Documentation

Codex: Key Bridge Wireless Technical Documentation

The Codex is the comprehensive technical reference for Key Bridge Wireless platforms and services, including our Spectrum Access System (SAS), Spectrum Sensing Platform (SSP), Spectrum Exchange (SPX), and related components for dynamic spectrum sharing.

This living document provides in-depth guides, API references, protocol specifications, implementation tutorials, deployment best practices, and architectural decisions to support developers, system integrators, and administrators in building, deploying, and maintaining scalable, interoperable, and regulatory-compliant dynamic wireless networks.

Whether you're integrating certified spectrum controllers for CBRS, transitioning legacy systems to shared spectrum bands, or exploring automated frequency coordination across multiple jurisdictions, the Codex equips you with the knowledge to leverage Key Bridge's innovative solutions effectively.

What Is CBRS?

Citizens Broadband Radio Service, or CBRS, is a way to share radio frequencies in the United States so that more people and businesses can use wireless networks without interfering with each other or with important government systems. Imagine it like a smart traffic system for radio waves: instead of everyone fighting over the same road, a central controller assigns lanes dynamically to keep things moving smoothly.

CBRS is a band of radio spectrum (specifically the 3.5 GHz range, from 3550 to 3700 MHz) that's open for shared use. It's like Wi-Fi but more powerful and reliable for things like private cellular networks in factories, schools, or stadiums. There are three "tiers" of users:

• Incumbents: The top priority group, like government radars or satellite stations—they always get first dibs.
• Priority Access License (PAL): Businesses that buy licenses for protected access on specific channels, similar to owning a reserved parking spot.
• General Authorized Access (GAA): Anyone can use it for free, but with less protection, like public parking where you might get bumped.

This sharing makes CBRS great for building your own mini-4G or 5G network without buying expensive licenses.

Why Does CBRS Exist?

Traditional radio spectrum is scarce and expensive—think of it like prime real estate. Governments auction it off for billions to big carriers like Verizon or AT&T. CBRS was created to open up spectrum for smaller players, like companies or local networks, while protecting military and other critical users. The "why" is to make wireless tech more accessible, foster innovation (e.g., private networks for smart factories or rural broadband), and use spectrum more efficiently. It's like turning a private highway into a carpool lane that everyone can share without crashes.

How Does CBRS Work?

At the heart of CBRS is the Spectrum Access System (SAS), which acts like DNS for the internet—but instead of assigning web addresses, it assigns radio channels. Here's the basic flow:

1. Registration: Your radio device (called a CBSD) connects to the SAS over a secure internet line (hard-line connection required) and registers its location, power capabilities, and other details. It's like checking in at a hotel desk.
2. Channel Assignment: The CBSD asks the SAS for a channel (via a "grant request"). The SAS checks for incumbents (using sensors called ESC to detect radars) and assigns a safe channel and power level. Radios need this channel assignment to transmit legally—without it, they're silent.
3. Heartbeat Check: Every minute or so, the CBSD "heartbeats" back to the SAS to confirm it's still okay. If conditions change (e.g., a radar activates), the SAS can suspend or adjust the grant.
4. Wireless Network Setup: Once assigned, the CBSD can set up a wireless network, broadcasting like a mini cell tower for phones, machines, or IoT devices in the area.

The SAS ensures no one steps on each other's toes, dynamically reallocating as needed. For example, if a military radar needs the channel, your device gets bumped to another one automatically.

In short, CBRS democratizes radio spectrum, making it easier and cheaper to build custom wireless networks, all managed by a smart SAS "traffic cop." If you're setting up one, start with a SAS provider—they handle the complex parts.