Public Briefing and Community Input 

July 12, 2022

CBRS Sharing Ecosystem Assessment: 

Test Framework and Approach

7/12/2022 – DRAFT – PRE-DECISIONAL – POSTED FOR PUBLIC INPUT 

7/12/2022 – DRAFT – PRE-DECISIONAL – POSTED FOR PUBLIC INPUT 
• Communicate Test Framework and Scope of Project

• Communicate recommended approach and context

• Roadmap of how each task supports the Objectives (Noise Floor, Always-On, Data)

• Review modeling that led to recommendations

• Identify analysis outcomes

• Identify appropriate venues for coordination with stakeholders

Briefing Goals

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7/12/2022 – DRAFT – PRE-DECISIONAL – POSTED FOR PUBLIC INPUT 
National Advanced Spectrum and Communications Test Network (NASCTN)

NASCTN is a multi-agency, chartered organization that 

includes DoD, NASA, NIST, NOAA, NSF, and NTIA.

The purpose of NASCTN is to improve opportunities for 

successful spectrum sharing through accurate, reliable, and 

unbiased measurements and analyses.

Through its members, NASCTN provides:

• Robust test processes and validated measurement 

data necessary to develop, evaluate and deploy 

spectrum sharing technologies

• Best practices for spectrum sharing metrology, 

testing, measurement, and data analysis to improve 

quality of information provided to the spectrum 

community

• Access to testing capabilities, spectrum test data, 

analyses, and reports NIST hosts NASCTN Program Office and a core team to ensure rapid 

response, access to key skills, consistency, and knowledge management.

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7/12/2022 – DRAFT – PRE-DECISIONAL – POSTED FOR PUBLIC INPUT 
National Advanced Spectrum and Communications Test Network (NASCTN)

NASCTN: 

• Develops Test Plans with independent technical experts

• Identifies and facilitates access to appropriate test 

facilities

• Executes and validates scientifically rigorous test 

methodologies

• Delivers detailed test methods and data with 

transparency, validity, and reproducibility 

• Protects all controlled information (proprietary, sensitive, 

classified) 

NASCTN does not make policy recommendations 

7/12/2022 – DRAFT – PRE-DECISIONAL – POSTED FOR PUBLIC INPUT 4

7/12/2022 – DRAFT – PRE-DECISIONAL – POSTED FOR PUBLIC INPUT 
NASCTN projects follow an open, transparent, comprehensive process for developing and executing independent, scientifically 

based test plans, validating test results, and reporting findings. Serves as a common architecture across all NASCTN projects. 

NASCTN 5-Stage Framework

5

7/12/2022 – DRAFT – PRE-DECISIONAL – POSTED FOR PUBLIC INPUT 

7/12/2022 – DRAFT – PRE-DECISIONAL – POSTED FOR PUBLIC INPUT 
TEST REQUEST: DoD CBRS Sharing Ecosystem Assessment (SEA) program

Test Request: CBRS Sharing Ecosystem Assessment (SEA)

Collect data required for DISA DSO to ascertain the effectiveness of the sharing 

ecosystem between CBRS systems as managed by Spectrum Access Systems (SASs), 

and DoD systems as monitored by Environmental Sensing Capabilities (ESCs). 

Provide insight into the sharing ecosystem’s effectiveness, and track changes in the 

spectrum environment over time.

4 Key Objectives:

Provide data driven insights into:

1. Efficacy of permanent sharing between CBRS systems as managed by SASs and DoD 

systems

2. Noise floor measurements through continuous automated observations

3. CBRS emissions within the Always-On Dynamic Protection Areas at Army and Marine sites

Support:

4. The development & management of a measurement data repository

2 Phases:

• Phase 1: Establish the measurement system requirements; develop, build, 

deploy a metrology system to measure the CBRS ecosystem performance at 

DoD sites.

• Phase 2: Long-term analysis phase, with continuous noise floor measurements 

and annual deep dive measurements and analysis.

Background: DoD 3.5 GHz Transition Plans focus on 

ecosystem validations, environmental assessments, 

and continued engagement on refining the CBRS 

infrastructure. One component was identified for 

submission to NASCTN, to evaluate the effectiveness 

of the CBRS sharing ecosystem to co-exist with DoD 

radar systems, via independent trusted agent

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7/12/2022 – DRAFT – PRE-DECISIONAL – POSTED FOR PUBLIC INPUT 
Citizens Broadband Radio Service (CBRS)

NASCTN Project: Provide data-driven insight into the 

CBRS sharing ecosystem’s effectiveness between 

commercial and DoD radar systems, and to track 

changes in the spectrum environment over time. 

