CBRS Certified Professional Installer (CPI) – Study Notes

Module 1 – CBRS Basics

What is CBRS?

• Citizens Broadband Radio Service
• 150 MHz of new bandwidth in 3550-3700 MHz range
• Established for shared usage in 2015 by FCC
• That spectrum was historically used by US Military and Navy
• Main Entities – FCC, CBRS Alliance (OnGo certification), Wireless Innovation Forum (WInnForum – define requirements and protocols in CBRS)

What is Spectrum Sharing?

Different owners sharing the same resource

Advantages of shared spectrum

• Efficiency – Low priority users use remaining spectrum when high priority users are not using it
• Time to market – Time to start using a license
• Cost – low cost with an option to pay more for guaranteed use
• Feasibility – more opportunities to explore

Why CBRS spectrum sharing is different?

• Ensuring that higher priority users aren’t disrupted requires an aggregate interference constraint
• Basic sensing like DFS is not sufficient
• Only way to do it is to use centralized cloud-hosted Spectrum Access System (SAS)

What CPI needs to know about shared spectrum?

• CPI ensures that the SAS has the right data to ensure protection of higher-priority users
• Educate their employers about CBRS

Vision for CBRS

Fixed and Mobile broadband access for use cases like:

• Private LTE Network
• Broadband service to homes or businesses from a central tower
• Broadband service similar to cellular for large outdoor area
• Localized broadband service

CBRS 3-tiered architecture

Tier 1 – Incumbents (users using it before CBRS was created)

• • Military ship-borne radar (3550-3650) mostly in San Diego, Norfolk (VA), Bremerton (WA) – significant usage
  • Military ground-based radar (3550-3700) – various bases – occasional usage
  • Fixed-satellite earth stations (3600-3700) – 35 sites – receive only
  • Wireless Broadband Service (3650-3700) – WISPs – thousands of locations – will transition to GAA or PAL tiers soon

Tier 2 – Priority Access License (PAL) – pay a license at auction. Protected from Tier 3, but cannot interfere with Tier 1

• • Each PAL – size of one county – 1 x 10 MHz channel
  • 3 year licensed lease of a 10 MHz channel between 3550 – 3650 MHz – Max 7 out of 10 channel allowed to be leased in a geography parcels (4000 people)
  • Each applicant can get a max of 4 PAL licenses in a given county
  • PPA – PAL Protection Area – contiguous area of combined services areas of PAL sites
  • Protection only in places where they actually installed – though the license allocation size is a county size, but the protection is given only to the PPA

Tier 3 – General Authorized Access (GAA) – free, but no protection from tier 1 and 2

• • GAA users can be operated along with PAL users – cannot use the PAL allocated spectrum within a PPA
  • Priority in last 50 MHz (3650-3700) over PAL users are PAL doesn’t cover that spectrum

Spectrum Access System (SAS)

• Cloud-based
• Keep tracks of location and characteristics of all devices
• Makes sure all FCC and WInnForum standards are followed
• Synchronizes daily with databases
• Makes sure aggregate interference of lower priority users is not affecting higher priority users
• Controls spectrum and TX powers of CBSDs

Terminology

• CBSD – Base stations or APs – will require SAS communication
• EUD – End User Devices – will not require SAS communication – cannot talk to each other – will need to talk through SAS
• DP – Domain Proxy – Some CBSDs communicate to SAS through DP (Ruckus cloud) – aggregates communications from multiple CBSDs and pass it to a SAS
• ESC – Environmental Sensing Capability – sensors along coastal line to detect if Navy uses the spectrum – ESC is considered to be a tier 1 device to make sure they do their job

Module 2 – Role of a CPI

The role of CPIs in CBRS:

• Provide accurate information about a CBSD to a SAS, so that it can manage any interference from the CBSDs to higher-priority users
• Determine installation parameters – 100% responsible for any errors
• Can physically install or monitor the work of others – don’t need to be physically present
• Ask photos or videos, if not present onsite to validate
• Can get the certification revoked or suspended, if error is detected
• Ensure CBSD is up and running
• Troubleshoot problem during and after registration
• CPI owns the certification, not the employer
• CPI-provided data may be checked by others
• Federal government may pursue legal action in the event of negligence or willful misconduct of a CPI

Division of Responsibility

• Equipment Manufacturer
  • Get FCC certified
  • Ensure it complies with all regulations and standards

• Network Owner
  • Plan network deployment
  • Select a SAS vendor
  • Purchase and physically install CBSDs
  • On-going maintenance of CBSDs
  • Make sure CPI is hired and report improper operation of CPI to TPI

• CPI Employer
  • Make sure CPI has a valid certification

• CPI
  • Provide accurate info to SAS
  • Keep up with changes in CBRS regulations

