CBRS is a band from 3.55MHz to 3.7MHz that has been designated by the FCC for shared use. The band is ideal for testing out spectrum-sharing schemes, as well as a variety of high-bandwidth applications. Powder has a variety of devices capable of operating in the CBRS band, and adding more devices with higher transmit power is a major future focus for the platform.
Several of the Powder rooftop nodes are available for experimentation in the CBRS band. Users working with low power protocols, such as LoRa, are ideally suited for using these resources. These `cbrssdr` radios can operate in TDD mode via the channel 0 TX/RX port at 20 dBm maximum power, with a Commscope VVSSP-360S-F antenna attached for modest 5 dBi of additional gain in CBRS. These radios are currently available via the following six radios/rooftops:
Additionally, most Powder Fixed and all Mobile endpoint sites are able to operate in the CBRS band via their NUC+B210 compute plus radio resources. All `nuc2` nodes on the Fixed Endpoints, and all `ed1` nodes on the Mobile Endpoints have NI B210 radios with the channel A TX/RX port connected to a Taoglas wideband antenna that surpports operating in CBRS. This allows for the same TDD mode and monitoring capabilities as the rooftop nodes, but from the fixed and mobile endpoint vantage points. As with the rooftop CBRS radios, there are currently no separate RF front-ends in front of these B210 radios at this time, meaning the maximum signal power available is about 12 dBm.
Users of Powder have successfully used the rooftop radios to operate enchanced low power WAN (LPWAN) communications with the ZCNET project. There has also been success operating a LoRa stack written for SDRs in CBRS across both rooftop, mobile, and endpoint radio devices (see profile links below). Additionally, general GNU Radio and UHD environments have been used for communicating in select cases using OFDM signals.
The Powder team is working on medium power and high power RF front-ends to extend the range of our rooftop and upcoming Dense Deployment sites. We anticipate the the medium power frontends, providing around 30 dBm of power, will be available in the summer of 2022. High power RF front-ends, able to run at 10 W (40 dBm) average, and about 100 W (50 dBm) peak will be available in 2023.