The cellular interface on the 7705 SAR-Hmc NA (3HE12472AA) and the 7705 SAR-Hmc NA variant 2 (3HE12473AA) supports the Citizens Broadband Radio Service (CBRS) B48 spectrum. When operating in the CBRS spectrum, the 7705 SAR-Hmc is classified as either an end-user device (EUD) or a Citizens Broadband Service Radio Device (CBSD), depending on the maximum effective isotropic radiated power (EIRP) of the device.
Table: Maximum EIRP and PSD lists the maximum EIRP levels for each device type, as defined by FCC 47 CFR Part 96.41 – General radio requirements.
The operator must calculate the maximum EIRP or Power Spectral Density (PSD) in order to choose the correct device, either EUD, Category A CBSD, or Category B CBSD.
Device |
Maximum EIRP (dBm/10 MHz) |
Maximum PSD (dBm/MHz) |
|---|---|---|
EUD |
23 |
n/a |
Category A CBSD |
30 |
20 |
Category B CBSD |
47 |
37 |
See the 7705 SAR-Hm and SAR-Hmc Software Release Notes for information about operating the node as an EUD.
To operate the node as a CBSD, the maximum EIRP that identifies the node as a Category A or Category B device must be determined and planned beforehand. The CBSD maximum EIRP of the 7705 SAR-Hmc is calculated using the antenna-gain and max-tx-power values configured in the CLI and must be within the range expected for the category of the CBSD and within the range that is expected by the Spectrum Access System (SAS). Operators can use these parameters to adjust the maximum EIRP in order to meet the CBSD category requirements expected for a particular site location.
The maximum transmit conducted power that the 7705 SAR-Hmc can operate is 23 dBm. If a detached antenna is used, the antenna gain can be equally increased to compensate for cable losses. The EIRP calculations are:
EIRP = PSD + 10log (channel width)
or
EIRP = Tx conducted power + antenna gain - cable losses
For all CBSDs, before the node can be enabled to operate as a CBSD, the network operator must register each device with the SAS by populating the SAS with the following information:
geographic location
antenna height above ground level (AGL), in meters
CBSD class, either Category A or B
requested authorization status, either priority access license (PAL) or general authorized access (GAA)
FCC ID
for the 7705 SAR-Hmc NA (3HE12472AA): AS57705SARHMC-1
for the 7705 SAR-Hmc NA variant 2 (3HE12473AA): AS57705SARHMC-2
call sign (for PALs only)
user contact information
air interference technology
serial number
sensing capability, if supported
Observe the following height restriction for Category A CBSDs, as defined by FCC 47 CFR Part 96.43 — Additional requirements for category A CBSDs:.
"Category A CBSDs shall not be deployed or operated outdoors with antennas exceeding 6 meters height above average terrain. CBSDs deployed or operated outdoors with antennas exceeding 6 meters height above average terrain will be classified as, and subject to, the operational requirements of Category B CBSDs."
Observe the following installation requirements as defined by FCC 47 CFR Part 96.45 – Additional requirements for category B CBSDs:
"(a) Category B CBSDs must be professionally installed."
"(c) Category B CBSDs are limited to outdoor operations."
For Category B CBSDs, the SAS must be populated with further information for each site, as follows:
antenna gain
antenna beamwidth
antenna azimuth
antenna downtilt angle
There are two procedural steps the CBSD needs to complete to be authorized by the SAS so that regular SR OS traffic is allowed on the cellular port:
complete the CBSD registration procedures with the SAS
complete the CBSD grant procedure and CBSD heartbeat procedure with the SAS
For information about the process and parameters required to register with the SAS, see the directions provided by the SAS provider and see the Wireless Innovation Forum Signaling Protocols and Procedures for Citizens Broadband Radio Service (CBRS): Spectrum Access System (SAS) – Citizens Broadband Radio Service Device (CBSD) Interface Technical Specification, Document WINNF-TS-001.
After the operator has successfully registered the node information with the SAS, the node must be enabled to communicate with the SAS over the cellular port that is installed with a SIM that can connect to the CBRS spectrum.
The cellular port cannot be enabled until all the CBSD parameters have been configured on the cellular port in the config>port>cellular>cbsd-authorization CLI context and the CBSD authorization procedure is enabled on the cellular port with the config>port>cellular>cbsd-authorization>no shutdown command. When the CBSD authorization parameters are configured and the authorization procedure is enabled, the cellular port can be enabled with the config>port>1/1/1|2>no shutdown command.
After the cbsd-authorization parameters are configured, when the CBSD authorization procedure is enabled using the no shutdown command and the PDN router interface is enabled, the system creates a dynamic filter that allows only SAS control traffic. See SAS CBSD registration with Network Group Encryption enabled for information about permitted traffic.
When CBSD authorization is enabled on the cellular port and the cellular port is enabled, the CBSD authorization procedure begins. The CBSD first establishes an HTTPS (HTTP over TLS) session between itself and the SAS. The CBSD signaling procedure is sent over the HTTPS session and is used to authorize the CBSD. When the CBSD authorization procedure is successful, regular SR OS traffic can use the CBRS spectrum.
The CBSD grant procedure and the CBSD heartbeat procedure must be completed successfully before regular router traffic is allowed on the cellular port. When the SAS authorizes the node to transmit, the dynamic filter is removed from the active PDN router interface and all CPM management and SR OS session traffic is enabled. The NSP NFM-P can discover and manage the node, BGP sessions can be established to head-end nodes, and GRE-MPLS-based services can be established.