The Citizens Broadband Radio Service (CBRS) is the “first of a 

kind” shared spectrum ecosystem, implemented nationwide.

• Shared band, 3 tier approach - Incumbent, Priority Access 

License, General Authorized Access

• Sharing stipulations

• Environmental Sensing Capability (ESC) detects incumbents and 

Spectrum Access Systems (SAS) coordinates spectrum access

Modeling &

Data Analytics

Laboratory 

Capabilities

Monitoring 

Expertise 7

7/12/2022 – DRAFT – PRE-DECISIONAL – POSTED FOR PUBLIC INPUT 

Reference: https://ongoalliance.org/the-technologybehind-spectrum-sharing-the-spectrum-access-system/
Passive Observation:

• Task 1 – Measure Aggregate CBRS Emissions in Coastal DPAs ▫ Characterize aggregate CBRS emissions with and without DPA activations.

▫ Obj 1: Assess ecosystem performance to timely respond

▫ Obj 2: Measure increase in noise floor due to deployment of CBRS systems over time

• Task 2 – Measure Aggregate CBRS Emissions in Always-On DPAs

▫ Characterize aggregate CBRS emission levels over time in always-on DPAs. ▫ Obj 1: Collect data to provide insights into the Always-On Dynamic Protection Areas

▫ Obj 2: Measure increase in noise floor due to deployment of CBRS systems over time

Active Experimentation:

• Task 3 – Evaluate ESC Performance in the Field (with Navy Ship)

▫ Assess ESC detection performance for a representative set of ESCs in the field.

▫ Obj 1: Collect data on ESC site alerting due to Navy transmission. Assess true-positive and false-positive rates

and independently verify incident power levels at ESC sensor locations

▫ Coordinated investigation with Federal and commercial stakeholders

Long Term Support:

• Task 4 – Long Term Data Analysis of the measurements from Task 1 and 2

• Task 5 – Support DoD Measurement Data repository

o Support the development & management of a measurement data repository

NASCTN SEA Project Approach

To achieve the 4 objectives, 5 major technical tasks were identified: DPA = Dynamic Protection Area

7/12/2022 – DRAFT – PRE-DECISIONAL – POSTED FOR PUBLIC INPUT 8

7/12/2022 – DRAFT – PRE-DECISIONAL – POSTED FOR PUBLIC INPUT 
Underlying Assumptions of the Approach

• Data driven insights into how the CBRS ecosystem shapes the spectrum 

environment for Federal incumbents are desirable

• Independent measurements and data that inform on the deployed 

CBRS ‘sense and vacate’ spectrum sharing strategy are valuable

• Characterizing the real-world detection performance of ESCs against actual 

in-situ radar emissions is of value to CBRS stakeholders and the spectrum 

sharing community

• The following slides highlight the technical and logistical challenges associated with 

observation and experimentation of systems in the real-world.

• The presented approach does not imply an endorsement by CBRS stakeholders

7/12/2022 – DRAFT – PRE-DECISIONAL – POSTED FOR PUBLIC INPUT 9

7/12/2022 – DRAFT – PRE-DECISIONAL – POSTED FOR PUBLIC INPUT 
• Characterize aggregate CBRS emissions with and without DPA activations.

▫ Obj 1: Assess ecosystem performance to timely respond

▫ Obj 2: Measure increase in noise floor due to deployment of CBRS systems over time (multiple years)

• Not Doing:

▫ Obj 1: Adjudication or attribution of timeliness to respond

▫ Obj 2: On-land measurements will not be translated to in-DPA

Task 1 – CBRS Emissions in Coastal DPAs

• Assumptions:

▫ DPAs East 1 and West 14 are desirable

▫ Knowledge of DPA activations can be obtained

▫ DPA activation & geographic impact can be modeled 

and is informative:

 NTIA OSM deployment models

 WInnForum’s reference move list algorithm

 ITM P2P propagation model

• Description:

▫ Shore based sensors provide for longitudinal study of 

CBRS on a per 10 MHz channel basis

▫ Information from CBRS stakeholders combined with 

standard models allow for optimized sensor locations

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7/12/2022 – DRAFT – PRE-DECISIONAL – POSTED FOR PUBLIC INPUT 
Measurement of aggregate CBSD emissions in an ideal case

Challenges for the Dynamic range of a COTS 

based sensor system

• Ability to distinguish between DPA On and 

Off  Simulation shows great difficulty 

even for highly specialized sensors

• DPA based sensor nodes would provide

limited insight into protection thresholds

• Requires sensor resiliency to strong 

incumbent signals

• High sensitivity and wide dynamic range 

are anticipated requirements

Task 1 - Key Technical Challenge of the Measurement Campaigns within DPA

Initial simulation results highlight the 

technical challenge

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CBRS Emissions

Sensor 

Measurement

DPA Active (On)

