OpenSSRF Learning Trail

Electromagnetic spectrum is a critical resource. SSRF data exchange can help systems use spectrum efficiently and effectively; enabling wireless systems and communications without interference.

Learning Trail Index

Overview

Standard Spectrum Resource Format (SSRF) is a standardized data format for exchanging spectrum management-related data.

While the original scope of use for SSRF is within the Department of Defense (DOD) many of the business processes enabled by SSRF are also required for commercial spectrum management and by national spectrum regulators and administrators as they introduce dynamic spectrum sharing rules and regulations.

Introduction

SSRF is a component technology supporting a number of DOD spectrum operations and systems. These include GEMSIS, Coalition Joint Spectrum Management Planning Tool (CJSMPT), Spectrum XXIO, Stepstone and others.

Common goals for these various systems are enabled by SSRF and include:

  • Transform spectrum operations to a responsive and agile capability to request, assign, allocate, and deconflict portions of the electromagnetic spectrum
  • End-to-end spectrum supportability frequency assignment
  • Software definable radio waveform spectrum management support
  • Strategic spectrum management planning
  • Modeling and simulation for mission planning, rehearsal, and acquisition
  • Increased common picture of spectrum situational awareness of friendly and hostile forces

Use in a Commercial Spectrum Access System (SAS)

It is anticipated that SSRF will be an important supporting technology for a Spectrum Access System (SAS). This has commercial interest specifically for a Spectrum Access System (SAS) for the 3550-3650 MHz band (3.5 GHz band), as proposed in the FCC's 3.5 GHz NPRM (GN Docket No. 12-354).

In a SAS we expect SSRF will be used to convey technical details and IEEE 1900.5.2 used when crossing security domains and to determine compatibility

As described in the 3.5 GHz NPRM, several high-level functions may be required for the proposed SAS to operate successfully:

  • First, the SAS would need access to a dynamic stream of location-specific spectrum usage and interference data.
  • Second, it would need a baseline set of standardized methods for interpreting and operating on this data to determine allowable operations across the various tiers of users.
  • Third, it would need to identify proper remedies to interference issues in a timely manner and communicate these instructions back to operational network nodes.
  • Finally, the SAS could use additional data from connected network nodes to monitor, and if necessary, enforce compliance by participating network nodes.

A high-level illustration of some of these concepts is shown below.

The 3.5 GHz NPRM proposes a three-tier, license-by-rule authorization framework that would facilitate rapid broadband deployment while protecting existing incumbent users of the 3.5 GHz Band. 3 Under this proposal, access to the 3.5 GHz Band would be governed by a dynamic SAS, building on the TV White Spaces database concept.

The 3.5 GHz NPRM proposes that the SAS would manage three service tiers:

  1. Incumbent Access;
  2. Priority Access (PA); and
  3. General Authorized Access (GAA).

Incumbent Access users would include authorized federal and grandfathered Fixed Satellite Service (FSS) users currently operating in the 3.5 GHz Band. These users would have protection from harmful interference from all other users in the 3.5 GHz Band. In the Priority Access tier, the 3.5 GHz NPRM proposes that the Commission authorize certain users with critical quality-of- service needs (such as hospitals, utilities, and public safety entities) to operate with some interference protection in portions of the 3.5 GHz Band at specific locations. Finally, in the GAA tier, users would be authorized to use the 3.5 GHz Band opportunistically within designated geographic areas. GAA users would be required to accept interference from Incumbent and Priority Access tier users.

SAS Background

The effectiveness of the proposed dynamic spectrum sharing regime depends on proper spectrum authorization and management among the various users that would operate in the 3.5 GHz Band. The proposed SAS is essential to realizing this goal.

It is likely that the SAS would take dynamic inputs from incumbents and existing authorized users regarding their spectrum utilization. Based on such inputs and other factors, the SAS could communicate with existing and potential 3.5 GHz Band users about the availability of spectrum and certain operational parameters (see Figure 1). Similar to the approach taken in the TV White Space proceeding,9 we assume infrastructure nodes, like Radio Access Networks Operation and Maintenance (RAN/O&M), Node B/Base Stations (eNB/BS), or Access Points (APs) would interact with the SAS and provide User Equipment/Mobile Stations/Access Terminals (UE/MS/AT’s) with operational parameters and updates.

To ensure consistent, predictable, and replicable system operation across different systems, some minimum standards regarding issues such as: (1) transmit and receive power levels; (2) co-channel interference thresholds; and (3) adjacent channel interference thresholds may need to be established. In addition, common methods of measuring, quantifying, encoding and communicating various technical information and interference events across systems using a variety of different technologies and deployment models may need to be implemented. These methods could take into account both co-channel and adjacent channel interference between nearby nodes, systems or devices that may not be synchronized or coordinated.

