CBRS low / high power question

I read that "low power" devices like cell phones will not be locked to the SAS.  Then I am seeing stuff being called "small cell" deployments that it appears will have reduced power but still be tied to a SAS ?  Then the fixed wireless seems discussed separately from "small cell" , has more power and is for sure tied to the SAS.

I was hoping there would be something we use in a micro-pop solution that didn't need high power (thus no SAS) because it only needed to reach a short distance (though still fixed, with SM's installed on the homes/businesses).

Will there be such a thing or is the low power no SAS stuff just for cell phones ? 

I've asked these questions and was told that none of Cambium's radios will qualify as 'low power'. All of them will need SAS access.

Check out THIS discussion regarding what you're asking and more CBRS details with Matt Mangriotis.


It is true that some devices will be considered Category A CBSD, which would avoid registration with the SAS. However, all PMP 450 equipment is considered Category B CBSD.

They need to have CPI (Certified Professional Installer) certification, and will need to communicate with the SAS.

All 450 equipment is considered outdoor fixed wireless equipment and will be capable of power levels exceeding those of Category A devices.

Eric, thanks for linking back to that discussion... there will be further communication on this topic as we get closer to launch, and keep the questions coming!

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Again, the rules need to be explained more clearly. There are, essentially, four types of CBRS Device:

#1: A Category A CBSD operates indoors, at up to +30 dBm/10 MHz EIRP, or in some cases may be outdoors, but think "park", not "WISP". IT MUST REGISTER WITH THE SAS. it may or may not need CPI, depending on how good its geolocation is, but in practice I expect it to need CPI all the time, because GPS doesn't have the required vertical accuracy. (That is, you can only waive CPI if you can get some unobtanium.)

#2: A Category B CBSD only operates outdoors, at up to +47 dBm/10 MHz EIRP. It needs CPI and SAS, always.

The original rules allowed a Category A CBSD to use a SAS without ESC (Environmental Sensing Capability, essentially a network of radar detectors feeding the SAS) outside of a fairly large coastal zone. That has been changed. Now, ESC is still needed in coastal zones but it doesn't matter if it's CatA or CatB, and it's based on whether the SAS it's attached to has ESC for the particular offshore zones called Dynamic Protection Areas (DPAs) that the CBSD may be impacted by. The "big three" (note -- mobile-friendly, not WISP-friendly) initial SASs have just gotten ESC approved. Other SASs coming down the line may not have access to ESC; that's to be seen.

#3: An End User Device (EUD) is a client of a CBSD base station, fixed or mobile, capped at +23 dBm/10 MHz EIRP. Think "cell phone". It is invisible to the SAS; it only transmits when and where it is authorized by a base station CBSD, and that's what the SAS authorizes. No CPI is involved.

#4: A CPE-CBSD is a special case of EUD that is allowed to operate at >+23 dBm/10 MHz EIRP because it is also a CBSD, registered with a SAS. The SAS fee for these will be lower than for a base station but usually not zero. Typically this will be a device with a high gain antenna, like a CBRS 450B. Approval processes for these are being worked out now and none are fully authorized yet. These are typically going to be Category B outdoor devices and WILL require CPI. BOTH the base station AND the CPE-CBSD will thus need to be authorized for the same frequency.


Fred - I just want to clarify something... in the case of #4 as you describe. These are still treated as Category B CBSD for the purpose of communicating with the SAS.  There is no concept of "special pricing" and for our (Cambium Networks) purposes, all 450 devices, regardless whether they are AP (base station), SM (CPE) or Backhaul are treated equally with respect to the SAS fees. There will be one set price per device per month.

We have done our best negotiating with all of the SAS vendors, and have arrived at the best agreements we can to help keep the SAS pricing as manageable as possible for our customers. We will be billing customers directly and passing those fees onto the SAS. By managing the relationship with the SAS, we hope to streamline the process, and limit the burden that this puts onto the end user.


Most SAS price quotes that I've seen -- and they're never public -- have a large difference, about an order of magnitude, between CPE and BTS. The CPE-CBSD is indeed a Category B for regulatory purposes, but the price that a SAS charges for a small cell is too high for a fixed operator. So they have come up with a two-tiered price model. There can of course be other negotiated deals; I'm referring to the quotes I've seen from all three existing SAS operators. I can also think of another likely model: One huge mobile carrier is buying its CPE-CBSDs from one particular vendor, who has little other US presence, and they are not including the ability to run it as an EUD. The implication is that their moby customer has a deal that doesn't charge by the CPE at all.

Now, putting on my WISP designer hat, I can think of three SASs that I would not currently feel comfortable with. All three are focused on other markets. One is tight with Big Cable. One is tight with Big Mobile. One is just so sure of itself that it doesn't accept customer input. All three believe that the SAS should select the specific channel that every CBSD operates on, even if there are multiple free channels in an area. That means you don't get to select FR1 vs. FR2, and the actual interference you receive simply doesn't matter if it contradicts their (lame) models. That doesn't apply in the immediate term ("Release 1"), but once they implement "Release 2 GAA coexistence", which is whatever the SAS wants it to be, they can shut you out of your choice of GAA frequency. I'm still trying to get a deal with a WISP-friendly SAS, probably in Wave 2. So bundling gear with a SAS contract is not a win. I certainly hope you can buy the gear without it. Unlike TVWS, where the radio is legally bound to a compatible database (only one being left), the SAS market is competitive and the SAS-CBSD interface is standardized precisely to allow the customer to choose.


Pardon my ignorance-Where can I find more information on CPE-CBSD? I cant seem to find anything in the standards or on FCC.

This concept was introduced as a KDB to the rules. An explanation of the handshake parameters is here.


Sorry to bring this topic from oblivion… But I have a question:

Could a CPE-CBSD that has not registered with the SAS operate as an EUD?

Meaning that it could transmit user data at or below 23 dBm, considering that there’s a BTS-CBSD transmitting in this spectrum which has received a Tx Grant from a SAS?

A product has to obtain a grant to operate as a specific type of device. It is possible that a device can obtain more than one grant. So, in theory, there could be a device that can operate as a Category B CBSD or an EUD.

However, none of the Cambium devices have such grants. All of the current Cambium CBRS radio equipment is authorized as Category B CBSD.

Vladimir, in the original CPE-CBSD rules, there was nothing to prevent a CPE-CBSD from operating as an EUD, without the SAS. But one of the SAS operators went to the FCC and got them to issue a v2 KDB saying that if a device is approved as a CPE-CBSD, it can’t be used as an EUD.
Now the way it actually works is that a piece of hardware is submitted to a test lab to get authorized as one thing or another. So in theory a piece of hardware could be sent through a test lab twice, once as EUD (no SAS, limited to +23 dBm EIRP) and once as CPE-CBSD. Then it could get two FCC IDs. But the silly rule states that the FCC ID has to be physically labeled on the device, generally by a sticker. So you’d have to re-sticker it to switch, making it legally two different devices. Or the device could have an LED panel on it that, in software, could display the currently-operative FCC ID, so that a bird flying on the roof next to the radio would see the FCC ID then in effect. No vendors have done this yet. That rule is, as they say, “for the birds”.