equipment for United States Air Force Global Broadcast Service applications. Operation is to be on 2620.250-2628.500 MHz.

• Raytheon Network Centric Systems filed an application for special temporary authority to test a Ground Surveillance Radar (GSR) system, intended to provide all-weather detection and tracking capability for facility/critical infrastructure and border security programs. Operation is to be on 3100-3500 MHz.

• Vexcel, a Microsoft subsidiary, filed an application (with associated exhibits) for experimental license to demonstrate a specialized short range, low power trailer-mounted radar system that illuminates a rock wall next to a highway and maps the surface profile in detail. Vexcel says that this technique can be used to detect potential dangerous rockfalls that could damage vehicles and travelers on the adjacent highway. Operation is to be on 10.7-11.2 GHz.

As background, Vexcel says that in October 2007, it “made a presentation to the Department of Transportation’s Federal Highway Administration (FHA) office proposing the use of Synthetic Aperture Radar (SAR) technology for the detection and monitoring of rock fall and landslides on steep slopes that border busy transportation corridors. Vexcel had previously demonstrated through software simulation that integrating the interferometric SAR data processing technique into a ground-based system would enable the measurement of surface displacements on the order of a millimeter at stand-off distances of up to several hundred meters. Since surface displacements are a precursor to rock wall failure, the ability to measure surface displacement over time yields a capability to predict wall failures. This predictive capability would enable transportation authorities to schedule mitigation activities during low traffic periods thereby minimizing the risk to life and limb of rock wall failures and significantly reducing their negative economic impacts.”

“To properly verify the system operation, Vexcel needs to measure several different types of rock formations. To do this, the system will be installed on a trailer which can be towed to each experimental site. A drawing depicting the trailer system is shown in Figure 1. Directional horn antennas are used to transmit and receive the radar’s radio frequency signal. The antennas are mounted on a linear rail system and are moved horizontally and vertically along the rails. The motion is such that the antenna pointing direction is not changed during operation. The horizontal rail allows for 5 meters of motion. The vertical rail allows for 1.6 meter of motion. The antenna’s highest position above the ground during operation is 2.6 meters.”

• TWC Wireless, the wireless division of Time Warner Cable, filed an application (with supporting exhibits) for experimental license to test WiMAX (IEEE 802.16e) equipment and applications over-the-air. These tests are intended to support system, application and device development, as well as quality assurance. Operation is to be on 2513-2535 MHz.

• L-3 Communications Linkabit Division filed an application (with associated exhibits) for experimental license to conduct a series of experiments with HF and VHF multiband radio equipment. The purpose of the experiment is to confirm performance of the equipment against engineering specifications, characterize field performance of the equipment, and rehearse scripted equipment demonstrations in support of marketing activities. Operation is to be on various frequencies from 1.8 to 107.5 MHz. The communications will be primarily voice with very limited digital data. Also, encrypted (AES 256) and unencrypted communications will be evaluated. Upon successful conclusion of the experiments, the equipment will be offered for sale worldwide, subject to US export regulations.

• Morehead State University filed an application for special temporary authority to operate a ground station and characterize the Mini-RF radar instrument, one of seven instruments on NASA’s Lunar Reconnaissance Orbiter (LRO). The LRO is currently orbiting the Moon. The science team has a program requirement to characterize the transmit and receive paths of the Mini-RF instrument on a regular basis. The characterizations require one week of testing and repeated every 9-12 months. Operation is to be on various frequencies from 2370 to 7150 MHz.

• Telcordia Technologies filed an application (with supporting exhibit) for experimental license to conduct testing on 495-505 and 525-535 kHz in support of deliverables under a Department of Defense research program for the Laboratory of Telecommunication Sciences. The project includes experiments to better understand vulnerabilities of critical infrastructure to natural and man-made phenomena. In particular, Telcordia proposes to conduct experiments on the impact of radio frequency interference (RFI) into advanced communications services such as broadband access. It proposes to do this by running short term transmission experiments at a number of locations using conventional AM transmissions, but just below the commercial AM band to avoid interference with commercial broadcasts.

On December 2, 2009, the FCC issued a Public Notice asking for more comment on spectrum licensed to broadcast TV stations, and on market-based mechanisms that would encourage broadcasters to make spectrum available for wireless.

TV broadcasters generally like their spectrum as it is. They argue that over-the-air TV is a public service. It is the only source of video programming for some. A large investment was made in the recent DTV transition. They are working on advanced technologies including Mobile DTV and other content delivery platforms. Multicasting provides greater choice in programming without the need to subscribe to a cable or satellite service.

Some broadcasters question the notion of a spectrum shortage for wireless broadband. MSTV and NAB, in a proposed framework accompanying their comments, find fault in analyses showing a need of hundreds of additional megahertz. Technologies such as femtocells, they say, can increase wireless system capacity. To the extent that more spectrum is needed, they want the FCC to conduct a comprehensive inventory of all spectrum users.

Several lesser-known companies propose new technologies for broadcasters. Adaptrum, a startup developing cognitive radio technology for white space, proposes allowing TV stations to deploy broadband services within their coverage contours. CTB proposes a distributed, cellular architecture for broadcasters that would allow them to provide both broadcast and two-way broadband services. Sezmi has a system in which popular video programming is delivered via broadcast, and the remaining programming is delivered via broadband.

Many wireless proponents acknowledge broadcasters’ public service but encourage the FCC to look at repacking the spectrum such that wireless services get more spectrum while broadcasters’ audiences continue to be served. Motorola, CTIA, and CEA suggest distributed antenna systems, also known as Single Frequency Networks (SFNs). Multiple antennas transmitting at lower power would reduce interference, reduce the frequency separation required between stations, and allow TV stations to be repacked into a smaller portion of the spectrum. CTIA and CEA estimate that 100-180 MHz of spectrum might be made available for mobile broadband. An advantage of this approach is that today’s TVs are not made obsolete, and the current 19.4 Mbps digital data stream is still available to stations. Presumably, those benefiting from this new scheme would help pay the broadcaster’s transition costs.

Professor and former FCC Chief Economist Thomas Hazlett draws on his previous writings to propose an overlay auction of the TV band. In his plan, the 294 MHz DTV band is divided into seven national overlay licenses, each 42 MHz wide. These licenses are sold at auction. Those auction winners have exclusive, flexible-use rights. Existing TV stations are grandfathered and protected. The overlay licensee, however, can negotiate with the TV station and pay it to modify its operation or even agree to go off the air. It is estimated that the broadcaster’s use of spectrum is worth two or three orders of magnitude less than the same spectrum deployed for more-flexible wireless purposes.

The emerging white-space ecosystem is at risk in some of these plans. Any scheme that repacks the broadcast spectrum more efficiently, such as SFN, reduces white space. Google, Dell, and Microsoft – all supporters of unlicensed white-space services – are concerned about this.

Several dozen sets of comments were received in response to the December 2 Notice. It is likely the FCC will not decide all these issues related to TV spectrum by its February 17 deadline, and will them further, perhaps in a rulemaking proceeding.