• SAS
  • Ensure higher priority protection
  • Ensure high availability
  • Coordination among GAA users and resolve conflicting use of band

• Training Program Administrator (TPA)
  • Train CPIs
  • Communicate rules and spec changes to CPIs
  • Investigate CPI errors

Corrective or disciplinary actions a TPA may take

• Can be reported by tier 1/2 users, CBSD owners, SAS admin, FCC
• Actions taken:
  • No disciplinary action – for insignificant errors – ask CPI to update or correct the error
  • Suspend and require retraining – for repeated material errors in info provided
  • Take disciplinary action – suspend or terminate a CPI’s credentials for willful errors

Module 3 – CBRS background

SAS-CBSD Communication

• Direct communication or through a domain proxy
• CBSD always initiates the communication and SAS will respond
• A SAS cannot proactively communicate to a CBSD
• SAS will always respond with a response code

• First Request – Registration request
  • From CBSD with information on the installation parameters (CPI-provided)
  • Installation Parameter types
    • Required – mandatory
    • Optional
    • REG-Conditional – must provide but could be optional in some cases
• First response – Registration Response
  • If approved, SAS will provide a CBSD ID that is unique for each CBSD and a response code

• Second Request – Spectrum Inquiry Request
• Second Response – Spectrum Inquiry Response
  • Response includes the available channels and TX power at each channel

• Third Request – Grant Request
  • Request lease of a specific channel and TX power
• Third Response – Grant Response
  • A Grant ID is provided for each spectrum allocated
  • A CBSD may have multiple Grants from the same SAS for each unique channel
  • A CBSD may not have multiple Grants from different SAS providers

• Fourth Request – Heartbeat Request
  • May I transmit with this grant?
  • Has to request at least once every 4 minutes
• Fourth Response – Heartbeat Response
  • Response codes:
    • Success
    • Terminated grant – need to get a new grant
    • Suspended grant – retains the grant, but has to wait. If needed a new grant may be requested by the CBSD.

 

Module 4 – How to do the CPI Job

When is a CPI required?

Height requirement for Category A CBSD

• HAAT – Height Above Average Terrain
• HAAT is only used to determine the CBSD Category
• FCC Rule – HAAT < 6 meters is Category A
• If higher, CBSD should be registered as Category B
• If register a Category A with > 6m, SAS will reject and there is no penalty
• Height required for calculation – elevation of location + height of antenna above ground
• Positive HAAT – above mountains
• Negative HAAT – Valleys

Determining Installation Parameters

SAS needs more info – CPI provides some of those

• FCC ID of CBSD (sticker, user manual, software, owner/operator)
• Serial Number of CBSD
• CBSD ID -> Unique ID -> FCC ID + Serial Number
• For Multiple Antenna CBSD -> each antenna is a CBSD (unique FCC ID, serial number)
  • CPI should provide unique serial number of each antenna (serial:1, serial:2)
  • CPI should report the location of each antenna
• Device Category – Category A, Category B
• Location – accuracy of 50 m or better (latitude and longitude)
  • Site survey
  • Google Maps
  • 3rd party sites
  • Phone GPS (outdoor or rural)
• Height – accuracy of 3 m or better
  • Don’t depend on your phone’s sensors
  • Report either:
    • Above Ground Level – AGL
    • Above Mean Sea Level – AMSL
  • Check the Network Planner – CBSD on a pole or building
  • Ask the building owner
  • Use a Laser measure for short distance
  • Tape measure for short distance
  • GPS may be used with caution
• Indoor vs. Outdoor
  • Use best judgement on sites like a football stadium

Determining Antenna Orientation and Characteristics

You will need to provide these:

• Antenna Azimuth (optional for Cat A)
  • Horizontal pointing angle of antenna relative to true north (north pole)
    • Range – 0 to 359
    • 0 deg – facing north
    • 90 deg – facing east
    • Omnidirectional – Enter 0 deg
  • If installing a CPE, use FCC calculator using base station location as a reference
  • Use compass, if necessary
    • Find front of antenna and use a compass to find the angle
    • A metallic object nearby could alter the result
    • Measurement should include ‘magnetic declination adjustments’ relative to true north
    • Magnetic declination – variation between compass shown north and true north
      • Positive – East (add)
      • Negative – West (subtract)

• Antenna Downtilt (optional for Cat A)
  • Vertical pointing direction – How far down the antenna is pointed
  • Range – -90 to 90 degrees
  • Negative – tilted above horizontal (towards sky)
  • Positive – tilted below horizontal (towards ground)
  • Some CBSD will have in-built marker
  • If not, use a digital level or inclinometer

