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Data CPI needs to have for a CBRS DAS or Private LTE Network

Christy Price

CBRS has 3 tiers of users with 3 different priorities. Information transaction, therefore, needs to be constantly orchestrated or coordinated. This is done through Spectrum Sensing & Coordination – unique, but the greatest feature of CBRS! At the center of the spectrum-sensing and coordination is SAS (Spectrum Access System). SAS is like a traffic controller or conductor of the orchestra.

The Spectrum Access System (SAS) is a cloud-based service that manages the wireless communications of devices transmitting in the CBRS band, in order to prevent harmful interference to higher priority users. (Source)

A CBRS device is known as CBSD. CBSD needs authorization from the SAS before it starts to transmit in the CBRS band. The SAS needs a lot of information about a CBSD - CPI provides only some of that information.

A CPI stands for Certified Professional Installer for CBRS radios.

The information the CPI is responsible for is truly essential, and if the information is wrong, the device could cause harmful interference. A CPI determines or validates the installation parameters of a CBSD and provides those parameters to an SAS. A CPI is 100% responsible for the completeness and correctness of any installation parameters that are sent to the SAS.

There are 2 types of CBSDs - Class A and B. A class A base station (CBSD) can be thought of as indoor or low power outdoor small cells with a maximum power of 24 dBm (per 10 MHz) and maximum EIRP of 30 dBm (1 watt). Class A CBSD is similar to “enterprise-class” small cells.

A class B base station (CBSD) is meant for outdoor use with a maximum EIRP of 47 dBm (50 watts) intended to be used for fixed wireless purposes.

So, what information does a CPI have to provide?

CBSD

CBSDs will need the following information:

  1. Location

  2. HAAT

  3. FCC ID

  4. CBSD’s Unique Serial Number

  5. Sector ID for CBSD with multiple antennas

  6. CBSD’s Air Interface

Location: CPI will have to manually enter latitude and longitude if the CBSD has no built-in GPS, or where GPS signal is weak (e.g., it’s indoors). CBSDs need to always stay in the location that's reported to the SAS.

HAAT: height above average terrain. It's a measure of how high an antenna site is above the landscape around it. A CPI is not actually reporting the device's HAAT to the SAS. The CPI reports the device's location and height above ground level, and the SAS does its own calculation of the HAAT. But the CPI needs to know a device's HAAT in order to know whether to register it as a category A or B.

FCC ID: FCC issued ID for the CBSD device model.

CBSD’s Unique Serial Number: Every CBSD will also have a unique serial number, and that serial number paired with the FCC ID adds up to a unique identifier for that specific device. The SAS will take these two identifiers and create its own CBSD ID for each device that registers.

Sector ID for CBSD with multiple antennas: Each separate antenna is going to be considered a separate CBSD. The CPI will assign a sector ID to the antennas and add that sector ID to the serial number of the base device. CPI can choose the sector ID numbers to be unique for this installation. For example, a CBSD has two antennas connected to it and its serial number is 1234. One antenna can now be registered with serial number 1234:1, and the other as 1234:2.

CBSD’s air interface: which means the type of radio technology being used by this device. This information should be written in the device manual. As of 1-29-20 (Document WINNF-SSC-0002 Version 8.0.0), there are 8 types of air interfaces defined:

  1. E_UTRA, which means the device is using LTE.

  2. CAMBIUM_NETWORKS, which means the devices using proprietary cambium network waveforms.

  3. 4_BBW_SAA_1 for IEEE 802.16E devices.

  4. NR (New Radio)

  5. DOODLE_CBRS

  6. CW: This air interface supports Continuous Wave (CW) transmissions that will be used for test purposes.

  7. REDLINE

  8. TARANA_WIRELESS: Proprietary & designed for fixed wireless access. The air-interface frame structure is compatible with TDD LTE.

The type of technology used by the CBSD you’re working with should be written in the device manual.

Check the document WInnForum recognized CBRS air interfaces and measurements (Document WINNF-SSC-0002 Version 8.0.0. 29 January 2020) to look for the latest approved air-interfaces.

Antennas

When antennas are attached to the CBSD, the CPI needs to report the following information about each of the antennas:

  1. Location

  2. Antenna height

  3. Azimuth

  4. Down Tilt

  5. Gain

  6. Beam width

Location: Latitude and longitude of the CBSD's antenna (i.e., location of the center of radiation for the antennas) to an accuracy of 50 meters or better. It’s not easy to determine the indoor lat & long of an antenna, but If the design is done in the iBwave program, this information can be pulled fairly easily.

Antenna Height: CPI has to report the antenna’s height within 3 meters. This is the height of the antenna itself, not the HAAT mentioned earlier. There are two different ways antenna height can be reported:

  1. Above ground level, or AGL, height and is usually more accurate. Or,

  2. Above mean sea level, or AMSL, measurement. This is the height of the antenna relative to the average level of the ocean. This is better.

Antenna azimuth: horizontal pointing angle of the antenna relative to true north. If you are using a compass, include magnetic declination adjustments. The azimuth is given as a whole number between 0 and 359 degrees. If the antenna is omnidirectional you can enter the azimuth as zero.

Antenna down tilt: The antenna down tilt is a measure of how far towards the ground or sky the antenna is pointed. The down tilt is going to be recorded in whole-number degrees. A negative number (for example, -90) means that the antenna is tilted above the horizontal toward the sky. A positive number (for example, +90) means that the antenna is tilted below the horizontal, so toward the ground.

Antenna gain: The antenna the gain describes how well the antenna converts input power into radio waves headed in a specified direction – i.e., how much boost of power this antenna adds to its output. This is also reported to the SAS as a whole number between -127 and +128 dBi. These values can be found in the device datasheet. If you have its value in dBd, just add 2.15 to get the value in dBi. Must report the values in whole numbers.

There isn't a limit on antenna gain for CBRS devices, but the SAS will limit the antenna's effective radiated power, or ERP.

Antenna beamwidth: Beamwidth is the aperture angle from where most of the power is radiated. It measures the spread of the antenna pattern, essentially how wide the pattern is. You'll need to use the 3-dB beamwidth of the antenna, and you'll report this as a whole number between 0 and 360 degrees. For an omnidirectional antenna, enter 360 degrees.