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Top 10 Questions on Spectrum

Since the end of August to today, I have spoken with more than 30 reporters on spectrum issues. Regardless of the latest report released or Congressional activity, I’ve noticed there are 10 questions routinely asked. I’m always happy to answer them, but thought I’d share the questions and our responses below.

  1. Why does spectrum need to be paired?
    Quite simply, it’s so your mobile device can send and receive information. One set of frequencies is used for transmissions from the cell tower to the phone transmissions and a second for transmissions from the phones to the cell tower. The broader the bands, the more efficiently they can be used, less frequency is wasted in the guard bands. If the spectrum is to be used for one-way radio or TV broadcast systems, then they need only one slice, although they may still require some space for guard bands between channels.
  2. Why are you so focused on certain spectrum bands?
    Due to the law of physics, certain bands work better for wireless technology. The longer the wave, the better the spectrum can penetrate objects (such as walls). The lower the frequency range, the longer the wave. Whether a frequency is good for wireless is determined by how fast the wave travels, the ability of the waves to penetrate through trees and other vegetation and the reflectivity of various objects to the waves. Good frequency ranges for wireless communications will have the ability to penetrate through trees and other vegetation. Other factors that can impact wireless connections include location (latitude, longitude, elevation); number of users trying to access the same tower; time of day; foliage (or lack of); and weather (rain, wind, etc).

    To put it another way, lower frequency bands have better propagation characteristics since it can penetrate buildings and cover distance.

  3. What proof do you have that broadcasters have unused or underutilized spectrum bands?
    In large city markets, every TV broadcaster gets 6 MHz of spectrum. In Washington, D.C., where there are 17 broadcasters, that's 102 MHz of spectrum that are being used. Yet they are allocated 294 MHz of spectrum, so that means 192 MHz are unused. This is typical in large cities where TV broadcasters were given 300 MHz yet they only use, at most, about 150 MHz.
  4. Will broadcasters who choose to participate in the incentive spectrum auctions impact consumers?
    No. The fewer than 10 percent of Americans who receive over-the-air television will not lose access to over-the-air service.
  5. Is there a general rule that the lower the frequency bands the better and that higher bands don’t work as well for wireless?
    The lower the spectrum the better able it is to penetrate buildings AND to cover distance. Thus, the current spectrum bands occupied by TV broadcast bands go further and penetrate buildings better than bands located higher in the spectrum. The higher the bands, the shorter the distance a signal travels before it “fades,” and the more it can be impeded by obstacles like foliage or even humidity in the air.
  6. Why don’t you use femtocell and other cell-splitting technology to improve efficiency?
    Wireless carrier‑provided femtocells help for signal fading issues, but typically do not increase capacity.

    However, carriers are already deploying and using many alternative solutions to meet consumer demands, such as Wi-Fi networks to offload network capacity. Carriers also incorporate technology efficiencies in their infrastructure equipment to maximize spectrum utilization. Wireless providers do use cell‑splitting technologies, including microcells, picocells and outdoor distributed antenna systems (DAS) to improve the capacity of their systems. Yet cell‑splitting often can be constrained due to technical, regulatory and financial limitations.

    Even accounting for the efficiency gains from these practices, demand vastly outstrips supply. For example, the Federal Communications Commission recently examined spectrum demand and determined that, even assuming a 240% gain in the technology and network density efficiencies described above, wireless “traffic growth will outpace efficiency gains by almost 3X.”

    We simply must get more spectrum. Wireless providers need more spectrum because it is the most efficient way to increase capacity. It is this additional capacity that will be required to accommodate the burgeoning demand.

  7. Why not do a spectrum inventory?
    We have been consistent supporters of a more robust inventory process, since that will help us identify opportunities to move spectrum to higher and better uses, but we should not allow the desire for an inventory to be an impediment to progress when we have already identified opportunities to make better use of some bands.

    For example, we don’t need an inventory to learn that broadcast spectrum is being underutilized in many markets. The same is true for some of the satellite spectrum. We can, and should, move ahead with reallocating some of that spectrum now. An inventory is a good idea to identify other spectrum that can be shifted to wireless use, but an inventory isn’t needed in the broadcast space.

  8. Why did the earthquake prove that the wireless industry needs more spectrum?
    During the earthquake, the wireless networks worked. No towers went down and no networks failed because of the earthquake. Some people did experience delays because wireless networks experienced a huge surge of communications across the nation at rates massively higher than normal.

    To illustrate the point, let me use an example with arbitrary numbers. A network is built to accept, let’s say 1,000 users. When the earthquake occurred, 10,000 people were trying to use the network at the same time. As soon as one of 1,000 users was done using the network, then one of the remaining 9,000 was admitted in. Essentially, there was a queue.

    When the earthquake hit, millions of Americans – wanting to check to make sure their loved ones were okay – used their wireless devices at the same time. This is not a usual occurrence, such as morning rush hour. This was an event that created demand that far exceeded New Year’s Eve or the Super Bowl.

    In our analogy about spectrum, cars are like our mobile devices, such as cellphones and smartphones. With the tremendous increase in the number of cars, or devices, and the amount of time they're spending on the “roads,” we need more lanes, or spectrum. Otherwise, wireless consumers will experience long delays when they want to access service, or they won't be able to get on the road at all.