CBRS Emissions

Sensor 

Noise Floor

Sensor 

Measurement

DPA Inactive (Off)

Protection 

Threshold

7/12/2022 – DRAFT – PRE-DECISIONAL – POSTED FOR PUBLIC INPUT 

7/12/2022 – DRAFT – PRE-DECISIONAL – POSTED FOR PUBLIC INPUT 
Anticipated Analysis Outcomes

• Passive observations of CBRS emissions

• Longitudinal (over time) study of CBRS emissions and power 

at select locations within neighborhood distances of DPAs 

East 1 and West 14

▫ Coordination sought to incorporate DPA state notifications to:

 Analyze CBRS emissions based on DPA state

 Quantify CBRS timeliness to respond to DPA activation and 

deactivation

Task 1 – Sensors Deployed near Coastal DPAs

ESC ?

SAS

CBSDs

Incumbent

NASCTN 

RF Sensor

NASCTN 

RF Sensor

NASCTN 

RF Sensor

NASCTN 

RF Sensor

NASCTN 

RF Sensor

NASCTN

?

?

7/12/2022 – DRAFT – PRE-DECISIONAL – POSTED FOR PUBLIC INPUT 12

7/12/2022 – DRAFT – PRE-DECISIONAL – POSTED FOR PUBLIC INPUT 
Objective:

• Estimate the max 95th percentile aggregate emissions from CBSDs 

at protection points (inside DPA) and sensor locations (outside DPA)

▫ Without DPA activation, i.e., emissions from neighbor list CBSDs

▫ With DPA activation, i.e., emissions from keep list CBSDs

Assumptions:

▫ Simulated CBSD deployment using the NTIA OSM full deployment 

assumptions2

▫ ITM P2P propagation model

▫ WInnForum's reference DPA move list algorithm

▫ Reference receive antenna (*)

▫ Set of receive 2D antenna patterns/gains

▫ Projected noise floor of sensor system (290K, 5 dB NF)

Simulations for Task 1

(*) reference receive antenna used in WINNF-TS-0112 V1.9.0 Antenna height set to 50m ASL for task 1B, and 2m AGL for 1C

CBSD Deployment

Neighbor list size 19,501

Keep list size 10,529

Protection Criteria

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San Diego (DPA West14)

DPA

CBSD

2 Deployment assumptions found in NTIA TR 15-517 & reflect the FCC authorized max power of CBSDs

2D Antenna Boresight

Azimuth 

(degree)

Downtilt

(degree)

0 0

20 0

0 10

120 6

CBSD Max EIRP 

(dBm/10MHz)

Height AGL (m) Location

Cat A 26 [3, 60] Indoor

Cat B [40, 47] [6, 100] Outdoor

2D Antenna Peak Gain 

(dBi)

Elevation Beamwidth 

(degree)

Azimuth Beamwidth 

(degree)

Vertical polarized 

omnidirectional 9.03 11.02 360

Slant polarized 

omnidirectional 11.13 Slant +45: 11.92Slant -45: 11.13 360

Panel antenna 17.18 6.02 90.80

7/12/2022 – DRAFT – PRE-DECISIONAL – POSTED FOR PUBLIC INPUT 
Simulation Results – West 14 / San Diego CA

CBSD emissions are above the noise floor, 

except at a few points further out to sea

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CBSD emissions at all example locations are 

above the sensor noise floor

CBSD emissions are above the sensor noise 

floor at some example sensor locations

Examples outside DPA

DPA

DPA Protection points

DPA

7/12/2022 – DRAFT – PRE-DECISIONAL – POSTED FOR PUBLIC INPUT 

CBSD emissions stay below the noise floor for 

all protection points
Task 2

7/12/2022 – DRAFT – PRE-DECISIONAL – POSTED FOR PUBLIC INPUT 15

7/12/2022 – DRAFT – PRE-DECISIONAL – POSTED FOR PUBLIC INPUT 
• Assumptions: 

▫ Camp Pendleton is a representative always-on 

DPA

▫ Sensors can be situated in locations informative 

to DoD stakeholders

• Description: 

▫ Longitudinal study measuring aggregate RF 

emissions in the CBRS band over several years.

▫ Select one or multiple location(s) within the 

always-on DPA, informed by simulation and 

stakeholder interaction.

Task 2 – CBRS Emissions in the Always-on DPAs

• Characterize aggregate CBRS emission levels over time in always-on DPAs.

