Spectrum Highways: Rules of the Road for Collaborative Radio Frequency Spectrum Sharing

By John Stine, Ph.D.

A spectrum highway is a dynamic spectrum access approach that enables spectrum sharing in congested environments, at fine time scales, with deference to high precedence users. It enables 5G sharing in government bands and EMS maneuver in warfighting.

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The spectrum highway system is a new approach to dynamic spectrum access (DSA) that is highly efficient at managing the access and reuse of spectrum in time and in space. Additionally, it resolves problems of congestion, distinguishes spectrum use based on precedence of users and uses, coordinates the rendezvous of spectrum-dependent systems (SDS) devices, avoids features that can be easily attacked and enables autonomous maneuver in the EMS. Further, the underlying technology that enables spectrum highways will fully support heterogeneous uses in the same spectrum, making spectrum convergence feasible even among distributed autonomous devices.

This DSA technique is most easily visualized using highways (or roadways) as a metaphor. Following this metaphor, highways are created by setting aside spectrum in geographical locations and subdividing that spectrum into lanes. 

Like vehicles on a highway, many SDSs can operate on the same lane of the highway, with their use separated either spatially or temporally, or on separate lanes for spectral separation. SDSs can autonomously move among the lanes and, if necessary, merge lanes for broader bandwidth access. They can also move among highways. 

SDSs contend among themselves to use the highway lanes by using a signaling protocol that is highly effective at resolving contention in congested conditions and orchestrating spatial reuse of the highway lanes. This same signaling is used to arbitrate precedence among the SDSs for lane access. 

Similar to the way an emergency vehicle can alert other vehicles to its presence and precedence using a siren and flashing lights, an SDS can use the signaling methods of the highway. The signaling can indicate which SDS a contending device belongs thus removing the challenges of rendezvous. 

The behaviors of SDSs that cause them to cooperate efficiently are created by the access protocol, its rules for access behavior, and authorizations given to SDSs that govern their use of precedence signaling when using highways.

Given a collection of SDSs designed to operate on highways, the concept of operations is to provide those SDSs with information about the highways and the precedence levels they are permitted to use and then let them operate autonomously thereafter. There is no requirement for SDSs to remain connected to a database and the use of signaling removes any ambiguity about spectrum availability. 

In operation, each SDS autonomously decides which highways and lanes to use and cooperates with others on the same highway and lane using the access protocol and its associated rules. There is no burden on system operators. 

This access paradigm can achieve the same results as access using a database, (e.g., the spectrum access system (SAS) used by the Citizen’s Band Radio Service in 3.5 GHz), without the need for constant connectivity between the devices and the SAS. Better, the devices can be mobile, thus avoiding the expense of professional installation, localization, and registration. 

Spectrum highway DSA can achieve the same results as a sensor-based DSA approach without risk of interfering with passive users. As long as SDSs follow the rules for access and behavior on the highway, their use of the spectrum will be compatible with other SDSs on the highways. The autonomy and flexibility this approach provides, enable SDSs to have initiative in selecting the spectrum to use which gives them an advantage in a contest against an adversary. 

The report provides a comprehensive description of how to design highways and signaling to enable the outcomes described above. It lists the rules that devices must follow in operating on spectrum highways. It describes how to define a highway using the IEEE 1900.5.2 Standard for Modeling Spectrum Consumption.