    The earthquake delays were caused by an enormous number of users who were trying to use the same highway at the same time, which caused the jam. With more spectrum, we'd have more lanes that would ease congestion and allow more users to access the wireless highway.

  9. Why doesn’t the industry build networks that can handle massive call volume, such as Mineral, VA earthquake?
    In D.C., it’d be like expanding the 14th Street bridge to handle the rare instances, such as the earthquake, when Virginia residents are trying to get home from their offices in D.C. For New Yorkers, it’d be expanding the Holland Tunnel. No one builds roads to handle the maximum possible traffic that may occur only a day or two a year, at most. It’s the same for our networks.

    Carriers have been working at a breakneck pace to expand capacity, but to use our analogy about spectrum and lanes, we’re finding the usual traffic – such as rush hour – is becoming impossible for our members to adequately serve without more spectrum, or roads.

  10. What happens if the wireless industry doesn’t get more spectrum?
    While it’s impossible to identify with precision all of the potential harms of not bringing sufficient spectrum to market, analyst Peter RysavyPDF says that there are multiple adverse technical, service and market consequences. Failure to augment capacity through additional spectrum will have adverse consequences not only to U.S. wireless innovation, but also to investment, job growth and improvement in the health care, education and energy sectors.

A few weeks ago, Deloitte released a study on 4G impactPDF that showed the next-gen network build-out could mean $25-53 billion in network investment for the U.S. by 2016; create 371,000-771,000 jobs and GDP growth between $73 billion-$151 billion.

Clearly, making more spectrum available for the U.S. wireless industry means great things for our nation, our economy and our people.

We can’t afford to wait.

5 Responses to “Top 10 Questions on Spectrum” Leave a reply ›

  • avatar

    The real problem is architecture and impact of data related services (photos, videos, etc.). For example, if a voice call takes up 7kb/s, a single 350 kB photo 'consumes' the equivalent of almost 7 minutes of network 'talktime'. A single two minute video consumes 167 minutes of network 'talktime'. How many photos and videos do you suppose were sent/received/distributed? Folks rushed to 'see' what was going on, looking to get streaming video services. If Mobile DTV (broadcast!) was widely available, a HUGE amount of data would be off-loaded from the network.

    Instead of fighting for reallocation, if CTIA is committed to solving the problem, a candid discussion that could lead to collaboration with television broadcasters would go a LONG ways towards solving the problem. Simply moving spectrum from one service (broadcast) to another (unicast) creates a 'revolving door' that will NEVER solve the problem. Steve, give me a call! Open to helping broker a deal, or at least creating the understanding that a deal is possible. :-)

  • avatar

    There is useful information for journalists and the public here, but some of it needs updating. A few comments:

    1. Why does spectrum need to be paired?

    With Time Division Duplex (TDD) in LTE it does not need to be paired. TDD may make more sense, and can make more efficient use of spectrum, for typical internet traffic with its unbalanced download to upload ratio. It is also easier to use odd pieces of spectrum that don’t have an obvious pairing.

    2. Why are you so focused on certain spectrum bands?
    5. Is there a general rule that the lower the frequency bands the better and that higher bands don’t work as well for wireless?

    The lower frequencies have the advantages you state. Higher-frequencies have technical advantages too, such as smaller transmit and receive antennas (easier to deploy higher-sector-count base stations, easier to fit multiple-input multiple-output (MIMO) antennas into a phone, etc.). The FCC’s latest wireless competition report suggests the difference in frequencies is not so significant. Worldwide, it appears today that the 1800 MHz band is going to be the most popular for LTE.

    6. Why don’t you use femtocell and other cell-splitting technology to improve efficiency?

    In the first femtocells that came out a few years ago capacity increases were questionable. Newer femtocells that incorporate better interference management techniques can indeed increase capacity. Qualcomm says femtocells can increase capacity 10-times or more depending on the deployment scenario. (See Qualcomm’s paper “How to meet data demand,” June 2011, slide 23.)

    7. Why not do a spectrum inventory?
    As indicated above, some operators might prefer spectrum in higher frequency ranges to increase capacity in congested areas, especially if they already have wide-area coverage on lower frequencies. The higher government frequency bands thus become more important. An inventory of those bands becomes more important given the GAO’s report earlier concluding that the sorry state of NTIA’s databases makes it “uncertain if spectrum management decisions are based on accurate and complete data.”

    8. Why did the earthquake prove that the wireless industry needs more spectrum?

    9. Why doesn’t the industry build networks that can handle massive call volume, such as Mineral, VA earthquake?

    10. What happens if the wireless industry doesn’t get more spectrum?
    More spectrum would allow for capacity increases in emergencies but so would network enhancements such as femtocells and Wi-Fi offloading. Furthermore, these other enhancements permit the user’s device to transmit with less power, increasing battery life which is also important in emergencies. Adding spectrum does not reduce device transmit power.

  • avatar

    I am a little confused.
    Here is a portion of Answer #2 for the FAQ's: " The lower the frequency range, the longer the wave. Whether a frequency is good for wireless is determined by how fast the wave travels, the ability of the waves to penetrate through trees and other vegetation and the reflectivity of various objects to the waves."
    I was always taught that all frequencies of radio waves travel at about 3.0 X 10^8 m/s through space.
    Was this a typo, or did the person doing the proof-reading just miss this "physics" fact?

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