How to Request and Manage Spectrum Grants

This guide explains how to implement the Grant procedure as defined in WINNF-TS-0016.

Overview

A Grant is the formal authorization from the SAS for a CBSD to transmit on a specific frequency range with defined power limits. Grants are required before any transmission begins.

The process uses:

• GrantRequest (sent after registration and optional spectrum inquiry)
• GrantResponse (approves, denies, or suspends the request)

Grants have states: GRANTED (active after heartbeat), AUTHORIZED (transmitting), SUSPENDED (temporarily halted).

Prerequisites

• Successful CBSD registration with cbsdId
• Desired frequency range (can be the full CBRS band 3550-3700 MHz or narrower)
• Knowledge of CBSD EIRP capability and Category (A or B)

Tip: The request must include a frequency range in operationFrequencyRange. You can request the entire CBRS band (lowFrequency: 3550000000, highFrequency: 3700000000) to let the SAS select the best available channel(s).

Step 1: Construct the GrantRequest

Required Parameters

operationParam Sub-parameters

Optional but Recommended

Example JSON (requesting full band)

{
  "grantRequest": [
    {
      "cbsdId": "SAS123/CBSD-001",
      "operationParam": {
        "maxEirp": 37.0,
        "operationFrequencyRange": {
          "lowFrequency": 3550000000,
          "highFrequency": 3700000000
        }
      },
      "measReport": {
        "rcvdPowerMeasReports": [
          {
            "measFrequency": 3550000000,
            "measBandwidth": 50000000,
            "measRcvdPower": -60.5
          }
        ]
      }
    }
  ]
}

Step 2: Send the Request

• HTTPS POST to SAS grant endpoint
• Mutual TLS authentication
• Content-Type: application/json

Tip: Request multiple narrower ranges in separate grantRequest objects if you want specific channels; SAS may grant partial ranges.

Step 3: Process the GrantResponse

Key Parameters

Common responseCode Values

Example Successful Response

{
  "grantResponse": [
    {
      "cbsdId": "SAS123/CBSD-001",
      "grantId": "GRANT-789",
      "channelType": "GAA",
      "operationParam": {
        "operationFrequencyRange": {
          "lowFrequency": 3620000000,
          "highFrequency": 3630000000
        },
        "maxEirp": 30.0
      },
      "grantExpireTime": "2026-01-08T12:00:00Z",
      "response": {
        "responseCode": 0,
        "responseMessage": "Success"
      }
    }
  ]
}

Step 4: Activate the Grant (Heartbeat)

After SUCCESS, immediately start sending HeartbeatRequest using grantId to move grant to AUTHORIZED state.

Best Practices & Tips

• Always request the full CBRS band initially if flexible — SAS will assign the best available contiguous channel.
• Request conservative maxEirp to increase approval chances in contested areas.
• Handle partial grants (narrower range or lower EIRP) gracefully.
• Implement multiple concurrent grant requests for channel diversity/redundancy.
• Monitor grantExpireTime and renew via heartbeat before expiry.
• Log grantId persistently for recovery after reboot.

Common Issues & Troubleshooting

Next Steps

1. Start heartbeat loop for the granted channel
2. Begin transmission only after first successful heartbeat (transmitStatus: AUTHORIZED)