6GHz

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The discrepancy is because incumbents are already using the 6GHz band and their operations may be interfered with by newcomers. This includes microwave and fixed satellite services and radio astronomy. To limit the potential for interference, the FCC has introduced power limits for standard power devices which includesany outdoor device, both base stations and fixed clients.

The following table outlines the differences between the 6 GHz AFC and the CBRS SAS.

Table 1: CBRS SAS vs. 6GHz AFC operation

When a device needs to contact the AFC, it can use an AFC domain proxy (similar to what happens with a SAS). In the case of Tarana devices, Tarana Cloud Suite (TCS) acts as the domain proxy and works with the ComSearch AFC. A single request and response called Available Spectrum Inquiry (ASI) is sent between the6GHz device and the AFC system every 24 hours. The client device (or its proxy) sends certification details and a list of preferred frequencies. The AFC responds with the maximum power values for each of the preferred channels. By default, TCS requests power levels for all available channels in order to make the best decision.

How Much Interference Should I Expect?

One thing to understand about standard power 6GHz operation: anyone can use the spectrum, assuming there is no conflict with an incumbent. AFCs exist to prevent interference with protected incumbents but will do nothing to prevent unlicensed users from interfering with each other. Just like with 2.4 and 5GHz, interference can and will be a concern for operators. The expectation is that the spectrum will be relatively clean to begin with and become more crowded and noisier, as time goes on. At Tarana, we believe 6GHz is an important tool for operators; G1 will leverage field-proven innovations like interference cancelation to help make the most of this valuable resource. As the popularity of 6GHz grows, the need to manage and eliminate harmful interference will only become more important.

6GHz Channel Planning

The 6GHz band is structured by operating classes that correspond to channel width. Channel numbers range from 0–233, and represent 5 MHz increments along the spectrum. Tarana devices use operating classes 131 (2 x 20 MHz) or132 (1 x 40 MHz) for each carrier. It’s important to note there could be different allowed power permitted for different channels.

For class 131 operations, in which two 20 MHz channels are combined, TCS will always select the highest power combination of two contiguous channels for each carrier. In the example shown in figure 3, TCS received the given power values from the AFC. In this case, channels 13 and 17 would be selected since they offer full power (36 dBm).

If two combinations have the same power, the lower frequency combination willbe selected. In the example above, if channel 1 was available at 36 dBm power,channels 1 and 5 would have been selected instead, since they are lower frequencies than 13 and 17. Channels in the UNII-7 band will be used if there is no combinationin UNII-5 that offers the same or higher power.

For 40 MHz (class 132) operation, TCS will assign the channel with the highest power. In cases of a tie, the lowest frequency channel will be selected. In figure 4,channel 35 is the lowest frequency with the highest power.

Tarana G1 Updates

Tarana’s G1 6GHz base node and remote node models include several enhancements to streamline the deployment process and take full advantage of the spectrum.

New Remote Node Features

The 6GHz remote node includes an integrated GPS module. This is used todetermine installation parameters and has an accuracy of 2.5 meters. GPS-determined installation parameters allow the remote node to operate at a higher maximum power, 36 dBm, when the GPS is locked. In cases where there is no GPS lock, the remote node will function at reduced power (maximum of 30 dBm) to comply with FCC regulations for non-GPS-enabled devices.

Priority Search list

Scanning the entire allowed 6GHz spectrum could be a lengthy process. The remote node web UI includes an option to select preferred frequencies at installation time. This reduces the amount of spectrum the remote node must scan while searching for base nodes and speeds up overall installation time. It is best practice to select the frequencies for the nearest base nodes, as they will typically be the best serving.

Air Interface Protocol (AIP)

Base nodes and remote nodes use the Tarana air interface protocol (AIP) to communicate. Current 5GHz models use AIP version 0. The 6GHz models introduce a new AIP version 1. The new AIP version offers improved control channel communications to reliably deliver commands and avoid truck rolls. This includes:

• Trigger full search on remote node
• Reboot the remote node
• Reset saved based node state or other presistent state on the remote node

The AIP version is set at the sector level. Remote nodes must use firmware thatsupports the desired version of AIP.

In cases where a mixture of models (5GHz and 6GHz) will be deployed, it’s important to ensure the correct version of AIP is used. A 6GHz remote node using AIP version 1 will require a base node that is also using AIP version 1. A 5GHz remote node using AIP version 1 can connect to a base node that is using AIP version 0 or version 1.

All software versions of 1.2 or greater support AIP version 0 and 1 for base nodes, while remote nodes will have different requirements depending on the model. The following compatibility matrix shows how this works.

5GHz base nodes default to AIP version 0, while 6GHz base nodes default to AIP version 1. It is important to ensure the correct version of AIP is used during deployment. When upgrading from AIP version 0 to AIP version 1, 5GHz remote nodes running 0.9xx firmware should always be upgraded before the base node to avoid stranding the remote node. Figure 6 shows the 3-step process necessary to upgrade a 5GHz remote node to AIP version 1.

If 6GHz remote nodes are already field deployed, the remote nodes in step 1 of Figure 7 should be upgraded from 0.9xx to 1.2+ software and use AIP version 0 to connect to their base node (5GHz or 6GHz). If the remote node is offline, it should be upgraded when it is online again. As shown in step 2, the base node must stay configured to AIP version 0 to avoid a truck roll. Once all remote nodes have been upgraded, the base node can be changed to AIP version 1 (step 3). This allows all remote nodes to connect using AIP version 1.

Changing the AIP version on the base node will disconnect all remote nodes, and require that they reconnect with the new AIP version.

x2 Mode

x2 (or 4-carrier) mode, which enables 4 x 40 MHz carriers on the base node and remote node, will be available as a software upgrade in early 2024. With x2 mode, the RF chains and antennas are split in half, allowing for 4 x 40 MHz operation. For the base node, this means dual 2 x 40 MHz carriers with 8 antennas each. The remote node configuration will consist of dual 2 x 40 MHz carriers with four antennas each. Using this configuration, the maximum performance of a link increases from 800 Mbps of aggregate throughput to 1.6 Gbps.

Appendix A: G1 Supported Frequencies

Tarana 6GHz devices support UNII-3, -4, -5, and -7 channels. For 6GHz operation (UNII-5 and UNII-7), class 131 and 132 channels are supported. The following table shows the supported center frequencies in Hertz for each band.

*UNII-4 frequencies require a special temporary authority (STA) license from the FCC