• Antenna Gain in dBi – Mandatory
  • Ratio of actual radiated power to conducted power
  • Range: -127 to 128 dBi
  • Listed in datasheet or the equipment itself
  • Check with the network planner
  • If listed in dBd, add 2.15 to get the value in dBi
  • If listed as fractional, round to the nearest whole number
  • No limit on antenna gain, but SAS will limit the EIRP accordingly

• Antenna Beamwidth – (Optional for Cat A)
  • Spread of antenna pattern
  • Range: 0 to 360
  • Listed in datasheet or the equipment itself
  • Check with the network planner
  • If omni-directional, list 360 degree
  • If listed as fractional, round to the nearest whole number

• Air Interface
  • The radio technology used by the CBSD
  • Types:
    • E_UTRA (LTE)
    • Cambium_Networks (proprietary)
    • 4G_BBW_SAA_1 (IEEE 802.16e – Fixed and Mobile Broadband Wireless)

• Measurement Capability
  • Ability to measure and report spectrum occupancy
  • Types:
    • Received_Power_Without_Grant (able to perform measurement before getting a spectrum grant from SAS)
    • Received_Power_With_Grant (able to perform measurement after getting a spectrum grant from SAS)

• CBSD Group ID (Optional) – usually sent by CBSD – not mandatory for CPI to know
  • Name of special set of CBSDs that should be treated differently by SAS

Getting Information from the CPI to the SAS

Two ways:

1. Single-step registration – CPI -> CBSD -> SAS
   1. CPI digitally signs using CPI credentials into CBSD interface (signed and encrypted)
   2. CBSD or a Domain Proxy sends this info to SAS
   3. CBSD to SAS registration request is in plain text and unsigned
   4. CPI registration ID (CPIR ID) and name required for signing
   5. Installation certification time – time stamp – YYYY-MM-DD-UTC-Time-Z
2. Multi-step registration – CPI -> SAS <- CBSD
   1. Info is loaded into SAS before CBSD is registered. SAS combines this info with the info it receives from CBSD.
   2. CPI enters parameters into SAS interface (either manually or bulk upload)
   3. No digital signature like single-step (prove identity using credentials)
   4. CPI matches incoming CBSD info with FCC ID and serial number CPI entered

Entering info into SAS

• May require an account with the SAS provider
  • Email, password, mobile phone
• May need your CPI credentials
  • CPIR ID – CPI Registration ID
  • Your full name
• Login – https://sas.commscope.com/
• Account request – sas-info@commscope.com
• Info input – Provisioning->CPI
  • Manual entry form for a single site entry
  • Bulk upload in CSV format (sample template available)
• SAS will validate the data and flag any incorrect info in the form for incorrect info like FCC ID
• Erroneous info can be fixed by resubmission using the same FCC ID and CBSD serial number

CPI Password

• Need to send parameters in a tamper-proof way
• Password – to digitally sign the input
• More secure than the average password
• Verify CPI identity
• Format – .p12 extension
  • Private Key – to sign
  • Certificate – to identify you as a the signer (signed by a CA)
• Private key – securely store it
  • Lock your computer
  • Don’t share
  • Don’t send in email or USB

What can go wrong?

• SAS may not accept your CPI credentials
  • Single-step – As your enter directly into SAS, it will show invalid value (103) as the response in registration request. It can also give “cpiId or cpiSignatureData” in the error message
  • Multi-Step – Varies according to the SAS, but some of above may apply
• Troubleshooting
  • Is certification valid – <5 years
  • Valid credentials?
  • Verify if you’re listed in WInnForum CPI database (takes 24 hours to update)
  • Verify correct CPIR ID
  • Verify states is Active

SAS Rejection

Module 5 – Steps to Certification

Steps:

1. Complete the course
2. Pass CPI exam >75%
3. Obtain CPI certificate
   1. Obtain digital certificate from INSTA (protect the key)
4. Register with WInnForum – CommScope will do this

Replacing CPI credentials

• If lost or compromised, contact online – www.commscope.com/wisupport or call tech support
• Valid for 5 years
• Reminder 3 months before expiration
• You can still recertify without taking the full training, if you take the test within 1 year of expiration
• SAS will no longer accept your credentials after the expiration date

Module 6 – The Future

Responsibilities

• Provide accurate info to SAS
• Correct any inaccurate info ASAP
• Learn how to use proprietary interfaces
• Stay current on regulatory standards and protocols
• Keep your certificate safe. If compromised or lost, notify the TPA
• Notify TPA, if contact info changes
• Respond to TPA inquiries
• Re-certify in 5 years

TPA responsibilities

• Training CPIs
• Update CPIs on regulatory changes
  • If not reviewed on time, CPI certification will be suspended for CPIs
• Provide CPI info to WInnForum
• Interact with INSTA and provide digital certificate
• Investigate reports of CPI errors