AT&T quietly revealed yesterday that it has agreed to acquire FiberTower and its millimeter wave (mmWave) spectrum assets as part of its 5G network strategy. Financial details of the transaction were not revealed.

The carrier said it plans to deploy small cells using a centralized RAN (C-RAN) architecture that incorporates mmWave spectrum. The goal is to use small cells to densify its network in urban areas, which in turn will add capacity and provide the foundation for 5G. The company added that the C-RAN architecture will allow it to store all the “brains” of each small cell or tower in one location. That strategy will then make it easier for AT&T to transition to a network that relies on software-defined networking (SDN).

FiberTower holds an extensive footprint of mmWave spectrum in the 24 GHz and 39 GHz bands, which were formally known as LMDS bands and were used for fixed wireless services. The company also has some fiber and microwave assets.

FiberTower was known for its backhaul services that it provided to wireless operator Clearwire, which was later acquired by Sprint. FiberTower ended up filing for bankruptcy in 2012. And most of its recent activity has involved offering fixed wireless broadband services for small cities and campus environments as well as providing backhaul for public safety networks.

Coincidentally, Verizon today completed its $1.8 billion acquisition of XO Communications. Verizon's strategy behind the deal is to expand its metro and on-net fiber network using XO’s fiber assets as well as lease XO’s mmWave spectrum holdings with an option to buy those leases in 2018.