How to Get a Grant

This guide explains the complete process to obtain a spectrum grant from the SAS as defined in WINNF-TS-0016.

Overview

Getting a grant involves four main steps:

1. Successful registration (obtain cbsdId)
2. Optional but recommended spectrum inquiry (discover available channels)
3. Grant request (ask for specific frequency/power)
4. Heartbeat (activate and maintain the grant)

A grant is required before any transmission.

Step-by-Step Process

1. Register the CBSD

• Send registrationRequest with all required parameters (userId, fccId, cbsdSerialNumber, installationParam, etc.)
• Receive cbsdId on success (responseCode 0)

Tip: Include measCapability and optional groupingParam here to maximize future grant quality.

2. Perform Spectrum Inquiry (Recommended)

• Send spectrumInquiryRequest with desired operationFrequencyRange (can be full CBRS band: 3550-3700 MHz)
• Include measReport if capable
• Review availableChannel list for viable options

Key Bridge SAS Tip: Inquiry with measurements often reveals higher EIRP possibilities than blind grant requests.

3. Request the Grant

• Send grantRequest with:
  • cbsdId
  • operationParam (maxEirp, operationFrequencyRange)
• Request full band if flexible, or specific range from inquiry

Example JSON

{
  "grantRequest": [
    {
      "cbsdId": "SAS123/CBSD-001",
      "operationParam": {
        "maxEirp": 37.0,
        "operationFrequencyRange": {
          "lowFrequency": 3550000000,
          "highFrequency": 3700000000
        }
      },
      "measReport": { /* optional but encouraged */ }
    }
  ]
}

• On success (responseCode 0): Receive grantId, granted frequency range (may be partial), and grantExpireTime

4. Activate and Maintain via Heartbeat

• Immediately send first heartbeatRequest with:
  • grantId
  • operationState: "GRANTED"
  • grantRenew: true
• On success: Receive transmitExpireTime and heartbeatInterval
• Begin regular heartbeat loop (every ~60 seconds)
• Only transmit after first successful heartbeat when transmitExpireTime is in the future

Best Practices for Better Grant Success

• Send Measurements: Include rcvdPowerMeasReports in inquiry, grant, and heartbeat requests (optional but highly effective)
• Use Grouping: Declare consistent groupingParam (e.g., INTERFERENCE_COORDINATION) across related CBSDs
• Request Conservatively: Start with moderate maxEirp; SAS may grant higher if conditions allow
• Full Band First: Request 3550-3700 MHz initially — SAS assigns best contiguous channel
• Multiple Grants: Request several overlapping or adjacent ranges for redundancy
• Monitor Responses: Adjust strategy based on past denials (e.g., lower power in dense areas)

Common Reasons Grants Fail & Fixes

Full Example Flow Summary

1. Register → get cbsdId
2. Inquiry (full band + measurements) → identify possibilities
3. GrantRequest (full band, conservative EIRP + measurements) → get grantId
4. Heartbeat loop → authorize transmission

Key Bridge SAS: Users who consistently send measurements and use grouping typically achieve higher EIRP, more channels, and greater stability.