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.
- 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.
- 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.
- 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.
- 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.
- 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.
- 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.
- 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.
- 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.
- 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.
- 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 Rysavy 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.