▫ Obj 1: Collect data to provide insights into the Always-On Dynamic Protection Areas

▫ Obj 2: Measure increase in noise floor due to deployment of CBRS systems over time

• Not Doing:

▫ Obj 1: Adjudicate or attribute the protection threshold

7/12/2022 – DRAFT – PRE-DECISIONAL – POSTED FOR PUBLIC INPUT 16

7/12/2022 – DRAFT – PRE-DECISIONAL – POSTED FOR PUBLIC INPUT 
Task 2

Camp Pendleton: sites surveyed on recent field visit

DPA limits:

▫ Frequency: 3550 MHz – 3650 MHz

 Licenses channelized to 10 MHz blocks

▫ Protection criteria varies by frequency:

Anticipated Analysis Outcomes:

▫ Noise floor change over time

▫ Quantify CBRS aggregate emissions levels at a set of 

locations within the always-on DPA

▫ Collect data to provide insights into R2-IPM-05: SAS’s shall 

manage CBSD aggregate interference levels for inland 

DPAs

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7/12/2022 – DRAFT – PRE-DECISIONAL – POSTED FOR PUBLIC INPUT 
Task 3

7/12/2022 – DRAFT – PRE-DECISIONAL – POSTED FOR PUBLIC INPUT 18

7/12/2022 – DRAFT – PRE-DECISIONAL – POSTED FOR PUBLIC INPUT 
Description:

▫ Independently verify CBRS band incident power levels at 

ESC sensor locations.

▫ Compare ground truth radar presence to CBRS stakeholder 

system key performance indicators (KPIs).

Task 3 – Evaluate ESC Performance in the Field

Not Doing: Adjudication or Attribution of results

Objective: Assess ESC detection (True/False-Positive and True/False-Negative rates) for a representative set of ESCs in the 

field.

Anticipated Analysis Outcomes:

▫ True-Positive, False-Positive, True-Negative, False-Negative rates

▫ Potential bonus insights into:

 Path loss models

 ESC whisper zones

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7/12/2022 – DRAFT – PRE-DECISIONAL – POSTED FOR PUBLIC INPUT 
Concept: Coordinated in DPA “ground truth” incumbent with designed periods of 

radar activity and “quiet” times. Evaluate ESC performance using system key 

performance indicators. Independently verify incident power levels at ESC sensor 

locations.

Advantages:

• Known ground truth for radar presence – necessary to verify specified 

performance level

• Focused measurement campaign in a DPA

• Better control and more efficient data collection than passive observation

• Does not require developing and testing radar detection algorithms.

• Need to measure incident power levels. 

Task 3 - Recommended Approach: Active Experiment

Sites: Investigate and select DPA for 

suitability of active experimentation

7/12/2022 – DRAFT – PRE-DECISIONAL – POSTED FOR PUBLIC INPUT 20

7/12/2022 – DRAFT – PRE-DECISIONAL – POSTED FOR PUBLIC INPUT 

Disadvantages:

• Mistakes have high opportunity cost

• High level of coordination with incumbent operators

• Potential for being highly disruptive to CBRS end users

• Shorter measurement campaign means less representative range of weather & propagation conditions ― Could mitigate by 

repeating at different time of year
Goal: Provide data-driven insight into the CBRS sharing ecosystem’s 

effectiveness between commercial and incumbent DoD radar systems, and to 

track changes in the spectrum environment over time.

• NASCTN Test Framework has proposed a test approach under a set of 

assumptions that need to be verified to enable tractable measurements

• The team is working through the Test Plan Development Phase

• Two test plans will be generated, one for Tasks 1&2, another for Task 3

Summary

7/12/2022 – DRAFT – PRE-DECISIONAL – POSTED FOR PUBLIC INPUT 21

7/12/2022 – DRAFT – PRE-DECISIONAL – POSTED FOR PUBLIC INPUT 
• The team will develop the Test Plans for this project, then hold another 

public briefing where they will be presented

• The draft Test Plans will be posted to the NASCTN website for review

▫ Formal written comments may be submitted by anyone

• All comments and their adjudications will be posted to the NASCTN 

website along with the updated draft Test Plan

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Test Plan

7/12/2022 – DRAFT – PRE-DECISIONAL – POSTED FOR PUBLIC INPUT 

7/12/2022 – DRAFT – PRE-DECISIONAL – POSTED FOR PUBLIC INPUT 
nasctn@nist.gov

Contact Us

NASCTN Program:

▫ https://www.nist.gov/ctl/nasctn

Updates on the Project:

▫ https://www.nist.gov/programsprojects/cbrs-sharing-ecosystem-assessment

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7/12/2022 – DRAFT – PRE-DECISIONAL – POSTED FOR PUBLIC INPUT