Spectrum Management Basics

Traditionally, spectrum management has been viewed as a system of frequency allocations, allotments, and assignments. The entire spectrum is divided into frequency bands called allocations. The allocations specify the allowed use of the frequencies in the band. These uses are referred to as radio services (e.g., fixed, mobile, broadcasting, radiolocation, radionavigation, amateur, satellite, radio astronomy, etc.).6 These allocations may then be further subdivided into allotments. Frequency channels are allotted within the band in accordance with an agreed plan for use by one or more administrations in one or more identified countries or geographic areas and under specified conditions. For example, an allocation to the broadcasting service is subdivided into channel allotments for television broadcasting in the Western Hemisphere. Allotments attempt to prevent interference among users that are managed by different administrations. For example, one is the allotment of channels in plans to avoid interference along borders of countries that are members of the plan. There are separate allotment plans for maritime mobile, aeronautical mobile route services, and certain satellite services where frequencies and orbit positions are included in the allotment plan.

Finally, an assignment is a grant of authority or license to a specific user for a band of frequencies or a radio frequency channel under specified conditions. Assignments are the final subdivisions of spectrum. Some assignments are exclusive, meaning the licensee is protected from interference. Other assignments are issued on a nonexclusive basis, requiring the users to cooperate on an informal basis to avoid interference. Some bands are available for specific uses without assignment, such as Citizen Band (CB) radio and the various Industrial, Scientific, and Medical (ISM) bands.

In the United States, the National Telecommunications and Information Administration (NTIA) has authority to grant frequency assignments to government agencies, while FCC grants authority to use radio frequencies or channels by issuing licenses to private sector entities and local and state governments.

Definitions (As Defined by the ITU Radio Regulations)

  • Administration: Any governmental department or service responsible for discharging the obligations undertaken in the Constitution of the International Telecommunication Union, in the Convention of the International Telecommunication Union and in the Administrative Regulations.
  • Allocation (of a frequency band): Entry in the Table of Frequency Allocations of a given frequency band for the purpose of its use by one or more terrestrial or space radiocommunication services, or the radio astronomy service under specified conditions. This term shall also be applied to the frequency band concerned.
  • Allotment (of a radio frequency or radio frequency channel): Entry of a designated frequency channel in an agreed plan, adopted by a competent conference, for use by one or more administrations for a terrestrial or space radiocommunication service. in one or more identified countries or geographical areas, and under specified conditions.
  • Assignment (of a radio frequency or radio frequency channel): Authorization given by an administration for a radio station to use a radio frequency or radio frequency channel under specified conditions.

United States Frequency Allocations

Frequency bands are allocated primary and secondary services. Users of the primary service have priority over the users of the secondary service. Users of secondary services are usually required to operate with greater restrictions to avoid causing interference and must accept interference from the primary users. Exceptions to allocations may also occur and appear as footnotes. These footnotes allow uses of bands under specific conditions for other services and users than listed as primary.

U.S. frequency allocations are divided further into government and non-government use. Figure 3-1 illustrates the allocation of spectrum to services and to users in the U.S. and its Possessions. Unique in this allocation is the subdivision of spectrum into red, green, and black activities, delineating the portion of the spectrum where the primary use is exclusively for non-government use, green; government use, red; and shared government and non- government use, black. This has particular relevance in the current spectrum management environment where Congress has and may further convert government bands to non- government use. Current government exclusive allocations are listed in Table 3-1. (A large version of is published by the NTIA.

U.S. Frequency Allocation Chart as of October 2011

Spectrum Management Objectives

The objective of spectrum management (within DOD) is to “enable electronic systems to perform their functions in the intended environment without causing or suffering unacceptable interference" [DoDD 4650.1].

Key desirable features of systems that support the spectrum management process include:

  • Interoperability between all joint, national, coalition, and single service tools;
  • Access to an authoritative data repository of spectrum-related information at tactical, JTF, COCOM, Service/Agency, and national levels;
  • Supports ITU and national radio regulations.

Spectrum Management Actors

Spectrum management actors are all the entities (organizations or personnel) involved in the processes related to spectrum management (see Annex C for explanations of UML terms like "Actors").

There are three basic elements of spectrum management:

  • International and National Spectrum Allocation
  • Spectrum Supportability
  • Frequency Assignments / Allotments

All nations participate in the International and National Spectrum Allocation and Frequency Assignment activities. Some nations participate in the Spectrum Supportability process. The relationship between these three elements is shown in Figure 1.4.2 and is discussed in the following paragraphs. The organizational context for the conduct of these activities is defined in Figure 1.4.3.

The hierarchal relationship between positions within the organization is dependent upon the scenario.

Spectrum Management Tasks & Business Processes

SSRF supports numerous spectrum management business processes. These processes and respective requirements are broken down into several operational tasks which must be performed to accomplish spectrum management. To conduct core spectrum management a common set of data is required: tables of allocations, locations, force elements, equipment, and antennas. The general sequence of core spectrum management operational tasks to ensure effective spectrum usage is illustrated below and individual tasks are described in detail in their respective documents.

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