FCC rule changes for the 5.8 GHz band (U-NII-3)

The FCC reviewed and changed the rules affecting the 5 GHz U-NII bands recently. The situation can be a bit confusing, particularly in the case of the 5.8 GHz (U-NII-3 band), where the rules have been changed twice. We'll summarise the 5.8 GHz rules in force today, and provide a short history lesson on the rule changes. Of course, if you're not operating in the USA, the information that follows will not be especially important to you.

Almost all equipment authorised for operation in the 5.8 GHz band has been approved under the FCC rules in Section 15.247. These rules allow up to one watt conducted power for PTP operation, with unlimited antenna gain, and a relaxed requirement for out-of-band emissions (OOBE). These are now known as the "old" rules.

Section 15.407 of the FCC rules provided an alternative way to approve equipment for 5.8 GHz. Section 15.407 has not been an attractive option in the past because of a lower radiated power limt and a much more restrictive out-of-band emissions (OOBE) limit.

The FCC released a Notice of Proposed Rulemaking FCC 13-22 on February 20, 2013. One of the proposed changes was to remove the possibility of approving 5.8 GHz devices under Section 15.247.

The FCC introduced rules changes in the First Report and Order FCC 14-30 released on April 1, 2014. As expected, the new rules do not allow 5.8 GHz equipment approved under 15.247. The radiated power limit was removed for PTP operation in 15.407, matching the old 15.247. However the existing OOBE limits from 15.407 were retained. The rule changes in FCC 14-30 are known as the “new” rules.

Manufacturers and operators of 5 GHz outdoor wireless products petitioned the FCC to modify or reverse the new rules, and this lead eventually to Memorandum Report and Order FCC 16-24 released on March 2, 2016 . FCC 16-24 relaxes the 5.8 GHz OOBE rules in 15.407 relative to the “new” rules, but the relief does not quite take us back to the generous OOBE limits in the “old” rules.

FCC 16-24 helpfully extends the deadline for approving new equipment under the old rules to March 2, 2017 and extends the deadline for ceasing to market units approved under the old rules until March 2, 2018.

Cambium products available today are approved for FCC 5.8 GHz (U-NII-3) under the "old" rules. It seems quite likely that these products will continue to be offered for sale under the existing approval until the 2018 deadline, and under the modified new rules thereafter.

You'll see that the rule changes affect the approvals process and the sale of equipment. Equipment approved under the old rules and sold before the 2018 deadline can continue to be used under the old rules indefinitely.

 We have updated the PTP 670 hardware design with a new tighter RF filter. This filter reduces out-of-band emissions (OOBE) at the edges of the U-NII-3 band, and ensures that PTP 670 ODUs will comply with the modified new rules defined in Part 15.407.

The new hardware is identified by a Part Number with the "B” suffix, as follows:

  • C050067B003B: PTP 670 (4.9 to 6.05 GHz) Connectorized ODU (FCC)
  • C050067B001B: PTP 670 (4.9 to 6.05 GHz) Integrated 23 dBi ODU (FCC)

The power limits for U-NII-3 are set by Regulatory Band (RB) 101.

Select RB 101 for links in FCC 5.8 GHz where one or both ends use the PTP 670 with the "B" suffix.

Use the existing RB 1 if both ends of the link use the older PTP 670 with the "A" suffix Part Number.

There is a marginal advantage in using RB 1 where this is allowed.