Wireless carriers in the United States are currently in a race to offer truly 5G networks and Sprint just announced that it plans on being the first one to roll out nationwide 5G coverage during the first half of 2019.
To achieve this, Sprint CEO Marcelo Claure says the carrier will add new antennas to its towers that are capable of sending and receiving large MIMO transmissions. 5G support will be added to the towers/antennas with a software update, and unlike other carriers, Sprint will be deploying its 5G network through its 2.5GHz spectrum.
Over half of Sprint's towers already support the 2.5GHz standard, and the goal is to expand this to all operating towers by the end of 2018. Furthermore, to help ensure the 5G network's expansion, Sprint will utilize the power of 40,000 "outdoor small cell solutions" 15,000 strand-mounted cells, and as many as 1 million of the network's Sprint Magic Boxes (small signal boosters that customers can purchase and use in their homes).
Source: https://www.androidcentral.com/sprints-nationwide-5g-network-will-launch-first-half-2019