How to Get a Grant (Complete End-to-End Flow)

This guide walks through the complete process to obtain an active, transmitting spectrum grant using WINNF-TS-0016 protocols.

Overview: The Full Grant Lifecycle

Register → Get cbsdId
Spectrum Inquiry (optional but recommended) → Find available channels
Grant Request → SAS approves with grantId
First Heartbeat → Grant becomes AUTHORIZED; start TX
Ongoing Heartbeats → Maintain grant + renew

Key Bridge SAS Tip: Always include measurements (optional but requested) + grouping for best results. Full CBRS band requests work well.

Prerequisites

Valid CBSD certificate (test with health endpoint GET)
Accurate GPS location + antenna params (Cat B needs CPI data)
Hardware RF measurement capability (recommended)

Step 1: Register the CBSD

POST /cbsd/api/v1.2/registration
{
  "registrationRequest": [{
    "userId": "user@example.com",
    "fccId": "ABC123",
    "cbsdSerialNumber": "SN456789",
    "measCapability": ["RECEIVED_POWER_WITHOUT_GRANT", "RECEIVED_POWER_WITH_GRANT"],
    "installationParam": {
      "latitude": 38.95,
      "longitude": -77.1,
      "height": 10,
      "heightType": "AGL",
      "indoorDeployment": false,
      "antennaAzimuth": 0,
      "antennaDowntilt": 0,
      "antennaGain": 15.0,
      "eirpCapability": 37.0
    },
    "groupingParam": [{
      "groupType": "INTERFERENCE_COORDINATION",
      "groupId": "MyNetwork-Site1"
    }]
  }]
}

Success: Store cbsdId (e.g., "SAS123/CBSD-001")

Step 2: Spectrum Inquiry (Recommended)

Query full band for best options:

POST /cbsd/api/v1.2/spectrumInquiry
{
  "spectrumInquiryRequest": {
    "cbsdId": "SAS123/CBSD-001",
    "lowPowerIndicator": false,
    "operationParam": {
      "operationFrequencyRange": {
        "lowFrequency": 3550000000,
        "highFrequency": 3700000000
      },
      "maxEirp": 37.0
    },
    "measReport": {
      "rcvdPowerMeasReports": [{
        "measFrequency": 3550000000,
        "measBandwidth": 50000000,
        "measRcvdPower": -60.0
      }]
    }
  }
}

Success: Note top availableChannel (e.g., 3620-3630 MHz @ 30 dBm)

Tip: Full band request + measurements = highest approval chance.

Step 3: Request Grant

Use full band or narrow to preferred from inquiry:

POST /cbsd/api/v1.2/grant
{
  "grantRequest": [{
    "cbsdId": "SAS123/CBSD-001",
    "operationParam": {
      "operationFrequencyRange": {
        "lowFrequency": 3550000000,
        "highFrequency": 3700000000  // SAS picks best
      },
      "maxEirp": 37.0
    },
    "measReport": {
      "rcvdPowerMeasReports": [{
        "measFrequency": 3620000000,
        "measBandwidth": 10000000,
        "measRcvdPower": -55.2
      }]
    }
  }]
}

Success: Receive grantId (e.g., "GRANT-789"), operationParam, grantExpireTime

Handle 400 GRANT_FAILURE: Lower maxEirp by 3-6 dB, narrow range, retry.

Step 4: Activate Grant (First Heartbeat)

Critical: Do NOT transmit until this succeeds!

POST /cbsd/api/v1.2/heartbeat
{
  "heartbeatRequest": [{
    "cbsdId": "SAS123/CBSD-001",
    "grantId": "GRANT-789",
    "grantRenew": true,
    "operationState": "GRANTED"
  }]
}

Success: Receive transmitExpireTime (future timestamp) + heartbeatInterval (e.g., 60s)

Now you can transmit on granted params until transmitExpireTime.

Step 5: Maintain Grant (Ongoing Heartbeats)

Every heartbeatInterval (± jitter):

{
  "heartbeatRequest": [{
    "cbsdId": "SAS123/CBSD-001",
    "grantId": "GRANT-789",
    "grantRenew": true,
    "operationState": "AUTHORIZED",
    "transmitExpireTime": "2026-01-07T14:30:00Z",  // Your current TX end
    "measReport": { /* optional ongoing measurements */ }
  }]
}

Monitor:

New transmitExpireTime ← Stop TX immediately if past
Updated operationParam ← Adjust power/range instantly
500/501 codes ← Suspend/Terminate handling

Best Practices & Quick Wins

Technique	Benefit
Full CBRS band request	SAS finds best channel automatically
Always send measurements	Higher EIRP, fewer denials, interference help
Use grouping	Coordinated power boost within your network
Heartbeat 5-10s early + jitter	Avoid synchronized failures
Multi-grant (2-3 channels)	Redundancy if one terminates

Error Recovery Flow

Grant Denied (400) → Lower EIRP → Retry (3x)
↓
Heartbeat Suspend (500) → Stop TX → Continue HB
↓
Terminate (501) → Relinquish → Back to Step 2

Complete Example Timeline

T0:  Register → cbsdId
T+2s: Inquiry → 3 channels available
T+3s: Grant Req → GRANT-789 (3620-3630 MHz, 30dBm)
T+4s: 1st HB → AUTHORIZED until 14:05
T+4s: **START TRANSMIT**
T+59s: 2nd HB → Renewed until 14:06
... (repeat every 60s)
T+5min: HB 500 → **STOP TX** (DPA), continue HB
T+7min: HB 0 → **RESUME TX**

Test First: Health endpoint → Sandbox SAS → Production

Get a Grant (End-to-End)