One of the tools in 3GPP Release 15 related to the 5G standard is something called Integrated Access and Backhaul (IAB) for—you guessed it—backhaul in 5G.
It’s not yet deployed in the U.S., but that’s likely to change within the next year or so. Queried by email, AT&T said it will use IAB in instances where it makes sense, like extending millimeter wave (mmWave) sites into hard-to-reach and costly locations.
“Fiber is still required in close proximity to serve the capacity coming from the nodes, so if it can be extended to each of the nodes, it will be the first choice,” said Gordon Mansfield, VP of Converged Access and Device Technology at AT&T. in an statement emailed to FierceWireless.
"From there, IAB can be used to extend to hard to reach and temporary locations that are in close proximity. As far as timing, we will do some testing in 2020 but 2021 is when we expect it to be used more widely,” he said.
Verizon also told Fierce that it has plans to incorporate IAB as a tool. It doesn't have any details to share at this time, but “it’s certainly on the roadmap,” the carrier said.
During the FierceWireless Next Gen Wireless Networks Summit in Dallas last month, 5G Americas President Chris Pearson mentioned IAB as one of the more interesting technologies coming down the pike. It’s not replacing fiber, but it’s a good tool when operators are densifying their networks and he expects operators to look at it very closely. “It could be a very efficient way of helping you to deploy more small cells,” he said in an interview.
According to 5G Americas, from a technical point of view, the larger bandwidths associated with 5G New Radio (NR), such as those found in mmWave spectrum, as well as the native support of massive MIMO and multi-beams, are expected to facilitate and/or optimize the design and performance of IAB.
The association flags these as primary goals of IAB:
- Improve capacity by supporting networks with a higher density of access points in areas with only sparse fiber availability.
- Improve coverage by extending the range of the wireless network, and by providing coverage for isolated coverage gaps. For example, if the user equipment (UE) is behind a building, an access point can provide coverage to that UE with the access point being connected wirelessly to the donor cell.
- Provide indoor coverage, such as with an IAB access point on top of a building that serves users within the building.
5G Americas also said that in practice, IAB is more relevant for mmWave because lower frequency spectrum may be seen as too valuable to use for backhaul. The backhaul link, where both ends of the link are stationary, is especially suitable for the massive beam-forming possible on the higher frequencies.