Spectrum 101

Spectrum refers to the invisible airwaves all around us that enable our wireless devices to send and receive information wherever we go. 

Policy Topics

Spectrum is a limited, natural resource, consisting of range of radio frequencies that can carry information through the air by the use of electromagnetic signals. 

How fast and how far those signals can travel – and how much data they can transmit – depend on the frequency being used. 

The federal government controls or shares the vast majority of spectrum, which is why it’s critical that policymakers and the wireless industry work together on a long-term plan to free up more spectrum for mobile broadband.  
All of our wireless devices, from smartphones and tablets to remote heart monitoring devices and smart energy meters – rely on spectrum. As mobile data use grows, we need more spectrum so that consumers experience a fast and reliable wireless experience.

When you use your mobile device, you’re sending a signal that is picked up by the nearest antenna – a cell tower along the highway or increasingly “small cells,” wireless infrastructure that can be as small as a pizza box. Your call or data goes from the antenna to a base station where, via cables in the ground or microwave antennas, is sent to its destination – another wireless caller, a landline or a website/application. 

Spectrum that the wireless industry uses to deliver service can be considered in three buckets: low-, mid- and high-band spectrum. Most smartphones today use low- to mid-band spectrum (under 3 GHz), because the wireless signals travel miles from a cell tower in your community to your device, providing broad coverage and capacity. 
 
Thanks to significant investments in R&D, wireless companies are now able to use high-band spectrum (above 24 GHz), which was long considered unusable for mobile wireless service. While low- and mid-band spectrum can travel long distances, high-band spectrum can only go meters. However, it can carry significantly more data traffic thanks to very large spectrum blocks. 

The federal government regulates the use of spectrum because the airwaves are a scarce natural resource and to protect against the interference that occurs when two different signals try to use the same spectrum frequency at the same time in the same location. 

Under the government’s policy framework, commercial spectrum is considered either licensed or unlicensed. Licensed spectrum means someone, like a wireless provider, purchases a license from the government to use a particular slice of spectrum in a set geographic area, and that license entitles the purchaser to use that spectrum exclusively. Licensed spectrum has driven the vast majority of the economic impact and job creation, but unlicensed spectrum is also important to meet Americans’ demand for mobile access anytime, anywhere. 

Unlicensed spectrum is open to any use without purchasing a spectrum license, subject to following minimum technical standards. Wi-Fi is a great example of the use of unlicensed spectrum, but baby monitors, cordless landline phones and garage door openers also use these airwaves set aside for permission-less innovation. Wireless carriers are also using unlicensed spectrum through LTE in Unlicensed Bands as well as encouraging users to offload their mobile usage from wireless networks to Wi-Fi  to help handle the significant increase in data demands.

We need both licensed and unlicensed spectrum for the U.S. to remain the world’s leading mobile industry. 
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