Citizens Broadband Radio Service

Enables Low Latency Private Wireless Networks for Industrial IoT Use Cases

The newly released 3.5 GHz Citizens Broadband Radio Service (CBRS) will play a significant role in the growth of new Industrial IoT use cases. CBRS is a very large swath of licensefree, shared spectrum formed to promote the development of new applications. The FCC calls it an “innovation band” with the intention for it to ignite new use cases, similar to what WiFi did over 20 years ago. Compared to WiFi, however, the CBRS band access is managed, which provides interference protection even though it is licensefree.  

Fig. 1 below illustrates the three types of access: General Access, Priority Access and Grandfathered Access.

  • The General Access is license free access for the widest possible group of users. GA users are permitted to use any portion of the 3550-3700 MHz band not currently assigned to other users. This license free access is intended to promote the innovation of new use cases.
  • The Priority Access users are licenses on a county-by-county basis through competitive bidding. Each PA license is for a 10 megahertz channel within the 3550-3650 MHz band. PAs are 10-year renewable licenses. Only seven PALs will be issued in any given county.
  • Grandfathered Access users include few Fixed Satellite Service providers (space-to-Earth). Currently there are only around 25 such earth stations in the USA and their licenses will sunset by 2023.
industrial high throughput transceiver

The key elements of the 3.5 GHz dynamic spectrum sharing are the cloud-based Spectrum Access System (SAS), the Citizens Broadband Radio Service Devices (CBSDs), and the End User Device (EUD). The SAS maintains a database of all CBSDs, their geographical location, and other pertinent information. These elements allow real-time knowledge of the spectrum being used at various locations, which helps to manage potential interference.  


high throughput wireless router

As required by the “device type approval” at power up, every CBSD must contact the shared Spectrum Access System (SAS) over the Internet and receive operating parameters like channel and RF power limit. The SAS provides this authorization in accordance with other CBSDs operating in the area. Once the CBSD receives the authorization from the SAS, it can then instruct the downstream EUDs to begin their operation. 

Here are some of the salient technical requirements that the CBSD must satisfy –

  • All CBSD must positively receive the SAS clearance prior to initiating any RF transmission.
  • No airborne applications are allowed (sorry Drones).
  • Maximum antenna height is limited to 6 meters (about 20 feet) from the floor.
  • All CBSD must periodically report their GPS location to the SAS.
  • Maximum 10 MHz channel size.
  • All CBSD must use Time Division Duplex (TDD), Digital Modulation Scheme.
  • The device category CBSD-A is defined for urban use cases and can transmit up to 30 dBm RF power (EIRP, including antenna gain).
  • End User Devices can transmit up to 23 dBm EIRP RF power.
  • High powered CBSD-B for rural-outdoor settings will be introduced in the future.

Mesh Rider- Enabling High Performance Private Wireless Networks

Mesh Rider is an innovative patented long-range wireless broadband mesh technology developed by Doodle Labs (refer to the Whitepaper: Mesh Rider – An Introduction for more details). It is a state-of-the-art wireless communication technology that combines various capabilities under a single umbrella: 

  • Long range 
  • High throughput 
  • Mobile mesh 
  • Licensed and license-free frequency bands 
  • Native flat IP architecture 
  • Feature rich networking 

In particular, Mesh Rider is designed for the deployment of robust and high performance private wireless networks. It has the simplicity of WiFi and can be used and operated under enterprise control. 

How does Mesh Rider Mesh compare with LTE and WiFi?

There is significant excitement and buzz in the market about the new opportunities enabled by the CBRS band. LTE vendors are investing heavily to take advantage of this license-free spectrum. WiFi is also used to deploy short range private network in license-free bands.  

Doodle Labs Mesh Rider for CBRS technology provides a higher performance solution to deploy private wireless networks for applications that require high throughput, long range, and low latency. The accompanying chart shows important comparative parameters for each of the technologies. 


high-throughput routing for multi-hop wireless networks and mimo radio system

Doodle Labs Mesh Rider technology has been extended to bring its capabilities to the CBRS band. RM-3625 Smart Radios are fully certified for CBRS regulatory compliance. 

The CBRS Band Smart Radio is an innovative dual role device. It can be software configured for either the CBSD-A role or the EUD role to simplify network planning and execution. The RM-3625 is available in 3 different form factors (Embedded, External, and Pocketable). The Smart Radios enable organizations to deploy private wireless networks as easily as WiFi. 

The FCC has authorized over 10 companies to operate the SAS. Doodle Labs has worked closely with Federated Wireless to ensure the interoperability with its SAS. The RM-3625 is pre-configured to make this a turn-key operation. 

Additional Industry Resources

After almost 5 years of planning, the commercial CBRS deployments have just begun in Q1 2020. The industry is excited to take advantage of the opportunities presented by such a large swath of unlicensed spectrum becoming available (For comparison, CBRS is 150 MHz while 2.4 GHz WiFi is only 70 MHz wide band). There are many things to learn and many experiences to share. Here we have curated some resources that we think may be useful in your research.

  1. An Overview of the Citizens Broadband Radio Service – Video Tutorial by Commscope (25 minutes)
  2. FCC’s Part 96 governing the use of CBRS band. For most users, the Subparts C and D are most relevant.
  3. CBRS Baseline Specifications Overview – A webinar explaining the details of the CBRS specifications. Wireless Innovation Forum.
  4. CBRS Standards committee – The Spectrum Sharing Committee (SSC) serves as a common industry and government standards body supporting the development and advancement of CBRS spectrum sharing technologies.